Handbook of Spine Surgery

Ali A. Baaj, MD

Alexander R. Vaccaro, MD, PhD

Instructor of Neurosurgery-Spine

The Everrett J. and Marion Gordon

Department of Neurosurgery

Professor of Orthopaedic Surgery

Johns Hopkins Hospital

Professor of Neurosurgery

Baltimore, Maryland

Co-Director, Delaware Valley

Spinal Cord Injury Center

Praveen V. Mummaneni, MD

Co-Chief, Spine Surgery

Associate Professor

Co-Director, Spine Surgery

Department of Neurosurgery

Thomas Jefferson University

Co-Director, UCSF Spine Center

The Rothman Institute

University of California-San Francisco

Philadelphia, Pennsylvania

San Francisco, California

Mark S. Greenberg, MD

Juan S. Uribe, MD

Assistant Professor

Department of Neurological Surgery

Director, Spine Section

and Brain Repair

Director, Biomechanical Laboratory

University of South Florida

Department of Neurosurgery

Chief, Neurosurgery Section

University of South Florida

James A. Haley Veterans Hospital

Tampa, Florida

Thieme

New York · Stuttgart

Thieme Medical Publishers, Inc.

333 Seventh Ave.

New York, NY 10001

Executive Editor: Kay Conerly

Editorial Assistant: Tess Timoshin

Editorial Director, Clinical Reference: Michael Wachinger

Production Editor: Kenneth L. Chumbley

International Production Director: Andreas Schabert

Senior Vice President, International Marketing and Sales: Cornelia Schulze

Vice President, Finance and Accounts: Sarah Vanderbilt

President: Brian D. Scanlan

Compositor: Prairie Papers Inc.

Printer: Sheridan Press

Library of Congress Cataloging-in-Publication Data

Handbook of spine surgery / [edited by] Ali A. Baaj . . . [et al.].

p. ; cm.

Includes bibliographical references and index.

ISBN 978-1-60406-419-3 (pbk. : alk. paper)

1. Spine—Surgery—Handbooks, manuals, etc.

2. Orthopedics—Handbooks, manuals, etc.

I. Baaj, Ali A.

[DNLM:

1. Spine—surgery—Handbooks.

2. Neurosurgical Procedures—methods—

Handbooks.

3. Orthopedic Procedures—methods—Handbooks.

4. Spinal Cord—surgery—

Handbooks. WE 39]

RD768.H354 2012

617.4′71—dc23

2011028108

is legally protected by copyright. Any use, exploitation, or commercialization outside the

narrow limits set by copyright legislation without the publisher’s consent is illegal and

liable to prosecution. This applies in particular to photostat reproduction, copying, mimeo-

graphing or duplication of any kind, translating, preparation of microfilms, and electronic

data processing and storage.

Important note: Medical knowledge is ever-changing. As new research and clinical experi-

ence broaden our knowledge, changes in treatment and drug therapy may be required. The

authors and editors of the material herein have consulted sources believed to be reliable

in their efforts to provide information that is complete and in accord with the standards

accepted at the time of publication. However, in view of the possibility of human error by

the authors, editors, or publisher of the work herein or changes in medical knowledge,

neither the authors, editors, nor publisher, nor any other party who has been involved in

the preparation of this work, warrants that the information contained herein is in every

respect accurate or complete, and they are not responsible for any errors or omissions or

for the results obtained from use of such information. Readers are encouraged to confirm

the information contained herein with other sources. For example, readers are advised

to check the product information sheet included in the package of each drug they plan to

administer to be certain that the information contained in this publication is accurate and

that changes have not been made in the recommended dose or in the contraindications for

administration. This recommendation is of particular importance in connection with new

or infrequently used drugs.

Some of the product names, patents, and registered designs referred to in this book are in

fact registered trademarks or proprietary names even though specific reference to this fact

is not always made in the text. Therefore, the appearance of a name without designation

as proprietary is not to be construed as a representation by the publisher that it is in the

public domain.

Printed in the United States of America

5 4 3 2 1

ISBN 978-1-60406-419-3

To my parents, Abdulwahab and Hana, to my wife, Gabriela, and to my first teach-

ers of spine surgery at the University of South Florida.

Ali A. Baaj

For my wife, Valli, and my children, Nikhita, Nikhil, and Neel, for their love and

support.

Praveen V. Mummaneni

To my parents, my wife, Catalina, and my two children, Sebastian and Camila.

Juan S. Uribe

I would like to dedicate this book to my wonderful children, Alex and Juliana,

whose unwavering love and support has sustained me through the most dif-

ficult of times.

Alexander R. Vaccaro

I dedicate this work to my father, Louis Greenberg, who has guided me through-

out life with integrity, wisdom, and humor.

Mark S. Greenberg

Contents

Foreword

Howard S. An

Volker K. H. Sonnatag

xiii

Preface

Contributors

xvii

I Clinical Spine Anatomy

1 Embryology of the Spine

Akash J. Patel, Katherine Relyea, Daniel H. Fulkerson, and Andrew Jea

2 Craniovertebral Junction

Ali A. Baaj, Edwin Ramos, and Juan S. Uribe

3 Cervical Spine

Eric A. Sribnick and Sanjay S. Dhall

4 Thoracic Spine

Ryan J. Halpin and Tyler R. Koski

5 Lumbar Spine

Hormuzdiyar H. Dasenbrock and Ali Bydon

6 Sacral-Iliac Spine

Amit R. Patel and Ravi K. Ponnappan

II Clinical Spine Surgery

7 Physical Examination

Mark S. Greenberg and Daniel Marin

8 Spinal Imaging

Ishaq Y. Syed, Barrett I. Woods, and Joon Y. Lee

9 Neurophysiologic Monitoring in Spine Surgery

Glen Aaron Pollock, Naomi Abel, and Fernando L. Vale

10 Pharmacology

Mark S. Greenberg

11 Interventional Pain/Nonoperative Spine Procedures:

Diagnostic and Therapeutic

Daniel Marin

12 Bedside Procedures

Daniel C. Lu and Praveen V. Mummaneni

13 Spinal Radiation Therapy

Edward A. Monaco III and Peter Carlos Gerszten

14 Spinal Navigation

Ben J. Garrido and Rick C. Sasso

vii

viii

Contents

Spinal Biologics

Rafael F. Cardona-Durán and Juan S. Uribe

III

Spinal Pathology

Congenital Anomalies

101

Rory R. Mayer, Katherine Relyea, and Andrew Jea

Trauma

114

Daniel K. Park and Ravi K. Ponnappan

Infection

127

William D. Long III and Peter G. Whang

Tumors of the Spine

136

Camilo A. Molina and Daniel M. Sciubba

Cervical and Thoracic Spine Degenerative Disease

146

Clinton J. Burkett and Mark S. Greenberg

Degenerative Lumbar Spine Disease

154

Michael Y. Wang

Deformity

163

David T. Anderson and Jeffrey A. Rihn

Vascular Pathology of the Spine

172

Timothy D. Uschold and Steven W. Chang

Spondyloarthropathies

180

Amir Ahmadian and Fernando L. Vale

Spinal Emergencies

190

Mohammed Eleraky and Frank D. Vrionis

Surgical Techniques

Occipitocervical Fusion

199

Edwin Ramos and Juan S. Uribe

Chiari I Decompression

204

Mark S. Greenberg

Transoral Odontoidectomy

209

Frank M. Phillips and Colin B. Harris

C1-C2 Techniques

215

Jau-Ching Wu and Praveen V. Mummaneni

Direct Fixation of Odontoid Fractures

221

Andrew T. Dailey and Jose Carlos Sauri-Barraza

Cervical Arthroplasty

227

Jau-Ching Wu, Ali A. Baaj, and Praveen V. Mummaneni

Anterior Cervical Corpectomy

232

Mohammad Said Shukairy and Frank M. Phillips

Contents ix

Anterior Cervical Discectomy

238

Daniel C. Lu, Kevin T. Foley, and Praveen V. Mummaneni

Anterior Cervical Foraminotomy

243

Matthew J. Tormenti and Adam S. Kanter

Cervical Laminectomy with or without Fusion

248

Ali A. Baaj and Fernando L. Vale

Cervical Laminoplasty

253

Sarah I. Woodrow and Allan D. Levi

Posterior Cervical Foraminotomy

259

Matthias Setzer, Nam D. Tran, and Frank D. Vrionis

Cervical Open Reduction Techniques:

Anterior and Posterior Approaches

265

Harminder Singh, George M. Ghobrial, and James Harrop

Resection of Pancoast Tumors

271

Jean-Paul Wolinsky and Ziya L. Gokaslan

Cervical-Thoracic Junction Technique

276

Matthew B. Maserati and David O. Okonkwo

Thoracic Pedicle Technique

285

Ryan J. Halpin and Tyler R. Koski

Lateral Extracavitary Approach

291

Beejal Y. Amin and Muwaffak Abdulhak

Transpedicular Approach

296

Frank La Marca, Paul Park, and Juan M. Valdivia

Costotransversectomy

300

Dean B. Kostov and Adam S. Kanter

Thoracoscopic Approach

304

Timothy D. Uschold and Steven W. Chang

Pedicle Subtraction Osteotomy/Smith Peterson Osteotomy

309

Frank La Marca, Paul Park, and Juan M. Valdivia

Transthoracic Approach

314

Brian Kwon and David H. Kim

Retroperitoneal Approaches to the Thoracolumbar Spine

318

Camilo A. Molina, Ziya L. Gokaslan, and Daniel M. Sciubba

Open and MIS Lumbar Microdiscectomy

325

Ali A. Baaj and Mark S. Greenberg

Lumbar Foraminotomy (MIS)

330

Ali A. Baaj and Juan S. Uribe

Lumbar Laminectomy

333

Armen Deukmedjian, Ali A. Baaj, and Juan S. Uribe

x Contents

Posterior and Transforaminal Lumbar Interbody

Fusion (PLIF/TLIF) (Open)

336

Devin Vikram Amin and Adam S. Kanter

Minimally Invasive Transforaminal Lumbar

Interbody Fusion (MIS TLF)

341

Michael Y. Wang

Percutaneous Pedicle Screw Placement

348

Michael Y. Wang

Minimally Invasive Lateral Retroperitoneal

Trans-Psoas Interbody Fusion (e.g., XLIF, DLIF)

354

Edwin Ramos, Ali A. Baaj, and Juan S. Uribe

Anterior Lumbar Interbody Fusion (ALIF)

359

Krzysztof B. Siemionow and Kern Singh

Axial Lumbar Interbody Fusion (AxiaLIF)

364

Elias Dakwar and Juan S. Uribe

Facet Screw Fixation/Fusion

368

Ben J. Garrido and Rick C. Sasso

Interspinous Process Decompression

373

Ravi Ramachandran and Peter G. Whang

Lumbar Arthroplasty

378

Ishaq Y. Syed, Barrett I. Woods, and Joon Y. Lee

Lumbosacroiliac Fixation

384

Amit R. Patel, Alexander R. Vaccaro, and Ravi K. Ponnappan

Sacrectomy

390

Ioannis Papanastassiou, Mohammad Eleraky, and Frank D. Vrionis

Vertebral Body Augmentation

398

Mohammed Eleraky and Frank D. Vrionis

Spinal Cord Tumor Resection

404

Michelle J. Clarke and Timothy F. Witham

Surgical Resection of Spinal Vascular Lesions

410

Timothy D. Uschold, Alim P. Mitha, and Steven W. Chang

Appendices

I Positioning

419

Tien V. Le, Juan S. Uribe, and Fernando L. Vale

II Selected Spinal Orthoses

423

Tien V. Le, Juan S. Uribe, and Fernando L. Vale

III Scales and Outcomes

433

Mark S. Greenberg

Index

437

Foreword

Handbook of Spine Surgery, by Ali A. Baaj, Praveen V. Mummaneni, Juan S. Uribe,

Alexander R. Vaccaro, and Mark S. Greenberg, is indeed a great contribution to

the field of spine surgery. The authors are to be congratulated for preparing a

textbook that distills the vast amount of current information on spine surgery

in an extremely well-organized and succinct manner. The authors were also

fortunate to recruit prominent orthopedic and neurosurgical colleagues as well

as nonsurgical experts in the field of spine today.

The book is aptly organized into sections containing spinal anatomy, clinical

spinal surgery, spinal pathology, and surgical techniques, as includes useful ap-

pendices on positioning, spinal orthoses, scales, and outcomes. Each chapter is

divided into appropriate subheadings such as key points, anatomy, indications,

technique, complications, outcomes, frequently asked questions, and surgical

pearls. The surgical pearls are an invaluable part of this book, which are not eas-

ily found in other textbooks. The illustrations are of high quality and comple-

ment the text well.

This book is written primarily for orthopedic surgeons and neurosurgeons,

but is also great for residents and fellows-in-training, as well as nonoperative

physicians who take care of patients with various spinal disorders. Over the

past two decades, there have been great advances in the field of spine surgery,

and as a result, there has been enormous information overload with countless

articles, textbooks, and web content. This book serves well to digest the most

current and relevant information in an outline format with appropriate figures

so that the reader can assimilate information in an efficacious manner. This

book should be a daily companion for practicing spine surgeons and every or-

thopedic and neurosurgical resident and fellow.

Howard S. An, MD

The Morton International Endowed Chair

Professor of Orthopaedic Surgery

Director of Spine Surgery and Spine Fellowship Program

Rush University Medical Center

Chicago, Illinois

Foreword

This book provides a handy and practical guide to common spinal disorders

and includes nice reviews of relevant clinical and spinal anatomy; bedside tech-

niques, type of pathology affecting the spinal column and spinal cord, and, most

importantly, surgical techniques for the spine. Conveniently, each chapter begins

with key points. Toward the end of the chapters, useful surgical pearls are pro-

vided, followed by common clinical questions and answers to these questions.

I congratulate the authors on providing a quick and easy reference for pro-

fessionals who treat patients with spinal disorders. This book will be especially

helpful for students and residents and will also provide quick reference for

practicing spine surgeons.

Volker K. H. Sonntag (Retired)

Professor of Clinical Surgery

University of Arizona

Vice-Chairman, Department of Neurosurgery

Chairman, Spine Section

Director, Residency Program

Barrow Neurological Institute

Phoenix, Arizona

xiii

Preface

The discipline of spine surgery has evolved to encompass a wide range of diag-

noses and procedures. The burden to efficiently review and apply these prin-

ciples can be exhausting. With this in mind, we are happy to introduce the first

edition of the Handbook of Spine Surgery, a practical handbook aimed at pro-

viding the resident, fellow, or staff with quick access to key points of common

spinal diseases and management strategies.

The first of its kind in this discipline, this text has distilled a vast amount

of information into key background concepts and pertinent surgical pearls. It

is divided into four principal sections: Anatomy, Pathology, Clinical, and Tech-

niques. Each chapter is in bullet-point format to make it readable and focused.

Clinical pearls are emphasized, and simple board-style questions are included

to highlight the salient points.

This handbook is comprehensive, yet readable and portable. It is an excellent

tool for trainees not only to review spinal pathology but also to skim through

surgical techniques before going into the operating room. It is equally an excel-

lent resource for spine surgeons who choose to review the less routine pro-

cedures as described by experts in the field. This work was not meant to be a

comprehensive reference book on spine surgery as such texts already exist. The

strength of this handbook lies in its practicality and portability.

With the help of over sixty contributors from more than twelve academic

programs representing both orthopedics and neurosurgery, we have attempted

to bring a wide range of expertise to this project. It was our intent to obtain

the input of residents, fellows, and junior and senior faculty alike in compiling

this work. With the ultimate goals of advancing our field and enhancing patient

care, we hope you find this handbook both practical and valuable.

Acknowledgments

The editors would like to thank all chapter contributors for making this work

possible. We also thank Kay Conerly, Lauren Henry, and Tess Timoshin from

Thieme Medical Publishers for their assistance in the editing and publication

of this text.

Contributors

Muwaffak Abdulhak, MD, FRCS (C)

Clinton J. Burkett, MD

Director, Neuroscience Institute

Complex and Minimally Invasive

Spine/Neurotrauma Center

Spine Fellow

Henry Ford Hospital

Department of Neurosurgery

Detroit, Michigan

University of South Florida

Tampa, Florida

Naomi Abel, MD

Assistant Professor of Physical

Ali Bydon, MD

Medicine and Rehabilitation

Assistant Professor

Department of Neurosurgery

and Brain Repair

Johns Hopkins University School

University of South Florida

of Medicine

Tampa, Florida

Baltimore, Maryland

Amir Ahmadian, MD

Rafael F. Cardona-Durán, MD

Resident Physician

Director of Complex and Minimally

Department of Neurosurgery

Invasive Spine Surgery

and Brain Repair

Puerto Rico Neurological Spine

University of South Florida

Surgery, PSC

Tampa, Florida

San Juan, Puerto Rico

Beejal Y. Amin, MD

Steve W. Chang, MD

Resident Physician

Staff Neurosurgeon

Department of Neurosurgery

Division of Neurological Surgery

Henry Ford Hospital

Barrow Neurological Institute

Detroit, Michigan

Phoenix, Arizona

Devin Vikram Amin, MD, PhD

Michelle J. Clarke, MD

Assistant Professor

Assistant Professor of Neurosurgery

Department of Neurosurgery

Department of Neurologic Surgery

Southern Illinois University

Mayo Clinic

Springfield, Illinois

Rochester, Minnesota

David T. Anderson, MD

Elias Dakwar, MD

Resident Physician

Department of Orthopaedic Surgery

Department of Neurosurgery

Thomas Jefferson University Hospital

and Brain Repair

Philadelphia, Pennsylvania

University of South Florida

Tampa, Florida

Ali A. Baaj, MD

Instructor of Neurosurgery-Spine

Andrew T. Dailey, MD

Department of Neurosurgery

Associate Professor

Johns Hopkins Hospital

Departments of Neurosurgery

Baltimore, Maryland

and Orthopedics

University of Utah

Salt Lake City, Utah

xvii

xviii Contributors

Hormuzdiyar H. Dasenbrock, BS

Ben J. Garrido, MD

Johns Hopkins University School

Orthopedic Spine Surgeon

of Medicine

Lake Norman Orthopedic Spine Center

Baltimore, Maryland

Mooresville, North Carolina

Armen Deukmedjian, MD

Peter Carlos Gerszten, MD, MPH, FACS

Resident Physician

Peter E. Sheptak Professor

Department of Neurological Surgery

Departments of Neurological Surgery

University of South Florida

and Radiation Oncology

Tampa, Florida

University of Pittsburgh Medical Center

Pittsburgh, Pennsylvania

Sanjay S. Dhall, MD

Assistant Professor

George M. Ghobrial, MD

Department of Neurosurgery

Resident Physician

Emory University School of Medicine

Department of Neurosurgery

Atlanta, Georgia

Thomas Jefferson University Hospital

Philadelphia, Pennsylvania

Mohammed Eleraky, MD

Research Associate

Ziya L. Gokaslan, MD, FACS

H. Lee Moffitt Cancer Center

Donlin M. Long Professor

and Research Institute

Professor of Neurosurgery, Oncology,

NeuroOncology Program and

and Orthopaedic Surgery

Department of Neurosurgery

Vice-Chair

University of South Florida

Director of Neurosurgical Spine

Tampa, Florida

Program

Department of Neurosurgery

Kevin T. Foley, MD

Johns Hopkins University School

Professor of Neurosurgery

of Medicine

Director, Spine Fellowship Program

Johns Hopkins Hospital

Department of Neurosurgery

Baltimore, Maryland

University of Tennessee Health

Science Center

Mark S. Greenberg, MD

Director of Complex Spine Surgery

Assistant Professor

Semmes-Murphey Clinic

Department of Neurological Surgery

Medical Director

and Brain Repair

Medical Education and Research

University of South Florida

Institute

Chief, Neurosurgery Section

Image-Guided Surgery Research Center

James A. Haley Veterans Hospital

Memphis, Tennessee

Tampa, Florida

Daniel H. Fulkerson, MD

Ryan J. Halpin, MD

Assistant Professor of Neurological

Department of Neurological Surgery

Surgery

Northwestern University Feinberg

Department of Neurosurgery

School of Medicine

Indiana University School of Medicine

Chicago, Illinois

Goodman Campbell Brain and Spine

Indianapolis, Indiana

Colin B. Harris, MD

Orthopedic Spine Surgeon

Syracuse Orthopedic Specialists

Syracuse, New York

Contributors xix

James Harrop, MD, FACS

Dean B. Kostov, MD

Associate Professor

Chief Resident Physician

Departments of Neurological and

Department of Neurological Surgery

Orthopedic Surgery

University of Pittsburgh Medical

Chief, Spine and Peripheral Nerve

Center, Presbyterian

Surgery

Pittsburgh, Pennsylvania

Neurosurgery Director of Delaware

SCI Center

Brian Kwon, MD

Director, Neurosurgical Spine

Assistant Clinical Professor

Fellowship

Department of Orthopedic Surgery

Jefferson Medical College

New England Baptist Hospital

Philadelphia, Pennsylvania

Tufts University School of Medicine

Boston, Massachusetts

Andrew Jea, MD

Staff Neurosurgeon

Frank La Marca, MD

Director, Neuro-spine Program

Associate Clinical Professor

Assistant Professor

Chief of Spine Section

Texas Children’s Hospital Division of

Department of Neurosurgery

Neurosurgery

University of Michigan

Baylor College of Medicine Department

Ann Arbor, Michigan

of Neurosurgery

Houston, Texas

Tien V. Le, MD

Resident Physician

Adam S. Kanter, MD

Department of Neurosurgery and

Assistant Professor of Neurological

Brain Repair

Surgery

University of South Florida

Director, Minimally Invasive Spine

Tampa, Florida

Program

Department of Neurological Surgery

Joon Y. Lee, MD

University of Pittsburgh Medical

Assistant Professor of Orthopaedic

Center, Presbyterian

Surgery

Pittsburgh, Pennsylvania

Department of Orthopaedics

University of Pittsburgh Medical Center

David H. Kim, MD

Pittsburgh, Pennsylvania

Associate Clinical Professor

Department of Orthopaedic Surgery

Allan D. Levi, MD, PhD, FACS

Tufts University School of Medicine

Professor

Boston, Massachusetts

Department of Neurosurgery

University of Miami

Tyler R. Koski, MD

Miami, Florida

Assistant Professor of Neurological

Surgery

William D. Long III, MD

Director of Spinal Deformity Program

Resident Physician

Northwestern University Feinberg

Department of Orthopaedic Surgery

School of Medicine

and Rehabilitation

Chicago, Illinois

Yale-New Haven Hospital

Yale University School of Medicine

New Haven, Connecticut

xx Contributors

Daniel C. Lu, MD, PhD

Praveen V. Mummaneni, MD

Assistant Professor

Associate Professor

Department of Neurosurgery

University of California-Los Angeles

Co-Director, UCSF Spine Center

Los Angeles, California

University of California-San Francisco

San Francisco, California

Daniel Marin, MD

Assistant Professor

David O. Okonkwo, MD, PhD

Physiatrist

Associate Professor

Cahill Spine Institute

Department of Neurological Surgery

University of South Florida

University of Pittsburgh

Tampa, Florida

Pittsburgh, Pennsylvania

Matthew B. Maserati, MD

Ioannis Papanastassiou, MD

Resident Physician

Consultant

Department of Neurological Surgery

Department of Orthopaedics

University of Pittsburgh Medical Center

Agioi Anargyroi

Pittsburgh, Pennsylvania

Athens, Greece

Rory R. Mayer, BS

Daniel K. Park, MD

Department of Neurosurgery

Attending Spine Surgeon

Baylor College of Medicine

Department of Orthopedic Surgery

Houston, Texas

William Beaumont Hospital

Royal Oak, Michigan

Alim P. Mitha, MD

Cerebrovascular/Skull Base Fellow

Paul Park, MD

Endovascular Fellow

Assistant Professor

Division of Neurological Surgery

Department of Neurosurgery

Barrow Neurological Institute

University of Michigan

Phoenix, Arizona

Ann Arbor, Michigan

Camilo A. Molina, BA

Akash J. Patel, MD

Research Fellow

Resident Physician

Howard Hughes Medical Institute

Department of Neurosurgery

Department of Neurological Surgery

Baylor College of Medicine

Johns Hopkins University School

Houston, Texas

of Medicine

Baltimore, Maryland

Amit R. Patel, MD

Resident Physician

Edward A. Monaco III, MD, PhD

Department of Orthopaedic Surgery

Resident Physician

Hospital of the University of

Department of Neurological Surgery

Pennsylvania

University of Pittsburgh Medical Center

Philadelphia, Pennsylvania

Pittsburgh, Pennsylvania

Frank M. Phillips, MD

Professor

Department of Orthopaedic Surgery

Rush University Medical Center

Chicago, Illinois

Contributors xxi

Glen Aaron Pollock, MD, DVM

Daniel M. Sciubba, MD

Resident Physician

Assistant Professor of Neurosurgery,

Department of Neurosurgery

Oncology, and Orthopaedic Surgery

and Brain Repair

Director, Spine Research

University of South Florida

Director, Minimally Invasive Spine

Tampa, Florida

Surgery

Johns Hopkins University

Ravi K. Ponnappan, MD

Baltimore, Maryland

Assistant Professor

Department of Orthopaedics

Matthias Setzer, MD

Thomas Jefferson University

Department of Neurosurgery

Philadelphia, Pennsylvania

Johann Wolfgang Goethe University

Frankfurt am Main, Germany

Ravi Ramachandran, MD

Resident Physician

Mohammad Said Shukairy, MD

Department of Orthopaedic Surgery

Department of Neurosurgery

Yale New Haven Hospital

Community Spine and Neurosurgery

New Haven, Connecticut

Institute

Munster, Indiana

Edwin Ramos, MD

Assistant Professor of Neurosurgery

Krzysztof B. Siemionow, MD

Department of Neurosurgery

Assistant Professor

University of South Florida

Department of Orthopaedic Surgery

Tampa, Florida

University of Illinois-Chicago

Weiss Memorial Hospital

Katherine Relyea, MS

Chicago, Illinois

Medical Illustrator

Department of Pediatric Neurosurgery

Harminder Singh, MD

Baylor College of Medicine

Assistant Professor

Houston, Texas

Department of Neurosurgery

Stanford University School of Medicine

Jeffrey A. Rihn, MD

Stanford, California

Assistant Professor

Department of Orthopaedic Surgery

Kern Singh, MD

Thomas Jefferson University Hospital

Department of Orthopaedic Surgery

The Rothman Institute

Rush University Medical Center

Philadelphia, Pennsylvania

Chicago, Illinois

Rick C. Sasso, MD

Eric A. Sribnick, MD, PhD

Professor

Resident Physician

Chief of Spine Surgery

Department of Neurosurgery

Clinical Orthopaedic Surgery

Emory University

Indiana University School of Medicine

Atlanta, Georgia

Indiana Spine Group

Indianapolis, Indiana

Ishaq Y. Syed, MD

Assistant Professor

Jose Carlos Sauri-Barraza, MD

Department of Orthopaedics

Wake Forest Baptist Medical Center

Centro Médico ABC

Winston-Salem, North Carolina

Mexico City, Mexico

xxii Contributors

Matthew J. Tormenti, MD

Fernando L. Vale, MD

Neurosurgical Resident Physician

Professor and Vice-Chair

Department of Neurological Surgery

Residency Program Director

University of Pittsburgh Medical Center

Department of Neurosurgery

Pittsburgh, Pennsylvania

University of South Florida

Tampa, Florida

Nam D. Tran, MD, PhD

Assistant Professor

Frank D. Vrionis, MD, PhD

H. Lee Moffitt Cancer Center

Chief of Neurosurgery

University of South Florida

H. Lee Moffitt Cancer Center

Tampa, Florida

Professor of Neurosurgery and

Orthopedics

Juan S. Uribe, MD

University of South Florida College

Assistant Professor

of Medicine

Director, Spine Section

Tampa, Florida

Director, Biomechanical Laboratory

Department of Neurosurgery

Michael Y. Wang, MD, FACS

University of South Florida

Associate Professor

Tampa, Florida

Departments of Neurological Surgery

and Rehabilitation Medicine

Timothy D. Uschold, MD

University of Miami Miller School

Neurosurgery Resident Physician

of Medicine

Division of Neurological Surgery

Miami, Florida

Barrow Neurological Institute

Phoenix, Arizona

Peter G. Whang, MD

Associate Professor, Spine Service

Alexander R. Vaccaro, MD, PhD

Department of Orthopaedics and

The Everrett J. and Marion Gordon

Rehabilitation

Professor of Orthopaedic Surgery

Yale University School of Medicine

Professor of Neurosurgery

New Haven, Connecticut

Co-Director, Delaware Valley

Spinal Cord Injury Center

Timothy F. Witham, MD, FACS

Co-Chief, Spine Surgery

Associate Professor of Neurosurgery

Co-Director, Spine Surgery

Director, The Johns Hopkins Bayview

Thomas Jefferson University

Spine Program

The Rothman Institute

Department of Neurosurgery

Philadelphia, Pennsylvania

Johns Hopkins University

Baltimore, Maryland

Juan M. Valdivia V, MD

Clinical Lecturer

Jean-Paul Wolinsky, MD

Department of Neurosurgery

Associate Professor of Neurosurgery

University of Michigan

and Oncology

Chief, Neurosurgery

Clinical Director of the Johns Hopkins

Ann Arbor Veteran’s Affairs Health

Spine Program

Care System

Johns Hopkins University

Ann Arbor, Michigan

Baltimore, Maryland

1 Embryology of the Spine

Akash J. Patel, Katherine Relyea, Daniel H. Fulkerson, and

Andrew Jea

I. Key Points

- The developing vertebral column is formed from somites,

which develop into sclerotomes.

- Myotomes bridge the intervertebral spaces, allowing them to

develop musculature that affords movement of the spine.

- The developing sclerotomes undergo chondrification and then

ossification to form each vertebral unit.

- The HOX genes regulate the shape of each vertebral body.¹

- Epiblast cells migrate to form the primitive groove, which in

turn forms the notochord.

- The anterior neuropore closes on day 25 and the posterior on

day 27.

- Neuroblasts form the mantle layer; the ventral portion forms

the basal plates (motor) and the dorsal portion forms the alar

plates (sensory).

- The caudal portion of the tube undergoes retrogressive differ-

entiation and relative ascension of the conus.

II. Bony Anatomy

- Paraxial mesoderm forms 42 to 44 somites.

- Somites differentiate into ventromedial sclerotomes and dor-

solateral dermomyotomes.

- In week 4, cells of the sclerotomes move to surround the spinal

cord and notochord.²

- The sclerotome can be divided into a cranial area of loosely

packed cells and a caudal area of densely packed cells with a

“cell-free space” in between.²

- Sclerotomes are separated by intersegmental mesenchyme and

flanked by segmental nerves, myotomes, and intersegmental

arteries. Sclerotomes develop into definitive vertebrae, which

causes myotomes to bridge intervertebral spaces, allowing

movement of the spine.

- Between days 40 and 60, the process of chondrification begins

and ossification follows, leading to the formation of each ver-

tebral unit.

I Clinical Spine Anatomy

- Cells from the caudal portion of the sclerotome migrate to the

cell-free space to form the annulus fibrosus of the disc, and re-

gressing notochord forms the nucleus pulposus.

- The caudal portion of each sclerotome fuses to the cephalic

portion of the adjacent sclerotome during week 6. After fu-

sion, arteries cross vertebral bodies, with the nerves residing

between them.

- Fusion of adjacent sclerotomes creates the centrum, which de-

velops into the vertebral body.

- Cells adjacent to the neural tube form vertebral arches (or neu-

ral arches) that consist of the posterior elements.

- In general, each vertebra develops from three primary ossifi-

cation centers: one for the body and one for each half of the

vertebral arch.

• There are five secondary ossification centers for subaxial

vertebrae, located at the superior and inferior end plates of

the body, the spinous process, and the tip of each transverse

process.

• C1 develops from the three primary ossification centers for

the left and right posterior arches and for the anterior arch.

• C2 develops from five primary ossification centers: two for

the body of the dens, one for the vertebral body, and one each

for the left and right neural arches.³

◦The tip of the dens represents a secondary ossification

center.

- The shapes of different vertebral bodies are regulated by HOX

genes.¹

- The thoracic kyphosis is present during the fetal period, and

the cervical and lumbar lordoses develop after birth.

III. Neural Anatomy

- By week 2, the embryo begins gastrulation and has two lay-

ers: epiblast and hypoblast. During gastrulation, epiblast cells

migrate to the dorsal midline to form the primitive streak and

subsequently the primitive groove.

- At the end of gastrulation there are three layers: ectoderm, me-

soderm, and endoderm.

- At the edge of the primitive groove is a pit, the primitive node,

where the notochordal process is formed by migrating epiblasts.

- By day 18 the primitive groove has regressed caudally and the

notochord has formed.

1 Embryology of the Spine

- At three weeks’ gestation, the edges of the neural plate begin to

elevate to form neural folds, and their subsequent fusion in the

cervical region forms the neural tube (Fig. 1.1).²

• The anterior neuropore closes on day 25.

• The posterior neuropore closes on day 27.

- Neural crest cells detach from the neural folds and migrate to

form glia, arachnoid, pia, melanocytes, chondrocytes, chromaf-

fin cells, osteocytes, Schwann cells, and enteric ganglia.

- The wall of the neural tube consists of neuroepithelial cells

forming a pseudostratified epithelium connected by junctional

complexes that differentiate into neuroblasts.²

- Neuroblasts form the mantle layer around the neuroepithelial

layer that forms the gray matter of the spinal cord (Fig. 1.2).²

• The ventral mantle layer forms the basal plates (motor horn),

and the dorsal mantle layer forms the alar plates (sensory

horn).

• At the thoracic (T1 to T12) and upper lumbar (L1 to L2) region,

the intermediate horn contains sympathetic neurons of the

autonomic nervous system.

• The boundary between the basal and alar plates is the sulcus

limitans.

Fig. 1.1 Dorsal view of the human embryo during the third week of gestation. Note

the somites on each side of the neural tube as it begins to fuse in the cervical region.

The fused neural tube then continues to close both rostrally and caudally.

6 I Clinical Spine Anatomy

Fig. 1.2 Cross-section of the developing spinal cord demonstrates how the migrat-

ing neuroblasts from the neuroepithelial layer form dorsal and ventral mantle layers.

These ultimately become the gray matter of the spinal cord. In addition, note the

development of the dorsal root ganglion as well as the outward growth of the motor

axons.

- The marginal layer contains nerve fibers from neuroblasts in

the mantle layer that ultimately form the white matter of the

spinal cord.

- The caudal tube forms during canalization (days 28 to 42).

- From day 43 to day 48, the ventriculus terminalis (a cystic struc-

ture at the caudal neural tube end) undergoes retrogressive dif-

ferentiation, which is completed postnatally at 2 months.²

• This results in relative ascension of the conus to its final level

at L1-L2, and formation of the cauda equina and filum termi-

nale (Fig. 1.3).

IV. Surgical Pearls

- Failure of the ventriculus terminalis results in a terminal my-

elocystocele. This cyst is lined with ependyma and communi-

cates with the central canal.

- The sulcus limitans is the border between the sensory (dorsal)

and motor (ventral) areas.

- The conus ascends to its adult level, L1-L2, by 2 months of age.

It is important to keep this in mind when performing a lumbar

puncture on the neonate.

- The notochord involutes and remains to develop the nucleus

pulposus of the intervertebral disc

- Complete fusion of the ossification centers of C2 does not occur

until age 12. Prior to this, synchondroses between ossification

centers can be mistaken for fractures.

2 Craniovertebral Junction

Ali A. Baaj, Edwin Ramos, and Juan S. Uribe

I. Key Points

- The craniovertebral junction (CVJ) includes the base of the oc-

ciput (O), the occipital condyles, and vertebrae C1 and C2.

- Principal motion at O-C1 is flexion-extension and at C1-C2

axial rotation.

- The CVJ ligamentous complex is key to the stability of this re-

gion (Fig. 2.1).

Atlanto-occipital

Alar

Tectorial

capsule

ligaments membrane

Longitudinal

Transverse

fascicles

Cruciform

foramen

ligament

Transverse

of atlas

Posterior

ligament of

arch of atlas

atlas

Intervertebral

Lateral

disk

atlantoaxial joint

Vertebral

body

arch

Transverse

process

Posterior

longitudinal ligament

Fig. 2.1 CVJ ligamentous structures (from THIEME Atlas of Anatomy, General Anat-

omy and Musculoskeletal System, (c) Thieme 2005, Illustration by Karl Wesker).

10 I Clinical Spine Anatomy

II. Bony Anatomy

- CVJ refers to the base of the occiput, the atlas (C1), and the axis

(C2).

- The boundaries of the foramen magnum are the basion an-

teriorly, the opisthion posteriorly, and the occipital condyles

inferolaterally.

- C1 has no vertebral body or spinous process. It has a posterior

arch and an anterior arch. It’s the widest cervical vertebra, and

its superior concave articular surface accommodates convex

occipital condyles (Fig. 2.2).

Posterior arch

Posterior

tubercle

Superior

Groove for

articular

vertebral artery

Lateral

facet

masses

Transverse

process

Transverse

foramen

Facet for dens

Anterior arch

tubercle

Superior

Groove for

articular facet

vertebral artery

Posterior

tubercle

Posterior

arch of atlas

Transverse

foramen

process

Inferior

articular facet

Fig. 2.2

(A) Superior and (B) lateral view of the atlas (from THIEME Atlas of Anatomy,

General Anatomy and Musculoskeletal System, (c) Thieme 2005, Illustration by Karl

Wesker).

2 Craniovertebral Junction

- The C1 anterior tubercle (C1 “button”) is the attachment site

of the anterior longitudinal ligament (ALL) and the longus colli

muscle.

- The vertebral artery and C1 nerve run along the superior lateral

groove on C1 (sulcus arteriosus). In less than 15% of the popula-

tion the groove is roofed, forming a foramen (arcuate foramen).

- C2 consists of the body, odontoid process, articulating surfaces,

pedicles, pars interarticularis (note that pars and pedicles are

distinct anatomical landmarks), lamina, and large, bifid spi-

nous process (Fig. 2.3).¹

Spinous process

Vertebral

Vertebral arch

foramen

Pars

Inferior

Dens

articular

process

Transverse

Pedicle

process

Superior

Transverse

articular

foramen

facet

Anterior articular facet

Dens

articular facet

Posterior

articular facet

Superior

articular facet

Spinous

Transverse

process

foramen

Body

Transverse

Inferior

Vertebral

process

articular facet

arch

Pars

Fig. 2.3 Superior (A) and lateral (B) view of the axis (from THIEME Atlas of Anatomy,

General Anatomy and Musculoskeletal System, (c) Thieme 2005, Illustration by Karl

Wesker).

12 I Clinical Spine Anatomy

- The C2 odontoid (Gr. “tooth”) process projects superiorly and

has multiple (and overlapping) ligamentous attachments to C1

and the occiput.

III. Neural Anatomy

- Cervical nerve roots exit above their corresponding level (i.e.,

C2 nerve root exits above C2 pedicle).

- C1 nerve root: the posterior division (suboccipital nerve) is

more prominent than the anterior division. It innervates suboc-

cipital muscles and occasionally branches to the lesser/greater

occipital nerve.

- C2 nerve root: posterior, medial (greater occipital nerve), and

lateral divisions innervate suboccipital muscles and scalp from

occiput to vertex.

- The lesser occipital nerve is formed by dorsal divisions of C2

and C3.

IV. Vascular Anatomy

- The vertebral artery (VA) leaves the C2 transverse foramen (be-

coming V3), takes a 45 degree lateral projection, and ascends

(vertical portion of V3) into the C1 transverse foramen.

- The VA then courses medially (horizontal portion of V3) along

the C1 sulcus arteriosus and then anteriorly through the atlan-

tooccipital membrane, where it becomes intradural (beginning

of V4 segment).

- Blood is supplied to the CVJ primarily through branches of the

vertebral and occipital arteries.

- The base of the dens of C2 receives blood supply from vertebral

artery branches (posterior circulation); the top is supplied by

apical branch of the hypoglossal artery (anterior circulation).

- Lymphatic drainage of the CVJ is through retropharyngeal and

deep cervical nodes (Grisel’s syndrome: CVJ instability with

concomitant retropharyngeal inflammation/infection).

V. Ligamentous and Muscular Anatomy (Table 2.1)

- Suboccipital muscles and the CVJ (Fig. 2.4)

• Superior oblique: C1 transverse process laterally to occiput

medially

• Inferior oblique: C1 transverse process laterally to spinous

process of C2 medially

2 Craniovertebral Junction

Table 2.1

Principal CVJ Ligaments: Their Attachments and Modes of

Action

Ligament

Attachments

Action

Apical

Odontoid tip (superiorly) to

Limits O-C2

basion

distraction

Alar

Odontoid tip (laterally) to

Limits O-C2

medial tubercle of occipital

subluxation/

condyles and lateral masses

hyperrotation

of C1

Cruciate

Vertical component: body of

Prevents C1/C2

C2 to basion

subluxation and

Transverse component:

O-C1/C2 distraction

medial tubercles of C1 lateral

masses to posterior dens

Tectorial

Posterior aspect of vertebral

Limits hyperflexion,

bodies, dorsal to cruciate

distraction

ligament

(continuation of PLL)

ALL

Anterior aspect of vertebral

Limits hyperexten-

bodies

sion, distraction

Accessory

C2 body laterally to medial

Limits atlantoaxial

atlantoaxial

C1 lateral masses

hyperrotation

Capsular

O-C1 and C1-C2 articulating

Stabilizes facet joints

facets

Anterior and poste-

Anterior: basion to C1 tu-

Limit atlantooccipital

rior atlantooccipital

bercle (C1 button)

distraction

membranes

Posterior: opisthion to C1

posterior arch

Abbreviations: ALL, anterior longitudinal ligament; O, occiput; PLL, posterior longitu-

dinal ligament.

14 I Clinical Spine Anatomy

Superior

Inferior

Rectus capitis

nuchal line

posterior minor

Obliquus

capitis superior

Mastoid process

Rectus capitis

posterior major

Posterior

tubercle of atlas

Transverse

Spinous

process of atlas

process of axis

Obliquus

capitis inferior

Fig. 2.4 Muscles of the suboccipital triangle (from Atlas of Anatomy, (c) Thieme

2008, Illustration by Karl Wesker).

• Rectus capitis posterior major: spinous process of C2 up to

base of occiput

• Rectus capitis posterior minor: posterior tubercle of C1 up to

base of occiput

• Semispinalis capitis: transverse processes of cervical verte-

brae to nuchal ligament and occipital bone; superficial to sub-

occipital muscles

• Longissimus capitis: similar to semispinalis but runs and at-

taches more laterally to the occiput

VI. Surgical Pearls

- C1 nerve root, if present, can be sacrificed; though we don’t

routinely perform this, C2 nerve root may also be sacrificed

(with minimal risk of occipital neuralgia).²

- Integrity of cruciate ligament must be considered before any

CVJ stabilization procedure is undertaken.

- Venous plexus around C2 ganglion may cause considerable

bleeding, which should not be mistaken for VA injury.

- Thin-cut CT of the CVJ and/or CT angiography (CTA) should be

obtained prior to C1/C2 fixation to verify route and patency of

the vertebral arteries, as well as dimensions of the pars interar-

ticularis and/or pedicle.

2 Craniovertebral Junction

Common Clinical Questions

1. What is the source of the blood supply to the odontoid process

of the axis?

2. What forms the continuation of the posterior longitudinal liga-

ment (PLL) at the CVJ?

References

1. Menezes AH, Traynelis VC. Anatomy and biomechanics of normal craniover-

tebral junction (a) and biomechanics of stabilization (b). Childs Nerv Syst

2008;24(10):1091-1100

2. Squires J, Molinari RW. C1 lateral mass screw placement with intentional

sacrifice of the C2 ganglion: functional outcomes and morbidity in elderly

patients. Eur Spine J 2010;19(8):1318-1324

Answers to Common Clinical Questions

1. Superior part: apical branch of hypoglossal artery; base: branch-

es of the vertebral artery

2. Tectorial membrane

3 Cervical Spine

Eric A. Sribnick and Sanjay S. Dhall

I. Key Points

- The subaxial cervical spine includes C3 to C7.

- The cervical spine normally demonstrates a lordotic curvature.

- Posterior instrumentation often uses lateral mass screws be-

cause the pedicles are narrower than in the thoracic and lum-

bar spine, increasing the risk of neurovascular injury.

- The size and volume of lateral masses decrease from the upper

to lower subaxial cervical spine.

II. Bony Anatomy

- Radiographic landmarks¹: C3 is at the hyoid, C4 is at the thyroid

cartilage, and C6 is at the cricoid cartilage.

- Palpable landmark: the anterior tubercle of the C6 transverse

process (Chassaignac tubercle) is palpable.

- The width of vertebral body is usually 17 to 20 mm.

- In the coronal plane, uncovertebral joints are noted at the an-

terolateral aspect of the vertebral body (Fig. 3.1).

- The spinal canal is triangular and has a greater lateral than an-

teroposterior (AP) dimension.

- The AP diameter of the spinal canal decreases caudally²: 17 mm

at C3, 15 mm at C7.

Fig. 3.1 Cervical vertebrae superior (A) and oblique (B) views.

3 Cervical Spine

- Lateral masses of the subaxial spine are composed of the supe-

rior and inferior articulating processes (the facet).

- A lateral mass begins lateral to where the lamina and pedicle

meet.

- C7 is a transitional vertebra: the lateral mass is thinner and the

pedicle is wider than in C3 to C6.

- The normal lordotic curvature of the cervical spine is 16 to 25

degrees.³

- Cervical disc herniation occurs most frequently at C5/6 and

C6/7.

- Biomechanical studies show maximal flexion-extension at C4/5

and C5/6 and maximal lateral bending at C2/3, C3/4, and C4/5.

- The least mobile segment is C7/T1.

III. Neural Anatomy

- C3 to C7 nerve roots exit above their corresponding level (e.g.,

C7 exits above the C7 pedicle).

- The C8 nerve root exits above the T1 pedicle.

- The cervical spinal cord enlarges caudally and reaches a maxi-

mal cross-sectional area at C6.

- Nerve roots enter the intervertebral foramina laterally, occupy

approximately one-third of the foramina, and are covered by

epidural fat and venous plexus above.

- Nerve roots exit the spine at a point that is anterolateral to the

superior joint facet.

- The cervical plexus is formed by the anterior rami of C1 to C4.

- The brachial plexus is formed by the anterior rami of C5 to T1.

- The cervical plexus gives rise to (1) the ansa cervicalis (sup-

plies a branch to the hypoglossal nerve and innervates the strap

muscles, except for the thyrohyoid), (2) phrenic nerve (C3 to C5,

but mainly C4), and (3) cutaneous nerves of the posterior head

and neck.

IV. Vascular Anatomy

- Vertebral arteries usually originate from the subclavian ar-

tery and ascend between the anterior scalene and longus colli

muscles.⁴

- Vertebral arteries enter the spine at the transverse foramen of

C6 (occasionally at C7).

- Vertebral artery segments: V1 (pre-foraminal), origin to trans-

verse foramen entrance; V2 (foraminal), C6 to C2; V3, C2 to

dura; V4, intradural segment to basilar artery.

18 I Clinical Spine Anatomy

- The transverse foramen is lateral to the vertebral body and an-

terior to the nerve root groove.

- At C3 to C5, the lateral-most aspect of the transverse foramen is

often anteromedial to the midpoint of the lateral mass.

- At C6-C7, a portion of the transverse foramen is often anterior

to the midpoint of the lateral mass.

- Blood supply to spinal cord includes the anterior spinal artery,

the two posterior spinal arteries, and the segmental medullary

arteries.

- The anterior spinal artery originates from the vertebral arteries.

- The posterior spinal arteries originate from either vertebral ar-

teries or the posterior inferior cerebellar arteries (PICA).

- Venous drainage of the spinal cord: three anterior and three

posterior longitudinally running veins.

- Spinal cord is surrounded by an anterior and a posterior venous

plexus.

- The anterior venous plexus is most pronounced medial to the

pedicles.

V. Ligamentous and Muscular Anatomy

- The anterior longitudinal ligament covers anterior vertebral

bodies and limits extension.

- The posterior longitudinal ligament covers posterior vertebral

bodies and limits flexion.

- The interspinous and supraspinous ligaments run between ad-

jacent spinous processes and form the ligamentum nuchae.

- The ligamentum nuchae makes up the midline avascular plane.

- The carotid triangle of the neck is an important surgical land-

mark for anterior approaches, formed laterally by sterno-

cleidomastoid, superiorly by dorsal portion of the digastric,

and anteriorly by omohyoid.

- The carotid triangle contains the carotid sheath (common ca-

rotid, internal jugular, and vagus nerve).

- Longus colli muscles lie anterolateral to vertebral bodies and

are elevated during anterior spinal procedures (Fig. 3.2).

20 I Clinical Spine Anatomy

- During posterior cervical procedures, the patient can be placed

in a slight reverse Trendelenberg position to reduce venous

engorgement.

- C7 is a transitional-level vertebra. For a posterior fusion involv-

ing C7, some surgeons advocate extending the fusion to T1 to

reduce adjacent-level disease.

Common Clinical Questions

1. Where does cervical disc herniation most often occur?

2. What is the normal curvature of the cervical spine?

3. Which arteries provide the majority of blood circulation to the

spinal cord?

References

1. Clark CR, Benzel EC, Currier BL, et al, eds. The Cervical Spine. 4th ed. Philadel-

phia, PA: Lippincott Williams & Wilkins; 2005

2. Herkowitz HN, Garfin SR, Eismont FJ, et al, eds. Rothman-Simeone: The Spine.

5th ed. Philadelphia, PA: Elsevier; 2006

3. Gore DR, Sepic SB, Gardner GM. Roentgenographic findings of the cervical

spine in asymptomatic people. Spine (Phila Pa 1976) 1986;11(6):521-524

4. Ebraheim NA, Xu R, Yeasting RA. The location of the vertebral artery fora-

men and its relation to posterior lateral mass screw fixation. Spine (Phila Pa

1976) 1996; 21(11): 1291-1295

Answers to Common Clinical Questions

1. C5/6 and C6/7

2. The cervical spine normally has a lordotic curvature between 16

and 25 degrees.

3. The spinal cord is supplied by the anterior spinal artery (from

the vertebral arteries), two posterior spinal arteries (from ei-

ther the vertebral arteries or PICA), and segmental medullary

arteries.

4 Thoracic Spine

Ryan J. Halpin and Tyler R. Koski

I. Key Points

- The normal thoracic spine includes 12 rib-bearing vertebral

segments; anatomical variations can have 11 or 13 rib-bearing

segments.

- Compared with the cervical and lumbar spine, the motion of

the thoracic spine is limited due to the osteoligamentous rela-

tionship with the rib cage.

- Normal thoracic kyphosis is 10 to 40 degrees with the apex at

T7.¹

II. Bony Anatomy (Figs. 4.1 and 4.2)²

- The dorsal, ventral, and lateral diameters of the vertebral bod-

ies increase from the upper to lower thoracic spine.³

- Thoracic kyphosis results from the wedge shape of the verte-

bral bodies, in which the anterior vertebral body height is less

than the posterior vertebral body height.^1,3

Superior

vertebral notch

articular facet

Superior

Transverse

costal facet

process

Costal facet on

transverse

process

Body

Inferior

vertebral notch

Inferior

costal facet

Inferior

Spinous

articular facet

process

Fig. 4.1 Lateral view of thoracic vertebra (from THIEME Atlas of Anatomy, General

Anatomy and Musculoskeletal System, (c) Thieme 2005, Illustration by Karl Wesker).

22 I Clinical Spine Anatomy

Costal facet on

Spinous

transverse process

process

Lamina

Transverse

process

Pedicle

Superior

articular facet

Inferior

Superior

costal facet

vertebral notch

Superior

Body

costal facet

Fig. 4.2 Superior view of thoracic vertebra (from THIEME Atlas of Anatomy, General

Anatomy and Musculoskeletal System, (c) Thieme 2005, Illustration by Karl Wesker).

- The ribs from T2 to T9 articulate with two vertebral bodies (at

the demifacets) and the transverse costal facet of the caudal

vertebral body (i.e., T2 rib articulates with T1 and T2 at the

demifacets and the T2 transverse facet).

- The T1, T11, and T12 (and often T10) ribs have a full facet for

articulation with the corresponding vertebrae.

- The eleventh and twelfth ribs do not articulate with the trans-

verse process of the corresponding vertebral body.

- The thoracic facets are oriented in an intermediate plane com-

pared with the relatively coronally oriented cervical facets and

the sagittally oriented lumbar facets, and provide stability in

flexion and extension.^1,3

- Sagittal pedicle height gradually increases from the upper to

lower thoracic spine.³

- Transverse pedicle width decreases from the upper thoracic

spine to the mid-thoracic spine (T5-T6) before gradually in-

creasing through the lumbar spine.^1,3

- The transverse pedicle angle decreases from T1 to T12.³

- The diameter of the spinal canal is smaller in the thoracic than

in the cervical and lumbar regions.

4 Thoracic Spine

III. Neural Anatomy

- The thoracic nerve roots exit below the pedicle of the corre-

sponding vertebra (i.e., T3 nerve root exits below the T3 pedicle).

- Thoracic nerves supply the trunk and abdomen. Important tho-

racic dermatomes include T4 at the nipple line, T6 at the base of

the sternum, and T10 at the umbilicus.

- The spinal cord runs through the length of the thoracic spinal

canal and ends at the conus medullaris, usually at the L1-L2 level.

IV. Vascular Anatomy

- The anterior spinal artery arises from vertebral arteries and

runs in the anterior median fissure of the spinal cord.

- The paired posterior spinal arteries usually arise from the posterior

inferior cerebellar arteries and travel lateral to the posterior me-

dian sulcus of the spinal cord.

- Segmental arteries from the lumbar and intercostal arteries

supplement the arterial supply of the cord through six to eight

radicular arteries.

- The artery of Adamkiewicz is the largest radicular artery and

provides the main arterial supply to the cord from approxi-

mately T8 to the conus. It arises from the T9-L2 region in 85%

and from the left side in 80% of people.^1,3

V. Ligamentous and Muscular Anatomy (Table 4.1)

- Muscles of the thoracic spine

• Deep layers

◦ Rotatores longus and brevis, levatores costarum longus and

brevis, multifidus, semispinalis thoracis, and external costal

muscles

• Intermediate layers

◦ Splenius cervicis, serratus posterior superior and inferior,

and erector spinae: spinalis thoracis, longissimus, iliocostalis

• Superficial layers

◦ Rhomboid, latissimus dorsi, and trapezius

VI. Surgical Pearls

- Laminectomy of the thoracic spine can increase the risk of pro-

gressive kyphosis due to the loss of the posterior tension band.

- Injury to the artery of Adamkiewicz can cause a spinal cord infarc-

tion due to the tenuous blood supply of the lower thoracic cord.

24 I Clinical Spine Anatomy

Table 4.1 Principal Thoracic Ligaments: Their Attachments and

Modes of Action

Ligament

Attachments

Action

Anterior longitudinal

Ventral vertebral body

Limits extension and

and annulus

distraction

Thickest in thoracic

spine

Posterior longitudinal

Dorsal vertebral body

Limits flexion and

and annulus

distraction

Thickest in thoracic

spine

Ligamentum flavum

Lamina of adjacent

Limits flexion

vertebra

Interspinous

Spinous processes of

Limits flexion and

adjacent vertebra

distraction

Supraspinous

Tips of spinous process-

Limits flexion and

es and thoracolumbar

distraction

fascia

Facet capsule

Superior and inferior fac-

Supports facet joint

ets of adjacent vertebra

stability

Radiate

Rib and adjacent ver-

Stabilizes rib

tebral disc space and

attachments

vertebral body anteriorly

Contributes to limita-

Costovertebral

Rib and adjacent

tion of thoracic flexion,

vertebral disc space

extension, lateral bend-

and vertebral body

ing, and axial rotation

dorsolaterally

The rostral rib neck and

costotransverse

the transverse process

of the vertebra one level

above

Posterior

The transverse process

costotransverse

to the tubercle of the rib

at the same level

4 Thoracic Spine

- Due to variable thoracic pedicle anatomy, a thin-cut computed

tomography (CT) scan can be useful prior to thoracic pedicle

screw placement to assist with surgical planning and avoid

neural injury.

- Avoid ending spinal constructs at the thoracic kyphotic apex to

prevent early instrumentation failures.

Common Clinical Questions

1. True or false: The pedicles on the concavity of a scoliotic curve

tend to be larger than the pedicles on the convexity of the curve.

2. True or false: Each rib usually articulates only with its corre-

sponding vertebral body.

3. The apex of normal kyphosis in the thoracic spine is at which

level?

A. T2-T3

B. T5-T6

C. T7-T8

D. T9-T10

E. T11-T12

References

1. Frempong-Boadu AK, Guiot BH. Thoracic spine anatomy and biomechanics. In

Batjer H and Loftus C, eds. Textbook of Neurological Surgery: Principles and

Practice. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:1544-1551

2. Gray’s Anatomy 1918 edition, public domain

3. Yoganandan N, Halliday AL, Dickman CA, Benzel E. Practical anatomy and

fundamental biomechanics. In Benzel EC. Spine Surgery Techniques, Com-

plication Avoidance, and Management. 2nd ed. Philadelphia PA: Elsevier;

2005:109-135

Answers to Common Clinical Questions

1. False: Pedicles on the concavity are usually smaller.

2. False: The majority of ribs articulate with the corresponding

body as well as the body below.

3. C. Normal thoracic kyphosis is between 10 and 40 degrees and

has an apex at T7-T8. Pathologic kyphosis can be centered at

any level.

5 Lumbar Spine

• Middle column: posterior half of the disc and vertebral body,

as well as the posterior longitudinal ligament

• Posterior column: posterior bony arch, facet joint and its cap-

sule, supraspinous and intraspinous ligaments, and ligamen-

tum flavum.

II. Bony Anatomy (Tables 5.1 and 5.2)

- The intervertebral discs lie between adjacent vertebral bodies. The

annulus fibrosus is the outer layer of the disc; made of rings of col-

lagen surrounding fibrocartilaginous zones, it limits the rotation

between the vertebrae. The nucleus pulposus lies in the center of

the disc; primarily gelatinous, its function is to absorb compres-

Table 5.1

Bony Borders of the Vertebral Column

Bone

Column

Description

Major pathology

Ver-

Ante-

Lumbar vertebral bodies are the

Compression or

tebral

rior and

largest in the spine

burst in trauma,

body

middle

Major weight-bearing

osteoporosis, or

component

tumor

Anterior portion of the verte-

bral column

Pedicle

Posterior

Short and strong

May fracture in

Arise from the upper and

trauma, osteopo-

posterolateral vertebral body,

rosis, or tumor

forming the bilateral anterolat-

eral portions of the vertebral

column

Frequently, transpedicular

instrumentation is placed for

stabilization or fusion

Lamina

Posterior

Short broad plates

May fracture in

Form the bilateral posterolat-

trauma, osteopo-

eral borders of the vertebral

rosis, or tumor

column

May be removed in decompres-

sive surgery

Spinous

Posterior

At the meeting point of the two

process

laminae

Forms the posterior border of

the vertebral column

28 I Clinical Spine Anatomy

Table 5.2 Borders of the Intervertebral Foramen

Posterior borders of the adjacent vertebral bodies and

discs

Superior

Inferior border of the pedicle of the superior vertebrae

Posterior

Pars interarticularis and facet joint

Inferior

Superior border of the pedicle of the inferior vertebrae

sion forces. Posterolateral herniation of the disc can compress an

individual nerve root; central herniation can compress the entire

cauda equina.¹

- At the level of the pedicle, the transverse process arises. The

processes of the first three lumbar vertebrae are long and slen-

der, and those of the fourth and fifth are more pyramidal. In

posterolateral lumbar fusion, the bone graft is often placed in

the lateral gutter—the area lateral to the facets where the trans-

verse processes lie.

- The pars interarticularis, also referred to as the isthmus, is a

thin bone of the posterior arch of the lumbar vertebrae where

the lamina and the inferior articular process join the pedicle

and superior articular process. A fracture in the pars interar-

ticularis is referred to as spondylolysis, can be found in 5 to 6%

of the population, and predisposes the individual to the devel-

opment of isthmic spondylolisthesis.¹

- The facet joint is composed medially of the inferior articulating

process of the superior vertebrae and laterally of the superior ar-

ticulating process of the inferior vertebrae. Surrounding the facet

joint is an articular capsule. Hypertrophy of the facet joint and its

capsule can contribute to both spinal and foraminal stenosis.²

III. Neural Anatomy

- The spinal cord ends at the conus medullaris, most frequently at

the level of the L1 vertebral body or the L1/L2 disc space. Inferi-

orly, the roots descend within the thecal sac as the cauda equina

before they exit individually (Fig. 5.2).³

- The exiting nerve roots leave the vertebral column through the

intervertebral foramen, closer to the superior pedicle. Far lat-

eral disc herniations can compress the nerve root at this point

(leading patients to present with radiculopathy); in such cases,

30 I Clinical Spine Anatomy

IV. Vascular Anatomy

- Segmental arteries arise primarily from the lumbar arteries,

which in turn divide into anterior and posterior radicular ar-

teries, which enter the intervertebral foramen along with the

nerve roots. The arterial feeders of the spinal cord include

branches of these radicular arteries as well as the segmental

medullary arteries, which also come off of the segmental spinal

arteries, with one artery coursing anteriorly and two coursing

posteriorly. The cauda equina is supplied by branches of the

lumbar, iliolumbar, lateral, and median sacral arteries.³

- Two different plexuses of veins, one external and the other in-

ternal, extend along the vertebral column. The anterior exter-

nal plexus lies in front of the vertebral bodies, and the posterior

external plexus lies around the posterior arch of the vertebral

column. The internal vertebral plexus is a network of veins in

the epidural space within the vertebral canal that are in com-

munication with the basivertebral plexus; the veins tunnel

through the cancellous tissue of the vertebral bodies. Intradural

venous drainage of the spinal cord involves retrograde anterior

and posterior central veins.³

- Approaching the lumbar spine from an anterior approach, the

great vessels (the aorta and the inferior vena cava) lie directly

anterior to the vertebral bodies, with the bifurcation of the ves-

sels at the level of the L4/L5 disc space or at the level of L5.

The L5/S1 disc can generally be accessed inferior to the bifurca-

tion; to reach the L4/L5 disc, these vessels must be retracted

laterally.¹

V. Ligamentous and Muscular Anatomy (Table 5.3)

- Exposure of the lumbar spine from a posterior approach re-

quires traversing the throracolumbar fascia. In the lumbar re-

gion, the thoracolumbar fascia is thick and is attached to the

spinous processes and the supraspinous ligament. It then ex-

tends laterally, covering the erector spinae muscles.²

- Deep in the thoracolumbar fascia lie the erector spinae mus-

cles, which arise from the sacrum, the spinous processes of the

lumbar and thoracic vertebrae, and the iliac crest. The erector

spinae muscles include the iliocostalis, longissimus, and spina-

lis muscles, which are important in flexion, extension, and lat-

eral rotation of the vertebral column. Deep in the erector spinae

muscles are the multifidus and rotatores muscles.²

Lumbar Spine

Table 5.3 Ligaments of the Lumbar Spine

Ligament

Column

Attachment

Major pathology

Anterior margins of the

May be disrupted

longitudinal

vertebral bodies and

in fracture-

ligament

intervertebral discs

dislocation trau-

matic injuries and in

spondylolisthesis

Posterior

Middle

Posterior margins of the

May be disrupted

longitudinal

vertebral bodies and

in fracture-dislo-

ligament

intervertebral discs

cation or seatbelt

trauma and in

spondylolisthesis

Ligamentum

Posterior

Anterior border of

May be hypertro-

flavum

adjacent laminae and

phied in spinal

spinous processes

stenosis

Supraspinal

Posterior

Posterior borders of

ligament

spinous processes

Interspinous

Posterior

Inferior border of superior

process

spinous process and su-

ligaments

perior border of inferior

spinous process

VI. Surgical Pearls

- During transpedicular instrumentation placement, the land-

marks used for cannulation of the pedicles are the meeting

point of the pars interarticularis, the superior articulating pro-

cess, and the transverse process. There is a small ridge of bone

at that level called the mammillary process.

- For lumbar disc herniation, after a laminotomy is performed,

feel for the inferior pedicle (L5 in an L4-L5 disc herniation). Pal-

pate its medial wall with a Woodsen dissector. Immediately in-

ferior is the nerve root (L5). With a nerve hook, retract the root

medially and dissect superiorly until you feel a bulge (which is

the herniated disc fragment).

32 I Clinical Spine Anatomy

Common Clinical Questions

1. Compression of the nerve root in the neural foramen is most

often due to hypertrophy of which facet?

2. An L4/L5 far lateral herniated disc will compress which nerve

root?

References

1. Greenberg MS. Handbook of Neurosurgery. 6th ed. New York: Thieme Medi-

cal Publishers; 2006

2. Drake RL, Vogl W, Mitchell AWM. Gray’s Anatomy for Students. Philadelphia,

PA: Elsevier; 2005

3. Netter FH. The Netter Collection of Medical Illustrations. Volume 1: Nervous

System. Part 1: Anatomy and Physiology. Teterboro, NJ: Icon Learning Sys-

tems; 1983

Answers to Common Clinical Questions

1. The superior articulating facet of the lower vertebral body

2. The exiting L4 root (not the traversing L5 root)

6 Sacral-Iliac Spine

Amit R. Patel and Ravi K. Ponnappan

I. Key Points

- The sacrum is the structural link that distributes load from the

lumbar spine to the pelvis through the sacroiliac joints (and

vice versa).

- The bulbocavernosus reflex involves the S2 to S4 sacral nerves,

and its absence or presence has prognostic significance in spi-

nal cord trauma.

- Because of the location of the lumbosacral plexus in relation to

the sacrum, sacral fractures have a high incidence of neurologic

injury (up to 25%).¹

II. Bony Anatomy

- The normal adult spine consists of five fused sacral vertebrae

that form the wedge-shaped sacrum and four fused coccygeal

vertebrae that form the coccyx (the skeletal remnants of a tail).

- The sacrum has four paired sacral foramina, a sacral canal, a

sacral promontory (anterior projection of the S1 body), and a

sacral hiatus (clinically useful for caudal epidural anesthesia)²

(Figs. 6.1 and 6.2).

- The sacroiliac (SI) spine has many palpable bony landmarks,

including the sacral cornu and the iliac crest. The posterior su-

perior iliac spine may be difficult to palpate but is readily iden-

tifiable by the permanent skin dimples above the buttocks.³

• An imaginary line connecting the dimples passes through the

S2 spinous process and the middle of the SI joint in the ante-

rior-posterior plane.

• An imaginary line connecting the highest points of the iliac

crest passes through the L4/L5 intervertebral disc space.

- The sacrum has multiple points of articulation:

• The S1 body articulates with the L5 body via the L5/S1 disc

to form the lumbosacral angle, which varies from 130 to 160

degrees.³

• The inferior facet of L5 articulates with the superior facet of

S1 and acts as a buttress to resist anterior translation.³

• The apex of the sacrum articulates with the coccyx.

6 Sacral-Iliac Spine

• The lateral aspects of the sacrum articulate with the two coxal

(innominate) bones to form the SI joint (a true synovial diar-

throdial gliding joint with limited motion). Only the anterior

25% is synovial in nature (the rest is ligamentous attachment).¹

III. Neural Anatomy

- Ventral and dorsal branches of the sacral nerves exit the four

pairs of anterior and posterior sacral foramina, respectively;

the anterior foramina are larger in caliber than their posterior

counterparts.²

• Dermatomes are supplied by sacral nerves (Fig. 6.3).

- The sacral canal contains the nerve roots of the cauda equina.

- The pelvic splanchnic nerves are composed of parasympathetic

fibers derived from S2 to S4 and supply autonomic innervation

to various abdominal and pelvic viscera.

- The lumbosacral plexus is composed of the ventral rami from

T12 to S3 and lies posterior to the psoas muscle.

- Following are major nerves that arise from this plexus³:

• Sciatic nerve: composed of the ventral rami from L4 to S3, it

has an anterior preaxial tibial division and a postaxial perone-

Fig. 6.3 Dermatomal map of sacral nerve roots.

36 I Clinical Spine Anatomy

al division; most commonly it exits the pelvis via the greater

sciatic foramen inferior to the piriformis muscle.

• Pudendal nerve: composed of the anterior divisions of the

ventral rami of S2 to S4, it supplies the perineum and external

genitalia.

• Superior gluteal nerve: composed of the posterior divisions

of the ventral rami of L4 to S1, it supplies the gluteus medius,

gluteus minimus, and tensor fascia lata.

• Inferior gluteal nerve: composed of the posterior divisions of

the ventral rami of L5 to S2, it courses with the inferior gluteal

artery to supply the gluteus maximus.

IV. Vascular Anatomy

- The abdominal aorta begins at the aortic hiatus in the dia-

phragm at the level of T12 and bifurcates into the common iliac

arteries at the level of L4.³

- The common iliac veins unite at the level of L5 to form the in-

ferior vena cava.³

- The common iliac artery bifurcates anterior to the SI joint to

form the internal iliac artery and descends posteriorly into the

greater sciatic foramen to supply the pelvis, buttocks, medial

thigh, and perineum.

• The internal iliac vein sits between the SI joint and the inter-

nal iliac artery.

- The median sacral artery and vein form an unpaired vessel that

originates from the posterior aspect of the abdominal aorta to

supply the lower lumbar vertebrae, sacrum, and coccyx.³

- The lateral sacral arteries are paired and branch from the inter-

nal iliac artery and course through the anterior sacral foramina

to supply the spinal meninges.³

6 Sacral-Iliac Spine

V. Ligamentous and Muscular Anatomy

- The iliolumbar ligament attaches the transverse process of L5

with the ilium.²

• Unstable vertical shear fractures can avulse off the L5 trans-

verse process.

- The anterior SI, posterior SI, and interosseous ligaments sus-

pend the sacrum between the ilia.³

• The posterior SI and interosseous ligaments are thicker and

limit motion.

- The sacrotuberous ligament attaches the sacrum to the ischial

tuberosity; the sacrospinous ligament attaches the sacrum to

the ischial spine.

• These ligaments function to limit upward movement of the

caudal portion of the sacrum and delineate the greater and

lesser sciatic foramina.

- See Table 6.1 for major muscles of the sacroiliac spine.

VI. Surgical Pearls

- Transitional vertebrae can lead to incorrect surgical localization.²

- Aggressive exposure of sacral ala for posterolateral fusion can

endanger the L5 nerve root.¹

- A low L5-S1 disc may not be accessible via an anterior approach

due to pubic symphysis obstruction.²

- Anterior dissection of the superior hypogastric sympathetic

plexus can result in retrograde ejaculation in males, with rates

ranging from 0.42 to 5.9%.⁴

Table 6.1 Sacroiliac Muscle Anatomic Relationships

Muscle

Origin

Insertion

Innervation

Comment

Gluteus maximus

Dorsal sacrum, ilium Gluteal tuberosity

Inferior gluteal

Extends hip, external rotates thigh

Gluteus medius

Medial ilium

Greater trochanter

Superior gluteal

Abducts thigh

Gluteus minimus

Lateral ilium

Anterior greater trochanter

Superior gluteal

Abducts thigh

Iliacus

Iliac fossa

Lesser trochanter

Femoral

Flexes hip

Psoas

T12-L5 vertebrae

Lesser trochanter

Femoral

Flexes hip, overlies lumbosacral

plexus

Erector spinae

Sacrum, iliac crest,

T- and C-spinous process, mas-

Dorsal rami

Composed of iliocostalis, longissi-

L-spinous process

toid process

mus, and spinalis

Multifidus

C2 to S4 transverse

Spinous process

Dorsal rami

Flex, rotate spine

process

6 Sacral-Iliac Spine

Common Clinical Questions

1. Of the listed nerves, which is the most susceptible to injury dur-

ing an anterior approach to the SI joint?

A. S1 nerve root

B. Femoral

C. Ilioinguinal

D. L5 nerve root

E. Genitofemoral

References

1. Mehta S, Auerbach JD, Born CT, Chin KR. Sacral fractures. J Am Acad Orthop

Surg 2006;14(12):656-665

2. Hollinshead WH. Anatomy for Surgeons: The Back and Limbs. 3rd ed. Phila-

delphia, PA: Harper & Row; 1982:88-92

3. Moore KL, Dalley AF. Clinically Oriented Anatomy. 4th ed. Philadelphia, PA:

Lippincott; 1999:339-340, 347-355, 434-467

4. Sasso RC, Kenneth Burkus J, LeHuec JC. Retrograde ejaculation after anterior

lumbar interbody fusion: transperitoneal versus retroperitoneal exposure.

Spine (Phila Pa 1976) 2003;28(10):1023-1026

Answers to Common Clinical Questions

1. D. The L5 nerve root runs just anterior to the SI joint and is sus-

ceptible to injury not only in open procedures but also with

percutaneous sacroiliac screw placement. It courses 2 to 3 mm

medial to the SI joint.

7 Physical Examination

Mark S. Greenberg and Daniel Marin

I. Key Points

- There are four main components to the spinal exam: motor,

sensory, reflex, and mechanical. This is in addition to the gen-

eral exam, which includes observation for cutaneous and nail

changes, deformity, pain behaviors, and other signs.

- Although components of a general survey nature should always

be included, the physical exam is tailored to specific situations

based on the history, the region of suspected involvement, and

abnormal findings during the survey exam.

- No protocol can cover every contingency, and the exam must

be individualized based on patient-specific factors. The order

of the exam procedures must also be tailored to the situation.

II. Main Components of the Spinal-Related Exam

- Motor (strength, coordination, spasticity, muscle bulk/tone in-

cluding atrophy/fasciculations)

• Strength evaluation is usually graded using the Royal Medical

Research Council of Great Britain (MRC) scale, shown in Table

7.1.

◦ An overview of survey muscle groups to examine is shown

in Table 7.2.

◦ Further motor testing, as indicated, may include the tibialis

posterior and gluteus medius (in cases of foot drop to dis-

tinguish radiculopathy from peripheral neuropathy), first

lumbrical (median nerve), and abductor digiti minimi (ulnar

nerve).

- Sensation (pinprick, light touch, proprioception, temperature)

• Pinprick testing. Dermatomes and sensory distributions of

peripheral nerves are shown in Fig. 7.1.

• Proprioception (posterior column function) is assessed by

testing joint position sense in the second toe on each foot,

and/or vibratory sense with a low-frequency (128 Hz) tuning

fork applied to bony prominences in the ankles.

• Temperature sense may be crudely assessed by pressing the

cool metal of a reflex hammer handle to the skin.

7 Physical Examination

Table 7.2 Survey Muscle Groups

Major root

Muscle

innervation

Peripheral nerve

Action to test

Upper extremity

Deltoid

C5, C6

Axillary

Abduct shoul-

der over 90

degrees above

horizontal

Biceps brachii

C5, C6

Musculocutaneous

Flexion at el-

bow with fore-

arm supinated

Brachioradialis

C5, C6

Radial

Flex elbow with

thumb point-

ing up

Extensor carpi radialis

C5, C6

Radial

Wrist extension

Triceps brachii

C7, C8

Extension at

elbow

Flexor digitorum

C7, C8, T1

Flex distal pha-

profundus I and II

interosseus

langes digits 2

and 3

Lower extremity

Iliopsoas

L2, L3

Femoral and L1,

Thigh flexion

L2, L3 roots

Quadriceps femoris

L3, L4

Femoral

Knee extension

Biceps femoris

L5, S1, S2

Sciatic

Knee flexion

Tibialis anterior

L4, L5

Deep peroneal

Ankle

dorsiflexion

Extensor hallucis

L4, L5

Deep peroneal

Great toes

longus

extension

Gastrocnemius

S1, S2

Tibial

Ankle

plantarflexion

- Reflexes (muscle stretch reflexes, pathologic reflexes, cutane-

ous reflexes, sacral reflexes, and priapism)

• Muscle stretch reflexes are usually graded as shown in Table

7.3. The muscle stretch reflex involved is shown in Table 7.4.

• Babinski sign, Hoffmann sign, and testing for ankle clonus. As-

sessment for long tract signs should be made in all patients to

disclose unsuspected cervical or thoracic myelopathy or other

causes of upper motor neuron deficit.

46 II Clinical Spine Surgery

Table 7.3 Muscle Stretch Reflex (Deep Tendon Reflex) Grading

Scale

Grade

Definition

No contraction (total paralysis)

0.5

Elicitable only with reinforcement*

Low normal

Normal

More brisk than normal (hyperreflexic)

Hyperreflexic with clonus

Sustained clonus

*In the lower extremities, reinforcement consists of having the patient hook the tips

of the fingers of the left hand into the tips of the hooked fingers of the right hand

and pulling (Jendrassik maneuver). Reinforcement in the upper extremities consists of

having the patient clench the teeth.

• Further reflex testing, as indicated, includes abdominal cuta-

neous reflexes, anal wink, and bulbocavernosus.

• Priapism may indicate spinal cord injury.

- Mechanical factors (including observation for cutaneous changes,

pain behaviors, muscle bulk/tone, and provocative maneuvers)

• Gait and station. Casual gait is assessed in all patients to check

balance, weakness that compromises gait, and pain manifes-

tations. Tandem gait and/or the Romberg test can further as-

sess balance and posterior-column (proprioceptive) function.

• Cervical spine

◦ Cervical range of motion and specific levels of tenderness

should be documented to distinguish myofascial from bone-

related factors. Specific facet pain diagram patterns can be

reviewed with the patient to identify problem levels.

◦The Spurling maneuver (axial loading on the vertex of the

head with rotation to one side, repeated with rotation to the

other side) may reproduce cervical nerve root symptoms in

a patient with herniated cervical disc or foraminal stenosis.

◦ Shoulder pathology can often mimic cervical spine pathol-

ogy. Tenderness of the acromioclavicular joint to palpation

or a positive empty-can test suggests primary shoulder pa-

thology as a cause of shoulder pain.

• Lumbar spine

◦ Lumbar range of motion and specific levels of tenderness should

be documented to distinguish myofascial from bone problems.

◦ Nerve root tension signs. “Pull” on the nerve root, which can re-

produce pain in situations where the nerve root is compressed.

7 Physical Examination

Table 7.4 Muscle Stretch Reflexes

Nerve root involved

Corresponding muscle stretch reflex

Deltoid and pectoralis*

Biceps and brachioradialis

Triceps

Finger flexor*

Patellar (knee jerk)

Medial hamstrings*

Achilles (ankle jerk)

*A reflex that is not widely used and may be difficult to elicit.

◦Laségue sign or straight-leg raising (SLR). Supine patient

raises one lower extremity (LE) at a time. Classically positive

findings include pain or paresthesias in the distribution of

the involved nerve root (not just back pain) at less than 60

degrees elevation. In response the patient may lift the hip on

the involved side off the exam table. This procedure helps

to differentiate radiculopathy from hip pathology (e.g., tro-

chanteric bursitis). Positive in 83% of cases with nerve root

compression, it is more sensitive for compression in L5 or S1

than in upper lumbar roots.

◦ Femoral stretch test or reverse straight-leg raising. With pa-

tient prone, the knee is flexed on one side at a time. This

test is more likely to be positive than SLR with upper lumbar

nerve root compression (L2, L3, or L4).

• Hip and sacral pain. It is important to distinguish hip-mediat-

ed pathology and low back pathology.

◦ Palpation over spinous processes, paraspinal muscles, great-

er trochanters (to assess for greater trochanteric bursitis),

and SI joints (Fortin finger test) may suggest sacroiliitis.

◦ FABER (acronym for flexion, abduction, external rotation,

also called the Patrick test) test of the hip with the patient

supine: back pain suggests musculoskeletal lower back or

sacroiliac pain; groin or hip pain suggests hip pathology.

◦ Shear test can help distinguish sacral pain. Patient prone, the

examiner applies pressure to the sacrum while applying a

traction force caudad with the corresponding limb. A test is

positive if it reproduces the patient’s typical pain.

◦ FADIR (acronym for flexion, adduction, internal rotation)

test of the hip with the patient supine can help to distin-

guish piriformis syndrome. Positive reponse: pain reproduc-

48 II Clinical Spine Surgery

tion centered at half the distance between the S3 foramen

and the ipsilateral greater trochanter.

• Vascular considerations: Palpation for pedal pulses to rule out

vascular insufficiency.

III. Clinical Pearls

- Babinski sign or a positive Hoffmann sign: if there is no known

etiology in a given patient, further investigation is required (to

rule out cord compression or brain involvement).

- Cervical radiculopathy does not cause pain with shoulder

abduction.

- Painless weakness in the LE is almost never due to lumbar

nerve root compression. Consider diabetic neuropathy, cervical

spondylotic myelopathy, or motor neuron disease, for example.

Common Clinical Questions

1. A 55-year-old male presents to your clinic with progressive

lower extremity weakness and difficulty ambulating. He brings

with him an MRI that shows grade 1 spondylolisthesis L5-S1

with severe central canal stenosis. Flexion/extension lumbar

spine x-rays show no instability. His exam shows diffuse weak-

ness of the LEs, diffuse reduction of pinprick sensation in the

LEs, reduced Achilles reflexes, and bilateral upgoing toes. Ac-

tions that could be taken include:

1. Decompressive laminectomy L5-S1 with attempt at reduc-

tion with bilateral pedicle screw/rod instrumentation.

2. Lateral interbody fusion L5-S1 with lateral vertebral body

plating.

3. Anterior lumbar interbody fusion with percutaneous L5-S1

pedicle screw/rod instrumentation.

4. MRI of the thoracic and cervical spine.

The appropriate options to take at this time are:

A. 1 and 3

B. 2 and 3

C. 1, 2, and 3

D. 4

7 Physical Examination

2. A patient presents with a 2-month history of left UE pain radi-

ating to the thumb and index finger that has not responded to

conservative therapy. He has a positive Spurling sign with the

head turned to the left. Strength is normal. Reflexes are normal

except for a reduction in the left biceps. An MRI of the cervi-

cal spine shows disc degeneration with protrusion into the left

neural foramen at both C5-6 and C6-7. Flexion/extension cer-

vical spine x-rays are without instability. After providing in-

formed consent, he indicates he wishes to proceed with surgical

treatment. Appropriate surgical options include the following

except:

A. ACDF C5-6

B. ACDF C5-6 and C6-7

C. ACDF C6-7

D. Cervical disc arthroplasty C5-6

3. A 60-year-old male has diffuse weakness of the UEs with re-

duced reflexes, and hyperreflexia in the LEs with bilateral upgo-

ing toes. Etiologies that could be considered include:

1. Cervical spine stenosis.

2. Left C5-6 foraminal herniated cervical disc.

3. Motor neuron disease (amyotrophic lateral sclerosis).

4. Coincident severe lumbar and cervical spinal stenosis.

From the above list, appropriate diagnoses for this patient are:

A. 1 and 3

B. 2 and 4

C. 1, 2, and 3

D. 4

References

1. Greenberg MS. Handbook of Neurosurgery. 7th ed. New York: Thieme Medi-

cal Publishers; 2010

2. Aids to the Examination of the Peripheral Nervous System. 4th ed. Edinburgh:

W.B. Saunders On Behalf Of The Guarantors of Brain; 2000

3. Malanga G, Nadler S. Musculoskeletal Physical Examination: An Evidence-

Based Approach. Philadelphia, PA: Elsevier Mosby; 2006

50 II Clinical Spine Surgery

Answers to Common Clinical Questions

1. D. Upgoing toes and diffues LE weakness and hypalgesia are

never caused by compromise at L5-S1. MRI to look for cord com-

pression above the lumbar spine is appropriate.

2. C. The sensory changes and reflex changes indicate that the C6

nerve root is involved, which implicates the disc at C5-6. Some

surgeons would also treat the disc at C6-7 at the same time

since it may deteriorate rapidly following fusion of C5-6, and

some would perform arthroplasty at C5-6 in order to try and

shield the disc at C6-7 from some of the forces that would occur

with C5-6 fusion. Operating on C6-7 alone is inappropriate since

this is currently not a symptomatic level.

3. A. Both cervical spinal stenosis and ALS can produce lower mo-

tor neuron findings in the UEs and lower motor neuron findings

in the LEs. A unilateral foraminal herniated cervical disc will

not cause this. In coincidental lumbar and spinal stenosis, the

lumbar stenosis generally masks the hyperreflexia in the lower

extremities.

8 Spinal Imaging

Ishaq Y. Syed, Barrett I. Woods, and Joon Y. Lee

I. Key Points

- A complete history and physical should be the initial step in

evaluating a patient to formulate a preliminary clinical diagno-

sis and to select the appropriate imaging modality.

- Findings on imaging exams must be clinically correlated to pre-

vent a high false-positive rate.

- Multiple imaging modalities are available to supplement eval-

uation of spinal pathology, to confirm diagnosis, and to guide

treatment.

II. Description

- Plain radiographs

• Convenient, universally available, and inexpensive

• Initial imaging modality for degenerative disorders, defor-

mity, trauma, neoplasm, and infection (for spinal deformity,

consider 36 in long-cassette standing x-rays)

• Limited ability to define subtle bony pathology and at least 30

to 40% bone loss needed for detection on plain radiographs

• Inability to directly visualize neural structures and allow bone

and soft tissue discrimination

• Appropriately timed dynamic radiographs may help assess in-

stability and the presence of spondylolisthesis.

◦ Important in evaluation of patients in the postoperative pe-

riod to assess instrumentation and successful arthrodesis

- Computed tomography (CT)

• Provides optimal visualization of bony detail and high sensi-

tivity in detecting fractures, with accuracy rates ranging from

72 to 91% (Fig 8.1)

• Can help distinguish neural compression due to soft tissue

versus bony pathology

• CT scan alone is limited in visualization of neural structures

and demonstration of intrathecal and soft tissue pathology.

• For optimal bony detail, multiple thin cuts (1.5 to 3 mm) can

be obtained with the gantry parallel to the plane of the disc.

• Multirow detector rapid thin-slice acquisitions allow contigu-

ous 3 mm slices to be obtained from L1 to S1 in less than 30

seconds.

52 II Clinical Spine Surgery

• Cognizance of radiation exposure to patients is essential.

- Myelography

• Intrathechal water-soluble contrast material mixes with cere-

bral spinal fluid and outlines the dural sac.

• Diagnosis is indirectly inferrable from changes in the contour

of the contrast agent-filled thecal sac.

• Compression is demonstrated by extradural impression on the

dye column and filling defects of the nerve root sleeve (Fig. 8.2).

• CT myelography improves visualization of foraminal and lat-

eral recess stenosis with axial and reconstructed images.

• Advantageous in patients with stainless steel implants that

cause significant metal artifact with MRI and patients with

implantable devices (e.g., pacemaker) who cannot obtain

MRI, and in evaluating fusion in postoperative patients with

suspected nonunion

• Disadvantages of myelography include invasiveness and lack

of diagnostic specificity.

- Magnetic resonance imaging (MRI)¹

• The imaging modality of choice for the majority of spinal pathology

Fig. 8.2 Lateral plain radiograph af-

Fig.

8.1 Sagittal CT scan image dem-

ter intrathecal contrast demonstrat-

onstrates C5-6 perched fracture facet

ing complete block due to massive

dislocation.

central herniated disc.

8 Spinal Imaging

• Enhanced, noninvasive depiction of soft tissue pathology,

including hematoma, infection, tumor, and ligamentous dis-

ruption, and identification of compression of neural elements

(Fig 8.3)

• Utilizes pulsed radiofrequency (RF) and requires no radiation

exposure

• T1-weighted images

◦ Short repetition time (TR), 400 to 600 ms; echo time (TE), 5

to 30 ms

◦ MRI findings: cortical bone, low; free water, low; adipose,

high

• T2-weighted images

◦TR = 1500 to 3000 ms, TE = 50 to 120 ms

◦ MRI findings: cortical bone, low; free water, high; adipose, low

• Gadolinium contrast can help distinguish postoperative scar

(vascular, enhances) from recurrent disc herniation (avascu-

lar, does not enhance) on T1-weighted sequence images.

• Contrast may also be helpful in detecting tumor and infection.²

◦ Infection: decreased signal on T1, increased signal on T2, en-

hancement with gadolinium, and often involves disc space

◦ Tumor: intervertebral disc often spared, similar homoge-

neous changes present involving entire vertebral body. With

metatastic disease, may show multiple noncontiguous ver-

tebral bodies involved, indicating skip lesions and involve-

ment of the pedicle.

• Spinal cord injury

◦ Quantifies degree of spinal cord compression and injury

Fig.

8.3 Sagittal T2-weighted

MRI image of the lumbar spine

demonstrates large dorsal ab-

scess causing severe compres-

sion of the neural elements at

L4-5.

II Clinical Spine Surgery

◦ High sensitivity in identifying ligamentous injury, including

status of the posterior ligamentous complex, that may oth-

erwise be missed on plain radiographs or CT

◦ Helps distinguish spinal cord edema (T1 low, T2 high) from

hemorrhage (T1 high, T2 high)

• Disc degeneration

◦ Advanced imaging should be reserved for patients with true

radicular symptoms, with objective evidence of root irrita-

tion on examination, who have failed an appropriate course

of conservative nonoperative management.

◦ High-intensity zone (HIZ): radial tear of the posterior an-

nulus, fissure extending from nucleus to the periphery, un-

known clinical significance

◦ Herniated disc can be found in 21% of asymptomatic indi-

viduals between the ages of 20 and 39 years.

◦ Disc herniation nomenclature³:

▪Protrusion: Herniation that maintains contact with the disc

of origin with a bridge as wide as or wider than the diam-

eter of the displaced material

▪Extruded: Diameter of the disc material beyond the inter-

space is greater than the width of the bridge that may or

may not connect to the disc of origin.

▪Sequestered: An extrusion that is no longer contiguous with

the disc of origin

◦ Degenerative changes in the cervical and lumbar spine are

age related and equally present in asymptomatic and symp-

tomatic individuals.

◦ MRI findings must be strictly correlated with the clinical

presentation.

◦ Modic end plate changes²:

▪Type 1

▫T1 low, T2 high

▫Associated with segmental spine instability and pain

▪Type 2

▫T1 high, T2 normal

▫More common than type 1, and may be less symptomatic

▪Type 3

▫T1 low, T2 low

▫Indicative of advanced degeneration and sclerosis with

less segmental instability

• Poor imaging will result from metal artifact from implants

unless specific techniques are used (plastic < titanium < tan-

talum < stainless steel < cobalt chrome).

• Contraindications: pacemaker, inner ear implant, metal de-

bris in the eye, ferrous metal implant in the brain

8 Spinal Imaging

- Bone scintigraphy

• Standard part of workup for assessing metastatic bone disease

(monostotic versus polyostotic). Helps point to area for more

advanced imaging and evaluation.

• May be of value in distinguishing acute and chronic pars in-

terarticularis fractures

III. Surgical Pearls

- Prior to obtaining any advanced imaging, a clear plan must be

established for how the results will be utilized to facilitate the

next line of treatment.

- A clinical diagnosis should be established based on a complete

history and physical and correlated with findings on imaging

prior to instituting a surgical or nonoperative treatment plan.

- Advanced imaging can be invaluable in confirming diagnosis

and identifying treatment that has the best chance of clinical

success.

Common Clinical Questions

1. A 57-year-old female presents with one week of intractable back

pain, fever, chills, positive blood cultures, and elevated inflam-

matory markers. There is concern over discitis in the thoraco-

lumbar region. MRI will likely show:

A. Increased T1 signal and decreased T2 signal with disc space

involvement

B. Increased T1 signal, decreased T2 signal without disc space

involvement

C. Increased T2 signal and decreased T1 signal with disc space

involvement

D. Increased T2 signal and decreased T1 signal without disc

space involvement

E. Increased T2 signal and increased T1 signal with disc space

involvement

56 II Clinical Spine Surgery

2. Which of the following statements regarding spinal imaging is

true?

A. Adipose tissue causes a low-intensity signal on T1-weighted

sequences and a high-intensity signal on T2-weighted

images.

B. The presence of HIZ has been correlated with the presence of

symptomatic back pain.

C. As the patient ages the sensitivity and specificity of imaging

modalities such as CT and MRI improve.

D. Spinal cord edema can be distinguished from hemorrhage

via a low-intensity signal on T1-weighted images and a high-

intensity signal on T2-weighted images.

E. Benign Modic changes are characterized by a low-intensity

signal on both T1- and T2-weighted images.

3. What is the best imaging modality for studying the bony anatomy

preoperatively?

4. What is the appropriate initial radiographic study for spinal

deformity?

References

1. Herkowitz HN, Rothman RH, Simeone FA. Rothman-Simeone: The Spine. 5th

ed. Philadelphia, PA: Saunders Elsevier; 2006

2. Modic MT, Ross JS. Lumbar degenerative disk disease. Radiology 2007;245(1):

43-61

3. Fardon DF, Milette PC; Combined Task Forces of the North American Spine

Society, American Society of Spine Radiology, and American Society of Neu-

roradiology. Nomenclature and classification of lumbar disc pathology. Rec-

ommendations of the Combined Task Forces of the North American Spine

Society, American Society of Spine Radiology, and American Society of Neu-

roradiology. Spine (Phila Pa 1976) 2001;26(5):E93-E113

Answers to Common Clinical Questions

1. C

2. D

3. Thin-slice CT of the pertinent region

4. 36 in long-cassette standing x-ray

9 Neurophysiologic Monitoring in Spine Surgery

Glen Aaron Pollock, Naomi Abel, and Fernando L. Vale

I. Key Points

- Somatosensory evoked potentials (SSEPs). Monitor the electro-

physiologic integrity of the dorsal column-medial lemniscus

pathway. The vascular supply of this tract in the spinal cord is

predominantly from the paired posterior spinal arteries. Taken

as a single modality, SSEPs monitor only the dorsal aspect of

the spinal cord.

- Motor evoked potentials (MEPs). Monitor the electrophysi-

ologic integrity of the corticospinal tract. The vascular supply

of this tract in the spinal cord is from the single anterior spinal

artery. MEPs monitor tracts in the ventral aspect of the spinal

cord.

- Spontaneous electromyography

(sEMG). The measurement

of spontaneous electrical activity within a specific monitored

muscle. Reflects neurotonic discharges within the muscle

caused by mechanical, thermal, or metabolic irritation of the

nerve or nerve root. Useful for monitoring nerve roots and pe-

ripheral nerves.

- Triggered electromyography

(tEMG). The measurement of

electrical activity within a specific muscle caused by electrical

stimulation of the nerve, usually by stimulation of a structure

in proximity to the nerve, such as the pedicle, by way of pedicle

screw stimulation, to evaluate for disruption of the pedicle wall.

Also allows discrimination of nervous tissue from non-nervous

tissue during surgery for spinal cord tumors or the release of

tethered spinal cord.

II. Essentials of Neuromonitoring

- SSEPs

• The stimulation of mixed sensory and motor fibers caudal to

the region of the spinal cord at risk, together with the record-

ing of signals rostral to the region of spinal cord at risk. The

most commonly stimulated nerves are the median and ulnar

nerves for the upper extremity and the posterior tibial and

peroneal nerves for the lower extremity. Responses are then

monitored over the dorsal neck and scalp.

II Clinical Spine Surgery

◦ Technique

▪Electrodes are placed over the ulnar nerve at the wrist and

the posterior tibial nerve at the level of the medial malleolus.

▪One method involves a constant current of 15 to 25 mA

for the ulnar nerve and 25 to 35 mA for the posterior tib-

ial nerve, provided via a square wave pulse of around 4.7

times per second. The duration of the pulse is between 10

ms and 2 ms.¹ The intensity of stimulation is based on the

maximal-amplitude response for a given patient.

▪Averaging of signals continues until a clear, reproducible

waveform is identified. Supramaximal stimulation results

in the activation of axons of both the dorsal column and

spinothalamic pathways.

▪The largest contribution to the signal is from the dorsal col-

umn due to the presence of the A-a and A-b fibers, the larg-

est and fastest-conducting of the sensory fibers.

▪Baseline recordings are obtained and evaluated immediate-

ly after the induction of anesthesia but prior to positioning.

SSEPs are assessed again after positioning and every few

minutes thereafter until completion of the surgery.

▪Alarm criteria are a 50% or greater decrease in amplitude

and/or a 10% increase in latency.²

▪Advantage

▫Allows continuous monitoring of spinal cord integrity

▪Disadvantages

▫Delay in assessment caused by signal averaging

▫Assesses only sensory pathways (predominantly dorsal

column-medial lemniscus)

▫Not sensitive to indicators of motor pathway or nerve root

injury

▫Susceptible to signal degradation due to halogenated an-

esthetics, nitrous oxide, hypotension, and hypothermia

▫Signals undergo central amplification and can retain am-

plitude despite nerve root injury

◦ Technical pearls

▪SSEPs can be recorded from cortical or subcortical sources.

Cortical sources have larger amplitude and may supply the

only response when there is previous root damage; how-

ever, they are more susceptible to the effects of inhaled

anesthetics.

▪Recordings at the level of the medulla reflect the nucleus

gracilis and cuneatus with no intervening synapses be-

tween the sites of stimulation and recording. These record-

ings are more resistant to the effects of anesthetic agents.

9 Neurophysiologic Monitoring in Spine Surgery

▪Detailed examination of the dorsal column pathway prior

to surgery should be performed because prior deficits can

affect the ability to record accurate signals. This should in-

clude assessment of two-point discrimination, vibration,

and position sense.

▪Alterations in anesthetic depth can affect the ability to ob-

tain useful signals. This problem is minimized by the use of

raw electroencephalography (EEG) by the anesthesia team

to monitor anesthetic depth.

- MEPs

• Involve the transcranial stimulation of the corticospinal path-

way with assessment of compound motor action potential at

the level of the innervated muscle

◦ Technique

▪Subdermal needle electrodes or electrode discs in con-

tact with the skin are used for transcranial electrical

stimulation.

▪Multipulse electrical current of 200 to 500 V is delivered

using five to nine pulses 1.1 to 4.1 ms apart with pulse

trains lasting around

50 ms.³ The resulting compound

motor action potential (CMAP) at the level of the muscle

is of high enough amplitude that signal averaging is not

required. The resultant descending excitation of the cor-

ticospinal pathway and its generation of a CMAP is then de-

tected via surface electrodes on the skin over the selected

muscle groups or via the subdermal needle electrodes.

▪There are three types of monitoring options: recording at

the muscle (CMAP), nerve (neurogenic MEP, CNAP), or di-

rect spinal cord recording (D wave and I wave). The most

frequently used monitoring utilizes electrodes at the level

of specific muscle groups.

▪Interpretation of the response is based on the prelimi-

nary baseline; warning signs include a complete loss of

response, a decrease in amplitude greater than 80%, an

increase in threshold of greater than 100 V to elicit the

CMAP response, and changes in the morphology of the re-

sponse. The “all or nothing” response and the 80% decrease

in amplitude are the two most commonly used methods of

interpretation.²

◦ Advantages

▪Allows assessment of corticospinal tracts

▪Allows for the option of increasing stimulation intensity

to increase the size of the current field, increasing the

distribution of stimulation to the cortex and subcortical

II Clinical Spine Surgery

fibers. This correlates with greater axonal recruitment to

overcome low signal response in patients with preexisting

deficits.

▪Stimulation trains can be used to increase the tempo-

ral summation at the level of the a motoneuron, thereby

increasing the likelihood of achieving a response when

pathologic conditions exist.

◦ Disadvantages

▪MEPs do not allow for continuous monitoring.

▪MEPs cause muscle contraction during surgery, so the sur-

gical team must be informed prior to each round of testing.

Tongue laceration may result from forced contraction of fa-

cial muscles, requiring the placement of a bite block.

▪Obtaining MEPs is more technically demanding and has a

lower success rate compared with SSEPs. Preexisting mo-

tor deficits significantly reduce the likelihood of obtaining

useful signals, especially from the lower extremities.

▪Inhalant anesthetics decrease the pool of a motoneurons

available for recruitment. Higher doses of propofol can

cause suppression of a motoneurons. MEPs are affected by

muscle relaxants, volatile anesthetics, and nitrous oxide.

MEPs are also subject to anesthetic fade, which results in

the need for increasing stimulation thresholds to achieve

the same response in patients with prolonged exposure to

anesthetic agents unrelated to dose effects.

▪MEPs are contraindicated in patients with deep brain stim-

ulators or cochlear implants.

▪There is a slight risk of seizures with transcranial stimula-

tion, although it has been estimated at less than 0.03%.³

◦ Technical pearls

▪Minimize the use of inhalant anesthetics by selecting intra-

venous anesthesia regimens. MEPs are typically obtainable

when less than half the minimum alveolar concentration

(MAC) of inhaled anesthetic is used.

▪Alterations in anesthetic depth can affect the ability to

obtain useful signals. This can be minimized by the use of

bispectral index (BIS) EEG monitoring by the anesthesia

team.

- Electromyography (EMG) is the measurement of electrical ac-

tivity within a specific muscle.

• In sEMG, neurotonic discharges result in electrical activity

within the innervated muscle as a result of pulling, stretching,

9 Neurophysiologic Monitoring in Spine Surgery

or compression of the nerve or nerve root without any electri-

cal stimulation by the surgeon.

◦ Technique

▪Electrodes are placed in muscle of interest based on the in-

nervating nerve root.

▪Manipulation of a nerve root or peripheral nerve results

in an action potential that causes depolarization of the

muscle at the neuromuscular junction, resulting in a CMAP.

▪Allows for assessment of electrical discharges within the

innervated muscle that indirectly monitors the nerve root

at risk

▪Electrical discharges of interest manifest as spikes, bursts,

or trains. Trains are of concern during sEMG because they

are a continuous run of neurotonic discharges that repre-

sent continued force on the nerve or nerve root. Spikes and

bursts are discharges that can alert the surgeon to close

proximity to the nerve root or nerve. The surgeon should

also be alerted when trains of activity are observed.

▪Increasing frequency and amplitude of discharges repre-

sent increasing recruitment of muscle fibers with an in-

creasing chance of nerve injury. Muscles for monitoring

are chosen by the corresponding nerve root to maximize

coverage based on the operated spinal level. This utilizes

the anatomic redundancy of muscle innervation.

◦ Advantages

▪Allows for continuous monitoring of the nerve root or pe-

ripheral nerve

▪Can serve as a warning of close proximity to the nerve root

during retraction or manipulation when there is no direct

visualization

◦ Disadvantages

▪sEMG is subject to interference from high-speed drills, EEG

leads, cautery devices, and other equipment.

▪Underlying neurologic conditions can affect the ability to

obtain useful EMG signals, especially conditions affecting

the muscle directly, such as myasthenia gravis, previous

botulinum toxin therapy, or muscular dystrophy.

▪sEMG discharges serve as a warning since many innocent

surgical maneuvers can produce discharges of the nerve

root or nerve.

▪The absence of recorded muscle activity does not guaran-

tee nerve integrity since acute nerve transection or avul-

sion may result in a loss of nerve-derived signals.

II Clinical Spine Surgery

◦ Technical pearls

▪sEMG does not allow the use of muscle relaxants or para-

lytics during surgery. Patient must show at least three out

of four twitches for reliable monitoring.

▪To increase the ability to detect potential nerve root injury,

multiple muscles with overlapping nerve root innervation

are monitored for common injury levels. For example, the

C5 nerve root in the cervical spine is assessed by concurrent

monitoring of the deltoid and the biceps brachii muscles.

• tEMG. The measurement of electrical discharges within a giv-

en muscle as a result of electrical stimulation of the nerve root

or peripheral nerve within the surgical field. A nerve root or

nerve is stimulated, resulting in an action potential that causes

depolarization of the muscle at the neuromuscular junction,

in turn resulting in a CMAP in the innervated muscle. This is a

useful technique to identify the course or location of nerves,

demonstrate functional integrity, and identify tissue as nerve

or not nerve.

◦ Technique

▪Tissue can be stimulated directly by a probe in attempting

to identify nerve versus other tissue or tumor. This tech-

nique is useful in spinal cord tumor resection as well as in

surgery to relieve tethering of the spinal cord.

▪Pedicle screw stimulation is the most commonly employed

technique during spinal surgery. This involves direct stimu-

lation of a screw to identify breach of the bony cortex. This

leads to indirect stimulation of the nerve root and a CMAP

recorded in the corresponding muscle. An intact pedicle

will have a greater electrical resistance to current, requir-

ing greater levels of stimulation to achieve a response in

the specified muscle. If the cortex of the pedicle is violated,

the current will take the path of least resistance and lower

levels of stimulation will be needed to result in a CMAP.

▪Lumbar spine stimulus values less than 10 to 11 mA and

thoracic spine stimulus values below 6 to 8 mA are associ-

ated with pedicle cortical bone violation. Cervical stimulus

values below 10 mA are associated with cortical bone vio-

lation and screw malposition.²

◦ Advantages

▪Allows for assessment of screw placement during surgery

▪Allows for identification of lumbosacral nerve roots during

surgery for tethered cord and may alter surgical strategy in

up to 50% of cases⁴

9 Neurophysiologic Monitoring in Spine Surgery

▪Redirection of screws often closes off the cortical breach

with bony fragments, resulting in useful information when

the same pedicle screw is stimulated after repositioning.

◦ Disadvantages

▪Subject to the same interference and signal degradation as

sEMG

◦ Technical pearls

▪This technique does not allow the use of muscle relaxants

or paralytics during surgery. The patient must display at

least three out of four twitches for reliable monitoring.

▪During pedicle screw stimulation the screw itself must be

stimulated as opposed to the tulip; tulips are often made of

different materials, and stimulation of the tulip may lead to

false-negative assessment.

▪It is not typically possible to stimulate percutaneously

placed pedicle screws. The metallic screw extensions do

not allow for accurate EMG thresholds. Instead, stimulation

is performed on a sheathed tap (a metallic tapping instru-

ment housed in a plastic sheath) placed into the pedicle

prior to placing of the screw.

III. Practical Issues and Outcomes during Monitoring for

Spinal Surgery

The goal of intraoperative monitoring of the nervous system is to

prevent injury during surgical treatment of spinal disease. This is

often best accomplished by the use of multiple monitoring modali-

ties so that the most complete assessment of neurologic functional

integrity of the neural tissues applicable to the specific procedure is

obtained. SSEPs are used to monitor the dorsal column-medial lem-

niscus pathway, MEPS are used to monitor the corticospinal path-

way, and free-run sEMG is used for the assessment of the nerve roots

and peripheral nerves. tEMG is used to assess screw placement or to

guide resection of tumors or the filum terminale.

- Cervical spinal surgery. Spinal cord integrity is of major impor-

tance, so the combination of SSEPs and MEPs is used to assess

for injury to the cord itself. If nerve root injury is of concern,

sEMG can be added for additional safety. Although SSEPs as a

single monitoring modality have a relatively low sensitivity,

this is due to the fact that they do not assess the ventral cord

or corticospinal tracts. Sensitivity and specificity of SSEPs have

been reported as 52% and 100%, respectively, and sensitivity

and specificity for MEPs were reported as 100% and 96% in the

64 II Clinical Spine Surgery

same study,⁵ suggesting that combined MEP and SSEP monitor-

ing is the most comprehensive method of detecting neurologic

injury of the spinal cord.

- Thoracic spinal surgery. Spinal cord integrity is the major con-

cern, especially in light of the vulnerable blood supply to the

mid-thoracic region. SSEPs and MEPs, when combined, provide

assessment of the functional integrity of the spinal cord at this

level with relatively high sensitivity and specificity.

- Lumbar spinal surgery. Below the level of the conus the nerve

roots are the primary structures at risk, and sEMG and tEMG

in combination with SSEPs provide assessment of the nerve

root integrity. There is evidence to support multimodality

monitoring with SSEPs and EMG, as this combination leads to

an increase in sensitivity and specificity. One study reported a

sensitivity and specificity of 28.6% and 94.7%, respectively, for

SSEPs, compared with 100% and 23.7% for sEMG, in monitoring

for neurologic injury during lumbosacral spinal surgery.⁶

- Surgery for tethered spinal cord. The success of detethering de-

pends on the accurate identification of the lumbosacral nerve

roots. This can be accomplished with multimodality monitor-

ing. SSEPs have a very high specificity with the addition of

sEMG and tEMG to compensate for the low sensitivity of SSEPs

alone. Together, SSEPs, sEMG, and tEMG can provide near 100%

specificity and sensitivity.⁴ Also, the urethral and anal sphinc-

ters can be directly monitored with EMG.

- Surgery for intramedullary spinal cord tumor. As with other

surgeries in the cervical or thoracic spine, spinal cord integ-

rity is the major concern here. Multimodality monitoring with

SSEPs, MEPs, and both sEMG and tEMG can be used for the high-

est level of safety. Muscle and D wave MEPs have been shown to

have a high degree of correlation with absence versus presence

of postoperative motor deficits⁷ in spinal cord tumor surgery.

Common Clinical Questions

1. What neuromonitoring modalities are necessary for complete

coverage of the spinal cord during surgery on thoracic levels?

2. Which neuromonitoring modality does not display a significant

delay in obtaining signals?

3. Which modalities allow for continuous monitoring?

9 Neurophysiologic Monitoring in Spine Surgery

References

1. Chiappa K. Short Latency Somatosensory Evoked Potentials: Methodology.

Philadelphia, PA: Lippincott-Raven; 1997

2. Gonzalez AA, Jeyanandarajan D, Hansen C, Zada G, Hsieh PC. Intraoperative

neurophysiological monitoring during spine surgery: a review. Neurosurg

Focus 2009;27(4):E6

3. Cros DaC K. Motor Evoked Potentials. In: Chiappa K, ed. Evoked Potentials in

Clinical Medicine. 3rd ed. Philadelphia, PA: Lippincott-Raven; 1997

4. Paradiso G, Lee GY, Sarjeant R, Hoang L, Massicotte EM, Fehlings MG. Multi-

modality intraoperative neurophysiologic monitoring findings during sur-

gery for adult tethered cord syndrome: analysis of a series of 44 patients

with long-term follow-up. Spine (Phila Pa 1976) 2006;31(18):2095-2102

5. Kelleher MO, Tan G, Sarjeant R, Fehlings MG. Predictive value of intraoperative

neurophysiological monitoring during cervical spine surgery: a prospective

analysis of 1055 consecutive patients. J Neurosurg Spine 2008;8(3):215-221

6. Gunnarsson T, Krassioukov AV, Sarjeant R, Fehlings MG. Real-time continu-

ous intraoperative electromyographic and somatosensory evoked potential

recordings in spinal surgery: correlation of clinical and electrophysiologic

findings in a prospective, consecutive series of 213 cases. Spine (Phila Pa

1976) 2004;29(6):677-684

7. Kothbauer KF, Deletis V, Epstein FJ. Motor-evoked potential monitoring for

intramedullary spinal cord tumor surgery: correlation of clinical and neu-

rophysiological data in a series of 100 consecutive procedures. Neurosurg

Focus 1998;4(5):e1

Answers to Common Clinical Questions

1. MEPs and SSEPs are monitored to cover the dorsal aspect of the

spinal cord (dorsal columns) and the ventral aspect of the spinal

cord by monitoring the corticospinal tracts.

2. There is no significant delay in obtaining MEPs because they do

not require signal averaging.

3. EMG and SSEPs both allow for continuous monitoring.

10 Pharmacology

Mark S. Greenberg

I. Key Points

- Treating pain early with effective doses results in overall reduc-

tion in the consumption of pain meds.

- Adjuncts to opioids for pain: NSAIDs, muscle relaxants, acet-

aminophen, Tramadol (not a conventional opioid), and cen-

trally acting pain meds (e.g., gabapentin) for neuropathic pain.

- Use of steroids for spinal cord injury remains controversial, but

benefits probably do not outweigh risks.

- Deep vein thrombosis (DVT) prophylaxis in spinal cord injury is

critical. If prophylactic anticoagulation is contraindicated, then

a vena cava interruption filter should be considered.

II. Pain Medication^1,2

- Nonopioid analgesics

• Acetaminophen (APAP)

◦ An effective pain medication that does not inhibit peripheral

cyclooxygenase activity, and is therefore not associated with

altered platelet function, bronchospasm, or gastric ulceration

◦ Potentiates narcotic pain medication and NSAIDs

◦The main hazard is hepatic toxicity. Use with caution with

active liver disease, with chronic heavy alcohol consump-

tion, and with glucose-6 dehydrogenase deficiency.

• Nonsteroidal antiinflammatory drugs (NSAIDs)

◦ Antiinflammatory and antipyretic

◦ Single PRN doses are effective against pain even without

“antiinflammatory dosing.”

◦ Adverse effects include reduction of renal blood flow, plate-

let function inhibition (permanent with aspirin, temporary

with other NSAIDs), and peptic ulcers. Deleterious effect on

bone healing is controversial; many surgeons hold off on

NSAIDs for two weeks following fusion (a longer hiatus is

not appropriate).

◦ Examples of NSAIDs are naproxen (Naprosyn), diclofenac

(Voltaren), and ketorolac tromethamine (Toradol). They can

be given parenterally (parenteral use should not exceed 3 to

5 days). Oral dosing should be done only as continuation of

parenteral dosing, not for routine use as an NSAID.

10 Pharmacology

- Opioid analgesics

• No single agent has been shown to be most effective or best toler-

ated as a rule, although individual differences may make certain

opioids more effective in certain patients. Exception: meperidine

has multiple disadvantages and has limited usefulness.

• All produce dose-related respiratory depression. Some lower

the seizure threshold. Diversion of prescribed narcotics to sale

on the street for recreational use is a burgeoning problem.

• With chronic use, tolerance develops. All may be habit

forming.

• Dosing depends more on age and prior narcotic use than on

body weight.

- Weak opioids, for mild to moderate pain

• Codeine is typically prescribed in combination with APAP. It is

associated with a significant incidence of nausea and vomiting.

• Hydrocodone is available only as a combination drug (e.g.,

with APAP in Vicodin and Lortab or with ibuprofen in Vi-

coprofen) in the United States.

- Opioids for moderate to severe pain

• Oral: oxycodone with acetaminophen (Percocet)

• Parenteral (intramuscular [IM] or intravenous [IV]): mor-

phine, hydromorphone (Dilaudid). Monitor for respiratory

depression. May be used for patient-controlled analgesia

(PCA).

III. Anticoagulation

- Prophylactic anticoagulation

• For patients without risk factors for blood clots, prophy-

lactic anticoagulation for elective spine surgery is not

recommended.³

• For spinal cord injuries,⁴ prophylaxis with either

◦Low-molecular-weight heparin (LMWH), a rotating bed, ad-

justed-dose heparin, or some combination of these, or

◦Low-dose (mini-dose) heparin with pneumatic compression

stockings or electrical stimulation.

- Treatment for documented DVT or pulmonary embolism (PE)

• Therapeutic anticoagulation with heparin transitioned to

warfarin

• Postoperatively: in the first week or two after spinal surgery, be-

cause of the risk of spinal hematoma, a vena cava interruption

filter is preferred for DVT/PE. But for acute myocardial infarction

or cardiac ischemia, therapeutic heparin may have to be used;

in this case, monitor patient’s neurologic signs frequently.

68 II Clinical Spine Surgery

IV. Steroids

- Acute nerve injury

- Spinal cord injury protocol still controversial

• The assertion: administration of methylprednisolone accord-

ing to protocol within 8 hours of a spinal cord injury (SCI)

(complete or incomplete) benefits sensory and motor func-

tion at 6 weeks, 6 months, and 1 year.^5,6

• The controversy: results could not be replicated,⁷ steroid-

induced myopathy might have produced a transient initial

worsening that was misinterpreted as an improvement when

it subsided,⁸ and the risk of side effects (infectious and diabe-

togenic) is substantial.⁹

• Protocol: within 8 hours of SCI, bolus with methylpredniso-

lone 30 mg/kg IV over 15 minutes, wait 45 minutes, then start

a maintenance infusion of 5.4 mg/kg/h typically maintained for

23 hours. Do not start the protocol more than 8 hours postinjury.

• Spine tumors: for acute symptoms of spinal cord compression

from metastatic tumor, decadron 10 mg IV or orally every 6

hours for 72 hours, followed by 4 to 6 mg every 6 hours.

- Epidural steroids

• Perioperative epidural steroids after routine surgery for lumbar

degenerative disease may result in a small reduction of postop-

erative pain and length of stay, and increased risk of not return-

ing to work after one year,¹⁰ but most of the evidence originates

from studies not using validated outcome assessment and that

favor positive results, and further study is recommended (vari-

ous agents, dosages, and delivery methods were reported).

• As part of pain management

◦ Chronic low back pain: not recommended¹¹; may be used to

provide temporary relief in select cases

◦ Acute radiculopathy: prospective studies show varying

efficacy¹²

- Low back pain: oral steroids (e.g., steroid dose pack) may pro-

vide temporary improvement in symptoms; however, no differ-

ence from placebo is found at 1 week or 1 year follow-up. Use

caution when combining with NSAIDs because of gastrointes-

tinal (GI) irritation.

V. Muscle Relaxants

- Oral and IV agents used for low back pain have no activity at the

neuromuscular junction. They do exhibit some centrally act-

ing analgesic effect that appears to be independent of muscle

10 Pharmacology

spasms. The most consistent effect of these drugs is drowsiness/

sedation, which may help the patient rest. Tolerance develops.

- Commonly employed agents include cyclobenzaprine (Flexer-

il), diazepam (Valium), tizanidine (Zanaflex), and carisoprodol

(Soma).

VI. Clinical Pearls

- Pain medication: early treatment with effective doses before

pain becomes severe reduces the total quantity of medication

needed to control the pain.

Common Clinical Questions

1. Of the following options for DVT prophylaxis in spinal cord injury,

1. Low-dose (mini-dose) heparin alone

2. Low-molecular-weight heparin alone

3. Oral anticoagulation alone

4. Low-dose heparin and pneumatic compression device

which are recommended treatments?

A. 1 and 3

B. 2 and 4

C. 1, 2, and 3

D. 4

2. Which of the following drugs or classes of drugs causes a reduc-

tion in renal blood flow?

A. NSAIDs

B. Opioids

C. Heparin

D. Acetaminophen

3. Which of the following statements about the high-dose methyl-

prednisolone protocol for use in spinal cord injury is false?

A. Administration should not be undertaken more than 8 hours

after the injury.

B. The apparent benefit of methylprednisolone may have been

due in part to patients recovering from steroid-induced

myopathy.

C. The number of studies that have shown a benefit from em-

ploying the protocol are almost equal to the number showing

lack of benefit.

D. Risks of high-dose methylprednisolone include sepsis, pneu-

monia, and deleterious effects of elevated blood glucose.

70 II Clinical Spine Surgery

References

1. Australian and New Zealand College of Anaesthestists and Faculty of Pain Medi-

cine. Acute Pain Management: Scientific Basis. 2nd ed. Australian and New

Zealand College of Anaesthetists; 2005. Date accessed: March 4, 2010. URL:

http://www.nhmrc.gov.au/_files_nhmrc/file/publications/synopses/cp104.pdf

2. Greenberg MS. Handbook of Neurosurgery. 7th ed. New York: Thieme Medi-

cal Publishers; 2010

3. Hamilton MG, Hull RD, Pineo GF. Venous thromboembolism in neurosurgery

and neurology patients: a review. Neurosurgery 1994;34(2):280-296, dis-

cussion 296

4. Deep venous thrombosis and thromboembolism in patients with cervical

spinal cord injuries. Neurosurgery 2002;50(3, Suppl):S73-S80

5. Bracken MB, Shepard MJ, Collins WF, et al. A randomized, controlled trial

of methylprednisolone or naloxone in the treatment of acute spinal-cord

injury. Results of the Second National Acute Spinal Cord Injury Study. N Engl

J Med 1990;322(20):1405-1411

6. Bracken MB, Shepard MJ, Collins WF Jr, et al. Methylprednisolone or nal-

oxone treatment after acute spinal cord injury: 1-year follow-up data. Re-

sults of the Second National Acute Spinal Cord Injury Study. J Neurosurg

1992;76(1):23-31

7. Short DJ, El Masry WS, Jones PW. High dose methylprednisolone in the man-

agement of acute spinal cord injury: a systematic review from a clinical per-

spective. Spinal Cord 2000;38(5):273-286

8. Qian T, Guo X, Levi AD, Vanni S, Shebert RT, Sipski ML. High-dose methylpred-

nisolone may cause myopathy in acute spinal cord injury patients. Spinal

Cord 2005;43(4):199-203

9. Hurlbert RJ. Methylprednisolone for acute spinal cord injury: an inappropri-

ate standard of care. J Neurosurg 2000;93(1, Suppl):1-7

10. Ranguis SC, Li D, Webster AC. Perioperative epidural steroids for lumbar

spine surgery in degenerative spinal disease. A review. J Neurosurg Spine

2010;13(6):745-757

11. Resnick DK, Choudhri TF, Dailey AT, et al; American Association of Neuro-

logical Surgeons/Congress of Neurological Surgeons. Guidelines for the per-

formance of fusion procedures for degenerative disease of the lumbar spine.

Part 13: injection therapies, low-back pain, and lumbar fusion. J Neurosurg

Spine 2005;2(6):707-715

12. Cuckler JM, Bernini PA, Wiesel SW, Booth RE Jr, Rothman RH, Pickens GT. The

use of epidural steroids in the treatment of lumbar radicular pain. A prospec-

tive, randomized, double-blind study. J Bone Joint Surg Am 1985;67(1):63-66

Answers to Common Clinical Questions

1. B

2. A

3. C. The benefit initially demonstrated could not be replicated in

any other study encountered in a metaanalysis of the literature.

11 Interventional Pain/Nonoperative Spine

Procedures: Diagnostic and Therapeutic

Daniel Marin

I. Key Points

This chapter focuses on nonoperative diagnostic and therapeutic

spine procedures for the purpose of understanding their context,

purpose, technique, and diagnostic usefulness from a perspective

limited to the spine. Appropriate ordering and analysis of these pro-

cedures requires proper documentation of the severity of pain, pres-

ence of numbness, presence of weakness, and detailed distribution

of pain. The chapter is not intended to be a guide or a practicum to

the performance of these procedures.

II. Description

- Diagnostic procedures: disc stimulation (provocation discogra-

phy)

• Purpose: to identify pain originating from specific interverte-

bral discs (cervical, lumbar), typically axial in nature

• Single-needle technique: With particular attention to steril-

ity, and with fluoroscopic guidance, a spinal needle is inserted

obliquely and advanced carefully, avoiding the ventral ramus

(Fig. 11.1, DC), into the center of the intervertebral disc. Prov-

ocation follows using slow contrast injection attached to a

line pressure transducer. Attention to disc morphology is im-

portant, and level of pain/concordance, pressure, and volume

injected must continuously be monitored. Final documenta-

tion of nucleus pulposus morphology according to the Dallas

discogram scale should then be made, and the patient sent for

computed tomography (CT) imaging.¹

• Applicability: discogenic mediated pain

- Diagnostic procedures: medial branch block

• Purpose: to block pain transmission from the medial branches

of the dorsal primary rami (cervical, thoracic, lumbar) that

innervate the zygapophysial joints, significant mediators of

axial neck and back pain

• Technique: With fluoroscopic guidance, a spinal needle is in-

serted obliquely (thoracic, lumbar), or posteriorly/laterally

(cervical) and directed at the medial branch target, which is

72 II Clinical Spine Surgery

MB.

Fig. 11.1 Lumbar spine left oblique view.

DC, intradiscal target; MB, medial branch

target; TF, transforaminal target.

the centroid of the articular pillar in the cervical region (Fig.

11.2, MB), and the junction of the superior articular process

and the transverse process in the thoracolumbar region² (Fig.

11.1, MB). Each joint requires a block of the superior and infe-

rior medial branch components. Comparative local anesthetic

blocks should then be performed to diagnose the correct pain

level and exclude false-positives.

• Applicability: cervical spondylosis, thoracic spondylosis, lum-

bar spondylosis

- Diagnostic: sacroiliac joint block

• Purpose: to inject anesthetic into the sacroiliac joint and eval-

uate for alleviation of pain. Corticosteroid can be added to de-

crease inflammation and for therapeutic effect.

• Technique: Under the guidance of fluoroscopy, a spinal nee-

dle is inserted posteriorly and directed toward the inferior

and posterior sacroiliac joint line. Confirmation of location is

made with the use of contrast, and medication delivered.

• Applicability: sacroiliac pain

- Diagnostic procedures: selective spinal nerve block

• Purpose: to deliver a medication solution (usually anesthetic)

to a spinal nerve root selectively (cervical, lumbar) in correla-

tion with the alleviation (or absence) of a patient’s symptoms

• Technique: With fluoroscopic guidance, a spinal needle is in-

serted obliquely via a transforaminal approach into the neu-

roforamen of the spinal nerve root (cervical, thoracic, lumbar,

or sacral spine). The target is the 6 o’clock position of the ped-

11 Interventional Pain/Nonoperative Spine Procedures

Fig. 11.2 Cervical spine lateral view.

MB, medial branch target.

icle shadow of the corresponding nerve root level (Fig. 11.1,

TF). Confirmation of location is then achieved with the use of

contrast, and anesthetic delivered.

• Applicability: radiculopathy, polyradiculopathy, post-laminecto-

my syndrome

- Therapeutic procedures: epidural steroid injection

• Purpose: to alleviate pain by placing corticosteroids into the

epidural space in response to the symptoms of discogenic

pain, spinal stenosis, radicular pain, and epidural scarring

• Technique: With fluoroscopic guidance, a spinal needle is in-

serted posteriorly via a caudal, transforaminal (Fig. 11.1, TF),

or interlaminar approach into the epidural space (cervical,

thoracic, lumbar, or sacral spine). Confirmation of location

is then obtained with the use of contrast, and medication

delivered.

• Applicability: discogenic mediated pain, spinal stenosis, ra-

diculopathy, post-laminectomy syndrome

- Therapeutic procedures: percutaneous medial branch radiofre-

quency neurotomy

• Purpose: to alleviate pain transmission from the medial

branches of the dorsal primary rami (cervical, thoracic, lum-

bar) via ablation with a radiofrequency needle

• Technique: A radiofrequency electrode needle is inserted in

a manner identical to that used for the medial branch blocks

mentioned earlier. Sensory and motor stimulation test-

ing are then performed to ensure appropriate positioning

and nonstimulation of a nerve root. Upon confirmation, lo-

cal anesthetic is provided and medial branch nerve lesioning

commenced.

74 II Clinical Spine Surgery

• Applicability: cervical spondylosis, thoracic spondylosis, lum-

bar spondylosis

- Therapeutic procedures: percutaneous lead spinal cord stimu-

lation

• Purpose: to utilize the gate control theory¹ and block trans-

mission of pain signals through the spinal cord by electrical

stimulation over the dorsal column of the spinal cord after an

appropriate percutaneous trial has been conducted

• Technique: Place percutaneous lead(s) via an interlaminar ap-

proach, or a paddle surgical lead (typically improves coverage

of axial back pain) into the epidural space (cervical or tho-

racic) with appropriate intraoperative testing or targeting to

“cover” the patient’s pain.

• Applicability: post-laminectomy syndrome, chronic ra-

diculopathy, peripheral neuropathy, complex regional pain

syndrome

- Therapeutic procedures: trigger point injection

• Purpose: to break up lactic acid deposit in muscles to decrease

myofascial pain

• Technique: After identification of painful taut bands in mus-

cle, local anesthetic is applied and a small-gauge injection

needle is used to pierce the skin and enter the muscle belly

with the objective of breaking up the deposit.

• Applicability: myofascial pain

III. Pearls

- Specific diagnostic spinal injections can address targeted spinal

pain conditions with the goal of identifying the origin of the

pain and guiding surgery.

- Epidural injections typically target canal and foraminal medi-

ated pathology.

- Injections directed at the medial branch and dorsal primary ra-

mus typically target posterior element sources of pain.

Common Clinical Questions

1. Which procedure(s) could be beneficial in diagnosing axial lum-

bar back pain?

2. What is a potential benefit of the percutaneous approach to dor-

sal column stimulation over the paddle lead, and vice versa?

11 Interventional Pain/Nonoperative Spine Procedures

References

1. Sachs BL, Vanharanta H, Spivey MA, et al. Dallas discogram description. A new

classification of CT/discography in low-back disorders. Spine (Phila Pa 1976)

1987;12(3):287-294

2. International Spine Intervention Society. In: Bogduk N, ed. Practice Guide-

lines for Spinal Diagnostic and Treatment Procedures. San Francisco: Inter-

national Spine Intervention Society; 2004:47-65, 112-137

3. Melzack R, Wall PD. Pain mechanisms: a new theory. Science 1965;150(699):

971-979

Answers to Common Clinical Questions

1. Medial branch blocks and epidural steroid injections could be

considered in the diagnosis of axial lumbar back pain. Medial

branch blocks or facet injections could be used to selectively

target suspicious levels of spondylosis. Should the pain be axial

and be aggravated by maneuvers increasing intradiscal pres-

sure, discogenic pathology could be considered, as could epidu-

ral versus provocation discography. Sacroiliac pain typically will

present at a point lower than will axial lumbar back pain.

2. The percutaneous approach to spinal cord stimulation allows

for a testing period when the patient can “test” the system in his

or her own functional environment, and have the lead removed

easily if it is not found to be beneficial. The paddle (surgical)

lead approach provides the benefit of better coverage of axial

back pain, and would likely be the optimal choice in cases where

thoracic scar tissue would impede lead passage.

12 Bedside Procedures

Daniel C. Lu and Praveen V. Mummaneni

I. Key Points

- Halo orthosis and traction: Skull fracture or severe skull osteo-

porosis is a contraindication for halo placement. Scalp abrasion

or infection overlying the intended pin sites is also a contrain-

dication for the procedure.

- Lumbar puncture (LP) or lumbar drain: Known or suspected in-

tracranial mass, infection, tethered cord, or coagulopathy is a

contraindication to the procedure.

II. Indications

- Halo orthosis and traction: Halo orthosis is effective at control-

ling abnormal motion at the C1-C2 articulation due to fracture

or ligamentous injury. The purpose of the halo is to maintain

normal alignment and/or immobilize the cervical spine to pre-

vent further spinal injury and to allow for bony fusion in cases

of fractures. Halo traction is utilized to limit fracture-disloca-

tions and maintain normal alignment.^1,2

- Lumbar puncture or lumbar drain: A lumbar puncture is indi-

cated for collection and analysis of cerebrospinal fluid (CSF) for

infection, subarachnoid hemorrhage, or elevated intracranial

pressure. Additionally, intrathecal administration of medication

or contrast (for myelography) can be performed via a lumbar

puncture. A lumbar drain is placed if temporary CSF diversion is

indicated for hydrocephalus (communicating) or wound man-

agement (pseudomeningocoele, CSF leak, etc.).

III. Technique

Halo Orthosis and Traction

- Patients should be positioned either in a sitting head-neutral

position or a supine head-neutral position at the end of the bed

so that the head slightly overhangs the bed. A semi-rigid collar

may be used to immobilize the neck during halo application.³

- The appropriate-size halo ring is selected. The halo ring should

accommodate the entire head circumference with clearance of

approximately 1 cm.

12 Bedside Procedures

- Halo pin sites are selected at this time, with two anterior and

two posterior sites.

• The anterior sites are centered in the groove between the

supracilliary ridge and frontal prominences. Pins should be

placed just superior to the lateral half of the eyebrows to avoid

the supraorbital nerve and vessels. This location avoids mus-

cular structures to diminish discomfort.

• A posterior pin should be placed 1 cm above the apex of the

pinna of each ear. A line connecting the posterior pin site with

its contralateral anterior pin site should roughly bisect a line

drawn between the remaining two pin sites at a right angle.

This provides distribution of force for stability.

- The planned pin sites are sterilely prepared and injected with

1% lidocaine. The two pins—one front and the diagonally oppo-

site back pin—are then finger-tightened to just touch the skin;

this is repeated for the other pins. In children, multiple pins (>4)

are sometimes utilized to distribute the pressure more evenly.

- A torque screwdriver (set to 6 to 8 lb of pressure) is then used to

tighten the pins in diagonal pairs. The pins are now stabilized

and locked down with appropriate locking nuts to the halo

frame. The halo vest is then placed on the patient, the semi-

rigid collar is removed, and halo and vest are stabilized with

halo rods.

• The halo vest should be adjusted so that the straps make con-

tact with the patient’s trapezius and shoulder area. There is a

tendency for the vest to ride high and not touch the shoulders

unless care is taken during vest application.

- For traction placement, a variety of devices are available. Gard-

ner-Wells tongs or halo rings are the most common (Fig. 12.1).

Pin sites for Gardner-Wells tongs are 2 to 3 finger breadths (3 to

4 cm) above the ear pinnae. The Gardner-Wells pins are spring-

loaded with a force indicator; these pins are tightened until the

indicator protrudes 1 mm beyond the flat surface. Pins are re-

tightened daily until the indicator remains at this location for 3

days. If used, halo rings have the advantage of a compatible vest

orthosis to secure the tractioned position.

- After tong or halo ring placement, the patient is transferred to a

bed with a headboard attached to a pulley system with weights.

With the pulley placed above the patient’s head, flexion and

traction can be accomplished. If the pulley is placed at the level

of the pins, then straight traction forces can be applied. If the

pulley is placed below the level of the patient’s head, extension

and traction are possible. Lateral x-rays should be obtained im-

mediately after application of traction and after each weight

78 II Clinical Spine Surgery

Fig. 12.1 Proper fixation points for Gardner-Wells tongs application. (A) Posterior

placement of tongs to produce flexion of head. (B) Normal placement of tongs to pro-

duce straight traction. (C) Anterior placement of tongs to produce hyperextension of

head (from Vaccaro, A. Spine Surgery: Tricks of the Trade. 2nd ed. Thieme, p. 280, Fig.

73.1A-C).

adjustment. Typically, evaluation begins with 5 lb of traction

for upper C-spine injuries and 10 lb for lower C-spine injuries.

- For upper cervical injuries, evaluation of the atlanto-occipital

joints is important to rule out atlanto-occipital dislocations.

Such injuries should not use traction. For mid-cervical locked

facets, 5 lb per level of traction weight should be applied to the

injury (e.g., slowly work up to 50 lb for a C5 level facet sublux-

ation). Prior to applying traction for cervical facet subluxation,

consider MRI imaging to rule out a coincidental anterior her-

niated disc with cord compression. If a herniated disc is pres-

ent, consider anterior operative correction instead of a trial of

traction.

Lumbar Puncture or Lumbar Drain

- This bedside procedure can be performed with the patient sit-

ting or lying down.

• For the recumbent position, the patient is placed in a lateral de-

cubitus posture, with neck flexed and knees brought up to the

chest. This distracts the space between the spinous processes,

facilitating passage of a spinal needle into the thecal sac.

• For the sitting position, the patient should be sitting with

head and arms resting on a pillow placed on a bedside stand.

The back is sterilely prepared and draped.

12 Bedside Procedures

- LP can be safely attempted at the L3 to S1 interspaces in the

anatomically normal patient. The intercrestal line is identified

and palpated in the midline for the L4 spinous process.

• Initially

1% lidocaine is infiltrated subcutaneously. Subse-

quently, the lumbodorsal fascia is injected.

• The spinal needle with stylet is aimed slightly rostrally to the

umbilicus to approximately parallel the spinous process, and

the bevel should be turned parallel to the length of the spinal

column to reduce the chance of post-LP headaches.

• The needle is advanced with a midline trajectory and a “pop”

should be felt as the needle penetrates the ligamentum fla-

vum and passes into the dura.

• The stylet is then withdrawn to check for CSF flow; if none is

seen, reinsert the stylet and advance the needle further; if no

CSF flow is present, attempt another trajectory.

• If blood is seen, wait for the blood to drain and clear, as this

may represent a traumatic tap. If it does not clear, advance the

needle or attempt another trajectory.

- If a lumbar drain is selected, a lumbar drain needle (14-gauge

Tuohy) should be used. After entering the thecal sac with needle

bevel facing laterally, the bevel is turned superiorly, and a lum-

bar drainage catheter with wire stylet is inserted (20 to 40 cm).

- The needle and stylet are sequentially removed, and cerebro-

spinal fluid (CSF) flow is confirmed by dropping the catheter

below the patient.

• A 2 × 2 gauze section is placed around the insertion site of

the catheter and a Tegaderm (3M, St. Paul, MN) pad is placed

on top to secure the catheter.

• Several more Tegaderm pads are placed along the flank of the

patient to secure the catheter to the patient’s body.

IV. Complications

Halo Orthosis and Traction

- Pin loosening occurs in 60% of patients over a 3-month period.

Pins may require retightening.

- Pin site infection (10 to 20%). Treat by placing pin at a new,

adjacent site and give the patient oral antibiotics.

- Neurologic deterioration after traction may occur secondary to

retropulsed disc. Consider obtaining a pre-procedure magnetic

resonance image (MRI) to rule out this condition prior to traction.

- Overdistraction is another potential complication of halo/trac-

tion. This could manifest in deficits or pain and can typically be

identified on the lateral x-ray.

80 II Clinical Spine Surgery

Lumbar Puncture or Lumbar Drain

- Infection can occur in certain cases, especially those involving

prolonged use of lumbar drains.

• Superficial infection can be treated with drain removal and

antibiotic treatment.

• Epidural abscess (depending on size and neurologic compro-

mise) may require surgical intervention (laminectomy and

evacuation).

- Radicular pain can occur secondary to nerve root irritation. If

persistent, consider repositioning of drain.

- Post-LP headache

• Options include bed rest (24 hours), abdominal binder, des-

oxycortisone acetate, caffeine sodium benzoate, high-dose ste-

roids, and blood patch.

• If related to lumbar drain, consider decreasing output.

- Spinal epidural hematoma (usually in setting of coagulopathy

or anticoagulation)

- Tonsillar herniation (in the presence of mass-occupying lesion)

- Intracranial subdural hygroma or hematoma

- Epidermoid tumor (increased likelihood with needle introduc-

tion without stylet). This can occur in a delayed fashion but the

incidence is very low.

- Abducens palsy (often delayed 5 to 14 days post-LP and resolves

without intervention in 4 to 6 weeks)

V. Post-Procedure Care

Halo Orthosis and Traction

- The pins should be retightened once a day for about 3 days

at the same pressure and then retightened every week for 3

weeks.

• A persistently loose pin may indicate migration into the inner

table and should be removed, with a new one placed at dif-

ferent site.

• Post-procedure radiographs are taken to verify proper head

positioning with halo orthosis and traction placement.

Lumbar Puncture or Lumbar Drain

- For lumbar drain care, prophylactic antibiotics may be con-

tinued while the drain is in place, with dressings changed ev-

ery three days. Drains should be removed or changed after a

week.

12 Bedside Procedures

VI. Outcomes

- Halo orthosis: Fusion rates are as high as 84% in nonelderly pa-

tients with type II odontoid fracture treated with a halo; risk

factors for nonunion include advanced age and displaced odon-

toid fractures.

- Halo traction: Reduction of bilateral locked facets is typically

easier to achieve than reduction of unilateral locked facet.

- LP: Risk of persistent or disabling complication is rated at 0.1

to 0.5%.

VII. Surgical Pearls

Halo Orthosis and Traction

- Pin tension should be uniform. Unequal pin tension will lead

to migration of halo as pins migrate in the direction of the pin

with the least tension.

- Adjustments during follow-up should not be limited to the

halo pins. Inspection of alignment with the vest should be per-

formed to ensure that shoulder straps are making contact with

the trapezius and shoulder area. X-ray radiographs should ac-

company follow-up visits to ensure proper alignment.

Lumbar Puncture or Lumbar Drain

- Care must be taken in removing the Tuohy needle from the

lumbar catheter to avoid shear of the catheter by the sharp

bevel of the needle. The trajectory and rotation of the needle

must not be altered during removal.

- Evaluation of anatomy with preoperative radiograph is essen-

tial, especially in patients with degeneration and osteophyte

formation.

- If attempts at LP or drain placement are unsuccessful, place-

ment of lumbar drain under fluoroscopic guidance may be

necessary.

82 II Clinical Spine Surgery

Common Clinical Questions

1. Frontal halo pins may compromise which nerve?

2. During retightening of halo pins during a follow-up visit, it is

found that the pins can no longer be torqued to 6 lb after one

complete turn. What has happened and what should be done?

3. Patient develops nausea, vomiting, and headaches 2 weeks after

a workup for meningitis. What is the likely diagnosis and what

is the treatment?

References

1. Chan RC, Schweigel JF, Thompson GB. Halo-thoracic brace immobilization

in 188 patients with acute cervical spine injuries. J Neurosurg 1983;58(4):

508-515

2. Platzer P, Thalhammer G, Sarahrudi K, et al. Nonoperative management of

odontoid fractures using a halothoracic vest. Neurosurgery 2007;61(3):522-

529, discussion 529-530

3. Greenberg MS. Handbook of Neurosurgery. 6th ed. New York: Thime Medical

Publishers, 2006:304-306

Answers to Common Clinical Questions

1. Supracilliary nerve

2. The pin has likely breached the cortical inner table. The pin

should be removed and a new pin placed at a new site.

3. The patient has likely developed post-LP headache. Treatments

include bed rest, abdominal binder, hydration, and medication.

If these measures fail, a blood patch is indicated.

13 Spinal Radiation Therapy

Edward A. Monaco III and Peter Carlos Gerszten

I. Key Points

- Conventional fractionated radiotherapy, defined as radiation

delivered in one to two radiation beams without high precision

or highly conformal techniques, is well established and widely

accepted as an appropriate treatment modality for many spinal

tumors.

- Stereotactic spinal radiosurgery allows for the highly confor-

mal delivery of radiation to spinal lesions and avoids toxicity to

normal tissues.

- Spinal radiosurgery has proven effective in the treatment of be-

nign and malignant lesions along the entire length of the spine.

II. Description

Epidemiology

- Over 200,000 cases of spinal tumors are diagnosed yearly in

North America.¹

- Up to 40% of cancer patients will develop metastatic disease of

the vertebrae.

- In approximately 20% of patients, spinal metastases will prog-

ress to neural element compression.

- With improved multimodality approaches for cancer treatment

and greater long-term survival, the incidence and prevalence of

spinal metastases are likely to increase.

Overview

- The traditional therapy for spinal tumors, primary or meta-

static, includes open surgical excision, systemic chemotherapy,

and conventional fractionated radiation therapy, alone or in

combinations.

- In a randomized trial comparing conventional radiation thera-

py alone to surgery followed by radiation therapy for the treat-

ment of spinal metastases causing spinal cord compression,

Patchell and colleagues demonstrated that surgery combined

with conventional radiation therapy is a superior treatment in

its ability to preserve ambulation and decreases the need for

both corticosteroids and opioid analgesics.²

84 II Clinical Spine Surgery

- With conventional radiation therapy, one or two low-precision

radiation beams are delivered to the spine over several frac-

tions to allow for repair of the normal tissues.

- The goals of local radiation therapy have been palliation of

pain, prevention of local disease progression and subsequent

pathologic fractures, and halting progression of, or reversing,

neurologic compromise.

- Conventional radiation therapy is limited in its effectiveness by

the relative intolerance of the adjacent normal tissues (e.g., the

spinal cord, nerve roots, and conus medullaris) to high radia-

tion doses. Thus, treatment doses are limited to subtherapeutic

levels, resulting in disease recurrence or progression.

- Stereotactic spinal radiosurgery is the delivery of a highly con-

formal, large radiation dose to a specific target, often in a single

fraction (Fig. 13.1A,B).

- Radiosurgery offers the advantages of applying radiobiological-

ly effective doses to a target and sparing surrounding structures.

- Intensity-modulated radiation therapy is a technology that

provides the ability to vary the integrated intensities of radia-

tion beams for the delivery of therapy. With several radiation

beams all passing through multileaf collimators with different

apertures, the intensity of the radiation dosing can be shaped

in three-dimensional space.

Conventional Radiotherapy

- Three randomized trials have been published for spine

metastases.³

- Approximately

70% of patients remained ambulatory af-

ter conventional radiation therapy for epidural spinal cord

compression.

- Between 20 and 60% of patients regained ambulation after con-

ventional radiotherapy.

- Pain is palliated in 50 to 70% of patients.

- The most commonly used treatment is 30 Gy delivered in 10

fractions.

- The specific dose-fractionation schedule used has not been

found to have a significant impact on ambulatory status or the

probability of regaining ambulation.⁴

- Local control rates for spine metastases with conventional ra-

diotherapy are reported to be 60 to 90%.

- The effectiveness of conventional radiotherapy has been lim-

ited by the intolerance of the spinal cord to high-dose radiation.

86 II Clinical Spine Surgery

- Certain histologies such as sarcomas, melanoma, and renal cell

carcinoma are known to be relatively resistant to conventional

radiotherapy doses.

Radiosurgery

- No randomized data are available to date.

- Reported outcomes demonstrate 85 to 100% of patients experi-

encing palliation of pain.⁵

- Use of both single fraction doses (16 to 24 Gy × 1) and hypo-

fractionation (4 Gy × 4, 6 Gy × 5, 8 Gy × 3, 9 Gy × 3) has been

reported.

- Significant toxicity does not appear to be associated with any

fractionation schedule.⁶

- The majority of reported local control rates are around 90%.

Spine Radiosurgery: Two Fundamental Principles

- Target immobilization

• Early spinal radiosurgery protocols applied an approach simi-

lar to that of cranial radiosurgery through the application of

an invasive rigid frame directly to the spine.

• Frameless techniques have become the methodology of choice

because of their relative noninvasiveness.

• Perfect static positioning cannot be accomplished using fra-

meless methods; thus pre- and intratreatment imaging must

be obtained to account for target movement due to respiration.

- Target localization

• Frequent acquisition of localizing images during the delivery

of radiation combined with adjustments to the patient’s posi-

tion allow for accurate targeting of the desired lesion(s).

• Volumetric imaging allows for the detection of rotational er-

rors in patient setup, making robust automatic registration

procedures possible.

• Cone beam imaging uses gantry-mounted kilovolt sources

and detectors to acquire images during gantry rotation. The

images are converted to computed tomography (CT)-like

axial slices, yielding high spatial resolution and resulting in

submillimeter targeting errors.

Indications for Treatment with Spinal Radiosurgery

- Pain from spinal tumors

- Primary treatment modality for newly discovered spinal metas-

tases instead of open surgery or conventional radiation therapy

- Radiation boost for radioresistant tumors

13 Spinal Radiation Therapy

- Progressive neurological deficit

• May need to perform decompressive/debulking surgery for

patients with progressive myelopathy (instead of using radia-

tion treatment)

- Treatment of residual tumor after surgery

- Postsurgical tumor progression

Candidate Lesions for Spinal Radiosurgery

- Lesions associated with minimal spinal cord compromise

- Previously irradiated lesions

- Radioresistant lesions that would benefit from a radiosurgical

boost

- Residual tumor following surgery

- Recurrent tumor after prior surgical resection

- Lesions requiring difficult or morbid surgical approaches

- Short life expectancy of patient, precluding open surgery

- Significant medical comorbidities precluding open surgery

- Lesions not involving overt spinal instability

III. Surgical Pearls

- Conventional radiotherapy is safe and effective, with good

symptomatic response and local control of spine tumors, par-

ticularly for radiosensitive histologies, such as lymphoma, my-

eloma, and seminoma.

- Conventional radiotherapy is an appropriate initial therapy option

for spine tumors where no contraindication exists. Contraindica-

tions include spinal instability, prior irradiation, radioresistant

histology, and high-grade spinal cord compression.

• Consider surgical decompression/debulking/instrumented

stabilization procedures for cases where radiotherapy is

contraindicated.

- Radiosurgery is safe and effective, with durable symptomatic

response and local control for even radioresistant histologies,

regardless of prior fractionated radiotherapy.

- Radiosurgery should be preferred over conventional radiother-

apy for the treatment of solid-tumor spine metastases in the

setting of oligometastatic disease or radioresistant histology.

- Single-fraction, highly conformal large-dose radiosurgical

treatments offer excellent tumor control, symptomatic relief,

and patient convenience.

88 II Clinical Spine Surgery

Common Clinical Questions

1. What is the major factor limiting the effectiveness of conven-

tional radiotherapy for the treatment of spine tumors?

A. The relative resistance of the spinal cord to high-dose

radiation

B. The intolerance of the spinal cord to high-dose radiation

C. The resistance of tumors of the spine to even high doses of

radiation

D. The instability of the spine that develops after conventional

radiotherapy treatment

2. Which of the following statements is true?

A. The most commonly used radiation dose prescription for the

treatment of spine metastases is 20 Gy in 10 fractions.

B. Randomized clinical trials have demonstrated the superiority of

radiosurgery over conventional fractionated radiotherapy for the

treatment of spine tumors.

C. Certain histologies such as myeloma and lymphoma are

known to be relatively resistant to radiation therapy.

D. Reported outcomes demonstrate that 85 to 100% of patients

experiencing pain from spine metastases report improve-

ment after radiosurgery.

3. Radiosurgery should be considered as a first-line treatment for

a spine tumor over conventional radiotherapy in which setting?

A. In the setting of gross spinal instability

B. When the lesion has already undergone treatment using

fractionated radiotherapy with spinal cord tolerance doses

C. For lymphoma, myeloma, or seminoma

D. In the setting of widely metastatic spine disease

13 Spinal Radiation Therapy

References

1. Posner JB. Spinal metastases, neurological complications of cancer. Philadel-

phia: FA Davis Company; 1995:111-142.

2. Patchell RA, Tibbs PA, Regine WF, et al. Direct decompressive surgical resec-

tion in the treatment of spinal cord compression caused by metastatic can-

cer: a randomised trial. Lancet 2005;366(9486):643-648

3. Gerszten PC, Mendel E, Yamada Y. Radiotherapy and radiosurgery for meta-

static spine disease: what are the options, indications, and outcomes? Spine

(Phila Pa 1976) 2009; 34(22, Suppl):S78-S92

4. Maranzano E, Bellavita R, Rossi R, et al. Short-course versus split-course ra-

diotherapy in metastatic spinal cord compression: results of a phase III, ran-

domized, multicenter trial. J Clin Oncol 2005;23(15):3358-3365

5. Gerszten PC, Burton SA, Ozhasoglu C, Welch WC. Radiosurgery for spinal

metastases: clinical experience in 500 cases from a single institution. Spine

(Phila Pa 1976) 2007;32(2):193-199

6. Sahgal A, Ma L, Gibbs I, et al. Spinal cord tolerance for stereotactic body radio-

therapy. Int J Radiat Oncol Biol Phys 2010;77(2):548-553

Answers to Common Clinical Questions

1. B

2. D

3. B

14 Spinal Navigation

Ben J. Garrido and Rick C. Sasso

I. Key Points

- Allows intraoperative real-time navigation of instruments rela-

tive to the spinal anatomy

- Provides three-dimensional (3D) real-time anatomic information

- May increase the safety, accuracy, and efficiency of certain

spine procedures

- Eliminates intraoperative radiation exposure to surgeons and

accompanying staff members during procedures

- Provides a versatile array of techniques facilitating the ability to

perform complex spine surgery safely

II. Description

Spinal navigation uses computer vision technology to plan and guide

surgical interventions. It has evolved from a cumbersome to a more

user-friendly system. Early-generation systems required a complex

preregistration process through the use of either the paired-point

technique or surface mapping. These techniques introduced the

potential for error and were time consuming but critical in linking

image data to spinal anatomy. Most of the resistance to the univer-

sal adoption of image navigation stemmed from such requirements.

Newer systems combine high-precision robotics with unparalleled

imaging capability, eliminating the need for preregistration. Comput-

er-aided surgery now enables the acquisition of imaging data intra-

operatively prior to incision. Current software can use either a 2D or

3D image data set acquired intraoperatively by a fluoroscopy unit or

high-resolution computed tomography (CT) scanner. These images

are then automatically imported into the computer workstation and

used to create a 3D picture of the patient’s anatomy, completing the

registration process. This automatic registration process improves

the anatomic localization accuracy and eliminates the need for man-

ual point-based or surface-based registration. Subsequently, real-

time tracking data are matched with previously obtained image data

through the use of a fixed reference point on the patient, computer

workstation, and camera system. For spine procedures, affixing the

fixed reference frame/point to bone is the initial step in registration.

14 Spinal Navigation

Components of a Navigation System

After the intraoperative image data are obtained through one of the

commercial systems available, this data set is automatically upload-

ed to the computer workstation. A 3D image is created and linked to

your working position relative to the patient’s anatomy through a

tracking system. There are currently two types of tracking systems

that will triangulate your position in space: optical and electromag-

netic (EM). Both systems allow localization of surgical instruments

or implants in real time. In electromagnetic tracking an EM field is

created, and changes in field are monitored to localize a tracked de-

vice. With optical tracking, cameras track instrument positions rela-

tive to the fixed reference point through an active or passive method.

Active tracking entails the use of light-emitting diodes (LEDs) on the

instruments and passive tracking involves the reflection of infrared

light from the camera to reflective spheres on instruments. Both

systems require a direct line of view between the camera and the

tracked instruments to link surgical anatomy to the 3D data set in

the computer workstation. The system can then triangulate the in-

strument’s tip location, angle, and trajectory. The systems are com-

parable in positioning accuracy and can provide real-time, precise

3D imaging quality (Fig. 14.1).

Fig. 14.1 Examples of 3D images with navigation provided by the computer work-

station, with a superimposed projection of the navigated instrument or probe.

92 II Clinical Spine Surgery

Applications and Advantages

Image navigation has improved the safety of and ability to perform

complex procedures where visibility is not optimal or anatomic de-

formity is present. Numerous published studies have demonstrated

its effectiveness in improving pedicle screw placement for complex

multiplanar spinal deformities.¹ A meta-analysis of pedicle screw

placement accuracy demonstrated a 95% median accuracy with navi-

gation compared with 90% without it.² It is intuitive that the capabil-

ity to visualize a pedicle in 3D should minimize screw insertion risks

associated with pedicle asymmetry, smaller diameters, and vertebral

rotation and thereby prevent nerve root or spinal cord compression.

Because of the improved accuracy, operative times have also been

shown to decrease with the use of image navigation.³ Drawbacks re-

lated to increased operative time, patient registration, and data acqui-

sition are controlled with the current real-time intraoperative data

acquisition technology and software systems.³ In addition, mean ra-

diation exposure using image navigation has been shown to be statis-

tically significantly lower compared with conventional fluoroscopy.⁴

Aside from pedicle screw insertion, many other versatile appli-

cations are being described for image navigation, including C1-C2

transarticular and percutaneous translaminar facet screw place-

ment, lumbar disc arthroplasty placement, and balloon kypho-

plasty. These possibilities are incorporating the advantages of image

navigation and demonstrating feasibility, accuracy, and operative

time reduction while reducing radiation exposure.

III. Surgical Pearls

- All staff using the system should be properly trained, to prevent

errors that can lead to improper setup, inaccurate information,

and surgical complications.

- The fixed referenced frame must not be inadvertently bumped,

moved, or altered. This can lead to tracking and positional errors

during navigation. It’s important to keep the reference frame close

to the surgical field for maximum accuracy.

- Spinal navigation is not a substitute for fundamental knowl-

edge of anatomic landmarks and appropriate surgical tech-

nique. Improper use or malfunction of the system can cause

navigational inaccuracies.

- Image navigation should be used to confirm anatomic landmarks

and suspected locations and trajectories for hardware placement.

- The room setup plan should provide for a direct line of view

between navigation components (camera, computer worksta-

tion, and reference frame).

14 Spinal Navigation

Common Clinical Questions

1. Which of the following is not a feature of spinal image navigation?

A. Real-time views

B. Decreased operative time

C. Axial views

D. Increased radiation exposure

E. Improved accuracy

2. Current spinal image navigation systems provide real-time

tracking through what technique?

A. Paired-point preregistration

B. Surface mapping preregistration

C. Continuous fluoroscopic imaging

D. Optical or electromagnetic tracking

E. None of the above

References

1. Kotani Y, Abumi K, Ito M, et al. Accuracy analysis of pedicle screw placement

in posterior scoliosis surgery: comparison between conventional fluoro-

scopic and computer-assisted technique. Spine (Phila Pa 1976) 2007;32(14):

1543-1550

2. Kosmopoulos V, Schizas C. Pedicle screw placement accuracy: a meta-analy-

sis. Spine (Phila Pa 1976) 2007;32(3):E111-E120

3. Sasso RC, Garrido BJ. Computer-assisted spinal navigation versus serial ra-

diography and operative time for posterior spinal fusion at L5-S1. J Spinal

Disord Tech 2007;20(2): 118-122

4. Smith HE, Welsch MD, Sasso RC, Vaccaro AR. Comparison of radiation ex-

posure in lumbar pedicle screw placement with fluoroscopy vs computer-

assisted image guidance with intraoperative three-dimensional imaging. J

Spinal Cord Med 2008;31(5):532-537

Answers to Common Clinical Questions

1. D

2. D

15 Spinal Biologics

Rafael F. Cardona-Durán and Juan S. Uribe

I. Key Points

- Decision making for the choice of bone graft in spinal surgery

is important and should be a part of all preoperative planning.

- The inherent qualities—including advantages, disadvantages,

and costs—associated with each type of bone graft should be

appreciated by the surgeon.

- Host bone bed preparation is key to enabling bone grafts to

achieve their intended function of promoting fusion.

II. Description

Bone Graft Characteristics (Table 15.1)^1,2

- Osteoinduction: the recruitment of mesenchymal cells and

the stimulation of these cells to develop into osteoblasts and

osteoclasts

- Osteogenesis: formation of new bone by host or graft mesen-

chymal stem cells transformed into osteoblasts

- Osteoconduction: the scaffolding provided by the graft for the

proliferation of new blood vessels and bone

- Mechanical stability: the structural, anatomic, and biomechan-

ical support provided after discectomy, corpectomy, or verte-

bral tumor resection

Autograft: “Gold Standard”^1-3

- No histocompatibility or disease transmission issues

- Iliac crest (anterior or posterior) is the typical primary donor

site.

- Drawbacks

• 20% risk of long-term donor site pain

• Increased surgical risk of blood loss and infection

◦Cancellous

▪Fulfills all bone graft criteria, except mechanical stability

◦ Cortical

▪Provides superior and immediate mechanical strength

▪Diminished osteoconduction and osteoinduction

◦ Corticocancellous

▪Fulfills all of the bone graft criteria

▪Example: tricortical iliac crest wedge

Table 15.1 Characteristics of Bone Graft Materials^1,2,4

Material

Osteogenesis

Osteoinduction

Osteoconduction

Mechanical stability

Cancellous autograft^a

+++

++++

+/-

Cortical autograft^a

+++

Vacularized autograft^b

+++

Allograft

+/-

Bone marrow aspirate

+/-

Demineralized bone matrix

Bone morphogenic protein^c

Collagen

Ceramics

+++

Notes: - = no effect; +/- = minimal effect; + = mild effect; ++ = moderate effect; +++ = strong effect; ++++ = very strong effect.

^aAssociated with donor site morbidity.

^b Associated with high donor site morbidity and increased operative times.

^cU.S. Food and Drug Administration approval only for anterior lumbar interbody fusion.

96 II Clinical Spine Surgery

◦ Vascularized autograft

▪Technically challenging and time consuming

▪Very rarely used

▪Consider for host sites that are scarred or irradiated or that

span long segments

◦ Autologous bone marrow

▪Source of osteoprogenitor cells and osteoinductive substances

▪Diminished donor site risks

▪Offers no osteoconduction or mechanical stability

Allograft⁴

- Eliminates risks of autograft harvesting

- Acquired through multiple organ procurement agencies

- Mainly prepared frozen or freeze-dried

- Available in various sizes and types

• Ilium tricortical block, bicortical plug, or unicortical dowel

• Corticocancellous matchsticks or crushed

• Cancellous cubes, block, crushed, bone powder

• Sections from tibia, fibula, or femur

- Drawbacks

• Recommended for use with other types of grafts that may be

osteoinductive or osteogenic

• Minimal but present risk of disease transmission

Demineralized Bone Matrix^1,2

- Prepared by acid extraction, reducing antigenicity but preserv-

ing osteoinductive and some osteoconductive properties

- Several formulations

- Putty, gel, chips, granules, or powder

- Primarily to be used as adjunct to other grafting material or

graft extender

- Drawbacks

• Increased cost

• Variable efficacy between different preparations

• No mechanical or structural properties

• To be used with patient’s own bone

Bone Morphogenetic Proteins^2-5

- Molecules that induce the transformation of mesenchymal

stem cells into osteoblasts, capable of inducing ectopic bone

formation

- Approximately 20 different bone morphogenetic proteins (BMPs)

from the transforming growth factor-β family

- Produced using recombinant DNA technology

15 Spinal Biologics

- A carrier matrix is necessary to maintain the soluble factor at

the graft site, keeping the BMP solution from diffusing within

the adjacent tissues.

- U.S. Food and Drug Administration approval only for anterior

lumbar interbody fusion (ALIF)

• Recombinant human BMP-2 commercially available as Infuse

(Medtronic, Minneapolis, MN)

- Increases fusion rates

- Drawbacks

• Increased cost

• Ectopic bone formation, bone resorption, or remodeling at the

graft site is a potential problem if BMP is used in transforami-

nal lumbar interbody fusion (TLIF), posterior lumbar inter-

body fusion (PLIF), or corpectomy applications.

• Hematoma, neck swelling, and painful seroma are potential

problems with use in the cervical spine.

Collagen¹

- Contributes to vascular ingrowth, mineral deposition, and

growth factor binding, improving bone regeneration

- Used primarily as a carrier for other osteoinductive, osteocon-

ductive, or osteogenic materials and as a composite with other

graft extenders

- Drawbacks

• Minimal structural support

• Potential immunogenicity

Other Graft Extenders²

- Ceramics

• Tricalcium phosphates, calcium carbonate, and hydroxyapatite

• No risk of disease transmission

• Engineered, biocompatible osteoconductive materials

• Recommended for use only as bone graft extenders

• Combined with autograft, bone marrow aspirate, BMP, or oth-

er materials

III. Surgical Pearls

- Decortication and facet joint/end plate preparation, though

time consuming, are mandatory for excellent fusion.

- The costs and risks associated with pseudoarthrosis are high;

therefore, achieving arthrodesis is of paramount importance.

98 II Clinical Spine Surgery

Common Clinical Questions

1. What are the three principal properties of graft material in rela-

tion to fusion?

2. What is the “gold standard” for bone graft material (assuming

no contraindications)?

References

1. Giannoudis PV, Dinopoulos H, Tsiridis E. Bone substitutes: an update. Injury

2005;36(Suppl 3):S20-S27

2. Whang PG, Wang JC. Bone graft substitutes for spinal fusion. Spine J 2003;

3(2):155-165

3. Shen FH, Samartzis D, An HS. Cell technologies for spinal fusion. Spine J 2005;

5(6, Suppl):231S-239S

4. Tumialán LM, Pan J, Rodts GE, Mummaneni PV. The safety and efficacy of

anterior cervical discectomy and fusion with polyetheretherketone spacer

and recombinant human bone morphogenetic protein-2: a review of 200

patients. J Neurosurg Spine 2008; 8(6):529-535

5. Vaidya R, Sethi A, Bartol S, Jacobson M, Coe C, Craig JG. Complications in the

use of rhBMP-2 in PEEK cages for interbody spinal fusions. J Spinal Disord

Tech 2008;21(8):557-562

Answers to Common Clinical Questions

1. Osteoinduction, osteoconduction, osteogenesis

2. Autograft (typically from iliac crest)

102 III Spinal Pathology

raphy (CT) or CT myelogram to better delineate bony malfor-

mations and hydrocephalus. Use renal ultrasound to rule out

pelvic kidney, unilateral agenesis, and horseshoe kidney.

II. Anomalies of Notochord Formation

Diastematomyelia

- Background

• The spinal cord is divided vertically into two hemicords, each

with its own central canal, surrounding pia, and set of ante-

rior and posterior nerve roots.

• May result from bifurcation of the developing notochord

around an adhesion between the endoderm and ectoderm.

The split notochord may influence the formation of two neu-

ral tubes and subsequent hemicords and vertebral formation.

Consequently, it is common to have associated bony anoma-

lies (spurs) at the site of diastematomyelia.

• Accounts for 5% of congenital scoliosis and roughly 30 to 40%

of myelomeningoceles

- Signs, symptoms, and physical exam

• Most individuals have nonspecific symptoms and tethered

cords requiring surgical attention.

• The overlying skin in 66% of cases shows nevi, hypertricho-

sis, lipomas, dimples, hemangiomas, dermal sinus tracts, or

dermoids.

- Neuroimaging

• The conus is low lying in 75%, often with an associated thick-

ened or fatty filum.¹

• The hemicords usually reunite below the cleft, enveloped in a

single dura, with no spur or fibrous band found in 60% of cases

(Pang Type II).² In contrast, the presence of two dural tubes is

always associated with a fibrous or bony spur within the cleft

in the remaining 40% (Pang Type I).

• The type of spur, bony (50 to 60%) or fibrous (40 to 50%), is

likely determined by the amount of trapped mesenchyme be-

tween the hemicords.

- Treatment

• Untether the cord, coagulate and divide tethering fibrous

bands extending from the dura to the spinal cord, and excise

any bony spurs.

- Surgical pearls

• Remove the spur before untethering the cord to prevent re-

traction of the cord against the bony septum.

16 Congenital Anomalies

103

• Remove dural cuff and arachnoid covering the bony spur to

prevent regeneration of spur.

Split Notochord Syndrome

- Background

• Deviation or splitting of the notochord secondary to a retained

link between the endoderm and ectoderm. The most severe

form, a dorsal enteric fistula, is a communication between the

bowel and the dorsal skin. Dorsal enteric fistulae traverse the

prevertebral soft tissues, vertebral bodies, the spinal canal,

and its posterior elements. Any portion of the tract may invo-

lute or fibrose, leaving fistulae or cysts.

• Dorsal enteric sinuses open on the skin surface

• Dorsal enteric cysts are found in the intraspinal or paraspinal

compartments.

- Signs, symptoms, and physical exam

• Dorsal enteric fistula present in newborn with a bowel ostium

on the back.

• Intraspinal enteric cysts usually present between 20 and 40

years of age as episodic local or radicular pain that may prog-

ress to myelopathy.

- Workup

• Cyst incision, drainage, and pathologic examination to rule

out infectious processes

- Neuroimaging

• Radiography will help determine the presence and degree of

vertebral clefting.

• Follow with CT/MR imaging to define the degree of fistulation

or cyst involvement.

- Treatment

• Complete surgical excision is the best treatment. Chemical

arachnoiditis resulting from cystic material often produces

dense adhesions that make later operations more difficult.

III. Anomalies of Dysjunction

Spinal Lipomas³

- Background

• Fat and connective tissue masses attached to the spinal cord

and meninges

• Lipomyelomeningoceles and lipomyeloceles (84%) and intra-

dural lipomas (4%) may arise from premature separation of

the neuroectoderm from the cutaneous ectoderm, provid-

104 III Spinal Pathology

ing space for mesenchymal tissue to invade the canal of the

neural tube and promote fat formation. However, the exact

cell lineage and subsequent pattern of differentiation to adi-

pocytes have not yet been undetermined. Fibrolipomas of the

filum terminale (12%) probably result from an abnormality of

retrogressive differentiation.

- Signs, symptoms, and physical exam

• Multiple cutaneous anomalies including midline/paraspinal

mass, focal hirsutism, dermal sinus, rudimentary tail, atretic

meningocoele, and/or capillary hemangioma. Neurologic def-

icits affect 60 to 70% of patients, but younger children more

often have a cutaneous sign caused by tethering or by the li-

poma mass.

• Pain, an unusual finding in infants, is often the most common

presenting symptom in older children and adults. It often be-

comes worse with activity and is rarely radicular in nature.

• Lipomyelomeningoceles and lipomyeloceles

◦ Typically present before 6 months of age with bladder dys-

function common in 50% and half presenting without neu-

rologic compromise

◦ Neuroorthopedic syndrome (33 to 50%): lower-extremity

deformities such as clubfoot, length discrepancies, scoliosis,

trophic ulcers, and hip subluxations

• Intradural lipomas may present with an ascending monopa-

resis or paraparesis, spasticity, cutaneous sensory loss, or de-

fective deep sensation.

- Neuroimaging

• Use MRI for surgical planning and to detect associated mal-

formations (split cord, arachnoid cysts, meningoceles, and

syringomyelia). T1-weighted MRI helps visualize lipomas and

T2-weighted MRI is useful for meningoceles and syringomy-

elia. A low-lying conus is found in many patients and suggests

tethering in those with small filum lipomas.

• CT myelography is less informative and more invasive but

may be used if MR is contraindicated. CT may also be utilized

to assess for bony anomalies.

- Treatment

• Surgically debulk/resect lipomatous mass and untether if

symptomatic, or do so when the conus medullaris is low lying

in conjunction with a terminal filum lipoma.⁴

• Asymptomatic cases: there is debate over conservative treat-

ment versus prophylactic surgery.

16 Congenital Anomalies

105

◦ No significant difference in risk of neurological deterioration

• For subdural lipomas, the goal is decompression, not de-

tethering or complete excision.

• If considerable lipoma is found within the central canal, de-

bulk to reduce pressure on neural tissue but avoid full resec-

tion, for which a myelotomy may be needed.

- Surgical pearls

• When the neural placode is positioned dorsal to the open spi-

nal canal, consider the use of an ultrasonic aspirator or laser

to carefully debulk the lipoma.

Dorsal Dermal Sinuses⁵

- Background

• Thin, squamous, epithelia-lined channels associated with

(epi)dermoid tumors

• Due to a focal incomplete separation of neuroectoderm from

cutaneous ectoderm

- Signs, symptoms, and physical exam

• History of recurrent meningitis despite antibiotics due to bac-

terial passage along the tract or from chemical irritation if the

cyst (e.g., cholesterol crystals) ruptures

• A patent sinus tract may leak cerebrospinal fluid (CSF).

• A hairy nevus or hyperpigmented skin may be seen.

- Neuroimaging

• T1- or T2-weighted MRI usually reveals the dermal sinus tract

running at an oblique angle through the underlying tissues,

and diffusion MRI can define its margins.

• Anomalies of the bone may range from absent to focal or mul-

tilevel spina bifida.

- Treatment

• Treat early with excision of the dimple, tract, and any intradu-

ral connections or masses.

Myelocele and Myelomeningocele⁶

- Background

• A failure of closure of the neural tube linked to folate deficien-

cy in pregnancy. The neural and cutaneous areas of ectoderm

remain contiguous, forcing mesenchymal tissue that normally

forms the posterior elements to become displaced laterally.

- Signs, symptoms, and physical exam

• Newborn with an exposed, raw, red tissue placode positioned

in the midline

106 III Spinal Pathology

• Level determines severity of neurologic deficits, with the

most common being lumbosacral or thoracolumbar. Hydro-

cephalus is common secondary to Chiari II malformation.

- Workup

• Maternal serum a-fetoprotein (MSAFP) levels may be used

to screen at 16 to 18 weeks gestation. Use amniocentesis if

MSAFP and ultrasound suggest an abnormality.

- Neuroimaging

• Associated anomalies include syringohydromyelia, diastema-

tomyelia, lipoma, arachnoid cyst, dermoid/epidermoid, and

vertebral anomalies (e.g., hemivertebrae).

• Chiari II observed to varying degree in all patients with

myelomeningoceles.

◦The posterior neuropore may remain open too long, decom-

pressing the ventricular system and allowing the posterior

fossa to close when premature and small.

◦ Hydrocephalus usually results within 48 hours of myelome-

ningocele closure.

• The spine is rarely imaged prior to closure/repair, whereas

postoperative neurologic deterioration requires imaging.

Symptomatic retethering is a diagnosis of exclusion. If the

spine is normal, image the brain to rule out hydrocephalus or

shunt malfunction.

- Treatment

• Surgically close within 48 hours to stabilize neurologic defi-

cits and prevent infection

• Manage postoperative complications: CSF leak, retethering,

and/or hydrocephalus

- Surgical pearls (Fig. 16.2)

• Reconstruct the neural tube and close the pia, dura, thoraco-

lumbar fascia, and skin to prevent meningitis and to protect

functional tissue in the neural placode

IV. Anomalies of Caudal Cell Mass

Tight Filum Terminale Syndrome

- Background

• Incomplete retrogressive differentiation is the suspected

etiology.

- Signs, symptoms, and physical exam

• Possibilities are bladder dysfunction, sensory changes, ortho-

pedic deformities (e.g., clubfoot), radiculopathy, and scoliosis

associated with a short, thick filum and low-lying conus.

108 III Spinal Pathology

Fig. 16.2 (Continued)

(B) An inferior and lateral dissection toward the caudal edge

of the defect isolates the dura. The caudal defect is extended and the residual dura

dissected. In the midline, the dura is then approximated following that of the lateral

arachnoid. The lumbosacral fascia is identified and incised bilaterally with dissection

from the posterior iliac crest and sacrospinalis muscle, with care taken to not disrupt

the sacral fascial attachments. The lateral edges of the fascial flaps are then folded

toward the midline and sutured in place over the dorsal surface of the dura. The

subcutaneous tissue, if present, is closed. The placement of sutures in the area where

the dura joins the dermis will provide for tight internal sutures that will reduce ten-

sion during later skin closure.

16 Congenital Anomalies

109

- Neuroimaging

• Utilize T1-weighted MRI. Roughly half of patients have a thick,

fibrotic filum with tethered cord syndrome, and 23% have

small fibrolipomas. The conus is usually low lying, and 25%

have a small hydromyelia within the conus that resolves after

untethering.

- Treatment

• Resect the filum when clinical criteria for tethered cord syn-

drome are satisfied.

- Surgical pearls

• Ensure that there are no nerve roots adherent to the under-

surface of the filum.

Fibrolipomas of the Filum Terminale

- Background

• Fibrolipomas result from aberrations of filum terminale

development.

• A long and fibrous filum projects from the conus and pene-

trates through the subarachnoid space and dura, connecting

dorsally to the first coccygeal segment.

- Signs, symptoms, and physical exam

• Often asymptomatic, patients may not present with symp-

toms until late adulthood.

• Following presentation, monitor patient for signs of tethering.

- Neuroimaging

• May be found in conjunction with a tight filum terminale

- Treatment

• Resect lipomas of the filum to untether the spinal cord to pre-

vent progressive orthopedic deformity and neurologic deficit

and to preserve sphincter function

Syndrome of Caudal Regression

- Background

• Likely caused by a disruption of the caudal mesoderm before

the fourth week of gestation, resulting in an abnormal distal

spinal cord and vertebrae

• Approximately one-sixth of patients have diabetic mothers.

- Signs, symptoms, and physical exam

• Spectrum includes lower extremity fusion

(sirenomelia),

lumbosacral agenesis, anal atresia, malformed external geni-

talia, bilateral renal aplasia, and pulmonary hypoplasia with

Potter facies. The vast majority of patients present with a neu-

rogenic bladder.

110 III Spinal Pathology

- Neuroimaging

• The spinal canal is very stenotic above the last intact vertebra.

• MRI may demonstrate a wedge-shaped cord terminus, which

is characteristic.

• Lipomas or a lipomyelomeningocele may cause tethering.

- Treatment

• A large proportion of patients have a tethered cord that may

require untethering.

V. Anomalies of Segmentation

Klippel-Feil Syndrome⁷

- Background

• Congenital fusion of two or more cervical vertebrae. Spectrum

runs from vertebral body fusion (congenital block vertebrae)

to fusion of the entire vertebrae.

• Due to a failure, during 3 to 8 weeks of gestation, of normal

segmentation of prospective somatic mesoderm into discrete

cervical somites. This failure may involve disordered notch

signaling and the PAX gene family.

• Type I: fusions at C1 with or without associated caudal fu-

sions, most often with other congenital anomalies. Type II: fu-

sions no higher than C2-C3. Type III: fusions caudal to C2-C3.

Type IV: synonymous with Wildervanck syndrome.

- Signs, symptoms, and physical exam

• Often asymptomatic, although the classic triad (occurring in

less than 50%) involves a short neck, low posterior hairline,

and limited neck motion best elicited with flexion-extension

or lateral bending. C1-C2 fusions often present with pain in

childhood, whereas lower cervical fusions may present in the

second or third decade when symptomatic junctional degen-

eration occurs.

• May occur in association with basilar impression or atlanto-

occipital fusion

• Associated with scoliosis, facial asymmetry, torticollis or neck

webbing, Sprengel deformity (congenital elevation of the

scapula), synkinesia, or cervical ribs

• Systemic congenital anomalies: deafness (in 30%), unilat-

eral renal agenesis, cardiopulmonary (ventricular septal de-

fect most common), and a variety of central nervous system

findings

16 Congenital Anomalies

111

• Symptoms rarely relate directly to vertebral fusion, but may

result from adjacent hypermobile nonfused segments leading

to degenerative arthritic changes or instability.

- Workup

• Electrocardiogam, chest x-ray, and renal ultrasound. Audiol-

ogy testing may contribute to workup.

- Neuroimaging

• Initial studies to visualize fusion should include anteropos-

terior, lateral, and open-mouth odontoid views followed by

serial lateral flexion-extension C-spine radiography to evalu-

ate for instability of the atlanto-occipital, atlantoaxial, and

subaxial joints.

• Image the thoracic and lumbar spine to rule out scoliosis and

other abnormalities.

• Flexion-extension MRI is indicated if preliminary studies sug-

gest instability.

- Treatment

• Consider activity modification, bracing, and/or traction to re-

duce symptoms, delay surgery, and prevent major neurologic

deficits that may occur, even after minor trauma.

• Operate in case of progressive symptomatic segmental insta-

bility or neurologic deficits.

- Surgical pearls

• At the risk of further limitations in mobility, occasional fusion

of adjacent unstable nonfused segments may be needed.

• Sublaminar wires should be used with caution in cases of pos-

terior instrumented fusion because they carry an unaccept-

ably high risk of neurologic injury and may not be applicable

in children with anomalous vertebrae.

112 III Spinal Pathology

Common Clinical Questions

1. Myelomeningoceles result from:

A. An anomoly of notochord formation.

B. Premature dysjunction.

C. Nondysjunction.

D. Regression of the caudal cell mass.

2. The majority of spinal lipomas result from:

A. An anomoly of notochord formation.

B. Premature dysjunction.

C. Nondysjunction.

D. Regression of the caudal cell mass.

3. A tight filum terminale results from:

A. An anomoly of notochord formation.

B. Premature dysjunction.

C. Nondysjunction.

D. Regression of the caudal cell mass.

References

1. Gan YC, Sgouros S, Walsh AR, Hockley AD. Diastematomyelia in children:

treatment outcome and natural history of associated syringomyelia. Childs

Nerv Syst 2007;23(5): 515-519

2. Pang D, Dias MS, Ahab-Barmada M. Split cord malformation: Part I: A unified

theory of embryogenesis for double spinal cord malformations. Neurosur-

gery 1992;31(3):451-480

3. Finn MA, Walker ML. Spinal lipomas: clinical spectrum, embryology, and

treatment. Neurosurg Focus 2007;23(2):E10

4. Pang D, Zovickian J, Oviedo A. Long-term outcome of total and near-total

resection of spinal cord lipomas and radical reconstruction of the neural

placode, part II: outcome analysis and preoperative profiling. Neurosurgery

2010;66(2):253-272, discussion 272-273

5. Elton S, Oakes WJ. Dermal sinus tracts of the spine. Neurosurg Focus 2001;

10(1):e4

6. McLone DG, Knepper PA. The cause of Chiari II malformation: a unified theo-

ry. Pediatr Neurosci 1989;15(1):1-12

7. Tracy MR, Dormans JP, Kusumi K. Klippel-Feil syndrome: clinical fea-

tures and current understanding of etiology. Clin Orthop Relat Res 2004;

424(424):183-190

17 Trauma

Daniel K. Park and Ravi K. Ponnappan

I. Key Points

- The thoracolumbar spine (T11-L1) is the most common site of

spinal injury.

- Surgical treatment is indicated for progressive neurologic im-

pairment, patient mobilization, mechanical instability, and in-

tractable pain.

- Recognition is key to management and prevention of secondary

injury.

II. General Principles

- Field management

• A, airway; B, breathing; C, circulation

• Spinal immobilization

◦ Rigid cervical collar, lateral bolsters, rigid backboard

◦ Pediatric patients require recessed head board or pediatric

board.

- Emergency room management

• Repeat ABCs; add disability and exposure

• Standard imaging

• Neurogenic shock

◦ Hypotension in the presence of bradycardia

◦ Management with vasopressors and modest fluid

resuscitation

- Classification

• American Spinal Injury Association (ASIA) scoring scale (Table

17.1)

◦ Complete: no motor or sensory function below zone of injury

◦Incomplete: partial motor or sensory function below zone

of injury (Table 17.2)

• Ten to 15% of patients have noncontiguous spinal fractures.

• Orthogonal radiographs (anteroposterior [AP]/lateral C, T, and

LS spine)

• Computed tomography (CT)

◦ Useful for visualizing occipital-cervical and cervicothoracic

junctions

◦ Must include sagittal and coronal reconstructions if plain x-

ray not utilized

◦ Not as useful for ligamentous injury assessment

17 Trauma

115

Table 17.1 ASIA Neurological Scoring System

Grade

Description

Complete: No motor or sensory function is preserved in the

sacral segments

Incomplete: Sensory but not motor function is preserved below

the neurologic level and includes the sacral segments

Incomplete: Motor function is preserved below the neurologic

level, and more than half of the key muscles below the level have

a muscle grade <3

Incomplete: Motor function is preserved below the neurologic

level, and at least half of the key muscle groups below the level

have a muscle grade >3

Normal

Note: The caudal-most normal level is the neurologic level.

Table 17.2 Incomplete Spinal Cord Injury Patterns

Syndrome

Prognosis

Description

Central cord

Fair

Due usually to hyperextension injury with

greater upper extremity involvement and

more proximal than distal muscle groups

Anterior cord

Poor

Due to injury of anterior spinal artery; loss

of pain, temperature, and motor

Brown-Sequard

Best

Due to hemi-transection of cord or lateral

injury; ipsilateral motor loss, vibration,

and position sense and contralateral pain

and temperature

Posterior cord

Fair

Loss of vibration and position sense

• Magnetic resonance imaging (MRI)

◦ Required in all cases with neurologic impairment or deficit.

◦Ligamentous structures visualized on T1.

◦Edema visualized on T2 with short tau inversion recovery

(STIR).

- Steroid management

• Controversial, should be based on institutional protocol (see

Chapter 10).

- Surgical timing¹

• Early decompression (<72 h) may improve neurologic outcomes.

• Early decompression (<24 h) may result in better clinical

outcomes.

116 III Spinal Pathology

III. Cervical Trauma

Atlanto-occipital Dissociation (Fig. 17.1)

- Background

• Clinical suspicion paramount

• Mechanism: high-energy rotational or flexion-extension force

- Signs, symptoms, and physical exam

• Often fatal; neurologic presentation can range from no defi-

cits to quadraparesis²

• Derangements in cardiorespiratory parameters common

- Neuroimaging

• Powers ratio: ratio of distance from basion to C1 lamina di-

vided by distance from opisthion to anterior ring of C1

◦ Identifies anterior subluxation if ratio >1

◦ May miss posterior subluxation

• Wackenheim line

◦Line from posterior surface of clivus—normally its inferior

extension should barely touch posterior aspect of odontoid

tip

◦ If line runs behind odontoid, there is posterior dissociation.

◦ If line runs in front, there is anterior dissociation.

• Atlanto-occipital condyle distance

◦ Should be less than 5 mm

- Treatment

• Closed reduction with halo-vest application or occipitocervi-

cal fusion

Fig. 17.1 Powers ratio for assessing craniovertebral stability.

17 Trauma

117

• Traction should generally be avoided (10% risk of neurologic

deterioration).

- Surgical pearls

• Obtain a CT angiogram (CTA) or MR angiogram (MRA) to as-

sess vertebral artery integrity as part of the preoperative

planning.

• Use of MRI for assessing integrity of ligaments may help with

decision to fuse occiput to C1, C2, or a more caudal spot.

Atlas (C1) Fracture

- Background

• Neurologic injury is rare due to large space available for the

spinal cord.

• Can occur anterior, posterior, or combined (Jefferson)

• Status of transverse atlantal ligament (TAL) is critical to surgi-

cal decision making.

• Mechanism is axial loading.

- Signs, symptoms, and physical exam

• Typically does not lead to neurologic deficits

• With severe fractures, complete and incomplete injuries are

possible, including medullary dysfunction.

- Neuroimaging

• Open-mouth odontoid view to assess the relationship of lat-

eral mass of C1 on C2

• Spence rule (>7 mm composite overhang is unstable)

• CT scan with coronal and sagittal reconstruction

• CTA to rule out vertebral artery dissection/occlusion

• MRI to assess TAL integrity

- Treatment

• Rigid cervical orthosis or halo for 3 months if TAL intact

• C1-C2 fusion if nonunion or TAL incompetent

- Surgical pearls

• Obtain a CTA or MRA to assess vertebral artery integrity as

part of the preoperative planning.

Axis (C2) Fracture and Traumatic Spondylolithesis of C2

(Hangman’s Fracture)

- Background

• Associated with high-velocity trauma

• C2 fractures among the most common spinal fractures in the

elderly

• Mechanism is a combination of hyperextension, compression,

and rebound flexion (Fig. 17.2).

118 III Spinal Pathology

Fig.

17.2 The Levine and

Edwards classification of trau-

matic spondylolistheseis of

the axis (hangman’s fracture).

(From Feliciano DV, Mattox

KL, Moore EE. Trauma,

6th

Edition; http://www.access-

surgery.com.) Copyright

The McGraw-Hill Companies,

- Signs, symptoms, and physical exam

• Patients are typically asymptomatic with nonangulated, non-

displaced fractures.

• Complete or incomplete injuries are possible with severe

fractures.

• Cerebellar findings

(nausea/vomiting, asymmetric exam,

ataxia) may suggest vertebral artery injury.

- Neuroimaging

• CT scan with reconstructions

• CTA to rule out vertebral artery dissection/occlusion

- Classification/treatment

• Type I: minimal displacement (<3 mm) and halo for 12 weeks

• Type II: significant displacement (>3 mm) and angulation >11

degrees

◦ Cervical traction to reduce and halo for 10 to 12 weeks

• Type IIa: minimal displacement (<3 mm) but angulation >11

degrees

◦ Reduction in extension followed by halo; avoid traction

• Type III: associated facet dislocation—anterior C2-C3 or pos-

terior C1-C3 fusion

- Surgical pearls

• Obtain a CTA or MRA to assess vertebral artery integrity as

part of the preoperative planning

17 Trauma

119

Dens Fracture (C2)

- Background

• Among the most common spinal fracture injuries in the el-

derly after falls

• Sometimes associated with simultaneous C1 fractures

• Mechanism: hyperflexion or hyperextension (Fig. 17.3)

- Signs, symptoms, and physical exam

• Neck pain and tenderness on palpation typical

• Usually does not cause neurologic deficits (due to the width of

the canal in this region)

• Severe angulated fractures may cause complete or incomplete

injuries

- Neuroimaging

• CT scan with reconstructions recommended even if fracture is

evident on plain radiograph

• MRI may be helpful for assessing integrity of cruciate liga-

ment (surgical implications)

- Treatment³

• Type 1: avulsion fracture at tip—rigid collar

• Type II: at the waist/base (Fig. 17.1)—rigid collar versus halo

versus early fixation

◦ Anterior odontoid screw or posterior C1-C2 instrumented

fusion

Fig. 17.3

(A-C) Anderson D’Alonzo clas-

sification of dens fractures. (A) Type III

fracture, (B) Type II fracture, (C) Type I

fracture.

120 III Spinal Pathology

• Type III: within the body—halo or rigid collar, based on

displacement

• Posterior fixation options include wiring, transarticular, ped-

icle/pars, intralaminar

- Surgical pearls

• Ensure that the anterior cruciate ligament is intact before at-

tempting an anterior odontoid screw fixation.

Subaxial Spine (C3-C7)

- Background

• Particularly common in high-speed motor crashes and diving

accidents

• Allen-Ferguson classification system, based on mechanism

◦Flexion compression: blunting at anterosuperior margin →

loss of anterior height → teardrop fragment → <3 mm of dis-

placement of posterior body into canal → more severe dis-

placement of posterior body into canal

◦ Vertical compression: central cupping of one end plate →

disruption of both end plates

◦Flexion distraction: failure of posterior ligamentous com-

plex with facet subluxation only in flexion → unilateral facet

dislocation → bilateral facet dislocation → bilateral facet dis-

location with at least 100% vertebral body displacement

◦ Extension compression: unilateral posterior arch fracture →

bilaminar fractures → circumferential disruption

◦ Extension distraction: failure of anterior ligamentous com-

plex → involves posterior ligamentous complex

• Lateral flexion: ipsilateral fractures of the centrum and pos-

terior arch → fracture of body with contralateral bony or liga-

mentous failure in tension

- Signs, symptoms, and physical exam

• Mild compression fractures or nondisplaced facet fractures

may not cause deficits.

• Significant fractures (either in anterior or posterior columns)

may cause devastating deficits and/or radiculopathies.

- Neuroimaging

• CT and MRI typically necessary to appreciate the extent of

injury.

• CTA recommended if any fracture involves the transverse

foramen.

- Treatment

• Based on stability and neurologic injury

• Considerations

◦ Is there mechanical instability?

17 Trauma

121

◦ Is there neurologic compromise necessitating direct or indi-

rect decompression?

◦ Are there patient factors (e.g., multitrauma)?

• Stable: nonoperative, rigid cervical orthosis

• Unstable: surgical fusion via anterior versus posterior versus

combined approach

- Surgical pearls

• Ending a fixation construct at C7 posteriorly may lead to de-

layed cervical-thoracic junction kyphosis.

• Ensure the posterior elements are intact when an anterior cer-

vical vertebral body fracture is present. Posterior element in-

volvement may indicate a highly unstable, three-column injury.

Thoracolumbar Fractures

- Background

• Most common region is the thoracolumbar junction (T11-L2).

• Due to transition from fixed thoracic spine to mobile lumbar

spine

• Thoracolumbar injury classification and severity score (TLIC-

SS) proposes that operative treatment be based upon three

factors^4,5:

◦ Morphology of fracture

◦ Posterior ligamentous complex

◦ Neurologic status

• Compressive flexion (Fig. 17.4)

◦ Instability factors: >50% height loss, >30 degrees angulation,

>30 degrees of focal kyphosis

• Flexion-distraction injury (Chance fracture/seatbelt injury)

◦ Bony fracture without subluxation or dislocation

▪Treat with hyperextension body brace or cast

◦Ligamentous injury

▪Posterior instrumented fusion to restore tension band

• Torsional flexion (fracture-dislocation)

• Vertical compression (burst fractures)

◦ Anterior approach allows better decompression of retro-

pulsed fragment.

◦ Posterior approach allows restoration of the tension band

and reduction.

◦ Combined approach allows for optimal decompression and

reconstruction.

- Signs, symptoms, and physical exam

• Significant fractures at the level of the conus may cause bow-

el/bladder dysfunction as well as significant lower extremity

weakness.

17 Trauma

123

• Approach

◦ Anterior approach optimal for decompression

◦ Posterior ligamentous complex injury requires tension band

reconstruction.

• Timing^1,6

◦ Urgent medical/critical care stabilization/optimization

◦ Surgical intervention when medically optimized

◦Early treatment may provide better outcomes and fewer

complications.

◦ Definition of “early” is controversial.

- Surgical pearls

• Progressive neurologic deficits

(due to expanding hema-

toma, for example) are atypical but require urgent surgical

intervention.

• Short-segment and long-segment posterior fixation, as well as

anterior reconstruction, have all been shown to be effective

biomechanically. Choice of approach must be tailored to type,

location, and severity of fracture.

Sacral Fractures

- Background

• Classification (Fig. 17.5)

◦Zone 1: across the ala and can affect L5 nerve root

▪<10% have neurological injury

◦Zone 2: through the neuroforamina, causing unilateral

symptoms

◦Zone 3: through the body and highest incidence (~56% with

neurologic injury)

◦ Others

▪Transverse (may miss on plain radiograph)

▪U-shaped fractures

▪Results from axial load

• Central fractures (zone 3) have the highest incidence of neu-

rologic injury.

• L5 most common nerve root affected

• Mechanism: fall from height or associated pelvic ring fracture

- Signs, symptoms, and physical exam

• Depending on zone involved, sacral fractures can result in sig-

nificant deficits from L5 root to lower sacral roots.

• Ankle dorsiflexion/plantar flexion affected with L5/S1

involvement

• Bowel/bladder function affected with sacral root involvement

17 Trauma

125

Common Clinical Questions

1. List these incomplete spinal cord injuries in the order of best

prognosis to worst.

A. Brown-Sequard, anterior cord, central cord

B. Central cord, Brown-Sequard, anterior cord

C. Brown-Sequard, central cord, anterior cord

D. Anterior cord, central cord, Brown-Sequard

2. A patient presents with a ligamentous flexion distraction injury

of the thoracolumbar junction. The patient has focal 40 degrees

of kyphosis and a normal neurologic examination. Patient man-

agement should include:

A. Hyperextension brace

B. Posterior tension band reconstruction

C. Anterior spinal fusion

D. Physical therapy

3. A polytrauma patient is intubated with an unknown neurologic

injury. What is the best modality for assessing acute spinal cord

injury?

A. CT scan

B. T1-weighted MRI

C. T2-weighted MRI

D. Flexion and extension cervical radiographs

References

1. Fehlings MG, Perrin RG. The timing of surgical intervention in the treatment

of spinal cord injury: a systematic review of recent clinical evidence. Spine

(Phila Pa 1976) 2006; 31(11, Suppl):S28-S35, discussion S36

2. Harmanli O, Koyfman Y. Traumatic atlanto-occipital dislocation with survival:

a case report and review of the literature. Surg Neurol 1993;39(4):324-330

3. Maak TG, Grauer JN. The contemporary treatment of odontoid injuries. Spine

(Phila Pa 1976) 2006; 31(11, Suppl):S53-S60, discussion S61

4. Vaccaro AR, Baron EM, Sanfilippo J, et al. Reliability of a novel classifica-

tion system for thoracolumbar injuries: the Thoracolumbar Injury Severity

Score. Spine (Phila Pa 1976) 2006; 31(11, Suppl):S62-S69, discussion S104

5. Vaccaro AR, Lehman RA Jr, Hurlbert RJ, et al. A new classification of thoraco-

lumbar injuries: the importance of injury morphology, the integrity of the

posterior ligamentous complex, and neurologic status. Spine (Phila Pa 1976)

2005;30(20):2325-2333

6. Rutges JP, Oner FC, Leenen LP. Timing of thoracic and lumbar fracture fixation

in spinal injuries: a systematic review of neurological and clinical outcome.

Eur Spine J 2007;16(5):579-587

18 Infection

William D. Long III and Peter G. Whang

I. Key Points

- Swift and accurate diagnosis of spinal infections is necessary to

prevent structural instability or neurologic compromise.

- Hematogenous spinal infections develop from the seeding of

the cartilaginous end plates, which allows pathogens to propa-

gate within the avascular disc space before spreading to the ad-

jacent vertebral bodies.

- Granulomatous infections may be caused by one of several fun-

gal, bacterial, and spirochete pathogens that generally give rise

to an indolent clinical course.

- Postoperative infections most often develop secondary to di-

rect inoculation of the wound with skin flora and are character-

ized by pain and tenderness at the surgical site.

II. Pyogenic Vertebral Osteomyelitis and Discitis^1-4

- Background

• Vertebral osteomyelitis accounts for about 1% of all skeletal

infections.

• Discitis typically arises as a result of hematogenous spread

such that the pathogens emanate from the vascular end plates

into the avascular disc space before disseminating to the adja-

cent vertebral bodies.

• Pyogenic infections most frequently involve the lumbar spine

(58%), followed by the thoracic (30%) and cervical (11%)

regions.

• Gram-positive organisms such as Staphylococcus aureus and

Streptococcus species are the most commonly isolated organ-

isms (67 and 24% of cases, respectively).

- Signs, symptoms, and physical examination

• The most prevalent signs and symptoms are axial pain (86%)

and fever (60%).

• Neurologic changes such as radicular numbness and muscle

weakness may be present in as many as one-third of patients.

• Patients should be questioned regarding any ongoing consti-

tutional symptoms, travel history, or recent procedures that

may be suggestive of a diagnosis of infection.

128 III Spinal Pathology

- Workup

• White blood cell count (WBC) may be increased in these pa-

tients, although in many this value will be normal.

• Erythrocyte sedimentation rate (ESR) is more sensitive but is

relatively nonspecific for infection.

• C-reactive protein (CRP) is elevated in at least 90% of patients

with spinal infections and is a reliable indicator of the disease

course because it tends to rise acutely with the onset of an

infection but returns to baseline rapidly as it resolves.

• Blood cultures may be useful because they have been shown

to reveal the causative pathogen in up to 58% of hematoge-

nous spinal infections.

• Urinalysis and culture with sensitivities should also be ob-

tained to rule out an infection of the urinary tract, which may

spread to the spine.

- Neuroimaging

• Plain radiographs are the standard form of initial imaging

study for suspected cases of spinal infections and will fre-

quently exhibit abnormalities (89% of cases).

• Computed tomography (CT) may display early pathologic

changes within the spinal column as well as any fluid collec-

tions in the surrounding soft tissues.

• Magnetic resonance imaging (MRI) is the ideal diagnostic mo-

dality for identifying pyogenic discitis.

◦Edema and fluid may be evident within the discs and adja-

cent tissues on T2-weighted images.

◦ Addition of gadolinium contrast can enhance the visualiza-

tion of paraspinal and epidural enhancement suggestive of

active infection.

• Technetium-99m/gallium-76 citrate bone scans or indi-

um-111 tagged WBC studies are extremely sensitive for diag-

nosing spinal infection but are less specific.

- Treatment

• First-line treatment for pyogenic infections is administration

of broad-spectrum intravenous (IV) antibiotics for at least 6

to 8 weeks until culture-specific regimens may be initiated.

◦ Identify the pathogen with biopsy, blood, or tissue cultures

prior to treatment initiation.

• Immobilization may be beneficial for reducing pain and sta-

bilizing the spine.

• Surgery may be warranted if appropriate medical manage-

ment fails or if the patient develops neurologic deterioration

or spinal instability/deformity.

18 Infection

129

• The goals of surgery include debridement of the infected tis-

sue, decompression of the neural structures, and stabilization

of the spine.

- Surgical pearls

• Vertebral osteomyelitis and discitis frequently affect the spi-

nal column and may require an anterior procedure (Fig. 18.1).

• Posterior stabilization may also be necessary in instances

where there is significant instability or deformity.

◦ Avoid stainless steel implants in these cases as there is a ten-

dency for bacteria to form a biofilm on them.

◦ Titanium implants are preferred because they don’t promote

bacterial biofilm colonization.

• Autogenous bone is an excellent graft material for fusion in an

infected surgical field, although allograft and metal may also

be reasonable options for select cases.

Fig.

18.1 Cervical discitis/epi-

dural abscess with end plate in-

volvement, relative sparing of the

vertebral body, and epidural col-

lection compromising the cervical

canal.

130 III Spinal Pathology

III. Granulomatous Infections^1,2,4,5

- Background

• Granulomatous infections caused by certain bacteria, fungi,

and spirochetes are far less common than pyogenic infections

in the United States (US).

• Spinal inoculation generally is done within the peridiscal me-

taphysis of the vertebral body adjacent to the end plate.

◦ An inflammatory response produces a granuloma with a ca-

seous abscess.

◦The infection propagates along the anterior longitudinal

ligament to encompass contiguous levels.

• The most common pathogen is Mycobacterium tuberculosis,

an atypical bacteria that is more prevalent in underdeveloped

nations but is becoming more common in the US.

◦ Pott described the first surgical drainage of a tuberculous

abscess in 1779, and his name has become synonymous

with spinal disease.

◦ Neurologic deficits may be observed in up to 47% of affected

individuals.

◦The spine is the most common site of skeletal involvement

(1% of all patients and nearly 50% of those with musculosk-

eletal manifestations).

• Fungal species

(e.g., Aspergillus, Blastomyces, Coccidioides,

Cryptococcus, and Histoplasma), spirochetes (e.g., Actinomyces

israelii and Treponema pallidum), and parasites are more un-

usual causes of granulomatous spinal infections.

- Signs, symptoms, and physical examination

• Granulomatous spinal infections are characterized by a pro-

longed duration (i.e., months to years) of symptoms, including

back pain and constitutional complaints.

• The thoracic spine is the most common region of the spine

for infection, which may give rise to significant kyphotic

deformities.

• Neurologic compromise and paraplegia may develop more

frequently with tuberculous infections than with pyogen-

ic osteomyelitis due to their predilection for the posterior

elements.

- Workup

• All patients should be assessed with a tuberculin purified pro-

tein derivative (PPD) skin test.

• ESR, CRP, WBC, and blood cultures may be less informative in

these cases.

18 Infection

131

• Sputum should be acquired for acid-fast bacilli (AFB) and fun-

gal cultures.

- Neuroimaging

• Individuals suspected of having tuberculous infections should

be assessed with a chest x-ray, which may demonstrate pul-

monary disease as well as any extensive bony lesions or focal

kyphosis.

• MRI is the imaging modality of choice and will often show

destruction of the vertebral bodies with relative sparing of the

intervertebral discs.

- Treatment

• Pathogen-directed antimicrobial therapy

◦ Six to 12 months of a multidrug treatment, including isonia-

zid, rifampin, pyrazinamide, and streptomycin or ethambu-

tol is the standard regimen for Mycobacterium tuberculosis.

◦ Antifungals such as amphotericin B or ketoconazole are em-

ployed for culture-documented fungal disease.

• Surgical intervention is not routinely performed for these in-

fections unless there is a failure of pharmacotherapy, progres-

sion of deformity, instability, or neurologic decline.

- Surgical pearls

• These types of infections may bring about considerable de-

struction of the vertebral bodies, which may require recon-

struction of the anterior column.

• Supplementary posterior fixation may also be indicated to

minimize the risk of developing a postoperative deformity.

• Colonization of metallic implants rarely occurs with granuloma-

tous infections.

◦ Avoid stainless steel implants

◦ Postoperative imaging with CT and MRI is easier with tita-

nium implants (decreased artifact compared with stainless

steel implants).

IV. Epidural Infections

- Background

• Abscesses most often arise from adjacent vertebral osteomy-

elitis/discitis but may also develop from hematogenous ex-

tension or direct inoculation from spinal procedures.

• Staphylococcus aureus is the most common pathologic

organism.

• Epidural infections usually affect the thoracic and lumbar

spines, where they typically exist in the posterior epidural

132 III Spinal Pathology

space; in the cervical spine they are normally located anterior

to the thecal sac.

- Signs, symptoms, and physical examination

• Patients regularly complain of axial pain but symptoms may

be more subtle with less virulent organisms.

• Larger lesions may compress the neural elements and give

rise to neurologic deficits.

- Workup

• Standard infection laboratories (e.g., WBC, ESR, and CRP) with

blood cultures

• Identification of a specific pathogen may require a needle or

open biopsy to acquire tissue for culture.

- Neuroimaging

• MRI is the most sensitive and specific imaging study because

it clearly demonstrates any fluid collection in the epidural

space.

- Treatment

• Patients who are neurologically intact may be candidates for

nonsurgical treatment consisting of long-term antibiotic therapy.

• Surgical decompression ± stabilization is generally indicated

for individuals who have failed medical management or who

present with neurologic deterioration.

- Surgical pearls

• Operative approach is largely influenced by the location of the

infection.

• While a laminectomy may be sufficient to address posterior

abscesses, an anterior procedure may also need to be per-

formed in the setting of vertebral osteomyelitis or ventral

abscess.

• Concomitant arthrodesis may be warranted in cases where

spinal instability has been caused by the infection or any sub-

sequent decompression.

V. Postoperative Infections^1,2,4,6

- Background

• Surgical site infection (SSI) has been reported in up to 12% of

adults undergoing spinal operations.

• SSI is associated with longer hospital stays, higher complica-

tion rates, and increased mortality.

• Risk factors for SSI include increased age, obesity, diabetes,

tobacco use, poor nutritional status, greater intraoperative

blood loss, prolonged surgical time, complete neurologic inju-

18 Infection

133

ries, revision surgery, placement of instrumentation, dissemi-

nated cancer, and a posterior operative approach.

• Postoperative SSI ordinarily arises following direct inocula-

tion of the wound with normal skin flora.

- Signs, symptoms, and physical examination

• The typical SSI is clinically evident and associated with ob-

vious erythema, edema, and drainage from the incision, al-

though subfascial lesions may yield few external signs of

infection.

• Patients may or may not complain of pain or exhibit constitu-

tional symptoms.

- Workup

• WBC, ESR, and CRP are frequently elevated and may be used

as serial markers to confirm the resolution of a SSI.

• Wound cultures are essential for directing antimicrobial

therapy.

◦ Sampling of deep wound collections is preferable since su-

perficial drainage is prone to contamination with skin flora.

◦ Intraoperative cultures represent the ideal method for iden-

tifying the causative organism.

- Neuroimaging

• CT may reveal pathologic changes such as an abscess or hema-

toma, but these findings may be difficult to differentiate from

nonspecific postoperative changes.

• MRI is ideal for identifying fluid collections, but in many cas-

es there will be an increased signal on T2-weighted images

and contrast enhancement in the surgical field regardless of

whether a SSI is present.

- Treatment

• Prophylactic antibiotics administered 60 minutes before a

spinal procedure have been shown to reduce the incidence of

SSI by up to 60%.

• Additional doses of intraoperative antiobiotics should be dis-

pensed for prolonged surgical procedures with significant blood

loss or gross contamination.

• Definitive therapy for established SSI is open irrigation and

debridement.

• IV antibiotics are typically continued for a minimum of 6 weeks,

at which time patients may be switched over to oral medica-

tions depending on clinical course and laboratory profile.

- Surgical pearls

• Deep wound cultures should be obtained intraoperatively

prior to the delivery of antibiotics and irrigation of the tissues.

134 III Spinal Pathology

• Metallic hardware is frequently left in place to maintain sta-

bility, but any loose bone graft should be removed to prevent

the formation of a nidus of bacteria.

• Following open irrigation and debridement, the wound may

be closed primarily over drains, covered with a vacuum dress-

ing, or left open.

Common Clinical Questions

1. Which laboratory test is best for following the resolution of a

spinal infection?

A. White blood cell count

B. Erythrocyte sedimentation rate

C. C-reactive protein

D. Platelet count

2. What are the most common organisms that are isolated in cases

of vertebral osteomyelitis and discitis?

A. Gram-positive cocci

B. Gram-negative rods

C. Mycobacterium tuberculosis

D. Fungi

3. Surgical intervention is most clearly indicated for which of these

conditions?

A. L3-L4 discitis associated with low back pain

B. Incisional drainage following a recent discectomy

C. Granulomatous infection involving the T6-T7 vertebral bod-

ies with no obvious deformity or compression of the neural

elements

D. C5-C6 epidural fluid collection resulting in progressive

weakness and numbness

18 Infection

135

References

1. Whang PG, Grauer JN. Infections of the spine. In Lieberman JR, ed. AAOS

Comprehensive Orthopaedic Review. Rosemont, IL: American Academy of

Orthopaedic Surgeons; 2009:727-734

2. Tsiodras S, Falagas ME. Clinical assessment and medical treatment of spine

infections. Clin Orthop Relat Res 2006;444:38-50

3. Mylona E, Samarkos M, Kakalou E, Fanourgiakis P, Skoutelis A. Pyogenic ver-

tebral osteomyelitis: a systematic review of clinical characteristics. Semin

Arthritis Rheum 2009;39(1):10-17

4. An HS, Seldomridge JA. Spinal infections: diagnostic tests and imaging stud-

ies. Clin Orthop Relat Res 2006;444:27-33

5. Swanson AN, Pappou IP, Cammisa FP, Girardi FP. Chronic infections of the

spine: surgical indications and treatments. Clin Orthop Relat Res 2006;444:

100-106

6. Pull ter Gunne AF, Cohen DB. Incidence, prevalence, and analysis of risk fac-

tors for surgical site infection following adult spinal surgery. Spine (Phila Pa

1976) 2009; 34(13):1422-1428

Answers to Common Clinical Questions

1. C

2. A

3. D

19 Tumors of the Spine

Camilo A. Molina and Daniel M. Sciubba

I. Key Points

- Spine tumors are broadly organized into three general catego-

ries depending on the spine compartment invaded by the neo-

plasm: extradural, intradural extramedullary, and intradural

intramedullary (Fig. 19.1).

- Overall, magnetic resonance imaging (MRI) is the best modality

for viewing neoplasms in and around the spine and thus best

for determining the localizing compartment of a neoplasm.

- Determining which compartment is affected is essential to ev-

ery aspect of managing the patient. The crucial information

yielded includes the primary differential diagnosis (Fig. 19.1),

the pathophysiologic mechanism connecting the presence of

the tumor to the clinical syndrome, and the appropriate surgi-

cal strategy.

II. Metastatic Epidural Spine Tumors

- Background

• Metastatic spine tumors are more prevalent than primary

spine tumors.^1,2

• Out of 1.5 million annually incident cancer cases, 10% result

in symptomatic secondary metastases, and the bony spine is

the third most common site of metastases. The thoracic spine

is the most commonly afflicted.¹

• Peak incidence: fourth to sixth decade. Men are more likely to

be afflicted.¹

• The two most likely origins of spinal metastasis are breast and

lung cancer.¹

• The two most common mechanisms of spread to the spine are

hematogenous spread and direct extension.¹

- Signs, symptoms, and physical exam

• Presentation is a factor of systemic tumor spread, amount of

bony destruction, extent of neural compression, and tumor

growth rate.^1,3

• Physical examination is crucial to elicit appropriate signs of

neurologic dysfunction, pain, and palpable masses. A thor-

ough history is essential to elicit risk factors (e.g., cigarette

smoking).

19 Tumors of the Spine

137

Fig.

19.1

(A-C) Artistic rendition

demonstrating the structural rela-

tionship of differently compartmen-

talized neoplasms to the spinal cord

and adjacent structures. Differential

diagnosis based on compartmen-

talization of the neoplasm

(from

Khanna AJ, ed. Magnetic Resonance

Imaging for Orthopaedic Surgeons.

Thieme; Pg. 318, Fig. 12.1; pg. 329,

Fig. 12.17; pg. 332, Fig 12.22).

• Pain is the most common initial complaint and can be catego-

rized as radicular (radicular compression or foraminal stenosis),

mechanical (spinal instability due to compromised vertebral

bodies and adjacent structures), or local pain.

• Motor and autonomic dysfunctions are the second most com-

mon signs of metastatic epidural spinal cord compression

(MESCC).¹

138 III Spinal Pathology

• Sensory dysfunction signs such as anesthesia, hyperesthesia,

and paresthesias are the next most common. When signs are

of myelopathic origin, patients describe symptoms as being

distributed in a bandlike fashion.

• Compromise of bowel or bladder function and loss of the abil-

ity to ambulate are crucial prognosticators.

• Other important signs include those of systemic neoplastic

disease, such as marked weight loss.

- Workup and neuroimaging

• Diagnostic blood work should include prostate-specific anti-

gen assays, blood chemistry, and blood cell counts.

• The gold standard for imaging of metastatic spine disease is

MRI without and with contrast because of the quality of visual-

ization of the bone-soft tissue interface, elucidating compres-

sion or invasion of osseous, neural, and paraspinal structures.

T2-weighted images and T1 contrast-enhanced images have

the highest yield.^1,3

• Computed tomography (CT) is useful for detailed rendition of

osseous anatomy, myelography studies (in cases of MRI con-

traindication), evaluation of vascular supply, and whole body

scans to detect the tumor of origin.

• Plain radiographs are relatively insensitive but can be useful

to screen for pathologic fractures, spinal deformities, sclerotic

lesions, lytic lesions, and large masses.

- Treatment

• For the most part, treatment goals are therapeutic, as curative

treatment is possible only in select cases (i.e., solitary renal

cell carcinoma). Therapeutic goals include preserving neuro-

logic function, mechanical stabilization, and pain relief.

• Surgical candidacy factors include functional status (the most

prognostic factor of postoperative neurologic function),¹ age,

and life expectancy (with 3 months considered a minimum).

Objective scales are available for patient selection.³

• Surgical goals should be achieving optimal resection, decom-

pression, and stabilization (i.e., vertebral body reconstruction

and pedicle instrumentation).

• Nonsurgical candidates can be managed via minimally inva-

sive means such as vertebroplasty or kyphoplasty.

• Adjuvant treatments include pharmacotherapy (tumoricidal

and palliative) as well as radiation therapy (conventional ra-

diotherapy or stereotactic radiosurgery).¹

19 Tumors of the Spine

139

- Surgical pearls

• Although surgical exposure is always of utmost importance,

these patients often have poor healing capabilities due to sys-

temic cancer spread, previous use of corticosteroids, and ra-

diation exposure to the surgical field. For this reason, surgical

exposure and wound closure should be done with plastic sur-

gery as needed to avoid postoperative wound complications.

III. Primary Epidural Spine Tumors

- Background

• Ten percent of the tumors that affect the bony spine are pri-

mary epidural spine tumors, and they occur more frequently

in men than in women.²

• The most frequently encountered primary spine tumors are

chordomas, chondrosarcomas, osteosarcomas, and Ewing sar-

coma.^2,4 Chordomas are slow-growing tumors and represent

1% of primary spine tumors.⁵ Chondrosarcomas are respon-

sible for 7 to 12% of primary spine tumors.² Osteosarcomas

are less common but are the most common malignant tumor

of osseous origin. Predisposing factors include adolescence, a

family history of retinoblastoma, and previous exposure to

ionizing radiation.²

• Among children, eosinophilic granulomas and Ewing sar-

coma are the most common benign and malignant tumors,

respectively.²

• Hemangiomas are the most common benign and plasmacy-

tomas the most common malignant primary epidural spine

tumors in adults.²

• Other, rare tumors include giant cell tumors, aneurysmal

bone cysts, osteoid osteomas, and osteoblastomas.^2,4

- Signs, symptoms, and physical exam

• Chordomas: The most common symptoms are back and neck

pain. Nearly a third of patients will demonstrate signs of neu-

rologic deficit, and physical exam may identify a palpable

mass.^2,5

• Chondrosarcomas: Signs and symptoms of radiculopathy, my-

elopathy, cauda equina syndrome, and nocturnally exacerbat-

ed focal pain are common.^2,4

• Osteosarcomas: The most common presentation is an insidious

development of back pain that is exacerbated nocturnally.^2,4

140 III Spinal Pathology

• Ewing sarcoma: Patients most commonly present with symp-

toms of pain and local inflammation, and this is frequently

misdiagnosed as infection. Signs and symptoms of systemic

illness such as weight loss and fever are also common.^2,4

• Plasmacytomas: In addition to symptoms of pain and neuro-

logic deficit, patients commonly present with diffuse osteo-

porosis, bone fractures, and osteolytic bone lesions.^2,4

- Workup and neuroimaging

• Histopathological analysis of the lesion is crucial for select-

ing appropriate intervention in respect to each tumor ori-

gin (i.e., prognosis and sensitivity to pharmacotherapy or

radiotherapy).³

• MRI is the gold standard for chordomas and chondrosarcomas,

which are both hyperintense under T2 weighting.^2,5 However,

chondrosarcomas can be differentiated from chordomas and

other tumors via gadolinium enhancement, which yields a

characteristic ring-and-arc pattern.⁴

• The gold standard for imaging osteosarcomas is positron

emission tomography (PET) scanning due to its ability to mea-

sure bone turnover. Highly mineralized tumors are hyperin-

tense on T1-weighted MRI. Tumors with low mineralization

are hyperintense on T2-weighted imaging.²

• Ewing sarcoma lesions can be detected via conventional ra-

diography because they have a mottled, moth-eaten appear-

ance. The possibility of distant metastases should be ruled out

via a whole-body CT scan.²

• In case of suspicion of multiple myeloma, blood cell counts,

blood chemistries, and serum/urine electrophoresis should

be obtained. These studies may show evidence of renal fail-

ure, infections, hypercalcemia, anemia, or Bence-Jones pro-

teins. Diagnostic bone marrow biopsies are also appropriate.

The lesions can be imaged via CT or MRI (T2-weighted) and

are usually not hot (i.e., no increased uptake) on a bone scan.^2,4

- Treatment of primary epidural spine tumors

• The most important prognostic factors for primary spine tu-

mor include tumor identity, location or spread, size, and his-

tologic grade.

• Ideally, the neoplasms should be completely excised via en

bloc resection with wide surgical margins and avoidance of

tumor breach. Breach is correlated with a high local recur-

rence rate.²

• Local recurrence of the neoplasm can be avoided with con-

comitant adjuvant therapy such as chemotherapy and radio-

19 Tumors of the Spine

141

therapy (note, however, that osteosarcomas and chondrosar-

comas are radioresistant).

• Ewing sarcoma can be managed with chemotherapy, in par-

ticular a combination of four drugs: doxorubicin, cyclophos-

phamide, vincristine, and dactinomycin. In addition, Ewing

sarcoma is radiosensitive and can be treated via conventional

radiotherapy.²

• Plasmacytomas do not need surgical intervention. They can

be managed with pharmacotherapy (i.e., chemotherapy and

adjuvant bisphosphonates) and radiotherapy. Surgical inter-

vention is reserved for cases of marked spinal instability.²

- Surgical pearls

• Primary epidural tumors: En bloc spondylectomy is the gold

standard for radio-insensitive tumors (chordoma, chondro-

sarcoma, etc.). Such techniques should be attempted by sur-

geons experienced in such procedures, often in conjunction

with thoracic surgery, orthopedic surgery, general surgery,

vascular surgery, and plastic surgery.

IV. Intradural Extramedullary Spinal Cord Tumors

- Background

• Intradural extramedullary tumors are the second most com-

mon tumor type in the spine.⁶

• Primary lesions in this compartment arise from perineural

coverings of nerve roots or from the meninges; thus menin-

giomas, schwannomas, neurofibromas, and paragangliomas

account for the majority of tumors in this compartment.⁶

• Although the majority of tumors are benign, they can result in

significant neurologic dysfunction.

- Signs, symptoms, and physical exam

• Symptomatology is usually of insidious onset. The most

common complaint is localized or radicular (and thus not

pathognomonic) pain. Other signs and symptoms include gait

problems, weakness, paresthesia, impotence, and autonomic

dysfunction.⁶

• The presence of an acute headache should raise suspicion of

subarachnoid hemorrhage.

• Physical examination findings include Brown-Sequard syn-

drome and signs of long tract involvement, such as Babinski

sign, clonus, and hyperreflexia.

• Extramedullary tumors can sometimes be distinguished from

intramedullary tumors by the fact that intramedullary tumors

142 III Spinal Pathology

spare dorsal tracts whereas extramedullary tumors normally

affect all sensory modalities.⁶

- Workup and neuroimaging

• Imaging is essential to identifying the tumor compartment

(i.e., intramedullary versus extramedullary).

• MRI is the gold standard, but when it is contraindicated, CT

myelography is the imaging of choice.

• Meningiomas, schwannomas, neurofibromas, and paragangli-

omas are all hyperintense on MRI T2-weighted images. They

are all iso- or hypointense in T1-weighted images.⁶

• Schwannomas can be distinguished from meningiomas be-

cause schwannomas may demonstrate cystic changes within

the tumor and appear as focal areas of increased signal in

T2-weighted images. In contrast, meningiomas rarely de-

velop cystic changes. Schwannomas are also often dumbbell

shaped.⁶

• Paragangliomas demonstrate strong enhancement upon ad-

ministration of gadolinium contrast.

• Metastatic lesions should be suspected in a patient with a

previous history of cancer, and in such a case imaging should

include a whole-body scan to assess systemic spread of the

metastatic neoplasm.¹

- Treatment

• Complete microsurgical excision of intradural extramedullary

tumors is optimal but not always possible due to factors that

dictate surgical approach (i.e., anterior or posterior cord loca-

tion) and the degree to which neural structures are involved

by the neoplasm. For example, neurofibromas normally grow

from the central root as an enlargement of the nerve itself,

making complete surgical resection very challenging. This is

in contrast to schwannomas, which typically involve only one

fascicle of a nerve root, making it possible to completely dis-

sect the mass and preserve the remainder of the nerve root

function.⁶

• When complete resection is not possible without neurologic

compromise, partial resection that avoids neurologic compro-

mise is at times appropriate. This decision is individualized

to patient, and factors to consider are patient age, neurologic

status at presentation, tumor histopathology and size, and

factors predisposing to local recurrence, such as a medical

history of neurofibromatosis.

• The risk of local recurrence can be reduced postoperatively

with adjuvant chemotherapy and radiotherapy for sensitive

tumors.

19 Tumors of the Spine

143

• Radiosurgery can be considered in cases of recurrence, mul-

tiple lesions, and an absence of compressive myelopathy.

- Surgical pearls

• Careful attention should be given to removing such tumors

from the spinal cord rather than attempting to initially dissect

the tumor-spinal cord interface. Often this requires initial

internal tumor debulking. In this way, the spinal cord is not

manipulated in its most compressed state.

V. Intramedullary Spinal Cord Tumors

- Background

• Intramedullary spinal cord tumors make up roughly 6 to 8% of

all tumors of the central nervous system.⁶

• The two most common intramedullary spinal cord tumors are

low- or high-grade astrocytomas and ependymomas.⁶

• Low-grade astrocytomas are more common in children

whereas ependymomas are more prevalent in adults.⁶

• High-grade astrocytomas often have a poor prognosis because

they are highly infiltrative and have a high rate of recurrence.⁶

- Signs, symptoms, and physical exam

• Intramedullary spine tumors have a nonspecific presentation.

Initial signs and symptoms can be of insidious onset or follow

a trivial injury.

• Presenting signs and symptoms include radicular pain, local-

ized pain, dysesthesia, paresthesia, spasticity, torticollis, ex-

tremity weakness, Brown-Sequard syndrome, and autonomic

dysfunction.⁶

• In children, these tumors can present as a failure to achieve

developmental milestones.⁶

• Intramedullary tumors that localize to the cervical spine may

also be accompanied by hydrocephalus.²

- Workup and neuroimaging

• MRI is the gold standard for imaging intramedullary spinal

cord tumors.

• T1-weighted images reveal the solid tumor component when

performed before and after administration of gadolinium

contrast.

• T2-weighted images allow visualization of cystic elements

and the cerebrospinal fluid.

• When viewed axially, astrocytomas are located eccentrically

in the spinal cord and may display heterogeneous enhance-

ment under T1 weighting. In contrast, ependymomas are

visualized most often in the center of the spinal cord when

144 III Spinal Pathology

imaged axially. In addition, ependymomas most often exhibit

homogeneous enhancement.⁶

• Plain radiographs may be useful preoperatively as a baseline

reference for managing spinal deformity, as in the case of sco-

liosis patients.

• A CT myelography study is acceptable when MRI is

contraindicated.

- Treatment

• Histologic grade and preoperative neurologic function are the

most significant prognostic factors for surgical management

of intramedullary spinal cord tumors. High-grade astrocyto-

mas have approximately an 80% mortality rate within the first

6 months of diagnoses. Conversely, it is possible to completely

surgically resect and cure ependymomas.⁶

• The approach to surgical resection varies with tumor type

and tumor characteristics.

• Astrocytomas have a grayish yellow, glassy appearance. They

should be resected beginning at the midpoint of the neoplasm

and moving in an inside-to-outside fashion. The tumor should

be debulked until the border between the spinal cord and tu-

mor can be reasonably demarcated.⁶

• Ependymomas have a red or dark gray appearance and dis-

play a characteristic visible boundary in relation to the spinal

cord. Ependymomas can be resected en bloc and separation at

the tumor-spinal cord boundary can be achieved by applying

a microsurgical laser or plated bayonet in the axial direction.

• Electrophysiologic monitoring can be used to assess the pa-

tient’s neurologic status throughout the procedure. This in-

cludes somatosensory evoked potentials (SSEPs) and motor

evoked potentials (MEPs).⁶

- Surgical pearls

• Often these tumors can be easily suctioned off of the normal

parenchyma of the spinal cord when they are necrotic (high-

grade astrocytoma) or when a good plane is noted between

the tumor and cord (ependymoma or low-grade astrocy-

toma). Extreme care should be taken to avoid dissecting the

plane between tumor and cord with instruments as these ma-

neuvers contuse and stretch the cord; rather, suction should

be used for debulking and sharp dissection in locations where

the tumor is focally tethered to the cord.

19 Tumors of the Spine

145

Common Clinical Questions

1. The least common histology of metastatic tumor arising in the

spine is:

A. Breast adenocarcinoma

B. Prostate adenocarcinoma

C. Non-small cell lung adenocarcinoma

D. Transitional cell carcinoma of the bladder

2. Classic initial presentations of metastatic epidural spinal cord

compression include all of the following except:

A. Abdominal pain

B. Bladder retention

C. Localized back pain

D. Gait imbalance

3. The most important predictor of survival in patients with spine

tumor is:

A. Presence of metastases in the liver

B. Histopathology of the lesion

C. Number of spinal levels involved

D. Local invasion into paraspinal tissues

References

1. Sciubba DM, Gokaslan ZL. Diagnosis and management of metastatic spine

disease. Surg Oncol 2006;15(3):141-151

2. Sundaresan N, Rosen G, Boriani S. Primary malignant tumors of the spine.

Orthop Clin North Am 2009;40(1):21-36

3. Donthineni R. Diagnosis and staging of spine tumors. Orthop Clin North Am

2009; 40(1):1-7

4. Knoeller SM, Uhl M, Gahr N, Adler CP, Herget GW. Differential diagnosis of

primary malignant bone tumors in the spine and sacrum. The radiological

and clinical spectrum: minireview. Neoplasma 2008;55(1):16-22

5. Sciubba DM, Chi JH, Rhines LD, Gokaslan ZL. Chordoma of the spinal column.

Neurosurg Clin N Am 2008;19(1):5-15

6. Abul-Kasim K, Thurnher MM, McKeever P, Sundgren PC. Intradural spinal

tumors: current classification and MRI features. Neuroradiology 2008;

50(4):301-314

Answers to Common Clinical Questions

1. D

2. A

3. B

20 Cervical and Thoracic Spine Degenerative

Disease

Clinton J. Burkett and Mark S. Greenberg

I. Key Points

- Cervical and thoracic degenerative disease is a chronic condi-

tion but can present as acute.

- Magnetic resonance imaging (MRI) is usually the imaging mo-

dality of choice for diagnosis.

- Radicular and axial pain may be treated conservatively, but my-

elopathy or worsening neurologic function generally requires

surgical intervention.

II. Cervical Disc Herniation

- Background

• Dehydration and fragmentation of the nucleus pulposus of

cervical discs with age are natural processes.¹

• The annulus and often the posterior longitudinal ligament

tear, allowing the nucleus to herniate into the spinal canal,

where it may compress the cord or the adjacent root at its

foramen.¹

• Acute disc rupture occurs more often laterally in the spinal

canal due to the relative weakness of the posterior longitudi-

nal ligament in that area; as a result, root compression occurs

more often than cord compression.¹

• Infarction of the cord and root may occur if compression and

ischemia are severe, although it is rare.¹

- Signs, symptoms, and physical exam

• Lateral disc herniations cause pain that radiates from the

neck to the shoulder/arm and into the hand; the disc usually

impinges on a nerve exiting from the neural foramen at the

level of the herniation (e.g, a C6-C7 disc is associated with C7

radiculopathy).

• C5 symptoms: shoulder abduction (deltoid) weakness, shoul-

der paresthesias, deltoid and pectoralis reflexes diminished²

• C6 symptoms: forearm flexion (biceps) weakness; upper arm,

thumb, and radial forearm sensory alteration; biceps and bra-

chioradialis reflexes diminished²

• C7 symptoms: elbow extension (triceps) weakness; second

and third digit sensory alteration; triceps reflex diminished²

20 Cervical and Thoracic Spine Degenerative Disease

147

• C8 symptoms: hand intrinsic muscle weakness; fourth and

fifth digit sensory alteration; finger jerk reflex diminished²

• Central disc herniation can cause myelopathy and central

cord syndrome.

- Workup

• Complete history and physical

• Basic laboratory studies

- Neuroimaging

• Based on localization of signs and symptoms

• MRI is the imaging modality of choice for visualizing soft tis-

sue and the spinal cord/nerve roots.

• Computed tomography (CT) myelogram: when MRI cannot be

done or when better bone imaging is needed

• Plain CT: good for bone imaging

• Plain x-rays: good for bone imaging, anteroposterior (AP)/lat-

eral views useful for visualizing alignment, flexion/extension

views useful to assess subluxation/instability

- Treatment

• Over 90% of patients with acute cervical radiculopathy due to

cervical disc herniation can improve without surgery.²

• Surgery is indicated for those who fail to improve or those

with progressive neurologic deficit who are undergoing non-

surgical management.

• Anterior surgical options: anterior cervical discectomy with

or without fusion, plating, or artificial disc (arthroplasty), an-

terior cervical foraminotomy

• Posterior surgical options: posterior cervical laminectomy/

foraminotomy with or without fusion, keyhole laminectomy

(for lateral “soft disc” herniation)

- Surgical pearls

• Partial or complete corpectomy may be required if herniated

disc is sequestered posterior to vertebral body and is not ac-

cessible by discectomy.

III. Cervical Spondylotic Myelopathy

- Background

• Caused by the reduction in the sagittal diameter of the cer-

vical spinal canal as a result of congenital and degenerative

changes³

• Often due to degeneration of the intervertebral disc produc-

ing a focal stenosis due to a “cervical bar,” which is usually

a combination of osteophytic spurs and/or protrusion of disc

material²

148 III Spinal Pathology

• Most common type of spinal cord dysfunction in patients over

the age of 55 years²

• Cord injury likely occurs as the result of several interrelated

factors: direct compression of the cord, microtrauma associ-

ated with neck flexion and extension, and vascular injury.⁴

• Risk factors include cigarette smoking, frequent lifting, and

diving.

• Signs and symptoms may overlap with those of amyotrophic

lateral sclerosis (motor neuron disease).²

- Signs, symptoms, and physical exam

• Gait disturbance, often with lower extremity weakness or

stiffness, is a common early finding.⁴

• Cervical pain and mechanical signs are uncommon in cases of

pure myelopathy.

• Typical earliest motor findings are weakness in the triceps and

hand intrinsic muscles.

• Clumsiness with fine motor skills (writing, buttoning buttons)⁴

• Glove distribution sensory loss in the hands or several levels

below the area of cord compression

• Reflexes are hyperactive at a varying distance below the level

of stenosis; pathologic reflexes may be present (e.g., Hoff-

mann, Babinski, clonus).

• Central cord syndrome, in which motor and sensory deficits

affect the upper extremities more than the lower extremities,

may occur acutely after trauma with hyperextension in those

with cervical stenosis.

- Workup

• Complete history and physical

• Basic laboratory studies

- Neuroimaging

• Based on localization of signs and symptoms

• MRI is the imaging modality of choice for visualizing soft tis-

sue and the spinal cord and nerve roots, but cannot distin-

guish between disc and bone (Fig. 20.1).

• CT myelogram: when MRI cannot be done or when better

bone imaging is needed. Can still visualize spinal cord and

nerve roots, but does not provide information about changes

within the spinal cord parenchyma. Risks of lumbar puncture

and/or intrathecal contrast injection need to be considered.

◦ Plain CT: good for bone imaging and may demonstrate nar-

row canal, but does not provide adequate information re-

garding soft tissues.

20 Cervical and Thoracic Spine Degenerative Disease

149

Fig. 20.1 Sagittal T2-weighted MRI of the cervical spine demonstrating multilevel

degenerative disc disease, canal stenosis, and signal change in the cord.

◦ Plain x-ray: good for bone imaging, may demonstrate narrow

canal (posterior vertebral line to spinolaminar line <12 mm).

Flexion/extension view may demonstrate dynamic instability.

- Treatment

• Nonoperative management (prolonged immobilization with

rigid cervical bracing, eliminating “high-risk” activities, bed

rest, and antiinflammatory medications) may be considered

for mild myelopathy.

• More severe myelopathy should be treated with surgical

decompression.

• Surgical approaches

◦ Posterior—not ideal for correction of kyphotic deformity

▪Laminectomy alone (higher incidence of late kyphotic

deformity)

▪Laminectomy

+ instrumentation/fusion

(lateral mass

screws, etc.)

▪Laminoplasty (if patient has myelopathic symptoms with-

out axial neck pain)

150 III Spinal Pathology

◦ Anterior—ideal for correction of kyphotic deformities

▪Anterior cervical discectomy and fusion (ACDF)

▪Corpectomy and fusion: when compression extends be-

yond region of disc space

▪Combination of ACDF + corpectomy and fusion

▪Anterior procedures that include more than three disc lev-

els will need posterior instrumentation/fusion in addition

for stability.

- Surgical pearls

• Bone imaging (CT or x-ray) is important for detecting ossified

posterior longitudinal ligament (OPLL) when suspected based

on MRI. If present, may influence approach (posterior instead

of anterior) or procedure (corpectomy instead of ACDF) to

prevent intraoperative durotomy.

IV. Thoracic Disc Herniation

- Background

• Incidence of clinically significant herniation is 1 patient per 1

million people.⁵

• 0.25% of all herniated discs²

• <4% of operations for all herniated discs⁵

• 75% occur below T8; most common at T11/T12²

- Signs, symptoms, and physical exam

• Axial pain may be mechanical. Can sometimes be confused

with cardiac, pulmonary, or abdominal pathology.

• Lateral or centrolateral herniations can present with radicular

pain around chest wall along the path of an intercostal nerve

in a dermatomal pattern.

• Central herniations are associated with a high incidence of

spinal cord compression and long tract signs (lower extrem-

ity hyperreflexia, Romberg sign, Babinksi reflex, clonus, ataxic

gait, loss of rectal tone, and decreased perianal sensation).

• In severe cases, the lesion may cause loss of bowel or bladder

function and progress rapidly to incomplete or total flaccid

paraplegia.

- Workup

• Complete history and physical

• Basic laboratory studies

- Neuroimaging

• Based on localization of signs and symptoms

• MRI is the imaging modality of choice for visualizing soft tis-

sue and the spinal cord and nerve roots, but it cannot distin-

20 Cervical and Thoracic Spine Degenerative Disease

151

guish between disc and bone; scout film with MRI of entire

spine needed to localize level precisely.

• CT myelogram: when MRI cannot be done, or when better

bone imaging is needed along with ability to still visualize

spinal cord and nerve roots; does not provide information

about changes within the spinal cord parenchyma; can show

calcification in disc (occurs in 30 to 70% of symptomatic tho-

racic discs); risks of intrathecal contrast injection need to be

considered

◦ Plain CT: good for bone imaging but does not provide ad-

equate information regarding soft tissues

◦ Plain x-ray: good for bone imaging and essential as an intra-

operative reference to determine correct level

◦ Intraoperative fluoroscopy: it is often easier to count verte-

brae upward from the sacrum or to use the ribs as a refer-

ence than to count down from C1. Use AP to localize since

lateral is difficult to obtain, especially in upper/mid-thoracic

spine. If doubt persists, intraoperative myelography can be

performed to identify the correct level, but risks of intrathe-

cal contrast injection need to be considered.

- Treatment

• Asymptomatic thoracic disc herniations without evidence of

spinal cord compression require no treatment.

• Symptomatic thoracic disc herniations without evidence of

spinal cord compression should initially be treated nonopera-

tively (at least 4 to 6 weeks).

◦ Acute herniations resulting in axial pain

▪Activity modification

▪Nonsteroidal antiinflammatory drugs (NSAIDs)

▪Physical therapy

◦Radicular pain/paresthesias

▪Oral corticosteroids

▪Epidural steroid injections

◦ Surgery may be considered for unrelenting symptoms de-

spite nonoperative treatment.

• Symptomatic thoracic disc herniations causing spinal cord

compression should be treated surgically.

◦ Approaches

▪Anterior—good for midline or broad-based herniations or

densely calcified disc herniations

▫Transsternal or via resection of medial aspect of clavicle

(for upper thoracic lesions)

152 III Spinal Pathology

▪Anterolateral—good for midline or broad-based hernia-

tions or densely calcified disc herniations

▫Transthoracic transpleural via thoracotomy

(usually

right-sided to avoid heart)

▫Video-assisted thoracoscopic (VATS)—not widely used

▫Minimally invasive transthoracic transpleural or

retropleural

▪Posterolateral—good for lateral or soft disc herniation

▫Transpedicular

▫Costotransversectomy

▫Lateral extracavitary

▪Posterior (laminectomy)—not recommended due to high

incidence of neurologic injury

- Surgical pearls

• The anatomy involved in surgery for thoracic herniated discs

is not often encountered by the spine surgeon, who must un-

derstand this anatomy thoroughly before taking a patient to

the operating room.

• Calcified discs are difficult to treat via posterolateral ap-

proaches, so consider an anterior or anterolateral approach

for these lesions.

• Ensure that the disc level is precisely localized by intraopera-

tive fluoroscopy before proceeding with bone removal and

discectomy.

• Posterolateral approaches may require instrumentation, es-

pecially if performed bilaterally.

• Consider somatosensory evoked potentials (SSEPs) and motor

evoked potentials (MEPs) intraoperatively, especially if my-

elopathy is present.

Common Clinical Questions

1. A C6/C7 lateral disc herniation will compress which nerve root

and cause what physical exam findings?

2. On lateral C-spine x-ray, what spinal canal diameter is consid-

ered to be stenotic?

3. Is laminectomy the best approach for excising a herniated tho-

racic disc?

20 Cervical and Thoracic Spine Degenerative Disease

153

References

1. Hoff JT, Papadopoulos SM. Cervical disc disease and cervical spondylosis. In

Wilkins RH, Rengachary SS, eds. Neurosurgery. New York: McGraw-Hill;

1996:3765-3774

2. Greenberg MS. Handbook of Neurosurgery. 7th ed. New York: Thieme Medi-

cal Publishers; 2010

3. Placide RJ, Krishnaney AA, Steinmetz MP, Benzel EC. Surgical management

of cervical spondylotic myelopathy. In Schmidek HH, Roberts DW, eds.

Schmidek & Sweet Operative Neurosurgical Techniques: Indications, Meth-

ods, and Results. Philadelphia, PA: Elsevier; 2006:1865-1878

4. Kumar VGR, Madden C, Rea GL. Cervical spondylotic myelopathy. In Winn

HR, ed. Youman’s Neurological Surgery. Philadelphia, PA: Saunders; 2004:

4447-4458

5. Deckey JE. Thoracic disc herniation. In Devlin VJ, ed. Spine Secrets. Philadel-

phia, PA: Hanley & Belfus; 2003:264-266

Answers to Common Clinical Questions

1. C7 nerve root is compressed, causing triceps weakness, second

and third digit paresthesias and/or sensory loss, and diminished

triceps reflex.

2. <12 mm

3. No. Laminectomy is not recommended because of the high rate

of neurologic injury associated with this approach.

21 Degenerative Lumbar Spine Disease

Michael Y. Wang

I. Key Points

- Degenerative disease of the spine is a ubiquitous problem

and part of the natural aging process. Treatment, surgical or

otherwise, is directed at specific symptoms, pathologies, and

syndromes.

- Skeletoligamentous disorders are typically the result of inter-

vertebral disc disease, facet disease, or both. Sacroiliac and hip

joint pain can also be contributors to back pain.

- Determining the “pain generator” is not always straightforward

and requires a synthesis of data from the medical history, phys-

ical exam, provocative testing, and imaging.

II. Background

- Degeneration of the lumbar spine is the result of natural aging,

environmental insults, and genetic predisposition.

- Degenerative changes may be asymptomatic.³

- Specific disease states, such as rheumatoid arthritis and an-

kylosing spondylitis, can accelerate or alter the pathology and

clinical presentations.

- Changes that develop over time include loss of water volume

within the nucleus pulposus with loss of disc height, disc bulg-

ing, facet joint degeneration, and osteophyte formation across

the joints (both the intervertebral discs and facet joints). Even-

tual loss of motion occurs.

III. Specific Conditions

Radicular Pain

- Signs, symptoms and physical exam

• Diagnosis requires a correlation between the pain distribu-

tion and the compressed nerve root identified on imaging.

• Sharp, shooting pain in a given dermatome, but it may be dull

or aching as well

• Pain, paresthesias, weakness, and diminished reflexes can be

found on exam.

21 Degenerative Lumbar Spine Disease

155

- Workup and neuroimaging

• Diagnostic testing includes magnetic resonance imaging (MRI),

computed tomography (CT) scan (if the offending pathology is

suspected to be osseous), or in some cases CT myelogram.

• If there is doubt as to the level or location of the pathology,

a test nerve root injection with anesthetic may be diagnosti-

cally helpful.

• Classic pathology is a paracentral disc herniation; other pos-

sibilities include compression due to foraminal collapse, facet

joint overgrowth, or a far lateral disc herniation.

- Treatment

• Treatment of radiculopathy is directed at nerve decompres-

sion. This can be done with a laminectomy, laminoforaminot-

omy, or microdiscetomy.

• In cases where compression is from foraminal collapse due to

loss of spinal alignment (e.g., spondylolisthesis or degenera-

tive scoliosis) a fusion with intervertebral height restoration

may be indicated.

- Surgical pearls

• During a laminectomy, laminoforaminotomy, or microdiscec-

tomy, care must be taken to avoid excessive facet joint remov-

al. These joints are critical to the stability of the spine, and no

more than half of a joint should be removed in a unilateral

approach.

• Following surgical decompression scar formation can result in

radiculitis or, rarely, arachnoiditis. Minimizing manipulation

and nerve root retraction may be helpful.

Neurogenic Claudication

- Signs, symptoms, and physical exam

• Diagnosis is highly dependent on the history. Patients typi-

cally complain of unilateral or bilateral leg pain, numbness,

and weakness that can be precipitated by standing or walking.

• The ability to walk farther when bending forward (as when

pushing a shopping cart) is classic.

• Vascular claudication is suggested when relief occurs with

rest without the need to flex at the waist, and must be ruled

out by evaluating peripheral pulses (for suspected cases an

ankle-brachial index [ABI] may be useful).

- Workup

• Diagnostic testing includes an MRI or CT myelogram to evalu-

ate the size of the lumbar spinal canal and neuroforamina.

156 III Spinal Pathology

- Neuroimaging

• Compression may be due to congenital stenosis, disc bulg-

ing, ligamentum flavum hypertrophy, facet joint overgrowth,

spondylolisthesis, or any combination.

- Treatment

• Surgical intervention is directed at patients who have failed

conservative measures, such as epidural injections, and in-

cludes decompression with the possibility of an adjunct fusion.

• Standard treatment involves the use of a midline laminecto-

my with foraminotomies.

• Indirect decompression can be achieved with an interspinous

spacer device, which causes focal flexion and stretching of the

ligamentum flavum and facet joints.

• Unilateral hemilaminotomy for bilateral decompression is an-

other, less invasive option that preserves more of the skeleto-

ligamentous structures.

- Surgical pearls

• Curved Kerrison rongeurs can be useful to reach out to the

distal foramina and should be placed on the caudal and dorsal

aspect of the foramen, as this is the least likely location for the

exiting nerve root.

• In performing a hemilaminotomy for bilateral decompression,

care should be taken to preserve the ipsilateral ligamentum

flavum, which will displace the dura ventrally. This reduces

the risk of dural injury while work is being performed on the

contralateral nerve roots. Ipsilateral decompression can be

performed after the opposite side has been decompressed.

Axial Back Pain from Intervertebral Disc Disease (without

Deformity)

- Signs, symptoms, and physical exam

• The most classic disc-related mechanical pain syndromes pres-

ent as pain that worsens with activity and lessens with rest.

• Anterior thigh pain can also be associated with low back pain,

as the symptoms may follow a somatotopic pattern.

• Physical examination may reveal pain relief with extension

maneuvers and provocation with flexion, although these find-

ings are not universal.

• It is important to eliminate other insidious causes of axial

pain, such as infection or malignancies.

- Workup

• MRI to examine the disc and neighboring structures

• CT myelogram when MRI is contraindicated

21 Degenerative Lumbar Spine Disease

157

• Flexion-extension films to rule out spondylolisthesis

- Neuroimaging

• The disc nucleus progressively loses the high signal on T2 (so-

called “black disc”) and loss of disc height will also occur.

• Adjacent bony end plates may exhibit high T2 signal, classified

as Modic changes.

• Plain x-rays may also reveal degeneration, but dynamic flex-

ion and extension views may be more effective in revealing

any instability.

• CT scans may demonstrate osteophytes and are less useful. In

marginal cases a provocative discogram can be used to assess

the disc’s internal morphology, ability to tolerate the injec-

tate’s pressure, and any symptoms associated with injection.¹

- Treatment

• Treatment of disc-related pain remains controversial and

requires that patients have failed conservative treatment

measures.

• For patients who have intractable symptoms and demonstra-

ble pathology, treatment may be directed at disc removal or

the elimination of motion.

• This can be performed with a posterolateral instrumented fu-

sion; anterior, posterior, or transforaminal lumbar interbody

fusion (ALIF, PLIF, TLIF); lateral interbody fusion; extreme lat-

eral interbody fusion (XLIF), or total disc arthroplasty.

- Surgical pearls

• It is generally believed that if surgical treatment of disc-relat-

ed pain is warranted, then an interbody fusion is preferable to

posterolateral fusion.

• For patients who will undergo disc arthroplasty, care must

be taken to exclude those with facet disease, as the posterior

joints must continue to function after the operation.

Axial Back Pain from Facet Joint Disease

- Signs, symptoms, and physical exam

• The zygapophyseal joint (facet joint) is a synovial joint that

is prone to arthritic changes and is a possible pain generator.

• Pain that worsens with provocative maneuvers such as back

extension may be a simple diagnostic clue.

• Facet pain can radiate into the lower extremity, mimicking a

painful radiculopathy.

- Workup

• MRI, flexion-extension films, and single-photon emission

computed tomography (SPECT) bone scan helpful

158 III Spinal Pathology

• The definitive diagnostic test is an anesthetic or steroid injec-

tion (controversy surrounds the relative efficacy of intraar-

ticular versus periarticular joint injections).

• Hip or sacroiliac joint pathology must also be considered as a

possible source of “back pain.”

- Neuroimaging

• High T2 signal in the joint as well as increased focal uptake on

SPECT bone scans can be valuable predictors.⁴

- Treatment

• Interventional treatment of isolated facet joint disease is with

anesthetic/steroid injections or dorsal ramus rhizolysis.

• In addition, physical therapy and antiinflammatory medica-

tions are often helpful.

- Surgical pearls

• Obtain dynamic films to rule out spondylolisthesis.

• Fusion/fixation of the facet joint remains controversial.

Spondylolisthesis

- Signs, symptoms, and physical exam

• Spondylolisthesis may be the result of congenital, traumatic,

degenerative, or iatrogenic etiologies.

• A degenerative spondylolisthesis typically affects the L4/L5

level, although any level may become involved.

• A fatigue fracture of the pars followed by progression of slip-

page may also be classified as a form of degeneration due to

chronic mechanical load.

• The clinical syndrome may cause leg pain, back pain, or both.

- Workup

• MRI and flexion-extension films are mandatory.

- Neuroimaging

• Diagnostic testing can include MRI imaging to evaluate neural

entrapment. Flexion-extension x-rays are mandatory to as-

sess the gross stability of the level, which affects treatment

decisions (Fig. 21.1).

- Treatment

• Typically involves decompression and fusion. A common ap-

proach is laminectomy for decompression followed by instru-

mented fusion.

• Controversy exists over the utility of correcting the slippage.

• The use of interbody fusion increases the rate of arthrodesis

but poses the threat of higher complication rates.

- Surgical pearls

• High-grade slips where realignment is desired can often be

treated more effectively by instrumenting the level above (L4-

160 III Spinal Pathology

S1 in a L5/S1 slip) to bring the middle intermediary screw up

to a rod connecting the two end screws.

• The exiting nerve root at the slip level is displaced ventrally.

Aggressive correction of a high-grade slip can result in foot

drop. Close electromyographic (EMG) monitoring for nerve

root irritation may allow assessment of the stretch/tension on

this structure.

Degenerative Scoliosis and Kyphosis

- Signs, symptoms, and physical exam

• Evaluation of patients with spinal deformity requires not only

a standard physical examination but also an assessment of the

patient’s standing and lying postures.

• Any progression of deformity should also be evaluated with

serial imaging. The frequent coincidence of hip and sacro-

iliac joint arthritis and leg length discrepancies needs to be

assessed.

• Because this disease entity typically affects older females, an

evaluation of bone density may be warranted and the appro-

priate measures to augment bone density undertaken.

• In addition, assessment of any contributing hip flexion con-

tractures may be necessary.

- Workup

• Diagnostic imaging requires an assessment of neural element

integrity (MRI or myelography), disc and facet joint disease, as

well as local and global spinal alignment.

- Neuroimaging

• MRI, dynamic x-rays, and CT scanning are essential for preop-

erative planning.

• Thirty-six inch standing x-rays are mandatory to determine

coronal alignment (Cobb angle) and loss of sagittal balance.

- Treatment

• The treatment of this patient population is complicated, requir-

ing significant investment in preoperative planning, surgical

intervention, and postoperative care. Critical decision-making

factors include:

◦ Source and nature of complaints (pain, reduced activities

of daily living (ADLs), neurologic symptoms, abnormal pos-

tures, cosmetic concerns)

◦The degree of deformity and its relative contribution to the

patient’s symptoms

21 Degenerative Lumbar Spine Disease

161

◦The extent (levels and amount of correction) of the defor-

mity that needs to be treated

◦The amount (quality and number of levels) of fixation needed

◦The surgical technique necessary to achieve correction

◦ Need for fusion adjuncts (osteobiologics, bracing, and bone

stimulation)

◦ Anesthetic considerations and risks

◦ Nutrition and metabolic concerns

◦The extent to which rehabilitation will be necessary after

surgery

- Surgical pearls

• Careful preoperative planning, including measurements of

preop sagittal/coronal imbalance, is essential to achieving

good clinical and surgical outcomes.

Common Clinical Questions

1. Lumbar facet joint pain is best treated with:

A. Massage therapy

B. Electrostimulation

C. Joint injections

D. Surgical fusion

2. Causes of spondylolisthesis include all of the following except:

A. Neoplastic

B. Degenerative

C. Traumatic

D. Iatrogenic

3. Studies critical to the evaluation of a spinal deformity include:

A. Blood tests for rheumatoid arthritis

B. Genetic assessment of predilections for deformity

C. SPECT nuclear medicine bone scan

D. 36 inch standing x-rays

162 III Spinal Pathology

References

1. Carragee EJ, Chen Y, Tanner CM, Truong T, Lau E, Brito JL. Provocative discog-

raphy in patients after limited lumbar discectomy: a controlled, randomized

study of pain response in symptomatic and asymptomatic subjects. Spine

(Phila Pa 1976) 2000;25(23):3065-3071

2. Fujiwara A, Tamai K, Yamato M, et al. The relationship between facet joint

osteoarthritis and disc degeneration of the lumbar spine: an MRI study. Eur

Spine J 1999;8(5):396-401

3. Jensen MC, Brant-Zawadzki MN, Obuchowski N, Modic MT, Malkasian D, Ross

JS. Magnetic resonance imaging of the lumbar spine in people without back

pain. N Engl J Med 1994;331(2):69-73

4. Kim KY, Wang MY. Magnetic resonance image-based morphological predic-

tors of single photon emission computed tomography-positive facet arthrop-

athy in patients with axial back pain. Neurosurgery 2006;59(1):147-156

Answers to Common Clinical Questions

1. C

2. A

3. D

22 Deformity

David T. Anderson and Jeffrey A. Rihn

I. Key Points

- The scoliotic spine has, in addition to a coronal curve, a ro-

tational deformity in which the apical vertebra rotates. The

three-dimensional nature of the disease process must be taken

into account in planning surgery.

- A magnetic resonance image (MRI) should be obtained in

the workup of adolescent idiopathic scoliosis when there are

neurologic abnormalities, midline cutaneous findings, a left

thoracic curve, rapid curve progression, or a hyperkyphotic

thoracic alignment.

- In planning surgery for adolescent idiopathic scoliosis, all ma-

jor curves and structural minor curves should be included in

the fusion levels.¹

- In younger patients treated with posterior-only fusion, subse-

quent growth anteriorly can create a crankshaft phenomenon.

- Scheuermann kyphosis must be differentiated from postural

kyphosis, which reduces on hyperextension lateral radio-

graphs. Additionally, postural kyphosis does not exhibit the ac-

centuated hump on the Adam forward bending test that is seen

with Scheuermann kyphosis.

II. Adolescent Idiopathic Scoliosis

- Background

• Scoliosis is defined as an abnormal curvature of the spine in

the coronal plane greater than 10 degrees.

• Etiologies include idiopathic, which makes up 80% of all cases,

as well as congenital, neuromuscular, and syndrome-related.

• Idiopathic scoliosis is classified based on age at diagnosis: in-

fantile, 0 to 3 years; juvenile, 4 to 10 years; adolescent, 11 to

17 years; and adult, 18 years and older.

• Curves may be classified as major or minor. The major curve

is of the greatest magnitude and is considered the first to de-

velop (Fig. 22.1).¹

• Minor, or compensatory, curves develop later and basically

serve to balance the head and trunk over the pelvis.

164 III Spinal Pathology

Fig 22.1 Developed in 2001, the Lenke classification provides treatment recom-

mendations for various AIS deformities. Major and structural minor curves are in-

cluded in the instrumented fusion and the nonstructural curves are excluded. (From

Clements DH et al. “Did the Lenke Classification Change Scoliosis Treatment?” Spine

36(14):1142-1145.)

• Structural curves are rigid and cannot be corrected to less

than 25 degrees with lateral bending. Nonstructural curves

are less rigid and can be corrected.¹

• The normal spine has a thoracic kyphosis between 20 and 40

degrees and a lumbar lordosis between 40 and 70 degrees,

and is straight in the coronal plane without rotation.

• The scoliotic spine not only has a coronal curve, but also has a

rotational deformity where the apical vertebra rotates. Most

progressive AIS is convex right in the thoracic spine. Any left

thoracic curve should be worked up with MRI for underlying

abnormalities.

• Scoliosis causes changes in the physiology of the discs and

vertebrae due to compressive forces on the concave side of

the curve. Increased pressure reduces growth, causes wedg-

ing of discs, and changes the remodeling of the bone. All this

22 Deformity

165

contributes to continued asymmetric growth, worsens the

deformity, and perpetuates the process.

- Signs, symptoms, and physical exam

• The physician should include questions about the patient’s re-

cent growth, physical signs of puberty, onset of menses, and

axillary/pubic hair.

• Family history of scoliosis should be obtained.

• A thorough review of systems can shed light on other condi-

tions associated with scoliosis.

• Important findings in the history include severe back pain,

presence of neurologic symptoms, age at onset of scoliosis,

and rate of progression.

• Severe back pain with radicular or myelopathic symptoms re-

quires further imaging with MRI to rule out any specific un-

derlying etiology such as syringomyelia, Chiari malformation,

tethered cord, diastematomyelia, or intraspinal tumors.

• Neurologic history should include questions about difficulties

with writing, grasping, balance, walking, or climbing stairs;

loss of bowel or bladder function; weakness; or numbness

and tingling.

• Trunk shape and balance should be assessed. The posterior

torso should be examined with the patient standing. Look for

shoulder, trapezial, scapular, and trunk or flank asymmetry.

• A plumb line dropped from the C7 spinous process should fall

in line with the gluteal cleft.

• The lateral aspects of the rib cage should be aligned with the

ipsilateral iliac crest. Often patients perceive a curve in the

spine as a hip or pelvis problem.

• The Adam forward bending test should be performed. With

the knees straight and palms together, the patient is asked to

bend forward at the waist. The examiner observes the patient

from behind to assess lumbar and midthoracic rotation, from

the front to assess upper thoracic rotation, and from the side

to assess kyphosis.

• A scoliometer may be used to measure the angle of trunk rota-

tion (ATR). An ATR of 5 to 7 degrees is associated with a Cobb

angle of 15 to 20. The rib hump deformity can also be mea-

sured in centimeters.

• Pelvic tilt due to leg length inequality can be assessed by ex-

amining the patient from behind and placing blocks under the

short leg to equalize the lengths.

• Skin should be inspected for abnormalities such as café-au-

lait spots or axillary freckling, both associated with neurofi-

bromatosis. Dimpling of the skin, hair tufts, or any midline

166 III Spinal Pathology

cutaneous abnormality may indicate spina bifida and should

be further explored. In addition, any skin laxity may indicate

Marfan or Ehlers-Danlos syndrome.

• The neurologic exam should include assessment of the pa-

tient’s balance, sensation, and motor strength. Patient’s gait

and ability to heel-toe walk should be assessed. Abdominal

reflexes, deep tendon reflexes, Hoffman and Babinski signs,

and clonus should all be included in the test.

- Neuroimaging

• Standing posteroanterior (PA) plain radiographs of the entire

spine down to the pelvis on a single 3-foot cassette should

be obtained. Skeletal maturity can be assessed based on the

iliac apophysis (Risser method). The Cobb angle measures the

coronal plane curvature and is determined by the angle be-

tween the line parallel to the superior end plate of the most

tilted cephalad vertebra and the line parallel to the inferior

end plate of the most tilted caudal vertebra (Fig. 22.2).

Fig.

22.2 A full-length standing PA radio-

graph of a 16-year-old female with adolescent

idiopathic scoliosis. This patient has a right

thoracic curve. The Cobb method of curve

measurement is depicted. To perform a Cobb

measurement, lines are first drawn parallel

to the superior end plate of the most tilted

cephalad vertebra and the inferior end plate

of the most tilted caudal vertebra. Lines are

then drawn perpendicular to the end plate

lines. The angle between these perpendicular

lines is the Cobb angle.

22 Deformity

167

• Full-length standing lateral plain radiographs are obtained at

initial screening if there is back pain, or if there is an obvious

sagittal or coronal deformity. Also, lateral lumbar films are

obtained to evaluate for spondylolysis or spondylolisthesis.

• PA bending plain radiographs are obtained when surgery is

being contemplated. Bending films assess the flexibility of the

curve(s) and aid in operative planning. Again, if a curve cor-

rects to less than 25 degrees with lateral bending, it is consid-

ered non-structural.

• MRI is not routinely obtained in adolescent idiopathic scoliosis

(AIS). Neurologic abnormalities, midline cutaneous findings,

left thoracic curves, rapid curve progression, or hyperkyphotic

thoracic alignment warrants MRI.

- Treatment

• Curves less than 20 degrees should be monitored with radio-

graphs and clinical exam every 6 to 12 months. Patients grow-

ing rapidly should be seen more frequently.

• Curves 20 to 40 degrees are generally treated with a brace.

The effectiveness of bracing depends on the remaining spinal

growth. The Milwaukee brace has fallen out of favor (because

of the neck piece) and has given way to the more cosmetically

favorable and comfortable underarm braces like the Boston

and Wilmington braces. These should be worn full-time (23

hours a day). The Charleston brace is worn only at night.

• Patients with curves that progress to 45 to 50 degrees are usu-

ally candidates for surgery. Factors to consider include clinical

deformity, risk of progression, level of skeletal maturity, and

pattern of curve.²

• According to Lenke and colleagues, all major curves and struc-

tural minor curves should be included in the fusion levels.¹

• Posterior spinal fusion using instrumentation such as hooks,

pedicle screws, wires, or hybrid constructs is the mainstay

of surgical correction. Pedicle screws give an ability to apply

three-dimensional corrective forces that hooks cannot.

• Complications of operative treatment include neurologic in-

jury, blood loss, and implant failure. Spinal cord monitoring is

routinely used to decrease the risk of neurologic injury.

• In younger patients treated with posterior-only fusion, subse-

quent growth anteriorly can create a crankshaft phenomenon.

- Surgical pearls

• Large curves that measure over 70 degrees may be rigid and

technically difficult to correct. Combined anterior and poste-

rior fusion has been recommended by some surgeons. Remov-

ing the disc and releasing the anterior longitudinal ligament

168 III Spinal Pathology

(ALL) anteriorly allows increased flexibility of the curve along

with greater curve correction, and enables the surgeon to fuse

the anterior vertebral column, minimizing the risk of develop-

ing a crankshaft phenomenon.

III. Scheuermann Kyphosis

- Background

• Originally described by Holger Werfel Scheuermann, this is a

rigid sagittal deformity of the thoracic spine that cannot be

actively corrected.³

• The vertebral bodies are wedged anteriorly at three consecu-

tive levels.

• There are three types of Scheuermann kyphosis (SK). Type I is

the classic deformity with the apex between T7 and T9; type

II is thoracolumbar in nature, with the apex between T10 and

T12; and type III is a lumbar lordosis.

• The etiology of SK remains unknown; however, several theo-

ries have been proposed, including an avascular necrosis of

the vertebral ring apophysis, end plate deterioration and col-

lapse as a result of the herniation of disk material into the

vertebra, simple wedging caused by mechanical forces, and

endocrine and genetic factors.⁴

• Histology studies have revealed significant end plate irregu-

larities, including Schmorl nodes, which are essentially disk

herniations into the vertebral body.

- Signs, symptoms, and physical exam

• SK is typically idiopathic in nature but can be associated with

Turner syndrome and cystic fibrosis.

• A complete history and physical exam are important to distin-

guish SK from postural kyphosis.

• The typical patient presents around puberty and relays a his-

tory of a progressive thoracic kyphosis. Often a compensatory

lumbar lordosis can be appreciated on exam. Hamstring tight-

ness is often found.⁵

• Patients may have pain at the apex of the curvature. Pain is

more common in athletes.

• A complete physical exam noting the sagittal and coronal

alignment is important.

• Often a compensatory lumbar lordosis can be established.

This is associated with increased pelvic tilt, which leads to

hamstring tightness or contractures. Therefore, a straight-leg

raise test should routinely be performed.

• Patients may present with a stiff-legged, short-stride gait.

22 Deformity

169

• As with suspicion of any deformity, a forward bending test

should be performed to rule out a concurrent scoliosis, which

is present in up to one-third of patients with SK.

• With forward bending, the SK patient will display a sharp (of-

ten 90 degrees) hump, as opposed to the rounded back seen

in postural kyphosis.

• Flexibility testing and a complete neurologic exam should be

performed.

- Neuroimaging

• Standing full-length PA and lateral views should be obtained.

Diagnosis is made based on the lateral radiograph (Fig. 22.3).

Sorenson defined SK as a thoracic kyphosis greater than 45

degrees with anterior vertebral body wedging greater than 5

degrees at three or more consecutive levels. Normal thoracic

kyphosis is between 20 and 40 degrees.

• Postural kyphosis corrects on hyperextension lateral radiographs.

• Although Schmorl nodes are common in SK, they are not

pathognomonic.

• MRI should be obtained only if a patient presents with neuro-

logic symptoms.

Fig. 22.3 A full-length standing lateral

radiograph of a 17-year-old male with

Scheuermann kyphosis. This figure

demonstrates the technique for mea-

suring the degree of thoracic kyphosis,

which in this patient is 88 degrees.

170 III Spinal Pathology

- Treatment

• The severity of the deformity (greater or less than 50 degrees),

the age of the patient, skeletal maturity, and associated symp-

toms should all be considered in contemplating treatment.

• Nonoperative treatment ranges from observation with serial

radiographs to postural exercises to bracing.

• Bracing is usually utilized in skeletally immature patients

with a kyphosis of 50 to 75 degrees with an apex between

T6 and T9. Studies have shown that bracing can achieve a 50%

reduction in the kyphosis when worn full-time (>22 hours a

day) for 12 to 18 months, followed by part-time (>12 hours a

day) use until skeletal maturity is reached.

• Operative treatment should be considered in patients with

kyphosis greater than 70 degrees, adults with residual defor-

mity and intractable pain, a patient with progressive neuro-

logic deficit, and skeletally immature patients who are poor

candidates for bracing.⁴

• A posterior-only approach is indicated in patients with a ky-

phosis greater than 70 degrees that is correctable to 50 de-

grees. This approach avoids a thoracotomy, is technically less

demanding, and decreases surgical time. Drawbacks are pos-

sible hardware failure and loss of 5 degrees of correction in

long-term follow up.

- Surgical pearls

• Rigid curves that are not correctable to 50 degrees or less

on the hyperextension lateral radiograph may require an

anterior release prior to posterior fusion. Often these pro-

cedures are staged and entail longer hospital stay, higher

blood loss, and the morbidity of a thoracotomy. Anteriorly,

the ALL and the discs are removed at multiple levels to in-

crease flexibility.

22 Deformity

171

Common Clinical Questions

1. When is a MRI warranted in the workup of a patient with idio-

pathic scoliosis?

2. When planning for surgery in adolescent idiopathic scoliosis,

what levels should be included in the fusion?

3. What are the main differences between postural kyphosis and

Scheuermann kyphosis?

References

1. Lenke LG, Betz RR, Harms J, et al. Adolescent idiopathic scoliosis: a new clas-

sification to determine extent of spinal arthrodesis. J Bone Joint Surg Am

2001;83-A(8):1169-1181

2. Harrington PR. Treatment of scoliosis. Correction and internal fixation by

spine instrumentation. J Bone Joint Surg Am 1962;44-A:591-610

3. Scheuermann HW. The classic: kyphosis dorsalis juvenilis. Clin Orthop Relat

Res 1977; 128(128):5-7

4. Wenger DR, Frick SL. Scheuermann kyphosis. Spine (Phila Pa 1976) 1999;

24(24):2630-2639

5. Murray PM, Weinstein SL, Spratt KF. The natural history and long-term fol-

low-up of Scheuermann kyphosis. J Bone Joint Surg Am 1993;75(2):236-248

Answers to Common Clinical Questions

1. In the presence of neurologic abnormalities, midline cutaneous

findings, left thoracic curves, rapid curve progression, or hyper-

kyphotic thoracic alignment

2. According to Lenke and colleagues, all major curves and struc-

tural minor curves should be included in the fusion levels.

3. Postural kyphosis reduces on hyperextension lateral radio-

graphs. Additionally, postural kyphosis does not exhibit the ac-

centuated hump on the Adam forward bending test that is seen

with Scheuermann kyphosis.

23 Vascular Pathology of the Spine

Timothy D. Uschold and Steven W. Chang

I. Key Points

- The Spetzler et al nomenclature for spinal vascular lesions clas-

sifies arteriovenous malformations (AVMs) and arteriovenous

fistulas (AVFs) according to anatomic location. Lesion classifica-

tion does not rigidly dictate optimal treatment strategy but may

provide a useful framework to guide decision making.¹

- Spinal angiography is the gold standard and is warranted for all

arteriovenous lesions.

- Thorough understanding of spinal angiographic anatomy, surgi-

cal vascular anatomy, and segmental variability is essential for

decision making.

- A high index of suspicion should be maintained in the presence

of spinal vascular lesions. Protean clinical findings, imaging ap-

pearance, and low incidence often result in diagnostic delay.

II. Cavernous Malformations

- Background

• Cavernous malformations are benign vascular neoplasms that

may occur in sporadic or familial forms. Spinal cavernomas

favor thoracic over cervical locations, with lumbar next in

frequency.

• Intramedullary is the most common location, although intra-

medullary exophytic, intradural extramedullary, and extradural

locations have been reported.

• Peak incidence of symptomatic hemorrhage is reported in the

fourth decade.

- Signs, symptoms and physical examination

• Acute: due to large hemorrhage, may result in long-tract dys-

function or radicular symptoms (including pain) depending

on location; acute meningeal signs are rare.

• Progressive decline or stepwise deterioration: due to repeated

hemorrhages and/or hemosiderin toxicity; improvement be-

tween events is usually incomplete.

• Estimated bleed rates have been reported at 1.4 to 4.5% per

patient-year. The rate of subsequent hemorrhage may ap-

proach 66% per patient-year.

23 Vascular Pathology of the Spine

173

- Workup

• Magnetic resonance imaging (MRI) with gradient-recalled

echo (GRE) sequences

• Detailed family history, MRI of the brain, and possible familial

screening should be considered. As many as 50% of patients

may harbor intracranial cavernomas as well.²

- Neuroimaging

• MRI is the modality of choice. Cavernomas are angiographi-

cally occult.

• MRI appearance: T1 and T2 “popcorn” heterogeneity reflects

vascular sinusoids containing blood products of different ages.

Surrounding T1 and T2 hypointensity reflects the rim of hemo-

siderin-stained parenchyma. Hypointense “blooming” notable

on GRE sequences, with absence of flow voids.³

- Treatment

• Gross total excision is the treatment goal and is protective

against future hemorrhage.

• Conservative management is a consideration for small as-

ymptomatic lesions, especially deep-seated lesions that fail to

reach the pial surface on axial images.^2,4

- Surgical pearls (see also Chapter 64)

• Appropriate zones of entry from a posterior or posterolateral

approach include midline myelotomy, dorsal lateral sulcus, or

laterally between the dentate ligaments.

• Whenever possible, sharp dissection is preferred. Piecemeal exci-

sion is common.

• Care is necessary to preserve hemosiderin-stained parenchy-

ma surrounding the cavernoma. The developmental venous

anomaly should be preserved whenever possible.^2,4

III. Arteriovenous Lesion

- Background

• Intradural-dorsal AVF

◦ Considered an acquired lesion, attributed to venous outflow

dysfunction

◦Low-flow fistula involves radiculomedullary artery as it

pierces the dural root sleeve, resulting in arterialized coronal

venous plexus. Type B lesions recruit feeders from adjacent

levels, but a single fistulous point is always present.

◦ Accounts for 60 to 80% of spinal vascular lesions. Typically

affects males more than females, ages 40 to 60, and has pre-

dilection for the thoracolumbar spine.

174 III Spinal Pathology

• Intradural ventral

◦ High-flow anastomosis between anterior spinal artery (ASA)

and ventral venous plexus. Varix formation, flow rate, com-

plexity, and multiplicity of feeding pedicles increase with

types A to C.

◦ Occurs in younger patients (20 to 60 years) and favors the

thoracolumbar spine

• Extradural

◦ High-flow direct anastomosis between epidural artery and

vein, may receive multisegmental arterial contributions¹

◦ Sporadic de novo formation, congenital, syndromic associa-

tions (e.g., neurofibrosis (NF)-1), and traumatic etiologies

have all been reported (Table 23.1).

• Extradural-intradural AVM

◦ High-flow AVM, irrespective of tissue boundaries. Common-

ly involves multiple or entire spinal segments. May interdig-

itate with functional cord tissue. Commonly fed by ASA and

posterior spinal artery (PSA). Rare.

• Intramedullary AVM

◦ High-flow AVM with diffuse and compact forms. High-risk

features, including varix formation and associated aneu-

rysms, are common.

◦ Typically symptomatic early in life (10 to 30 years), with pre-

dilection for the cervical spine depending on report; repre-

sents 15 to 20% of all spinal vascular lesions

• Conus AVM: high-flow, complex shunting pattern found at co-

nus. Multiple shunts and nidi may be pial or intramedullary.

Rare (Table 23.2).¹

- Signs, symptoms, and physical examination

• Intradural-dorsal AVF: protean history of progressive myelop-

athy, dominated by gait and sphincter dysfunction. Patho-

physiology relates to venous vascular congestion.

• Intradural ventral: similarly protean, progressive, and vari-

able history dominated by myelopathic findings. Symptom-

atic progression due to steal, compression, and hemorrhage

increases with grade and flow rate.

• Extradural: Myeloradiculopathy is common, with symptoms

due to compression, steal, and hemorrhage. Venous conges-

tion is typically rare.

• Extradural-intradural AVM: malignant natural history char-

acterized by progressive myelopathy. Radicular pain referable

to the involved segment is typical. Pathophysiology involves

mass effect, steal, hemorrhage, and compression.

Table 23.1 Spetzler et al AVF Classification¹

Type

Shunt location

Pathophysiology

Symptoms

Imaging

Treatment

Intradural dorsal

Intradural entry

Vascular congestion

Progressive

MRI shows dorsal flow

Surgery vs endovascular

A (single-level

of radiculomedul-

due to venous outflow

myelopathy

voids and T2 cord

feeder)

lary artery at root

obstruction

change

B (multiple

sleeve

DSA gold standard

feeders)

Intradural ventral*

Direct fistula to

Mass effect, steal, or

Progressive

MRI shows ventral flow

Surgery. Endovascular

anterior spinal

hemorrhage progres-

myelopathy

voids

may be more appropri-

artery

sive with grade

DSA gold standard

ate alternative with

progressive grade

Extradural

Epidural artery and Primarily compres-

Progressive

MRI shows epidural

Primarily endovascular,

vein

sion and steal over

myelopathy

engorgement

except when decline

congestion

and/or

DSA gold standard

due to hemorrhage

May hemorrhage

radiculopathy

*Types are characterized by increasing flow rate, varix formation, and venous dilation.

Abbreviations: AVF, arteriovenous fistula; DSA, digital subtraction angiogram; MRI, magnetic resonance imaging.

Table 23.2 Spetzler et al AVM Classification¹

Type

Distinguishing features

Pathophysiology

Symptoms

Treatment

Extradural-

Irrespective of normal tissue

Steal, compression, Progressive myelopathy, of-

Multimodality, typically

intradural

planes

hemorrhage

ten with radicular-type pain

palliative

May involve entire metamere

Intramedullary

Typically with at least one ASA

Hemorrhage, steal, Acute or stepwise pro-

Primarily surgical

Compact nidus

feeder

compression

gression of radicular pain

Preoperative embolization

PSA feeders also common. High

and long-tract signs (e.g.,

typically useful

Diffuse nidus

flow-associated aneurysms and

myelopathy)

varices

Conus

Complex shunting and nidal pat-

Steal, hemorrhage,

Progressive myelopathy

Multimodality

terns typically involve ASA and

venous congestion

and/or radiculopathy

(endovascular + surgery)

PSA

Symptoms referable to conus

location

Abbreviations: ASA, anterior spinal artery; AVM, arteriovenous malformation; PSA, posterior spinal artery.

23 Vascular Pathology of the Spine

177

• Intramedullary AVM: malignant natural history characterized

by progressive myeloradiculopathy. Stepwise deterioration or

acute decline attributable to repeated hemorrhage, steal, and

compression.

• Conus AVM: progressive myeloradiculopathy, symptoms re-

ferable to conus¹

- Workup

• Spinal MRI/magnetic resonance angiography (MRA) has prov-

en especially useful for intradural dorsal lesions. MRA may

be sufficiently sensitive to identify the fistula type, to pin-

point the level(s) of the shunt, and to confirm treatment at

follow-up.

• Spinal angiography, however, remains the gold standard im-

aging modality (for all spinal AVFs and AVMs) and may be di-

rected more precisely after careful inspection of prior MRA.

- Neuroimaging

• AVMs

◦ MRI is most useful to delineate the size and configuration of

the nidus (compact vs diffuse), to evaluate for hemorrhage,

and to assess the angioarchitecture.

• Intradural dorsal AVF

◦ MRI: In the appropriate clinical setting, extensive intramed-

ullary T2 hyperintensity along with intradural flow voids

along the dorsal pial surface is nearly pathognomonic. En-

hancement may be variable.

◦ Angiography: Venous outflow is sluggish, and long venous

phase may be necessary. Suspected but occult intradural-

dorsal fistulas require surgical exploration.

• Intradural ventral

◦ MRI: reveals variable T2 hyperintensity and/or enhance-

ment with dilated flow voids along the ventral surface of the

spinal cord. Identifies varix formation.

◦ Angiography: reveals a direct fistula between the radiculom-

edullary artery and ASA. The ASA is identified by the classic

hairpin loop and may be displaced from midline. The ventral

arterialized vein often harbors a prominent venous varix.

• Extradural: MRI/MRA: prominent epidural flow voids and en-

hancement, typically with significant mass effect. Variable T2

intramedullary signal change.³

- Treatment

• Intradural-dorsal AVF: Microsurgical clip occlusion at intra-

dural fistulous point remains the gold standard. Embolization

with liquid agent now acceptable first-line treatment, but as-

sociated with greater risk of recurrence.⁵

178 III Spinal Pathology

• Intradural-ventral AVF: Microsurgical fistula obliteration re-

mains treatment of choice, but embolic strategies often used

as well. Vessel caliber (particularly type A and B) and proxim-

ity to ASA present challenges to endovascular management.

• Extradural AVF: Large-caliber feeding vessels favor coil

embolization.

• Extradural-intradural AVM: Curative resection is atypical.

Multimodal palliation strategies ameliorate symptoms due to

steal, compression, and/or hemorrhage.

• Intramedullary AVM: Surgical resection, typically via a pos-

terior or posterolateral approach, remains the gold standard

and is typically preceded by attempts at embolization in ap-

propriately selected patients.⁶

• Conus AVM: Multimodal strategies include aggressive embo-

lization and resection.¹

- Surgical pearls

• Indocyanine green angiography (ICG) is ideal for intraopera-

tive confirmation of location and essential for the identifica-

tion of angiographically occult lesions.

• Intramedullary AVMs are commonly fed by at least one branch

of the ASA. Steal phenomena may obscure ASA involvement

on preoperative angiography, but serial runs mid-resection

may reveal the ASA as shunting is progressively eliminated.

• Arterial supply is circumferentially addressed first for intra-

medullary AVMs. Venous outflow is spared until the lesion is

sufficiently devascularized.

Common Clinical Questions

1. The Spetzler et al nomenclature divides arteriovenous lesions

solely on the basis of what characteristic?

2. What imaging modality is the gold standard and is mandatory

for all spinal arteriovenous lesions?

3. Describe the typical imaging findings of an intradural-dorsal fis-

tula on MRI.

23 Vascular Pathology of the Spine

179

References

1. Spetzler RF, Detwiler PW, Riina HA, Porter RW. Modified classification of spi-

nal cord vascular lesions. J Neurosurg 2002;96(2, Suppl):145-156

2. Perrini P, Uygur E, Spetzler RF, Lanzino G. Cavernous malformations of the

spinal cord. In Lanzino G, Spetzler RF, eds. Cavernous Malformations of the

Brain and Spinal Cord. New York: Thieme Medical Publishers; 2008:88-93

3. Jackson J, Partovi S. Imaging of spinal cord vascular malformations. Operative

Techniques in Neurosurgery. 2003;6(3):125-140

4. Vishteh AG, Sankhla S, Anson JA, Zabramski JM, Spetzler RF. Surgical resection

of intramedullary spinal cord cavernous malformations: delayed complica-

tions, long-term outcomes, and association with cryptic venous malforma-

tions. Neurosurgery 1997;41(5):1094-1100, discussion 1100-1101

5. Steinmetz MP, Chow MM, Krishnaney AA, et al. Outcome after the treatment

of spinal dural arteriovenous fistulae: a contemporary single-institution se-

ries and meta-analysis. Neurosurgery 2004;55(1):77-87, discussion 87-88

6. Connolly ES Jr, Zubay GP, McCormick PC, Stein BM. The posterior approach to

a series of glomus (Type II) intramedullary spinal cord arteriovenous mal-

formations. Neurosurgery 1998;42(4):774-785, discussion 785-786

Answers to Common Clinical Questions

1. Anatomic location; all other characteristics follow suit

2. Angiography

3. Dorsal flow voids, extensive T2 signal change, variable and patchy

enhancement

24 Spondyloarthropathies

Amir Ahmadian and Fernando L. Vale

I. Key Points

- Spondyloarthropathies are subdivided into seronegative and

seropositive arthropathies (positive vs. negative antinuclear

antibody [ANA] or rheumatoid factor [RF]).

- A family of described disorders/syndromes with overlapping

symptomology with varying human leukocyte antigen (HLA)

associations, including ankylosing spondylitis (AS), psoriatic

arthritis, enteropathic arthritis, Reiter syndrome, ossification

of the posterior longitudinal ligament (OPLL), and rheumatoid

arthritis (RA)

- RA with high incidence of C-spine involvement (>85%)¹

- In RA, atlantoaxial subluxation (AAS) classified by anterior at-

lantodental interval (ADI) ≤3 mm (stable) and posterior atlan-

todental interval (PADI) ≤14 mm (increased risk of injury)

- OPLL: Asians, mostly asymptomatic, surgical approach contro-

versial. Computed tomography (CT) for evaluation of posterior

longitudinal ligament (PLL) calcification/ossification.

- Diffuse idiopathic skeletal hyperostosis (DISH): sacroiliac spar-

ing, osteophytic change, associated with globus and dysphagia

II. Ankylosing Spondylitis Seronegative Arthropathy

- Background

• Also called Marie-Strümpell disease.¹ Affects 0.1 to 0.2% of the

population, with a male : female ratio of 3 : 1. Peak age of on-

set: teens to fourth decade of life.²

• A chronic systemic inflammatory disease (strongest correla-

tion with HLA-B27). CD4, CD8, and cytokine (tumor necrosis

factor [TNF]-α and -β) mediated.^3-5

• AS specifically involves the sacroiliac joints and progresses to

involve the entire spine. It may also variably involve periph-

eral joints, eyes, skin, and the cardiac and intestinal systems.

• Increased risk (up to 20%) if there is a first-degree relative

with HLA-B27 and AS⁶

• Enthesitis: chronic inflammation at the insertion point of ten-

dons that leads to ossification⁵

24 Spondyloarthropathies

181

• Enthesopathy leads to osteoporosis of vertebral bodies and

disc with sparing of nucleus pulposus (bridging osteophytes),

producing the so-called bamboo spine.¹

- Signs, symptoms, and physical exam^1,5

• Initial nonradiating back pain and morning stiffness (>45

minutes) that improves with exercise/activity

• Stiffness of the gluteal and lumbosacral junction (sacroiliitis)

• Progression of symptoms to entire spinal axis

• Eventual decrease in range of motion (autofusion)

• Tendon/ligament involvement

(plantar fasciitis/Achilles

tendonitis)

• Differential diagnosis: rheumatoid arthritis (RF+), DISH (also

called Forestier disease) (spares facet and sacroiliac [SI] joint,

later age of onset than AS), psoriatic arthritis/Reiter syn-

drome (milder with asymmetric sacroiliitis)

• The Patrick or FABERE (flexion, abduction, external rotation,

extension) test: flex hip, flex knee, and place the lateral mal-

leolus on contralateral knee; then press the ipsilateral knee

downward (by stressing the hip joint); will cause pain in bur-

sitis, sacroiliitis, and other hip joint pathology

• Cauda equina syndrome: usually no obvious etiology or

compression

• Unstable rotatory subluxation (occipitoatlantal or atlanto-

axial joint)

• Myelopathy: due to bow stringing of cord

• Significant fractures with minimal trauma

- Workup

• Modified New York criteria (radiographic sacroiliitis and

back pain >3 months, limited spine motion in sagittal/frontal

planes, or limited chest expansion)

- Neuroimaging

• Plain x-rays (crucial for diagnosis): obtain x-rays of entire

spine (bamboo spine) and pelvis (SI joint) (Fig. 24.1)

• Magnetic resonance imaging (MRI): for further evaluation of

disc spaces and ligamentous changes

• Bone scan: increased uptake at SI joint

- Treatment

• Medical management with nonsteroidal antiinflamma-

tory drugs (NSAIDs), sulfasalazine, TNF-α antagonists, and

corticosteroids

• Stable fracture: treatment with rigid brace

• Surgical decompression for inpatients with unstable fractures

and/or progressive neurologic deficit

182 III Spinal Pathology

Fig. 24.1

“Bamboo spine” in

ankylosing spondylitis.

- Surgical pearls^1,5

• Special care needed with routine neck immobilization after

trauma intraoperatively in patients with AS. These patients

tend to have the neck fixed in flexed position. Forced inline

fixation may be deleterious, so fix neck in natural position.

• If patient is placed in traction, special attention to degree of

kyphosis is necessary. Traction must be in line with patient’s

natural kyphosis and not directly horizontal.

• No consensus on treatment for cord injury in AS patients (halo

vs internal fixation) without obvious compression

• Root/cord compression: laminectomy and fusion recommended

• Posterior approach should be strongly considered secondary

to anterior bridging osteophytes and concerns with fixation of

anterior plate for osteoporotic vertebral body.

• Consider posterior osteotomy and fusion for correction of se-

vere kyphotic deformity

III. Rheumatoid Arthritis

- Background

• Very high incidence of C-spine involvement (atlantoaxial sub-

luxation [anterior > posterior], basilar impression, pannus

granulation of odontoid)^5,7

24 Spondyloarthropathies

183

• 2 : 1 female : male ratio; peak incidence in fourth to fifth de-

cade of life

• Serum RF+: 1 to 2% prevalence

• AAS: erosion at C1-C2 joint and at transverse ligament

insertion

- Signs, symptoms, and physical exam

• Morning stiffness, symmetric multi-joint arthritis (particu-

larly the proximal interphalangeal [PIP], metacarpophalan-

geal

[MCP], and metatarsophalangeal [MTP]), rheumatoid

nodule (extensor surface)

• Radiographic decalcification at joints (x-ray hand)

• Neck pain with possible C2 radiculopathy

• Headache, paresthesias, difficulty with ambulation, and

signs of cervicomedullary junction compression

(basilar

impression)

- Workup

• ADI: ≤3 mm for evaluation of integrity of the transverse liga-

ment; does not correlate with risk of injury⁸

• PADI: essentially the amount of space for the cord at C1-C2;

does correlate with risk of injury if ≤14 mm^5,8

• Look for basilar impression and cervicomedullary junction

compression

- Neuroimaging

• Lateral C-spine x-ray: ADI (anterior aspect of odontoid to arch

of C1) / PADI (posterior aspect of vertebral body to spinolami-

nar line)

• MRI for evaluation of degree of stenosis (pannus)

- Treatment

• Surgical treatment of asymptomatic AAS can be considered

when ADI >6 to 10 mm.⁹

• AAS in RA will progress with time; therefore, treatment is rec-

ommended, especially if myelopathy exists.

• Rigid collar does not support C1-C2 and is therefore a poor

option.

• Immobilization of the C1-C2 joint via halo or posterior fusion

alone may reduce the size of pannus over time.

• May use halo traction to align the odontoid and return it to its

neutral position (start with 5 lb).

- Surgical pearls⁵

• Anterior, posterior, or vertical subluxation: most cases will

require 360 degrees of fusion.

• Rotational or lateral subluxation: posterior-only approach is

adequate.

184 III Spinal Pathology

• Posterior fusion with or without laminectomy (C1): C1-C2 fu-

sion, C2-occiput

• Anterior approach: odontoidectomy. For transoral approach

the patient’s mouth must be able to open at least 25 mm.¹

Patient is to remain in halo traction until fusion.

• RA with concomicant basilar impression should first be re-

duced and then fused.

• Transoral approach is associated with higher morbidity and

usually reserved as a second option to posterior fusion.

IV. Diffuse Idiopathic Skeletal Hyperostosis

- Background

• Significant osteophyte formation in absence of significant de-

generation. Distinct from degenerative disease, OPLL, and AS

(Fig. 24.2).¹⁰

• Males in seventh decade of life

• SI joint spared¹¹

• Osteophytes do not stabilize, and unfused they are unstable.

Minor trauma can lead to significant injury.

- Signs, symptoms, and physical exam

• Morning stiffness (milder than with AS)

• Globus: sensation of lump in the throat, secondary to large

anterior vertebral body osteophyte adjacent to esophagus

• Dysphagia with or without weight loss¹

Fig.

24.2 Diffuse idiopathic

skeletal hyperostosis in the

cervical spine. Note the con-

tinuous osteophyte formation

along the anterior border of

the cervical spine.

24 Spondyloarthropathies

185

- Neuroimaging/workup/treatment

• Dysphagia: speech therapy consult to rule out primary esoph-

ageal pathology, diet modification, barium swallow (to local-

ize obstruction). Progressive dysphagia with weight loss may

benefit from surgical debulking.⁵

• CT scan superior to x-ray for evaluation of osteophytic

structures

• Conservative treatment unless mass effect on esophagus or

surrounding structures causes significant health risk (i.e.,

weight loss from dysphagia, pneumonia, and respiratory

difficulty)

• Initially a change in diet to soft mechanical may be beneficial.

- Surgical pearls

• Anterior approach, drill down osteophyte. Special attention

needed for protection of surrounding structures.

• No instrumentation needed. Debulking only. Do not violate

disc space.⁷

• Initially, postop patients may have increased dysphagia. Risk

of gastrostomy tube requirement.¹

V. Ossification of the Posterior Longitudinal Ligament

- Background

• Calcification with subsequent ossification of PLL. Can occur in

any part of the spinal column and can extend into dura. Most

commonly cervical (C3-C6).

• Classified as segmental when ossification skips area behind

disc space and is present only behind each vertebral body.

(Mixed type and focal form exist.)

• Increased incidence in Asian (Japanese) population (preva-

lence around 2%).^5,12 Prevalence increases with age (average

age at time of diagnosis is mid-50s).

- Signs, symptoms, and physical exam

• Most are asymptomatic but can progress to myelopathy over

time.¹³

• Symptoms can range from subjective neck pain to severe

myelopathy.

- Neuroimaging/workup

• Plain x-rays will miss the ossification. Therefore, CT is sug-

gested when OPLL is suspected.

• MRI or CT with intrathecal contrast for evaluation of degree

of stenosis

• MRI: ossified PLL is dark on T1 and T2.

186 III Spinal Pathology

• Consider glucose level check given the higher frequency of

OPLL patients with diabetes mellitus (DM)

- Treatment

• Surgical treatment required to decompress the spinal cord. Pa-

tients with myelopathy can benefit from early decompression.

• Patients with mild subjective complaints can be treated

conservatively.

- Surgical pearls

• Nasotracheal/fiberoptic intubation should be strongly consid-

ered to prevent hyperextension.

• Surgeon’s prerogative as to whether or not to leave a thin rim

of ossified PLL attached to the dura during decompression.

Note that the ossification usually extends into the dura and is

inseparable.¹

• Anterior approach (corpectomy) as opposed to posterior (lami-

nectomy/laminotomy) decompression is controversial because

of the significant risk associated with resecting all of the OPLL.¹⁴

Leaving a thin layer of bone that is adherent to the dura is rec-

ommended. Nerve root decompression is required.⁷

• Somatosensory evoked potential (SSEP) monitoring highly

recommended.

24 Spondyloarthropathies

187

Common Clinical Questions

1. A 65-year-old male comes to the hospital after a motor vehicle

accident complaining of neck and back pain. Further question-

ing reveals that the patient has had a history of chronic neck

ache with morning “back stiffness.” He also admits to having

mild dysphagia with the sensation of a lump in his throat. Initial

x-rays show significant vertebral osteophyte formation but are

otherwise negative. Hip x-rays show normal hip and pelvic joints

with no fractures. What is the patient’s most likely diagnosis?

A. OPLL

B. DISH

C. Ankylosing spondylitis

D. Acute cervical fracture

2. A 65-year-old Japanese male comes to your office complaining

of not being able to keep objects in his hands and “dropping

things.” Your exam is positive for bilateral Hoffman 3+ reflexes

and 4/5 weakness of intrinsic hand muscles. Cervical spine MRI

with central canal stenosis and cervical dynamic x-rays are nor-

mal. Careful analysis of MRI indicates a hypointense signal on T1

and T2 lining the posterior side of the vertebral body at C3-C5

with sparing of disc space. What is the most likely diagnosis?

A. Primary bone tumor

B. Metastatic disease

C. DISH

D. Segmental OPLL

3. True or false: An ADI >3 mm correlates with increased risk of

cervical injury.

4. Dynamic imaging indicates C1-C2 instability. Which of the fol-

lowing is not a recommended treatment?

A. Cervical fusion secondary to ADI >10 mm

B. Rigid cervical collar with close follow-up

C. Halo fixation with subsequent close follow-up imaging in an

effort to decrease pannus size

D. Cervical fusion and decompression secondary to symptoms

of myelopathy

5. True or false: Enthesitis is a chronic inflammation at the inser-

tion point of the tendons into the spine that can become ossified.

188 III Spinal Pathology

References

1. Greenberg MS. Handbook of Neurosurgery. 7th ed. New York: Thieme Medi-

cal Publishers; 2010

2. Braun J, Sieper J. Ankylosing spondylitis. Lancet 2007;369(9570):1379-1390

3. Reveille JD, Ball EJ, Khan MA. HLA-B27 and genetic predisposing factors in

spondyloarthropathies. Curr Opin Rheumatol 2001;13(4):265-272

4. Reveille JD, Arnett FC. Spondyloarthritis: update on pathogenesis and man-

agement. Am J Med 2005;118(6):592-603

5. Schmidek HH, Roberts DW. Schmidek & Sweet Operative Neurosurgical Tech-

niques: Indications, Methods, and Results. 5th ed. Philadelphia, PA: Saun-

ders Elsevier; 2006

6. Khan MA. Update on spondyloarthropathies. Ann Intern Med 2002;136(12):

896-907

7. Burkus JK. Esophageal obstruction secondary to diffuse idiopathic skeletal

hyperostosis. Orthopedics 1988;11(5):717-720

8. Boden SD, Dodge LD, Bohlman HH, Rechtine GR. Rheumatoid arthritis of the

cervical spine. A long-term analysis with predictors of paralysis and recov-

ery. J Bone Joint Surg Am 1993;75(9):1282-1297

9. Papadopoulos SM, Dickman CA, Sonntag VKH. Atlantoaxial stabilization in

rheumatoid arthritis. J Neurosurg 1991;74(1):1-7

10. Resnick D, Guerra J Jr, Robinson CA, Vint VC. Association of diffuse idiopathic

skeletal hyperostosis (DISH) and calcification and ossification of the poste-

rior longitudinal ligament. AJR Am J Roentgenol 1978;131(6):1049-1053

11. Olivieri I, D’Angelo S, Palazzi C, Padula A, Mader R, Khan MA. Diffuse id-

iopathic skeletal hyperostosis: differentiation from ankylosing spondylitis.

Curr Rheumatol Rep 2009; 11(5):321-328

12. Nakanishi T, Mannen T, Toyokura Y. Asymptomatic ossification of the pos-

terior longitudinal ligament of the cervical spine. Incidence and roentgeno-

graphic findings. J Neurol Sci 1973;19(3):375-381

13. Matsunaga S, Sakou T, Taketomi E, Komiya S. Clinical course of patients with

ossification of the posterior longitudinal ligament: a minimum 10-year co-

hort study. J Neurosurg 2004;100(3, Suppl Spine):245-248

14. Epstein N. Diagnosis and surgical management of cervical ossification of the

posterior longitudinal ligament. Spine J 2002;2(6):436-449

24 Spondyloarthropathies

189

Answers to Common Clinical Questions

1. B. Diffuse idiopathic hyperostosis (DISH) is the most likely di-

agnosis. The patient admits to morning stiffness, chronic axial

spine pain, sensation of throat lump (“globus”) with dysphagia.

The formation of osteophytes and the sparing of the sacroiliac

joints also point to DISH as the most likely diagnosis. These

bridging osteophytes seen with DISH do not provide any added

stability.

2. D. The patient’s diagnosis is most consistent with segmental

OPLL. Calcified lesions are hypointense on T1 and T2. In addi-

tion, OPLL has a high incidence in the Japanese population. Fi-

nally, because the area behind the disc was spared, the OPLL is

classified at segmental.

3. False. A PADI >14 mm does, not an ADI.

4. B. A rigid collar is a poor choice here because it does not provide

stability at C1-C2.

5. True. It is seen particularly in patients with ankylosing spondyli-

tis, but it can also be seen in a variety of spondyloarthropathies.

25 Spinal Emergencies

Mohammed Eleraky and Frank D. Vrionis

I. Key Points

- Prompt and accurate diagnosis of spinal emergencies is criti-

cal because return of function is highly dependent on early

intervention.

- Magnetic resonance imaging (MRI) is often the imaging modal-

ity of choice in diagnosing spinal hematomas, acute herniated

nucleus pulposus, and spinal epidural abscesses.

- Trauma and tumors may also present as “spinal emergencies”

and are discussed elsewhere.

II. Spinal Hematomas

- Background

• As in the cranium, these include subdural, epidural, and sub-

arachnoid hematomas.

• In up to one-third of cases, no etiologic factor can be identified.

• Anticoagulant therapy and vascular malformations represent

the second and third most common causes.

• Spinal hematomas are typically localized dorsally to the spi-

nal cord at the cervicothoracic and thoracolumbar regions.^1,2

• Subarachnoid hematomas can extend along the entire length

of the subarachnoid space.

• Intramedullary hemorrhages, caused by cavernomas or ar-

teriovenous malformations (AVMs), typically produce devas-

tating neurologic symptoms but are often not managed with

emergent surgical decompression.

- Signs, symptoms, and physical exam

• Epidural and subdural spinal hematomas present with in-

tense, knife-like pain at the location of the hemorrhage (“coup

de poignard”).

• This may be followed by a pain-free interval of minutes to days.

• Subarachnoid hematoma can be associated with meningitis-

like symptoms, disturbances of consciousness, and epileptic

seizures (often misdiagnosed as cerebral hemorrhage based

on these symptoms).

• Symptoms depend on the location and extent of hemorrhage

and may include motor weakness, sensory and reflex deficits,

and acute bowel/bladder dysfunction.¹

25 Spinal Emergencies

191

- Workup

• Hematology (including platelets), electrolytes, and partial

thromboplastin time (PTT)/prothrombin time (PT)/Interna-

tional Normalized Ratio (INR)

• Disseminated intravascular coagulation (DIC) panel and spe-

cific hematology factors may need to be assessed.

• Appropriate neuroimaging

- Neuroimaging

• The imaging modality of choice is MRI with or without gado-

linium (Fig. 25.1).

• The appearance of hematomas in MRI is highly dependent on

the age of the clot.

• Hyperacute bleeding (<24 hours): T1 isointense, T2 slightly

hyperintense

• Acute bleeding (1 to 3 days): T1 slightly hyperintense, T2

hypointense

• Subacute bleeding (>3 days): T1 hyperintense, T2 hypointense

(T2 may be hyperintense for late subacute)

- Treatment

• The treatment of choice is correction of coagulopathy, if pres-

ent, and emergent surgical decompression.¹

Fig.

25.1 T2-weighted MRI of

the lumbar spine showing post-

operative mixed signal fluid col-

lection (consistent with epidural

hematoma) in the epidural space

compressing the dural sac.

192 III Spinal Pathology

• Benefit of surgical intervention is debatable if only symptom

is pain.

• Surgery typically involves laminectomy without the need for

fusion.

• For cervicothoracic and thoracolumbar junction multilevel

laminectomies, consider instrumentation and fusion.

- Surgical pearls

• Subfascial drains may diminish the incidence of symptomatic

epidural blood collections following multilevel laminectomy

procedures.

III. Cauda Equina and Conus Syndromes

- Background

• Cauda equina syndrome (CES) refers to the clinical condition

that results from compressive, ischemic, and/or inflammatory

neuropathy of multiple lumbar and sacral nerve roots in the

lumbar spinal canal.^3,4

• Conus syndrome has features similar to those of CES but in-

volves compression at the level of the conus medullaris (T12-

L1 typically).

• The most common cause is disc herniation in the lumbar

region.

• It may also be caused by traumatic injury, lumbar spinal steno-

sis, primary or metastatic tumors, epidural abscess, ankylos-

ing spondylitis, spinal subdural or epidural hematoma, spinal

manipulation, and vascular malformation.^3,4

- Signs, symptoms, and physical exam

• Urinary retention is the most consistent finding, occurring in

90% of patients presenting with CES.

• Anal sphincter tone diminished in 80% of patients.

• Saddle anesthesia is the most common sensory deficit (75%

of patients).

• Once total perineal anesthesia develops, patient will likely

have permanent bladder dysfunction.

• Low back pain and radicular symptoms

• Conus lesions have the same features except that motor and

sensory loss is typically asymmetric.

- Workup

• Basic laboratory studies and appropriate neuroimaging

• If imaging demonstrates pathology other than herniated nu-

cleus pulposus (HNP), further workup is indicated (e.g., tumor

or infection workup).

25 Spinal Emergencies

193

- Neuroimaging

• MRI is the best initial study if CES or conus syndrome is

suspected.

• MRI assesses soft tissue compression as well as signal changes

within the spinal cord.

- Treatment

• Prompt surgical decompression (<24 hours)

• Surgical strategy is usually focused on the underlying causes.

• Typically involves laminectomy and discectomy (for HNP)

• More extensive surgery (e.g., vertebrectomy, tumor removal)

may be necessary for other pathologies.

• Return of function is dependent on the extent and duration of

preoperative deficits.

- Surgical pearls

• Complete hemilaminotomy or laminectomy may be required

for removal of large central disc fragment causing conus or

cauda equina syndrome.

IV. Spinal Epidural Abscess

- Background

• Spinal epidural abscess (SEA) is responsible for 0.2 to 2 cases

per 10,000 hospitalizations.

• Thoracic level is the most common site (50%), followed by

lumbar (35%).

• Often associated with vertebral osteomyelitis/discitis

• Risk factors include diabetes mellitus, trauma, intravenous

drug abuse, alcoholism, and epidural anesthesia or analgesia.

• Skin abscesses and furuncles are the most common sources

of infection.

• Gram-positive Staphylococcus aureus is the most common

causative agent.

- Signs, symptoms, and physical exam

• Diagnosis is often achieved in delayed fashion due to vague-

ness of presenting signs and symptoms.

• The most common presenting symptoms include excruciating

pain localized over the spine, radicular pain, weakness, and

sensory deficits.

• Average time from back pain to root symptoms is 3 days, and

4.5 days from root pain to weakness.

• Leukocytosis and fever may be absent.

194 III Spinal Pathology

- Workup

• Hematology (complete blood count [CBC] with differential),

electrolytes (comprehensive metabolic panel [CMP]), acute

phase reactants (erythrocyte sedimentation rate [ESR], C-

reactive protein [CRP]), blood cultures. Cardiac echo to rule

out endocarditis may be indicated.

- Neuroimaging

• MRI with gadolinium is the modality of choice in diagnosing

SEA.

• Typical finding: T1 shows hypo- or isointense epidural mass;

vertebral osteomyelitis shows up as reduced signal in bone. T2

shows high-intensity epidural mass that often enhances with

gadolinium but may show minimal enhancement in the acute

stage when composed primarily of pus with little granulation

tissue.⁵

• Plain radiographs often helpful for suspected discitis and will

show chronic, erosive changes in the end plates.

- Treatment

• For SEAs that show clear involvement of the spinal canal and

cause dural compression, surgical decompression and intra-

venous antibiotic therapy are the treatments of choice.

• SEA is often seen in association with discitis/osteomyelitis.

In these cases, typically only a thin film of epidural enhance-

ment is seen. Surgical intervention not necessarily indicated

in these situations.

• Patients with severe neurologic deficit may show minimal im-

provement even with surgical intervention.

• SEA is fatal in up to one-third of elderly patients, and mor-

tality is usually due to the original focus of infection or as a

complication of neurologic compromise.

- Surgical pearls

• Most spinal instrumentation is safe, effective, and at times

necessary in the treatment of epidural abscess or discitis/os-

teomyelitis of the spine.

25 Spinal Emergencies

195

Common Clinical Questions

1. Cauda equina syndrome describes the clinical condition that

results from what neuropathy involving multiple lumbar and

sacral nerve roots?

A. Compressive

B. Ischemic

C. Inflammatory

D. All of the above

2. Conus lesions have the same features as cauda equina except:

A. Urinary retention

B. Anal sphincter tone diminished in 80% of patients

C. Saddle anesthesia

D. Motor and sensory loss typically asymmetric

References

1. Groen RJ. Non-operative treatment of spontaneous spinal epidural hemato-

mas: a review of the literature and a comparison with operative cases. Acta

Neurochir (Wien) 2004;146(2):103-110

2. Liu WH, Hsieh CT, Chiang YH, Chen GJ. Spontaneous spinal epidural hemato-

ma of thoracic spine: a rare case report and review of literature. Am J Emerg

Med 2008;26(3):384, e1-e2

3. Ahn UM, Ahn NU, Buchowski JM, Garrett ES, Sieber AN, Kostuik JP. Cauda

equina syndrome secondary to lumbar disc herniation: a meta-analysis of

surgical outcomes. Spine (Phila Pa 1976) 2000;25(12):1515-1522

4. Hussain SA, Gullan RW, Chitnavis BP. Cauda equina syndrome: outcome and

implications for management. Br J Neurosurg 2003;17(2):164-167

5. Karikari IO, Powers CJ, Reynolds RM, Mehta AI, Isaacs RE. Management of

a spontaneous spinal epidural abscess: a single-center 10-year experience.

Neurosurgery 2009;65(5):919-923, discussion 923-924

Answers to Common Clinical Questions

1. D

2. D

26 Occipitocervical Fusion

Edwin Ramos and Juan S. Uribe

I. Key Points

- Maintaining occipitocervical (OC) alignment, decompressing

neural elements, and achieving a strong arthrodesis are the

main goals of this procedure. This is accomplished by judicious

use of fluoroscopy/image guidance and meticulous technique

in decorticating and placing the graft material.

- Traction is not applied in cases of occipitocervical dislocation

or significant ligamentous injury on magnetic resonance imag-

ing (MRI).

- As part of preoperative planning, make sure to review the depth

of the midline suboccipital keel, thickness of the paramedian

cranium, and course of the vertebral artery.

- Prior to locking in the construct, verify that a neutral occipito-

cervical relationship has been achieved.

II. Indications

- Occipitocervical instability due to trauma, infections, rheuma-

toid arthritis, tumors, iatrogenic injury (after transoral odonto-

idectomy), congenital anomalies, cranial settling with brainstem

or cord compression¹

III. Technique

- For most of these patients fiberoptic intubation is performed,

and then baseline somatosensory evoked potentials (SSEPs)

and motor evoked potentials (MEPs) are obtained with the pa-

tient still supine.

- Maintaining cervical alignment, rotate the patient to the prone

position onto chest rolls or a Jackson frame.

- The head is secured with a Mayfield cranial fixation system

(Schaerer Mayfield, Randolph, MA) or in modest traction with

tongs when not contraindicated (OC dislocation).

- Cervical alignment is maintained and checked with fluorosco-

py to ensure a neutral OC relationship.

- The suboccipital area is shaved and cleansed. If autograft is re-

quired, the hip harvest site is incorporated in the prepped area.

200 IV Surgical Techniques

- A midline incision is extended from the inion to the lowest level

to be incorporated in the construct.

- Subperiosteal dissection with Bovie electrocautery

(Bovie

Medical Corporation, Clearwater, FL) is performed to expose

the suboccipital bone. Special care is taken to leave a cuff of

fascia near the inion for subsequent closure. This ensures that

the occipital plate will be fully covered by muscle, reducing the

chances of hardware eroding through the skin.

- Subperiosteal dissection is also used to expose the dorsal el-

ements of the cervical spine. When exposing the arch of C1,

blunt dissection with a Penfield 1 is recommended to avoid in-

jury to the vertebral artery.

- Any decompression required (suboccipital or cervical) is now

performed, with the bone saved for autograft.

- Occipital fixation can be performed using a variety of methods:

occipital wiring, occipital in/out buttons, occipital screw fixa-

tion (occipital plate) (Fig. 26.1), or occipital condyle screw fixa-

tion. The current evidence supports the superiority of cranial

screw fixation over wire and cable constructs with respect to

both clinical outcomes and fusion rates.

- First place the suboccipital plate in position and use one of the

plate apertures to mark the midline keel with a marking pen.

Fig. 26.1 Occipital plate and rod

system. Illustration of the Summit

occipital plating and rod system

(DePuy Spine, Raynham, MA). Note

that the occipital anchor plate is

extended to the cervical spine via

rods anchored by sublaminar wires

that pass through custom cable

connectors (reprinted with permis-

sion from DePuy Acromed; SCSCT

pg. 434, Fig. 26-14).

26 Occipitocervical Fusion

201

The plate is removed and a hand-held power drill is used to

make a bicortical hole. To avoid injury to the suboccipital neu-

ral structures, drill in a progressive fashion—first to a depth of

8 mm, then slowly increasing the depth in 2 mm increments

until bicortical penetration is felt, usually around 10 to 14 mm.

The hole is tapped (this is mandatory; the occipital keel is only

cortical bone) and then the plate is repositioned over this hole

and secured with an appropriate-length screw with a 4.5 mm

diameter. The other midline holes can now be drilled with the

plate in position.

- Some plates provide the option of paramedian holes for screw

placement. Keep in mind that the paramedian bone in the sub-

occipital region is not as thick as the midline keel.

- The cervical instrumentation can now be placed and incorpo-

rated to the suboccipital plate using rods bent to the appropri-

ate shape.

- The plate should be placed high in the suboccipital bone (closer

to the inion than to the foramen magnum) to leave a small area

of bone caudal to the plate for fusion surface.

- An alternative to plate systems is the occipital condyle screw

fixation.² It is particularly useful in situations where a suboc-

cipital decompression is required. With this technique a 3.5

mm × 20 to 22 effective length and 10 to 12 mm lag shank

screw (30 to 34 mm) is placed in the center of the condyle, infe-

rior to the hypoglossal canal. Although different techniques for

its placement have been described, in general the screw has a

medial trajectory (10 to 25 degrees) from an entry point about

5 mm lateral to the foramen magnum on the condyle itself. Im-

age guidance and free-running electromyography (EMG) moni-

toring of the hypoglossal nerve are highly recommended with

this technique.

IV. Complications

- In contemporary series, complication rates (minor and major)

range from 12 to 30%.^3,4

• Wound infection, cerebrospinal fluid (CSF) leak, intracranial

injury (sub-/epidural hematoma), spinal cord injury (instru-

mentation into spinal canal), vascular injury (hardware into

vertebral artery)

• Hardware failure (loosening, pullout, breakage)

• Nonunion requiring re-operation

• Fixation of patient’s neck in exaggerated flexion or extension

202 IV Surgical Techniques

V. Postoperative Care

- Upright x-rays with cervical collar

- Subfascial drain

- Prophylactic antibiotics for 24 hours

- Prompt mobilization with collar

VI. Outcomes

- Fusion rates of 94 to 97% with screw-rod constructs and more

than 85% neurologic improvement have been achieved in pa-

tients with myelopathy.^1,4

- Screw-rod constructs have a much lower pseudarthrosis rate

compared with wiring techniques (6 vs 27%) and result in a

higher rate of neurologic improvement (86 vs 40%).⁵

- Early biomechanical studies suggest that condyle screw fixation

is biomechanically equivalent to suboccipital plate systems in

terms of providing craniocervical stability.²

VII. Surgical Pearls

- Cervical traction is not applied in cases of occipitocervical

dislocation.

- As part of the preoperative planning, make sure to review the

depth of the midline suboccipital keel, thickness of paramedian

cranium, and course of the vertebral artery.

- Prior to locking in the construct, verify that a neutral occipito-

cervical relationship has been achieved.

Common Clinical Questions

1. Cervical traction is contraindicated in which occipitocervical in-

strumentation cases?

2. Before locking the construct down, why are anteroposterior and

lateral fluoroscopy views obtained?

3. Which construct has the lowest pseudarthrosis rate?

26 Occipitocervical Fusion

203

References

1. Lu DC, Roeser AC, Mummaneni VP, Mummaneni PV. Nuances of occipitocervi-

cal fixation. Neurosurgery 2010;66(3, Suppl):141-146

2. Uribe JS, Ramos E, Youssef AS, et al. Craniocervical fixation with occipital

condyle screws: biomechanical analysis of a novel technique. Spine (Phila Pa

1976) 2010;35(9):931-938

3. Deutsch H, Haid RW Jr, Rodts GE Jr, Mummaneni PV. Occipitocervical fixation:

long-term results. Spine (Phila Pa 1976) 2005;30(5):530-535

4. Nockels RP, Shaffrey CI, Kanter AS, Azeem S, York JE. Occipitocervical fusion

with rigid internal fixation: long-term follow-up data in 69 patients. J Neu-

rosurg Spine 2007; 7(2):117-123

5. Grob D, Crisco JJ III, Panjabi MM, Wang P, Dvorak J. Biomechanical evaluation

of four different posterior atlantoaxial fixation techniques. Spine (Phila Pa

1976) 1992;17(5): 480-490

Answers to Common Clinical Questions

1. Those performed for occipitocervical dislocation or when sig-

nificant ligamentous injury is suspected

2. To ensure adequate alignment and avoid exaggerated flexion or

extension

3. Screw-and-rod-based constructs

27 Chiari I Decompression

Mark S. Greenberg

I. Key Points

- Consistent feature of Chiari I: disruption of normal cerebrospi-

nal fluid (CSF) flow through the foramen magnum. Most symp-

tomatic cases have descent of cerebellar tonsils ≥5 mm below

the margins of the foramen magnum, which is best seen on

magnetic resonance imaging (MRI).

- Surgical treatment for symptomatic patients consists of enlarg-

ing the foramen magnum (suboccipital decompression), usu-

ally with C1 laminectomy.

- Syringomyelia, if present, will usually respond to suboccipital

decompression alone.

II. Indications

- Symptoms include

• Pain (the most common symptom; mostly suboccipital head-

ache that is exacerbated by neck extension), neck pain, arm

pain, weakness/numbness in one or more limbs, loss of tem-

perature sensation (dissociated sensory loss),¹ balance difficul-

ties. Fifteen to 30% of patients meeting radiographic diagnostic

criteria are asymptomatic.²

- Signs³ include

• Hyperactive lower-extremity (LE) reflexes, downbeat nystag-

mus, gait disturbance, hand muscle atrophy, cerebellar signs,

Babinski sign

III. Technique

- Position: Patient is prone on chest rolls with the neck flexed

and the head in a Mayfield head holder (Schaerer Mayfield,

Randolph, MA) or on a horseshoe head rest.

- Skin incision: midline incision from the inion down to the C2

spinous process

- The fascia is opened in a Y or T, leaving a cuff of tissue attached

to the occiput for use during closure.

- The occipital bone is exposed down to the foramen magnum

(FM). The posterior C1 arch is exposed (taking caution regard-

ing the vertebral arteries).

27 Chiari I Decompression

205

- At a minimum, the surgery consists of enlargement of the FM

(suboccipital decompression) often combined with C1 lami-

nectomy. The area of removal of occipital bone should be as

wide as the FM, but should be no more than 2.5 to 3 cm above

the FM (to avoid cerebellar herniation). Techniques include

thinning the bone with a high-speed drill and removing the

residual bone with a Kerrison rongeur (Fig. 27.1). Options to

suboccipital decompression include

• C2 laminectomy: reserved for cases with severe tonsillar de-

scent below the superior margin of C2 (Table 27.1)

• Duraplasty: A Y-shaped incision is made in the dura (some

surgeons preserve the arachnoid⁴) and a patch graft is sewn in

watertight closure with 4-0 Nurolon (Ethicon, Johnson & John-

son, Piscataway, NJ). Options for sources of graft: pericranium,

fascia lata, and dural substitutes. Pericranium can be harvest-

ed through the same incision by subcutaneous dissection.⁵

• Instead of opening the dura in all cases, some surgeons simply

lyse extradural constricting bands. Then intraoperative ultra-

sound may be used to determine if there is adequate room for

CSF circulation. If not, a duraplasty is performed.

• An alternative to duraplasty (primarily in pediatrics): partial

thickness scoring of the dura with several parallel passes of a

scalpel

- Closure: A multilayered water-tight closure is performed. Skin

approximation with sutures is preferred over staples. A wound

drain is not used. A lumbar drain is occasionally used for 2 to

3 days.

Fig. 27.1 Posterior exposure of the

dura after bony removal, showing an

outline of the Y-shaped dural incision.

(From Vaccaro AR and Albert TJ, Spine

Surgery: Tricks of the Trade, Thieme;

2009. Reprinted with permission.)

206 IV Surgical Techniques

IV. Complications

- The major complication from surgery is CSF leak. This may

be external (and can be initially treated by oversewing the

site of leak and temporary lumbar drainage) or subcutaneous

(pseudomeningocele).

- Overaggressive removal of occipital bone can lead to cerebellar

ptosis (sagging of the tonsils).

- Injury to brainstem or posterior inferior cerebellar arteries (PI-

CAs). Avoid aggressive treatment of tonsillar adhesions. Use an

operating microscope if needed.

- Post-op apnea or respiratory depression: tends to occur within

the first few days post-op. Monitor for apnea and increasing ar-

terial pCO₂.

V. Outcomes

Pre-op symptoms of headache or pain respond in 82% with a 4 year

follow-up.¹ Weakness is less responsive to surgery, especially if atro-

phy has occurred. Symptoms of greater than 2 years’ duration have

a worse prognosis.

Postoperative Care

- Intensive care unit (ICU) observation overnight with head com-

puted tomography (CT) the next morning to rule out epidural

hematoma.

- Mobilize and discharge typically in 24 to 48 hours post-

operatively.

- Early follow-up in clinic recommended to assess wound,

d/c sutures/staples, and ensure no pseudomeningocele has

developed.

VI. Surgical Pearls

- Treating the Chiari malformation via suboccipital decompres-

sion corrects syringomyelia in the majority of cases without

the need for any other procedure.

- Fifteen to 30% of patients with radiographic criteria of Chiari I

malformation are asymptomatic.²

27 Chiari I Decompression

207

Table 27.1 Variation with Age of the Location of the Inferior

Tonsillar Pole Relative to the Foramen Magnum⁶

Two standard deviations below

Age (years)

the FM (mm)

0-9

10-29

30-79

80-89

Abbreviation: FM, foramen magnum.

Common Clinical Questions

1. Three weeks following a suboccipital decompression with dura-

plasty for a symptomatic Chiari I malformation, a patient devel-

ops a tense, very painful fluid collection under the incision and

an MRI shows it has the appearance of CSF without any other

significant abnormalities. The best management options are:

A. Percutaneous tapping of the fluid after careful skin prep, and

then tightly wrapping the head with bandages to prevent

reaccumulation

B. Placement of a lumbar drain and having the patient lie flat in

bed for 3 days

C. Surgical exploration of the wound in the OR with repair of

dural defect, and placement of lumbar drain for 3 days with

the head of bed greater than 30 degrees

D. Placement of an external ventricular drain to divert the CSF

from the wound, and conversion to a ventriculoperitoneal

(VP) shunt if the patient is drain dependent after 5 days

2. A 48-year-old female elementary school teacher presents with a

20-year history of headaches that occur almost every day at the

same time. They vary from the left to right side and are often

associated with neck pain. No medication or change in position

has provided any relief. Her primary care physician ordered a

brain MRI, on which the only abnormality identified is that the

inferior pole of the cerebellar tonsils is 4 mm below the foramen

magnum. She is neurologically intact. You should:

A. Order a cine flow MRI

B. Have her see a neurologist to rule out other causes of chronic

headache

C. Order a cervical MRI

D. All of the above

208 IV Surgical Techniques

References

1. Paul KS, Lye RH, Strang FA, Dutton J. Arnold-Chiari malformation. Review of

71 cases. J Neurosurg 1983;58(2):183-187

2. Bejjani GK, Cockerham KP. Adult Chiari malformation. Contemp Neurosurg

2001; 23(26):1-7

3. Levy WJ, Mason L, Hahn JF. Chiari malformation presenting in adults: a surgi-

cal experience in 127 cases. Neurosurgery 1983;12(4):377-390

4. Sindou M, Gimbert E. Decompression for Chiari type I-malformation (with

or without syringomyelia) by extreme lateral foramen magnum opening

and expansile duraplasty with arachnoid preservation: comparison with

other technical modalities (Literature review). Adv Tech Stand Neurosurg

2009;34:85-110

5. Stevens EA, Powers AK, Sweasey TA, Tatter SB, Ojemann RG. Simplified har-

vest of autologous pericranium for duraplasty in Chiari malformation Type I.

Technical note. J Neurosurg Spine 2009;11(1):80-83

6. Mikulis DJ, Diaz O, Egglin TK, Sanchez R. Variance of the position of the cere-

bellar tonsils with age: preliminary report. Radiology 1992;183(3):725-728

Answers to Common Clinical Questions

1. C. The patient probably has a “ball-valve” effect through a dural

flap. Tapping the fluid will not prevent reaccumulation. Placing

the patient flat will actually put more pressure on the incision.

An external ventricular drain (EVD) and/or shunt has no role in

the absence of hydrocephalus.

2. D. The headaches sound atypical for Chiari malformation, and

she is borderline for the tonsillar descent (which is at two stan-

dard deviations below normal for her age; see Table 27.1). The

cine MRI may give additional helpful data, but before recom-

mending surgery it is critical to rule out other explanations for

her headache. A cervical MRI will rule out cervical spondylosis,

which may cause neck pain and headache, and it is also neces-

sary to rule out a syrinx associated with the tonsillar descent.

Since she is neurologically intact, there should be little risk in

proceeding cautiously.

28 Transoral Odontoidectomy

Frank M. Phillips and Colin B. Harris

I. Key Points

- The transoral approach allows the surgeon ventral midline

access from the top of the arch of the atlas to the C2-C3 disc

space.¹

- A thorough preoperative assessment is necessary to ensure that

the patient is free from any oral or dental pathology, which are

contraindications to this approach.

- A minimum of 2.5 to 3 cm of dental clearance should be present

to allow adequate exposure for odontoid resection.²

II. Indications

- Ventral spinal cord compression from rheumatoid pannus not

amenable to posterior decompression and fusion

- Midline ventral cord compression from intradural or extradural

spinal tumors

- Irreducible atlantoaxial subluxation with myelopathy and cord

compression¹

III. Technique

- The patient is positioned supine on the operating room table

with a Mayfield headrest (Schaerer Mayfield, Randolph, MA), or

in Mayfield tongs for greater control if there is instability of the

occipitocervical junction.

• Prophylactic antibiotics consist of intravenous cephalo-

sporin and metronidazole preoperatively and for 72 hours

postoperatively.

• Nasotracheal intubation is preferred to avoid manipulation of

the occipitocervical junction, and a nasogastric tube should

be placed to prevent postoperative wound contamination.

- A transoral tongue retractor is inserted to visualize the

oropharynx.

- A lateral fluoroscopic image is taken to localize the odontoid

process and anterior arch of the atlas, followed by infiltration

of 1% lidocaine with epinephrine into the planned incision site.

- A 2 cm full-thickness vertical incision is made in the midline,

dividing the mucosa and pharyngeal constrictor musculature.

210 IV Surgical Techniques

- A pharyngeal retractor is placed in a horizontal fashion, expos-

ing the anterior tubercle of the atlas, origin of the longus colli,

and anterior longitudinal ligament (Fig. 28.1).

- Cautery is used to skeletonize the ventral aspect of the arch of

the atlas and the odontoid.

- The central 10 to 15 mm of the arch of the atlas is removed

using a high-speed burr to expose the odontoid process in its

entirety.¹

- The odontoid is then resected using a high-speed burr for the

anterior cortex and cancellous portion.

- Angled curettes are used to detach the apical and alar ligaments

to allow the tip of the dens to be removed.

- Kerrison rongeurs (1 and 2 mm) and microcurettes are then

used to complete the resection of the posterior dens cortical

shell until the posterior longitudinal ligament and dura are

identified.

- In patients with rheumatoid arthritis, the retrodental soft-tis-

sue pannus is exposed following odontoid resection. Only loose

Fig. 28.1 Retropharyngeal anatomy and retractor. 1, anterior atlanto-occipital membrane;

2, armored nasotracheal tube; 3, longus colli muscle; 4, anterior longitudinal ligament;

5, clivus; 6, longus capitis muscle; 7, rectus capitis anterior muscle; 8, anterior tubercle

of C1; 9, lateral atlantoaxial joint capsule; 10, retropharyngeal soft-tissue retractor. (From

Haher T, Merola A, Surgical Technique for the Spine, Thieme; pg. 5, Fig. 1-5. Reprinted

with permission.)

28 Transoral Odontoidectomy

211

fragments should be debulked, as complete pannus removal is

usually unnecessary and risks a cerebrospinal fluid (CSF) leak.²

- The incision is irrigated with antibiotic solution, followed by

closure of the muscle and mucosa in two layers with absorb-

able 3-0 suture.

- The retractors are removed, and 1% cortisone cream may be ap-

plied to the lips and tongue to decrease postoperative edema.

- The patient may be repositioned prone with the Mayfield tongs

if a posterior stabilization and fusion procedure is planned.

IV. Complications

- Neurologic injury

• Awake nasotracheal intubation avoids manipulation of the

craniocervical junction.

• Somatosensory evoked potentials (SSEP) and motor evoked

potentials (MEP) can provide intraoperative warning of spinal

cord compromise.

• Keep mean arterial pressure (MAP) high to prevent ischemic spi-

nal cord injury.

- CSF leak

• Direct dural repair (if possible), followed by fascial or fat graft

• Placement of subarachnoid lumbar drain postoperatively can

be helpful.

- Airway obstruction

• Avoid premature extubation as reintubation can be very dif-

ficult and require emergency tracheostomy. Prior to extuba-

tion, evaluate for:

◦ Resolution of retropharyngeal swelling on lateral radiograph

(usually 24 to 48 hours postoperatively)¹

◦ Ability to breathe around orotracheal airway²

- Infection

• Can be minimized with meticulous wound closure and 72

hours of intravenous antibiotics

• Delay removal of nasogastric tube and oral fluid administration

for 4 to 5 days postoperatively to allow for mucosal healing.

- Vertebral artery injury

• Preoperative CT or MRI scans should be reviewed to deter-

mine if there is an aberrant medial course of the vertebral

212 IV Surgical Techniques

artery, which is more common in patients with atlantoaxial

rotatory subluxation.

• Dissection of the atlas should stay within 2 cm of the mid-

line, and dissection at the level of the C2-C3 disc should stay

within 1 cm of the midline.¹

V. Postoperative Care

- The patient should be kept intubated for 2 to 3 days postopera-

tively to allow airway edema to subside.²

- Temporary use of an endotracheal cuff leak and tube changer

can help anesthetist to guard against a difficult reintubation.²

- Once extubated, patient can be mobilized out of bed to chair in

a cervical collar or orthosis depending on stability.

VI. Outcomes

- No level I studies have been performed to evaluate outcomes

following transoral odontoid resection.

- Based on a review of smaller case series, improvement of pre-

operative neurologic deficits can be expected but is dependent

on chronicity of spinal cord compression.

- In one 10-year review of 72 cases, there were two postopera-

tive deaths and one pharyngeal infection requiring a repeat

operation, with improvement seen in all patients’ neurologic

function.³

VII. Surgical Pearls

- Care should be taken to avoid entrapment of the tongue against

the teeth with the retractor system.

- As an alternative to palatal retractors, a red rubber catheter can be

passed through the nares and sutured to the soft palate; it can then

be used as a retractor.²

- The soft palate and mandible can be split to provide extensile

exposure in the proximal and distal directions, respectively, al-

though the increased morbidity should be considered.

28 Transoral Odontoidectomy

213

Common Clinical Questions

1. Which of the following is the minimum clearance between the

upper and lower teeth needed for performing transoral odon-

toid resection?

A. 1 cm

B. 2 cm

C. 3 cm

D. 4 cm

2. Which of the following is not an indication for transoral (ante-

rior) odontoid resection?

A. Irreducible atlantoaxial subluxation with spinal cord

compression

B. Spinal cord tumors at the C1 level causing ventral spinal cord

compression

C. Rheumatoid pannus not amenable to posterior decompres-

sion and fusion

D. Atlantooccipital instability with myelopathy

3. Which of the following is the minimum average distance to the

vertebral artery from the midline (in the medial to lateral direc-

tion) in the transoral approach to the odontoid?

A. 1 cm at the atlas

B. 2 cm at the C2-C3 disc

C. 2 cm at the atlas

D. 3 cm at the C2-C3 disc

References

1. Mendoza N, Crockard A. Anterior transoral procedures. In An HS, Riley LH III.

An Atlas of Surgery of the Spine. London: Martin Dunitz Ltd; 1998:55-69

2. Mummaneni PV, Haid RW. Transoral odontoidectomy. Neurosurgery 2005;

56(5):1045-1050

3. Menezes AH, VanGilder JC. Transoral-transpharyngeal approach to the ante-

rior craniocervical junction. Ten-year experience with 72 patients. J Neuro-

surg 1988;69(6):895-903

214 IV Surgical Techniques

Answers to Common Clinical Questions

1. C. A minimum of 2.5 to 3 cm of clearance is necessary for odon-

toid resection. If less space is present, either splitting of the soft

palate (for more cephalad extension) or mandible (for caudal ex-

tension) may be necessary if this approach is chosen.

2. D. Cases presenting with instability should be treated with a

posterior decompression and fusion, as anterior decompression

alone would not address the instability.

3. C. The vertebral artery sits about 2 cm from the midline at the

level of the atlas, and lies more medial (1 cm from the midline)

in the transverse foramen at the level of the C2-C3 disc.

29 C1-C2 Techniques

Jau-Ching Wu and Praveen V. Mummaneni

I. Key Points

- Fixation choices are (1) C1 lateral mass screws in combination

with C2 pars screws, pedicle screws, or translaminar screws;

(2) C1-C2 transarticular screw (Magerl’s technique); or (3) wir-

ing techniques.

- Posterior C1-C2 fusion techniques are technically demanding

and caution should be used to avoid vascular (vertebral and ca-

rotid arteries) injury during screw placement.

- Preoperative computed tomography (CT) scan (with or without

CT angiography) is helpful to assess the position of the foramen

transversarium of C1 and C2.

II. Indications

- Most C1-C2 ligamentous instabilities (>3 mm atlantodental

interval [ADI] on flexion-extension x-rays in an adult without

rheumatoid arthritis)

- Traumatic fractures are among the most frequent indications

for posterior C1-C2 fixation.

- Certain subsets of type 2 and type 3 odontoid fractures are

amenable to posterior C1-C2 fixation.

• Type 2 odontoid fracture associated with

◦ Fracture of the atlantoaxial joint

◦ Anterior-inferior oblique fracture in the coronal plane

◦ Oblique fracture in the frontal plane

◦ Jefferson fracture

◦ Ruptured transverse ligament

◦ Old, unhealed type 2 odontoid fracture

• Type 3 odontoid fracture associated with

◦ Fracture of the atlantoaxial joint

◦ Jefferson fracture

◦ Chronic unhealed odontoid fracture after immobilization;

rotatory subluxation of C1-C2

- Congenital malformations of C2 (e.g., os odontoideum and

odontoid agenesis with C1-C2 dynamic instability)

- Inflammatory diseases (e.g., rheumatoid arthritis with >7 mm

ADI)

- Degenerative diseases (with instability and abnormal ADI)

216 IV Surgical Techniques

- Infections (with instability and abnormal ADI)

- Neoplasms (with instability and abnormal ADI)

III. Techniques

The procedure is technically demanding, and an exact three-dimen-

sional (3D) understanding of the anatomy of the region and of the

vertebral artery is mandatory.

The patient is positioned prone with head fixed by a Mayfield head

holder (Schaerer Mayfield, Randolph, MA). The neck should be in the

neutral position and the head kept in the military chin tuck position.

A midline posterior neck incision is then made from the suboccipital

area to the spinous process of C3, allowing exposure of C2-C3 facet

joints and the posterior C1 arch.

C1 Lateral Mass Screw with C2 Pars, Pedicle, or Translaminar Screws^1,2

- C1 lateral mass screw^5,6

• Control of hemorrhage from the venous plexus between C1

and C2 must be achieved by bipolar coagulation or hemostatic

agents. It is not necessary to expose the vertebral artery on

the superior aspect of the C1 arch (sulcus arteriosus). Usually

the C2 nerve root is mobilized caudally for exposure of the

C1 lateral mass inferior to the C1 arch. The medial border of

the C1 lateral mass is palpated. A pilot hole can be made with

a 3 mm drill bit at the center of C1 lateral mass. The screw

trajectory is 10 degrees medial angulation in the axial plane.

On lateral fluoroscopic imaging the drill is aimed toward the

anterior tubercle of C1. Stop the drill at the “back side” of the

anterior C1 tubercle to prevent plunging the bit into the retro-

pharynx. After tapping of the hole, the C1 lateral mass screw

is placed (usually 34 to 36 mm in length).

- C2 pars screws (Fig. 29.1)^5,6

• The C2 pars is defined as the portion of C2 vertebra connect-

ing the superior and inferior articular surfaces. A C2 pars

screw is placed in a trajectory similar to that of a C1-C2 tran-

sarticular screw, except that it is shorter. Its entry point is

about 3 mm rostral and 3 mm lateral to the inferior medial

aspect of the inferior articular surface of C2. The screw should

follow a steep trajectory, 45 to 60 degrees, with 10 to 15 de-

grees of medial angulation. Typical screw length is 16 mm, but

the screw must stop short of the transverse foramen (check

with preoperative CT scan). The risk of vertebral artery injury

for C2 pars screws is lower than that for C1-C2 transarticular

screws.

29 C1-C2 Techniques

217

Dens

Anterior articular facet

Pedicle

Superior articular facet

Lateral mass

Pars interarticularis

Transverse process

Inferior articular facet

Body

Dens

Posterior articular facet

Superior articular facet

Pedicle

Lateral mass

Fig.

29.1 Anatomy of the

Transverse process

axis (C2). (From Fessler/Sekhar,

Pars inter. articularis

Atlas of Surgical Techniques,

Inferior articular process

Thieme, pg. 138, Fig. 16.3A,B.

Spinous process

Reprinted with permission.)

Spinous process

- C2 pedicle screws

• The C2 pedicle is the portion of the C2 vertebra that connects

its posterior elements to the vertebral body. The entry point

of the C2 pedicle screw is in the pars of C2, lateral to the su-

perior margin of the C2 lamina. This is usually 2 mm lateral

and 2 mm superior to the C2 pars screw entry point described

above. The pedicle screw requires a medial angulation of 15 to

25 degrees with 20 degrees upward trajectory. For those with

very narrow C2 pedicles, risk of breach into the neural canal or

transverse foramen is high (check with preoperative CT scans).

- C2 translaminar screws

• Translaminar screws serve as a salvage technique for C2 pars

screws or pedicle screws in cases of the anomalous high-rid-

ing vertebral artery or very thin pedicle. The entry point is at

the junction of the spinous process and lamina. The trajec-

tory has to meet the slope of the lamina while aiming mildly

dorsally to avoid canal breach. If bilateral translaminar screws

are used, offset the entry points craniocaudal to keep the two

screw paths from intersecting.

• Using polyaxial screws, the C1 lateral mass screws can be eas-

ily connected with either of the three kinds of C2 screws de-

scribed above.

218 IV Surgical Techniques

- C1-C2 transarticular screws

• The advantage of the C1-C2 transarticular screw technique is

the complete obliteration of the rotational motion of the at-

lantoaxial joint. The drawbacks of this procedure are the need

for anatomical reduction of C1-C2 and the potential for verte-

bral artery injury. If placement of the first screw likely caused

vertebral artery injury, then screw insertion into the contra-

lateral side should not be attempted, because bilateral verte-

bral artery laceration could result in brain stem infarction and

death. The preoperative CT scan must be carefully examined

to exclude a high-riding vertebral artery or destruction of

bone at the site of intended screw placement.

• The screw entry point is approximately 3 to 4 mm rostral and

3 to 4 mm lateral to the inferior medial portion of the C2-C3

facet joint. The K-wire trajectory is typically 15 degrees medi-

al with the superior angle visualized by fluoroscopy aiming at

the C1 anterior tubercle (often 60 degrees). While the K-wire

is drilling, subtle changes in resistance may be perceived as

the K-wire traverses the four cortical surfaces along the path

into the C1 lateral mass: (1) the posterior C2 entry point, (2)

the superior articular surface of C2, (3) the inferior articular

surface of C1, and (4) the anterior cortex of the C1 ring. After

the K-wire is placed, a cannulated drill bit, tap, and screw can

be placed. Typical screw length is 36 to 46 mm.

- Wiring techniques

• Posterior wiring techniques require an intact posterior arch

in each of C1 and C2. Therefore, in cases of Jefferson fracture

or hangman’s fracture the K-wire is of no use. Double-braided

titanium cables are preferred (over steel wires) because they

are more flexible and have less chance of causing cord or dural

injury during the sublaminar passage. Several techniques of

sublaminar wiring and bone graft placement have been re-

ported, including the Sonntag wiring, the Brooks wiring, and

the Gallie wiring.

IV. Complications

- Vertebral artery laceration (unilateral vertebral artery occlu-

sion could be asymptomatic, but bilateral vertebral artery injury

could result in a large posterior circulation infarction and death).

If there is a unilateral vertebral artery injury, consider placing

the screw into the bone to tampanade the bleeding. Consider not

placing the contralateral screw. Consider taking the patient for a

postoperative angiogram to ensure there is no artery dissection.

- Dural injury or cord injury

29 C1-C2 Techniques

219

V. Postoperative Care

- No need for external orthosis if rigid screw fixation is achieved.

VI. Outcomes

- Transarticular screws together with the Sonntag wiring tech-

nique and bone graft essentially create a three-point fixation

that completely obliterates the rotational and flexion-exten-

sion motion of the C1-C2 joint. Apfelbaum reports that fusion

was achieved in 99% of 198 patients undergoing transarticular

screw fixation. However, Apfelbaum also reported a 16.7% com-

plication rate, including 5 patients with vertebral artery inju-

ries, one of which was bilateral and fatal.³

- C1 lateral mass screws connected to C2 pars/pedicle, or trans-

laminar screws, provide biomechanical strength and actually

facilitate anatomic reduction with a fusion rate higher than

95%.⁴

- Biomechanical analysis in cadaveric specimens showed crossed

translaminar fixation to be superior to pars screws in strength.

VII. Surgical Pearls

- Preoperative planning is crucial. The CT scan must be evaluated

to rule out an anomalous vertebral artery path and to assess the

bony anatomy.

- A thorough understanding of the 3D anatomy of the axis and

atlas is mandatory.

- Be aware of the robust venous plexuses around the C1-C2 re-

gion and use a hemostatic agent to diminish bleeding in this

area.

Common Clinical Questions

1. Where is the entry point for the C2 pars screw?

2. Where is the entry point for the C1-C2 transarticular screw?

3. Should you place a contralateral C2 pars screw if you have an ip-

silateral vertebral artery laceration during insertion of the first

C2 pars/pedicle or transarticular screw?

220 IV Surgical Techniques

References

1. Mummaneni PV, Haid RW. Atlantoaxial fixation: overview of all techniques.

Neurol India 2005;53(4):408-415

2. Yanni DS, Perin NI. Fixation of the axis. Neurosurgery 2010;66(3, Suppl):

147-152

3. Finn MA, Apfelbaum RI. Atlantoaxial transarticular screw fixation: update

on technique and outcomes in 269 patients. Neurosurgery 2010;66(3,

Suppl):184-192

4. Mummaneni PV, Lu DC, Dhall SS, Mummaneni VP, Chou D. C1 lateral mass fixa-

tion: a comparison of constructs. Neurosurgery 2010;66(3, Suppl):153-160

5. Goel A, Kulkarni AG, Sharma P. Reduction of fixed atlantoaxial dislocation in

24 cases: technical note. J Neurosurg Spine 2005;2(4):505-509

6. Harms J, Melcher RP. Posterior C1-C2 fusion with polyaxial screw and rod

fixation. Spine 2001;26(22):2467-2471

Answers to Common Clinical Questions

1. The C2 pars screw entry point is approximately 3 mm rostral

and 3 mm lateral to the inferior medial aspect of the inferior

articular surface of C2.

2. The same as for the C2 pars screw

3. No. Patients may tolerate a one-sided vertebral artery injury, but

a bilateral vertebral injury could be fatal.

30 Direct Fixation of Odontoid Fractures

Andrew T. Dailey and Jose Carlos Sauri-Barraza

I. Key Points

- Odontoid screw fixation is suitable for acute type II odontoid

fractures, which represent 60% of all dens fractures.¹

- Rigid immobilization alone has been associated with nonunion

in over 50% of cases in many series. Risk factors for nonunion

include age greater than 50, displacement more than 6 mm, an-

gulation, and smoking history.¹

- Odontoid screws allow for direct fixation of the fracture frag-

ments and have been reported to result in successful stabiliza-

tion in 80 to 90% of cases.²

II. Indications

- Type II or shallow type III fractures that are acute or subacute

- Contraindications include pathologic fracture, injuries with as-

sociated rupture of the transverse atlantal ligament, chronic

nonunion of odontoid (fractures present for more than 3 to 6

months), and comminuted fractures.

- Contraindications include severe osteoporosis, irreducible frac-

tures, barrel chest, and thoracic kyphosis where the trajectory

for a screw is not possible.

III. Technique

- Intraoperative fluoroscopy is essential to these procedures and

should be performed in the anteroposterior (AP) and lateral

planes (i.e., use two C-arms, Fig. 30.1).

- Place patient supine in halter traction or Gardner-Wells tongs.

- A bite block (cork) is useful for obtaining the AP image.

- Proper patient positioning with fracture reduction and exten-

sion of the neck to allow for proper screw trajectory is the most

important aspect of the procedure.

- A transverse incision at C5-C6 provides the proper trajectory.

- Dissection is carried down to precervical fascia exactly as in

approach for anterior cervical decompression.

- Medial-lateral retractors are placed under longus at C5 and

blunt dissection is carried up to C2-C3 disc space.

222 IV Surgical Techniques

Fig. 30.1 Simultaneous AP and lateral fluoroscopy with retractors in place and

K-wire pointing to the entry point for the screw. (Reproduced with permission of

Springer from Dailey et al 2010.)¹

- A cephalad retractor is used to protect the esophagus.

- Two general techniques may be used to place the screw: a can-

nulated screw system that allows the screw to be placed over a

K-wire, or a non-cannulated screw that is placed directly down

the path of the drill.

- The author prefers to use a non-cannulated system with spe-

cialized retractors and drill guides that allow for optimal posi-

tion of the screw in the dens (Fig. 30.1).

- The trajectory is chosen so that the screw enters the C2 body in

the anterior portion of the C2-C3 disc and not along the ante-

rior border of the body of C2.

- Once the entry point is chosen, three steps remain: drill, tap,

screw.

- Drilling is performed with fluoroscopic imaging to ensure that

the path of the screw is acceptable and that the distal fracture

fragment is not displaced cephalad during the drilling.

- The drill should engage the cortex at the distal tip of the dens to

allow the screw to penetrate and lag the two fragments of the

dens together (Fig. 30.2). It is this distal cortex that provides the

strength for the fixation. If not engaged, the screw can back out

and fixation will fail.

- The entire length of the screw trajectory is tapped, including the

distal cortex.

- Either one or two screws can be used. The first screw should be

a partially threaded or lag screw that will draw the fragments

30 Direct Fixation of Odontoid Fractures

223

Fig. 30.2 Lateral fluoroscopy showing the correct position of the tip of the drill

(left) and tap (right) so that the screw will engage the distal cortex of the dens. (Re-

produced with permission of Springer from Dailey et al 2010.)¹

together once the distal cortex is engaged. The second screw is

fully threaded.

- Once the screws are placed, the retractors are carefully re-

moved, the wound irrigated, and the incision closed like that

for an anterior cervical decompression and fusion. Meticulous

hemostasis is performed prior to closure to prevent a retropha-

ryngeal hematoma.

IV. Complications

- Nonunion. This can be treated with a posterior C1-C2

arthrodesis.

- Screw back-out

- Screw breakage. Rare with non-cannulated 3.5 mm screws.

- Dysphagia and hoarseness. In the elderly population, patients

may temporarily need a feeding tube due to dysphagia up to

25% of the time.³

- Aspiration pneumonia

- Retropharyngeal hematoma

V. Postoperative Care

- Mobilize patients immediately, particularly elderly patients.

224 IV Surgical Techniques

- Observe for signs of dysphagia and aspiration, particularly in

older patients. Advance diet with caution.

- A collar may provide some additional support, particularly

in osteopenic patients. Biomechanical studies show that the

odontoid is restored to half its intact strength with fixation us-

ing either one or two screws.

- Patients should be followed with serial x-rays for at least one

year, including flexion and extension films at 3, 6, and 12

months.

VI. Outcomes

- The largest series in the literature report fusion rates of around

90% in all patients regardless of age (Fig. 30.3).² Other studies

have reported similar rates of fusion.⁴

- There has generally been no reported difference in fusion rates

if one versus two screws are used.^1,2

- Two screws may lead to a better stabilization rate in patients

over 70, as a recent series reports a 96% stability rate with two

screws, but only a 56% rate with the use of one screw.³

VII. Surgical Pearls

- Preoperative planning and careful patient selection are key to

obtaining success with an odontoid screw.

- Proper positioning is crucial to successful screw placement.

- Always make sure that the screw tip engages the distal cortex

of the dens.

- Counsel patients and their families that if the procedure cannot

be completed, a posterior C1-C2 fusion will provide a suitable

alternative or “salvage” procedure.

- So-called anterior oblique dens fractures where the fracture

line runs posterior-superior to anterior-inferior are difficult to

realign with an odontoid screw, and higher failure rates have

been reported with this procedure.

30 Direct Fixation of Odontoid Fractures

225

Fig.

30.3 Sagittal computed tomog-

raphy with odontoid screw in position,

demonstrating healing of fracture at 1

year after surgery.

(Reproduced with

permission of Springer from Dailey et al

2010.)¹

Common Clinical Questions

1. Contraindications to odontoid screw placement include all of

the following except:

A. Pathologic fracture

B. Chronic nonunion

C. Type II fracture with associated stable C1 fracture

D. Type I fracture with associated atlantooccipital dislocation

2. The most common cervical spine fracture in the population over

age 65 is:

A. Hangman’s fracture

B. Type II odontoid fracture

C. Type III odontoid fracture

D. Type I odontoid fracture

3. What is the most common immediate postoperative complica-

tion following odontoid screw fixation in patients over age 65?

226 IV Surgical Techniques

References

1. Dailey AT, McCall TD, Apfelbaum RI. Direct anterior screw fixation of odon-

toid fractures. In Patel VV, Burger E, Brown C, eds. Spine Trauma Surgical

Techniques. Berlin: Springer; 2010:Chapter 3

2. Apfelbaum RI, Lonser RR, Veres R, Casey A. Direct anterior screw fixa-

tion for recent and remote odontoid fractures. J Neurosurg 2000;93(2,

Suppl):227-236

3. Dailey AT, Hart D, Finn MA, Schmidt MH, Apfelbaum RI. Anterior fixa-

tion of odontoid fractures in an elderly population. J Neurosurg Spine

2010;12(1):1-8

4. Platzer P, Thalhammer G, Ostermann R, Wieland T, Vécsei V, Gaebler C. An-

terior screw fixation of odontoid fractures comparing younger and elderly

patients. Spine (Phila Pa 1976) 2007;32(16):1714-1720

Answers to Common Clinical Questions

1. C. If there is no associated injury to the transverse atlantal liga-

ment and a C1 fracture could be treated using a collar, an odon-

toid screw can treat the dens fracture and a collar placed for the

associated C1 fracture.

2. B. The other fractures are much more common in the young-

er trauma population and are associated with higher-energy

mechanisms of injury.

3. Any anterior cervical procedure in older patients is associated

with difficulty with swallowing, and patients should be coun-

seled about this potential development preoperatively.

31 Cervical Arthroplasty

Jau-Ching Wu, Ali A. Baaj, and Praveen V. Mummaneni

I. Key Points

- Anterior cervical discectomy and fusion (ACDF) remains the

gold standard in the surgical management of symptomatic cer-

vical spondylosis and central disc herniation.

- The emerging option of cervical arthroplasty is aimed at pres-

ervation of segmental motion with maintenance of adequate

stability.¹

- Key elements to achieving a good result and avoiding complica-

tions with cervical arthroplasty:

• Appropriate patient selection (competent posterior elements,

without spondylolisthesis)

• Correct neck positioning during surgery (neutral to slightly

lordotic cervical curvature)

• Generous decompression with resection of the bilateral unco-

vertebral joints and posterior longitudinal ligament

• Precise end plate preparation (parallel or domed according to

device, with preservation of cortical end plates)

• Accurate midline acquisition

• Proper implant sizing (footprint coverage of disc space and

avoidance of overdistraction)

II. Indications

- The current indications for cervical arthroplasty in the Unit-

ed States include symptomatic one-level cervical radiculopa-

thy or myelopathy in patients who have failed nonsurgical

management.

- Relative contraindications include (1) cervical kyphosis, (2)

cervical spondylosis with incompetent or significantly degen-

erated facets (>2 to 3 mm subluxation on flexion-extension x-

rays), (3) cervical ankylosis, (4) osteoporosis, and (5) cervical

trauma with ligamentous or facet injury.

III. Technique

- Prophylactic antibiotics should be given; perioperative dexa-

methasone and intraoperative neuromonitoring are optional.

228 IV Surgical Techniques

- The patient is positioned supine with the neck in neutral or

slight extension, with shoulder retraction to allow adequate

fluoroscopic visualization of the target level.

- Create a transverse skin incision along preexisting skin crease

near the index level.

- Perform dissection between the carotid sheath and strap mus-

cles (anterior-medial to sternocleidomastoid muscle) to expose

the retropharyngeal space.

- The trachea and esophagus are retracted and protected medial-

ly by self-retaining retractors placed under the elevated longus

colli muscles for exposure of the anterior cervical spine.

- After confirmation of the index level by lateral fluoroscopic x-

ray, anterior cervical discectomy is performed with curettes,

rongeurs, or drill.

- Full bilateral nerve canal decompression must be achieved, in-

cluding removal of the uncovertebral joints.

- End plate preparation is crucial in cervical arthroplasty and

may differ between prostheses. Caution must be taken not to

violate the cortical surface, which would increase the risk of

implant subsidence or migration.

- Midline acquisition, implant sizing (including footprint size

and disc height), and insertion trajectory should be controlled

to allow physiological range of motion in the cervical spine af-

ter implantation of the prosthesis.

- There are several cervical artificial discs currently on the mar-

ket, and each has its unique design and fixation system (Fig.

31.1). Therefore, there are differences in the technique of final

implantation. But they all have the common feature of absolute-

ly requiring adequate decompression of the index level. Some

differences in material and biomechanics may provide advan-

tages in certain scenarios. In choosing one, the surgeon must

have a thorough understanding of the prosthesis’s biomechani-

cal design and familiarity with its implantation (Table 31.1).

IV. Complications

Complications are similar to those for ACDF; however, there are four

primary reasons to consider revision of cervical arthroplasty:

- Radiculopathy (or other new-onset neurologic deficit) after cervi-

cal arthroplasty

- Subsidence

- Implant migration

- Ankylosed joint (formation of significant heterotopic bone

around the implant)

31 Cervical Arthroplasty

229

Fig. 31.1

(A-C) Photographs of the

three arthroplasty devices currently

approved by the U.S. Food and Drug

Administration. (A) Bryan Device. (B)

Prestige Device. (C) Pro-Disc C Device.

(From Baaj et al, History of Cervical

Arthroplasty. Neurosurgical Focus.

September 2009, Figs. 2-4.)

V. Postoperative Care

Same as for ACDF, except for the following:

- Mummaneni et al suggested that perioperative oral nonsteroi-

dal antiinflammatory drugs (NSAIDs) for 2 weeks² might re-

duce the incidence of heterotopic bone formation.

- Avoid neck collar (encourage normal motion).

Table 31.1 FDA-Approved Cervical Arthroplasty Devices in the United

States

Device

Manufacturer Classification

Biomaterials

ProDisc-C

Synthes Spine,

Semicon-

CCM end plate with

West Chester,

strained

UHMWPE inlay

BRYAN

Medtronic Ltd., Unconstrained Titanium alloy shells

Memphis, TN

with polyurethane

nucleus

PRESTIGE ST Medtronic Ltd., Unconstrained Metal on metal

Memphis, TN

Abbreviations: CCM, cobalt-chromium-molybdenum; FDA, Food and Drug Administra-

tion; ST, stainless steel; UHMWPE, ultra-high molecular weight polyethylene.

230 IV Surgical Techniques

VI. Outcomes

To date, there have been three prospective randomized multicenter

U.S. studies comparing cervical artificial disc implantation with

ACDF in patients treated for single-level cervical disc disease with

radiculopathy or myelopathy.

- The largest of these studies compared the PRESTIGE ST Cervical

Disc System (Medtronic, Memphis, TN) with ACDF in a total of

541 patients. At 24 months’ follow-up, the arthroplasty group

demonstrated maintenance of physiologic segmental motion in

association with improved neurologic success, improved clini-

cal outcomes, and a reduced rate of secondary surgeries com-

pared with conventional ACDF.²

- Heller et al compared the BRYAN Cervical Disc (Medtronic,

Memphis, TN) with ACDF in 463 patients. At 24 months after

surgery, the arthroplasty group showed a statistically greater

improvement in the primary outcome variables: neck disability

index score and overall success. No statistical difference was

found between the arthroplasty and ACDF groups with regard

to secondary surgical procedures or implant-related adverse

events. The arthroplasty patients returned to work nearly 2

weeks earlier than the ACDF patients.³

- Murrey et al compared single-level ProDisc-C (Synthes Spine,

L.P., West Chester, PA) arthroplasty with ACDF in 209 patients.

At 24 months after surgery, visual analog scale (VAS), neck dis-

ability index (NDI), and neurologic success rate demonstrated

no statistical difference between the arthroplasty and ACDF

groups. Statistically fewer reoperations and less pain medica-

tion usage were noted in the ProDisc-C cohort.⁴

VII. Surgical Pearls

- Generous decompression of the neuroforamen bilaterally (in-

cluding asymptomatic side)

- Proper end plate preparation

- Correct implant selection (footprint size, height)

31 Cervical Arthroplasty

231

Common Clinical Questions

1. How many degrees of neck range of motion loss could result

from a single-level ACDF?

2. What is the incidence of development of symptomatic adjacent-

level disease after single-level ACDF?

3. Why should patients take oral NSAIDs and avoid neck collar use

after cervical arthroplasty?

References

1. Mummaneni PV, Haid RW. The future in the care of the cervical spine: in-

terbody fusion and arthroplasty. Invited submission from the Joint Section

Meeting on Disorders of the Spine and Peripheral Nerves, March 2004. J

Neurosurg Spine 2004;1(2):155-159

2. Mummaneni PV, Burkus JK, Haid RW, Traynelis VC, Zdeblick TA. Clinical and radio-

graphic analysis of cervical disc arthroplasty compared with allograft fusion:

a randomized controlled clinical trial. J Neurosurg Spine 2007;6(3):198-209

3. Heller JG, Sasso RC, Papadopoulos SM, et al. Comparison of BRYAN cervical

disc arthroplasty with anterior cervical decompression and fusion: clinical

and radiographic results of a randomized, controlled, clinical trial. Spine

(Phila Pa 1976) 2009;34(2):101-107

4. Murrey D, Janssen M, Delamarter R, et al. Results of the prospective, random-

ized, controlled multicenter Food and Drug Administration investigational

device exemption study of the ProDisc-C total disc replacement versus ante-

rior discectomy and fusion for the treatment of 1-level symptomatic cervical

disc disease. Spine J 2009;9(4):275-286

5. Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH. Radiculopa-

thy and myelopathy at segments adjacent to the site of a previous anterior

cervical arthrodesis. J Bone Joint Surg Am 1999;81(4):519-528

6. Tu TH, Wu JC, Huang WC, Guo WY, Wu CL, Shih YH, Cheng H. Heteroptic

ossification after cervical total disc replacement determination by CT and

effects on clinical outcomes. J Neurosurg Spine 2011;14(4):457-465

Answers to Common Clinical Questions

1. A fusion of one level of the cervical spine typically results in the

loss of 7 degrees of flexion and extension motion and 6 degrees

of rotational motion.²

2. Symptomatic adjacent-segment disease occurs at a rate of 2.9%

per year during the 10-year period after the operation (Hilli-

brand et al, 2008).⁵

3. NSAIDs and motion may reduce the occurrence of heterotopic

bone formation around the artificial disc.⁶

32 Anterior Cervical Corpectomy

Mohammad Said Shukairy and Frank M. Phillips

I. Key Points

- Anterior cervical corpectomy is a safe and effective technique

for decompression of the ventral cervical spinal cord.

- The surgical approach and exposure for corpectomy are similar

to the case for the more common anterior cervical discectomy

(see Chapter 33).¹

II. Indications

- Generally corpectomy is indicated when there is ventral

spinal cord compression and discectomy is inadequate for

decompression.

• Degenerative conditions, such as spondylotic myelopathy in

which ventral spinal cord compression is not restricted to the

disc level and/or is complicated by cervical kyphosis

• Tumor infiltration of the vertebral body causing vertebral

body collapse and spinal cord compression

• Traumatic cervical spine injury, such as a teardrop fracture

with associated spinal cord compression from retropulsion of

vertebral body fragments and spinal instability

• Osteomyelitis with epidural abscess and concomitant ventral

spinal cord compression

• Ossification of the posterior longitudinal ligament

III. Technique

- Intubation via fiberoptic technique, whether awake or asleep, is

safer in cases with significant cervical spinal cord compression,

myelopathic signs, myelomalacia, and/or cervical instability.

- Awake fiberoptic intubation allows for neurologic assessment

immediately following intubation to assess for changes in neu-

rologic function.

- Tape the endotracheal tube away from the side of surgical

incision.

- Steroid administration preoperatively or intraoperatively lacks

scientific support.

- Neurologic monitoring is prudent during operations on myelo-

pathic patients.

32 Anterior Cervical Corpectomy

233

- Some authors routinely use 8 to 10 lb of traction with Gardner-

Wells tongs or chin strap craniocervical traction to increase

disc space distraction.

- Place patient supine on the operating table.

• Pressure points should be padded, especially the ulnar nerve.

• A roll between the scapulae may improve lordosis and access

to the level of interest. In patients with myelopathy, neck ex-

tension must be avoided.

• Shoulders should be taped down to allow for fluoroscopic vi-

sualization of the level of interest; however, excessive traction

can injure the brachial plexus.

- Localize, with fluoroscopy or using external landmarks, the ap-

proximate level of incision along the neck.

- The surgeon may approach the anterior cervical spine from the

right or left side; the left-sided approach theoretically involves

less risk to the recurrent laryngeal nerve.²

- The incision may be made transversely or longitudinally

depending on the number of levels involved and surgeon

preference.

- After incision, identify the platysma beneath the subcutane-

ous layer, and divide it sharply in a transverse or longitudinal

fashion.

• Dissecting under the platysma superiorly and inferiorly al-

lows for better mobilization of the tissues.

- Identify the medial border of the sternocleidomastoid (SCM).

- Using Metzenbaum scissors, dissect in the areolar plane be-

tween the SCM and the medial structures.

• The carotid artery should be palpated to ensure that the tra-

jectory of dissection is correct.

- Using a hand-held retractor, retract the medial structures from

the SCM to expose the prevertebral fascia.

- Incise the fascia to expose the cervical spine; use Kittners to

sweep the prevertebral fascia superiorly and inferiorly.

- Use a spinal marker in the vertebral body (and not the disc) to

confirm the level with x-ray or fluoroscopy image.

- With electrocautery or periosteal elevator, dissect the longus

colli laterally from their midline attachments.

- Place self-retaining retractors and deflate the cuff of the endo-

tracheal tube to minimize esophageal/tracheal edema.

- Caspar pins may be placed into the vertebral bodies above and

below the level of interest, with distraction then applied.

- The discs above and below the level of interest should be in-

cised and removed with curettes and pituitary rongeurs.

234 IV Surgical Techniques

- When necessary, anterior osteophytes can be removed with a

rongeur.

- A burr can be used to thin the vertebral body to the posterior

longitudinal ligament (PLL).

- The PLL is carefully pierced with a small hook or curette.

- A small Kerrison rongeur (1 or 2 mm) can then be used to lift

the PLL away from the dura and complete the decompression.

- Lateral decompression (foraminotomy) is generally completed

at the level of the uncovertebral joint. The uncus can be thinned

with a burr and then removal is completed with a microcurette

or Kerrison rongeur (Fig. 32.1).

- A strut graft or cage with autograft, allograft, or bone graft sub-

stitute material is placed into the defect after contouring of the

vertebral body end plates.

- An anterior plate can be used to enhance fusion and prevent

graft migration. If possible, multiple points of screw fixation

should be established. Posterior instrumentation does, how-

ever, provide greater stability and may be required.

- Some authors recommend rigid anterior fixation to enhance ri-

gidity and reduce graft subsidence; others argue that variable

Fig. 32.1 Anterior view of the surgical field after single-level corpectomy in the cer-

vical spine.

32 Anterior Cervical Corpectomy

235

plates and screws may enhance fusion by dynamically loading

the graft (Wolf’s law). Data in support of either approach are

limited to theoretical considerations and retrospective studies.^3,4

IV. Complications

- Wound infection

- Transient hoarseness

• Reduce risk by reducing endotracheal cuff pressure.

• Avoid dissection into the carotid sheath.

• Some surgeons advocate a left-sided approach to avoid risk of

recurrent laryngeal nerve injury.

- Permanent hoarseness

- Transient or permanent dysphagia

- Nerve root or spinal cord injury⁵

- Acute airway obstruction from swelling or hematoma

• Immediately stabilize the airway and intubate.

• Open the wound at the bedside to allow for decompression

of the hematoma and thereby ease intubation in an emergent

setting.

- Cerebrospinal fluid (CSF) leak

• Extremely difficult to close primarily

• Cover with fibrin glue or dural sealant.

• Place lumbar drain to divert CSF if there is concern about the

risk of persistent drainage.

- Vascular injury

• Vertebral artery

◦The vertebral artery lies lateral to the uncovertebral complex

and is often surrounded by a collection of veins.

◦ Inadvertent injury can lead to massive bleeding.

◦ In the event of injury, the surgeon must immediately ad-

minister tamponade to the bleeding, usually with the aid of

Gelfoam (Pfizer, New York) or another hemostatic agent. The

vessel can be repaired primarily if visualized, or ligated sur-

gically with low risk of neurologic sequelae.^6,7

◦ An emergent angiogram should be considered to rule out

vertebral artery dissection and may require vertebral artery

embolization.

◦The artery can be sacrificed with little consequence if it is

nondominant; sacrifice of the dominant vertebral artery has

a higher incidence of ischemic injury to the brain stem.⁶

- Graft dislodgment/instrumentation failure

• Graft dislodgment may indicate pseudarthrosis, hardware

failure, infection, or a combination of factors.

236 IV Surgical Techniques

• Of primary importance is airway stablization; if there is sig-

nificant tracheal compression, emergent intubation and reop-

eration may be required.

• Revision of the graft may include the use of autograft, such as

iliac crest, and posterior cervical instrumentation and fusion

to supplement the anterior construct.

V. Postoperative Care

- After a prolonged procedure involving concern for anterior soft-

tissue swelling, consider keeping the patient intubated for 24 to

48 hours (until able to breathe around deflated airway cuff).

- Consider external immobilization of the cervical spine.

- Patients with myelopathy and gait unsteadiness may benefit

from physical and occupational therapy evaluations.

- Ensure that the patient is tolerating oral intake and swallowing

normally prior to discharge.

VI. Outcomes

- The goals of decompressive corpectomy are neurologic pres-

ervation, cervical spine stabilization, and/or reduction of

deformity.

- Available outcomes studies are limited in their retrospective

nature, but indicate excellent technical results (greater than

98% fusion rate) and improvement in radicular and myelopath-

ic symptoms in 86%.⁸

- Even in patients with severe myelopathy resulting in a bedrid-

den or wheelchair-bound condition, clinical outcomes showed

improvement in over 60% of patients who underwent surgery.⁹

VII. Surgical Pearls

- Identify the location of vertebral artery on preoperative imag-

ing studies.

- Avoid extension of the cervical spine during positioning.

- Generous dissection of the longus colli muscle allows better

identification of midline, proper placement of retractor blades

underneath the muscle fibers, and decreased pressure on vas-

cular structures laterally or esophagus and trachea medially.

- Begin decompression with discectomy cranial and caudal to the

intended corpectomy. This will assist in identification of the

appropriate depth and width (uncus to uncus) of corpectomy.

32 Anterior Cervical Corpectomy

237

- When the PLL is severely adherent, dissociation of the PLL from

the adjacent structures, thus eliminating its constrictive effect

on the spinal cord and preventing thecal sac manipulation, is

the primary goal. Removing the PLL entirely becomes a second-

ary goal if it can be safely achieved.¹⁰

Common Clinical Questions

1. True or false: The fusion rate after anterior cervical corpectomy

increases with augmented posterior fixation, especially after

two- and three-level corpectomies.

References

1. Aronson N, Filtzer DL, Bagan M. Anterior cervical fusion by the Smith-Robin-

son approach. J Neurosurg 1968;29(4):396-404

2. Bauer R, Kerschbaumer F, Poisel S, et al. Anterior approaches. In Atlas of Spi-

nal Operations. New York: Thieme Medical Publishers; 1993:4-12

3. Vaccaro A, Singh K. The role of anterior column reconstruction. In Anterior

Spinal Column Surgery. Philadelphia, PA: Hanley & Belfus; 1998:589-590

4. Ulrich C, Woersdoerfer O, Kalff R, Claes L, Wilke HJ. Biomechanics of fixation

systems to the cervical spine. Spine (Phila Pa 1976) 1991;16(3, Suppl):S4-S9

5. Flynn TB. Neurologic complications of anterior cervical interbody fusion.

Spine (Phila Pa 1976) 1982;7(6):536-539

6. Rao R, David K. Anterior cervical surgery. In Complications in Orthopaedics:

Spine Surgery. Rosemont, IL: American Academy of Orthopaedic Surgeons;

2006:4-16

7. Daentzer D, Deinsberger W, Böker DK. Vertebral artery complications in an-

terior approaches to the cervical spine: report of two cases and review of

literature. Surg Neurol 2003;59(4):300-309, discussion 309

8. Eleraky MA, Llanos C, Sonntag VK. Cervical corpectomy: report of 185 cases

and review of the literature. J Neurosurg 1999;90(1, Suppl):35-41

9. Scardino FB, Rocha LP, Barcelos AC, et al. Is there a benefit to operating on

patients (bedridden or in wheelchairs) with advanced stage cervical spon-

dylotic myelopathy? J Euro Spine, 2010

10. Sandhu H. Anterior cervical corpectomy. In Spine Surgery: Tricks of the

Trade. New York: Thieme Medical Publishers; 2003:44-45

Answers to Common Clinical Questions

1. True.

33 Anterior Cervical Discectomy

Daniel C. Lu, Kevin T. Foley, and Praveen V. Mummaneni

I. Key Points

- Appreciation of the surgical anatomy of vital structures (ca-

rotid, esophagus, recurrent laryngeal nerve) during approach

is essential.

- To decrease incidence and severity of dysphagia, endotracheal

cuff pressure can be decreased during the retraction phase of

the surgery. Additionally, intermittent relaxation of the retrac-

tion can be utilized.

II. Indications

- Symptomatic herniated nucleus pulposus

• Radiculopathy (after failed conservative therapy)

• Myelopathy

- Cervical spondylosis with radiculopathy or myelopathy

- Ossification of the posterior longitudinal ligament with myelopathy

- Cervical fracture with instability

III. Technique

- Place patient in supine position, arms tucked at sides.

• May use horseshoe headrest with weight strap (7 to 10 lb)

• May use foam doughnut head holder with shoulder retraction

using thick tape

• Intravenous (IV) bag placed longitudinally between shoulder

blades to provide mild head extension

- Localize with fluoroscopy or utilize landmarks (cricoid carti-

lage approximates C5-C6).

• If fluoroscopy is used, the incision is marked parallel to the

disc space.

• If multilevel procedure is performed, favor the incision place-

ment at the rostral disc space.

• A transverse incision 3 cm in length is adequate for single-lev-

el procedure; a longitudinal incision along the anterior border

of the sternocleidomastoid is preferable for a procedure with

three or more levels.

- Incision is made and the platysma undermined; the plane me-

dial to the sternocleidomastoid muscle is identified and bluntly

33 Anterior Cervical Discectomy

239

dissected with a finger or blunt instrument in a rostral-to-cau-

dal direction (Fig. 33.1). The omohyoid muscle overlies the C6

level and can be divided.¹

- The carotid is then palpated and the plane medial to the carotid

and lateral to the trachea and esophagus is developed by blunt

dissection in the rostral-to-caudal direction.

- The spine is then palpated, the prevertebral fascia is entered,

and the disc level is confirmed by x-ray or fluoroscopy.

- Hand-held Cloward retractors are used to retract and provide

protection medially (the trachea and esphogaus) and laterally

(the carotid sheath), while the longus colli muscles are mobi-

lized with Bovie electrocautery (Bovie Medical Corp., Clear-

water, FL). The midline is marked on the vertebral body to

facilitate alignment of the cervical plate.

- Self-retaining retractor (Trimline [Medtronic, Memphis, TN] or

equivalent) is placed underneath the longus colli. The endotra-

cheal tube cuff may be mildly depressurized at this point.

- Disc annulectomy is performed with a number 15 blade scal-

pel; additional disc removal is performed with a pituitary ron-

Carotid

Hyoid

sheath

Longus

coli muscle

Thyoid

cart.

SCM

Esophagus

Thyroid

gland

Tubercle

Trachea

longitudinal

ligament

Inferior thyroid

vessels

Fig.

33.1 Anterior exposure

to cervical spine. (From Haher

R, Merola A, Surgial Technique

for the Spine, Thieme; pg. 73,

Fig. 15-1B.)

240 IV Surgical Techniques

geur. The cartilaginous end plate is removed from the bony end

plate with curettes. Carefully remove the lateral disc demar-

cated by the uncovertebral joint.

- Osteophytes/calcified disc fragments are drilled down to the

posterior longitudinal ligament (PLL), the angle of drilling fol-

lows the angle of the disc space as seen with intraoperative ra-

diographs or fluoroscopy. Take care not to drill away the bony

end plate.

- The PLL is defined and first entered with a fine-angle nerve

hook; it is identified by round longitudinal fibers. It is resect-

ed further with fine Kerrison punches. The dural plane is now

evident.

- Allograft, autograft, or polyetheretherketone (PEEK)/carbon fi-

ber cages filled with bone may be sized and placed into the disc

space.² Temporary sizers are introduced into the intervertebral

space with head traction to assess the correct interbody spacer

size.

- An anterior cervical plate is placed aligning the midline with

previous mark.

- The wound is irrigated with saline (for non-bone morphogenic

protein [BMP] cases).

- A small subfascial drain may be placed.

- Closure of platysma is done with interrupted 2.0 Vicryl (Ethi-

con, a Johnson & Johnson company, New York) and the subcu-

taneous layer with interrupted 3.0 Vicryl. Skin is closed with a

subcuticular running 4.0 monocryl suture.

- Steri-strips (3M, St. Paul, MN) may be used for skin.

IV. Complications

- Nerve root injury (C5 nerve root palsy in up to 5%)³

- Spinal cord injury (especially in myelopathic patients; avoid

hyperextension)

- Wound hematoma (higher in multilevel cases; may be mitigat-

ed by drain placement)

- Hoarseness

- Dysphagia (due to edema or recurrent laryngeal nerve palsy)

- Esophageal perforation

- Carotid or vertebral artery injury (0.3%)

- Pseudarthrosis (2 to 20%)

- Wound infection (<1%)

33 Anterior Cervical Discectomy

241

V. Postoperative Care

- Decadron may be given for 24 hours to decrease soft-tissue

edema.

- Use soft cervical collar for comfort (single level) and hard collar

for immobilization (multilevel cases).

- Postoperative antibiotics for 24 hours

- May be discharged the same day with 6-hour observation in

recovery unit

VI. Outcomes⁴

- Anterior cervical discectomy and fusion (ACDF) is a successful

procedure when performed given the right indications.

- Adjacent-level disease occurs at a rate of around 2% per year in

patients undergoing one-level ACDF.

VII. Surgical Pearls

- For patient counseling, ACDF is not fully effective in patients

with predominant neck pain.

- The surgeon must know the course of the recurrent laryngeal

nerve (RLN) to avoid injury during surgery. On the right, the

RLN loops around the right subclavian artery, and the left RLN

loops around the arch of the aorta. It runs within the tracheo-

esophageal groove, where sharp dissection in the paratracheal

muscles or prolonged retraction against an inflated endotra-

cheal tube may cause injury. Injury causes hoarseness, cough,

aspiration, mass sensation, dysphagia, and vocal cord fatigue.

Studies have not demonstrated a difference in RLN injury when

comparing right and left anterior cervical exposure.

- Indirect decompression by removal of central disc material and

restoration of disc space height by an interbody graft may be

used for a laterally herniated disc; however, the definitive pro-

cedure is to remove all lateral disc demarcated by the uncover-

tebral joint. It is important to achieve a direct decompression of

a laterally herniated disc.

242 IV Surgical Techniques

Common Clinical Questions

1. What is the course of the recurrent laryngeal nerve, and what

symptoms would be manifested by a recurrent laryngeal nerve

injury?

2. What measures can be undertaken to minimize the risk of dys-

phagia in ACDF?

3. Destruction of vertebral body end plates during discectomy may

cause:

A. Subsidence of interbody

B. Cervical kyphosis

C. Plate failure

D. Successful fusion

E. All of the above

References

1. Greenberg MS. Handbook of Neurosurgery. 6th ed. New York: Thieme Medi-

cal Publishers, 2006:304-306

2. Tumialán LM, Pan J, Rodts GE, Mummaneni PV. The safety and efficacy of

anterior cervical discectomy and fusion with polyetheretherketone spacer

and recombinant human bone morphogenetic protein-2: a review of 200

patients. J Neurosurg Spine 2008; 8(6):529-535

3. Fountas KN, Kapsalaki EZ, Nikolakakos LG, et al. Anterior cervical dis-

cectomy and fusion associated complications. Spine

(Phila Pa

1976)

2007;32(21):2310-2317

4. Holly LT, Matz PG, Anderson PA, Groff MW, Heary RF, Kaiser MG, Mummaneni

PV, Ryken TC, Choudhri TF, Vresilovic EJ, Resnick DK. Joint Section on Dis-

orders of the Spine and Peripheral Nerves of the American Association of

Neurological Surgeons and Congress of Neurological Surgeons. J Neurosurg

Spine. 2009;11(2):238-244

Answers to Common Clinical Questions

1. The recurrent laryngeal nerve runs within the tracheoesoph-

ageal groove after looping around the aortic arch (left) or the

subclavian artery (right). Injury would cause hoarseness, cough,

aspiration, mass sensation, dysphagia, and vocal cord fatigue.

2. Decreased cuff pressure after placement of self-retaining retrac-

tors, intermittent release of retraction during surgery, and in-

traoperative use of Decadron

3. A

34 Anterior Cervical Foraminotomy

Matthew J. Tormenti and Adam S. Kanter

I. Key Points

- Spares disruption of the annulus fibrosus and avoids the need

for interbody fusion

- Contraindicated in treating posterior pathology and centrally

located anterior pathology

- Contraindicated in patients with evidence of instability

II. Indications

- Patients with cervical radiculopathy, myelopathy, or

myeloradiculopathy

- Anterolateral pathology such as disc herniations or anterior

osteophytes

- Lesions of the vertebral artery or foramen transversarium

- Progressive neurologic decline or failure of at least 3 months of

conservative management

III. Technique

Operating Room Setup

- The operating room is set up in the same manner as for other

anterior cervical approaches (e.g., anterior cervical discectomy

and fusion [ACDF]).

- General endotracheal anesthesia is induced.

- The patient is placed supine with a shoulder roll to enhance

cervical lordosis and access to the disc space. The patient’s

arms are tucked at the sides and secured with appropriate pad-

ding to avoid ulnar nerve entrapment.

Exposure

- A transverse incision is made along a natural skin crease to

avoid an aesthetically unacceptable scar.

- The subcutaneous tissues and platysma are carefully dissected

until the strap muscles and carotid sheath are identified.

- The carotid sheath is retracted laterally and the esophagus and

trachea retracted medially with Meyerding retractors.

- Fascial dissection is performed bluntly with a cotton-tipped

probe.

244 IV Surgical Techniques

- Prevertebral fascia is opened using either sharp dissection or

monopolar cautery.

- Radiographic localization is performed to ensure exposure of

the correct level.

- Meticulous hemostasis is maintained throughout the exposure.

- Self-retaining retractors are placed in the wound.

- An operating microscope is brought to the field.

Decompression

- The ipsilateral longus colli muscle is detached from vertebral

body.

- The medial borders of the transverse processes of the superior

and inferior vertebral body are exposed (Fig. 34.1).

- Uncovertebral joints are identified (Fig. 34.2).

- The inferior portion of the superior vertebral body constituting

the uncovertebral joint is removed.

- Approximately 4 to 5 mm of the inferior vertebral body is

removed.

Fig. 34.1 The area of interest be-

tween the superior and inferior

vertebral body is outlined. Bony re-

moval of the inferior border of the

superior vertebral body is under-

taken to reach the foramen.

Fig. 34.2 Anterior exposure and ap-

proach for a patient with right C4-C5

foraminal stenosis. Arrow indicates

the site of uncinate process take-

down with 2 mm cutting burr (indi-

cated by solid arrow within shaded

circle). TP

= transverse process.

(From Vaccaro AR, Albert TJ, Spine

Surgery: Tricks of the Trade 2nd ed,

Thieme; pg. 55, Fig. 15.1.)

34 Anterior Cervical Foraminotomy

245

- Bony removal continues until the posterior longitudinal liga-

ment (PLL) is visible.

- Osteophytectomy or fragmentectomy is performed for full de-

compression of the impinged nerve root.

- A nerve hook may be used to ensure decompression.

IV. Complications

- With the procedure in experienced hands, the complication

rate has been reported at <5%.^1-3

- Nerve root injury

- Spinal cord injury

- Cerebrospinal fluid (CSF) leak

- Recurrent laryngeal nerve injury

- Tracheal or esophageal injury

- Vascular injury (carotid artery, jugular vein, vertebral artery)

(Fig. 34.3)

- Horner syndrome (sympathetic trunk injury)

Fig. 34.3 Axial view of a vertebral body demonstrating approach for anterior fo-

raminotomy. Operative approach includes drilling down through uncinate process

to start point of foraminotomy. Special attention must always be paid to the nearby

vertebral artery. (From Vaccaro AR, Albert TJ, Spine Surgery: Tricks of the Trade 2nd

ed, Thieme; pg. 55, Fig. 15.2.)

246 IV Surgical Techniques

V. Postoperative Care

- May be outpatient procedure or involve overnight observation

- A soft collar may be employed for comfort measures immedi-

ately after surgery, but patient should be weaned off and dis-

continue use shortly thereafter.

- Throat lozenges can be used to treat postoperative swallowing

discomfort from esophageal irritation.

VI. Outcomes

- Jho and colleagues reported 79.8% resolution of symptoms in

patients with radiculopathy.²

- For myelopathy, 27.5% experienced resolution of all symptoms,

52% showed improvement, and 20% were unchanged.¹

VII. Surgical Pearls

- Proper setup and retractor placement is crucial to maximize

visualization and prevent complications.

- Knowledge of the course of the vertebral artery is essential to

prevent vascular injury.

- This approach is ideal for pathology located anterolateral to the

neural elements.

- Minimal destabilization avoids the need for concomitant fusion.

Common Clinical Questions

1. The anterior foraminotomy may be utilized to address what

type of pathology?

2. True or false: An arthrodesis procedure is necessary following

anterior foraminotomy.

3. True or false: Outcomes for this operation are better for radicu-

lopathy than for myelopathy.

34 Anterior Cervical Foraminotomy

247

References

1. Jho HD, Kim MH, Kim WK. Anterior cervical microforaminotomy for spondy-

lotic cervical myelopathy: part 2. Neurosurgery 2002;51(5, Suppl):S54-S59

2. Jho HD, Kim WK, Kim MH. Anterior microforaminotomy for treatment of cer-

vical radiculopathy: part 1—disc-preserving “functional cervical disc sur-

gery.” Neurosurgery 2002; 51(5, Suppl):S46-S53

3. Saringer W, Nöbauer I, Reddy M, Tschabitscher M, Horaczek A. Microsur-

gical anterior cervical foraminotomy (uncoforaminotomy) for unilateral

radiculopathy: clinical results of a new technique. Acta Neurochir (Wien)

2002;144(7):685-694

Answers to Common Clinical Questions

1. Disc fragments or osteophytes located anterolateral to the neu-

ral elements

2. False. The procedure is not destabilizing when performed cor-

rectly. Patients with cervical instability should undergo a decom-

pression/fusion procedure and not an anterior foraminotomy.

3. True. Approximately 80 to 100% of radicular complaints were

resolved in two early series.

35 Cervical Laminectomy with or without Fusion

Ali A. Baaj and Fernando L. Vale

I. Key Points

- Conservative therapy is the initial, primary treatment modal-

ity for neck pain and/or radiculopathy caused by degenerative

cervical spine disease.

- The surgical goal should be to decompress the neural ele-

ments and, when clinically warranted, provide stabilization via

instrumentation/fusion.

- Focal pathology may be better treated via anterior cervical ap-

proaches or posterior foraminotomy.

II. Indications

- Multilevel degenerative disc disease causing cervical stenosis

and myelopathy

- Cervical stenosis due to diffuse ossification of the posterior lon-

gitudinal ligament (OPLL)

- Epidural abscess

- Tumor

III. Technique

- Place patient in prone position.

• Awake, fiberoptic intubation may be necessary in cases of se-

vere stenosis or instability.

- Mayfield head fixation or the use of skull tongs to apply 5 to 10

lb of inline cervical traction is optional.

- Localize with fluoroscopy and make appropriate-length mid-

line incision.

- Even if localization is not needed (e.g., for long occipital-cervi-

cal incisions), it is advisable to obtain at least a lateral fluoro-

scope shot pre-incision with patient in the prone position to (1)

appreciate alignment and (2) determine if lower cervical levels

can be visualized.

- Dissecting down to the spinous processes in the midline avas-

cular plain maintains the integrity of posterior neck muscles

and minimizes bleeding.

- Perform subperiosteal dissection to expose the spinous pro-

cesses, the lamina, and the lateral masses of the desired levels.

35 Cervical Laminectomy with or without Fusion

249

• It may be desirable to reduce the monopolar cautery level as

dissection is carried laterally toward the edge of the lateral

mass to avoid denervation/atrophy of neck muscles.

- Perform the posterior cervical laminectomy.

• One technique is to use an AM-8 drill bit to create bilateral

troughs at the laminar-lateral mass junction and remove the

posterior elements “en bloc.”

◦ Advantage: no need to place instrument under the lamina

and risk cord compression

◦ Disadvantage: requires proficiency with the drill and places

the lateral mass at risk if the troughs are too lateral

• A second technique is to use a combination of Leksell and Ker-

rison instruments (manual laminectomy).

◦ Advantage: technique more familiar as it is widely used in

the lumbar spine

◦ Disadvantage: potential risk of neural injury with instru-

ments placed under lamina in severe stenosis

• The third technique is to use a footplate craniotome to cre-

ate bilateral troughs (no significant advantage and may carry

higher risks in authors’ opinion).

- Perform cervical lateral mass fixation (if necessary) (Fig. 35.1).

• Magerl technique

◦The lateral mass is divided into quadrants.

Fig. 35.1 Laminectomy. (A) The burr must be directed approximately 30 to 45 de-

grees in the sagittal plane to avoid burring into the facet joint. Doing so may risk loss

of orientation and cause one to burr too deeply, endangering the dural sac or spinal

cord. (B) En bloc removal of laminae. (From Vaccaro AR, Albert TJ, Spine Surgery:

Tricks of the Trade 2nd ed, Thieme; pg. 6, Fig. 2.2B,C.)

250 IV Surgical Techniques

◦The entry point is at the superior medial quadrant and the

trajectory is toward the superior lateral quadrant (“up and

out”) (Fig 35.2).

◦ Usually achievable for C3-C6

• Roy-Camille technique

◦The entry point is at the midpoint of the lateral mass.

◦The trajectory is 10 degrees lateral in the same axial plane.

◦ Typically employed at the C7 level

• If C7 is included in the fixation, pedicle screws are typically

used.

◦ A laminotomy to palpate the medial edge of the pedicle is

useful.

◦The entry point is in line with lateral mass entry points at

superior levels.

◦ Slight medial angulation is necessary to enter and traverse

the pedicle.

• Lateral mass screw size is typically 3.5 or 4.0 mm by 12 to 16

mm.

(Roy - Camille)

(Magerl)

Center position

1 mm medial and

1- 2 mm cephalad

10°

25°

0°

30°

Fig 35.2 The Magerl and Roy-Camille techniques for placement of lateral mass

screws in the subaxial cervical spine.

35 Cervical Laminectomy with or without Fusion

251

• C7 pedicle screw size is typically 3.5 or 4.0 mm by 16 to 24 mm.

- Insert appropriate-length rods and secure with set screws/caps.

• Ensure proper application of anti-torque when securing caps

to prevent lateral mass fracture/screw pullout.

- Decortication is performed using a high-speed drill; ideally, de-

corticate facets.

- Bone graft material (autograft plus carrier) is placed along the

lateral mass edges bilaterally.

• Ensure that no graft material is left within the canal or foramen.

- Place subfascial drain and close muscle, fascia, and skin layers.

IV. Complications

- Cerebrospinal fluid (CSF) leak

• Attempt primary repair using nonabsorbable suture.

• Alternatively, cover with Gelfoam (Pfizer, New York) and/or

fibrin glue.

- Nerve root injury

• May result either directly during foraminotomy or screw

placement or indirectly from stretching/recoiling

• C5 palsy: Incidence and etiology not well understood. May be

due to traction, given that the C5 root is shortest. Often tran-

sient but noticeable immediately post-cervical laminectomy.

- Vertebral artery injury

• Typically results from misplaced lateral mass screw

• Screw should remain in place and postoperative angiogram

used to delineate type of injury (e.g., occlusion, dissection).

- Wound infection

V. Postoperative Care

- Mobilize early with (typically in case of trauma) or without

cervical collar.

- Obtain postoperative (PO) upright anteroposterior (AP)/lateral

C-spine x-rays.

- Remove drain when output becomes less than 50 ml per 8-hour

shift (typically PO day 1 or 2).

- Discharge home when patient meets discharge criteria.

VI. Outcomes

- Class III evidence shows that 70 to 95% of patients show post-

operative neurologic improvement after cervical laminectomy

and fusion for myelopathy.¹

252 IV Surgical Techniques

VII. Surgical Pearls

- Preoperative cervical kyphosis and loss of lordosis are rela-

tive contraindications to posterior laminectomy without

instrumentation.

- Focal disc bulges/herniations should be treated via anterior

approaches.

- Positioning multiple lateral mass entry points in line facilitates

rod placement (often the frustrating step of the procedure).

Common Clinical Questions

1. In the Magerl technique why is the trajectory of lateral mass

screws “up and out”?

2. Which nerve root is most prone to indirect injury during poste-

rior cervical laminectormy?

3. Why is preoperative cervical spine alignment an important

consideration?

References

1. Anderson PA, Matz PG, Groff MW, et al; Joint Section on Disorders of the

Spine and Peripheral Nerves of the American Association of Neurological

Surgeons and Congress of Neurological Surgeons. Laminectomy and fusion

for the treatment of cervical degenerative myelopathy. J Neurosurg Spine

2009;11(2):150-156

Answers to Common Clinical Questions

1. “Up” to avoid the nerve root and “out” to avoid the vertebral

artery

2. C5 nerve root

3. Kyphosis or loss of lordosis may worsen after cervical laminec-

tomy without instrumentation.

36 Cervical Laminoplasty

Sarah I. Woodrow and Allan D. Levi

I. Key Points

- Laminoplasty is a procedure in which the spinal canal is ex-

panded with the integrity of the posterior elements preserved.

- Laminoplasty was developed in Japan in the 1970s as a “tissue-

sparing” alternative to laminectomy to minimize its associated

risk of instability and progressive kyphotic deformity and thus

improve outcomes.¹

II. Indications

- Multilevel spinal cord compression secondary to one or any

combination of the following:

• Ossification of the posterior longitudinal ligament (OPLL)

• Cervical spondylosis

• Congenital canal stenosis

- For consideration in children requiring laminectomies

- Not for isolated neck pain or for patients with a significant ky-

photic deformity

III. Technique

- In cases of severe stenosis, awake fiberoptic intubation should

be considered to minimize the risk of hyperextension injury

and allow for reexamination of patient prior to positioning.

- Place neurophysiologic monitoring leads

(include somato-

sensory evoked potentials [SSEPs], motor evoked potentials

[MEPs], and electromyograms [EMGs]) and obtain baseline re-

cordings prior to turning the patient.

- Secure patient’s head with or without pins (e.g., Mayfield three-

pin headrest [Schaerer Mayfield, Randolph, MA]) and turn the

patient prone with the head secured in a neutral to slightly

flexed position.

- Tape superior and dorsolateral aspects of both shoulders and

secure to the caudal corner of the operating table to aid in ra-

diographic visualization of the lower cervical vertebrae.

- Use fluoroscopy to plan an incision extending from the spinous

process of C2 to that of T1 and infiltrate with 1% lidocaine with

epinephrine to minimize skin bleeding.

254 IV Surgical Techniques

- Make a midline incision and use a subperiosteal dissection to

reflect the paraspinal muscles from the caudal end of C2 to the

rostral limit of T1.

- Remove the caudal third of the C2 lamina and the rostral third

of the T1 lamina using the combination of a high-speed air drill

and a 2 mm Kerrison punch, allowing visualization of the un-

derlying dura at these levels.

- Remove the spinous processes from C3 to C7 with a rongeur

and morselize the bone for subsequent autografting.

- Perform laminoplasty of lamina C3 to C7 by creating an “open”

side and a “hinged” side. The open side is generally the side

with the greatest compression and/or the side most clinically

symptomatic.

• Use the high-speed air drill with a small drill bit to create

troughs at the level of the lamina-facet junction from C3 to

C7 (Fig. 36.1).

• Drill through the outer and inner cortical margins of the

lamina on the open side, but only through the outer cortical

margin and cancellous bone (and not the inner cortex) on the

hinged side.

Fig. 36.1 Trough is drilled through the

inner and outer cortices at the lamina-

facet junction on the left (shown from

C3 to C6 only). Partial laminectomy of

C2 is shown. Purple crosshatching de-

notes area of drilling for closed door side.

36 Cervical Laminoplasty

255

- Prepare the bone allografts to stabilize the canal expansion.

• Using rib allografts and the high-speed drill, cut three sepa-

rate grafts each about 15 to 18 mm in length.

• Make transverse grooves along the cut surfaces of the rib

grafts, approximating the thickness of the cut laminae.

- Prepare to “open the door.”

• Use two small curettes placed into the trough on the open

side just deep to the outer cortex.

• Pull the curettes upward, thereby enlarging the lamina-facet

gap and creating a green-stick fracture along the trough on the

hinged side. Repeat the process on each successive lamina to ex-

pand the canal by about 4 mm (Fig. 36.2).

- Place the rib allografts in the gaps that have been created at the

C3, C5, and C7 levels (Fig. 36.3).

- Place the morselized spinous process autograft over the decor-

ticated bone surfaces of the facet and lamina on the hinged side

at C3, C5, and C7 to provide for an intersegmental fusion.

- If the patient suffers from radiculopathy as well as myelopathy,

one or more foraminotomies can be performed:

• Once the lamina has been elevated and the ligamentum fla-

vum excised, drill the mesial third of the facet over the exiting

Fig. 36.2 With a trough drilled through

Fig.

36.3 Rib allograft is cut and

the outer cortex only on the contralateral

secured into opening in lamina to ex-

side (closed door side), the laminectomy

pand the spinal canal, typically at C3,

door is “opened,” creating a greenstick-

C5, and C7.

type fracture on the closed side.

256 IV Surgical Techniques

nerve root and widen the opening as needed with 1 or 2 mm

angled Kerrison punches.

- Leave the subfascial drain (e.g., Hemovac [Gohar Shafa, Tehran,

Iran]) in situ to minimize hematoma formation.

- Variations in the approach

• Use spinous processes as autograft instead of the rib allograft

• Stabilize the rib allograft with mini-plates to the adjacent

lamina and facet on the open side or sutures

• Use titanium spacers to hold open lamina that is affixed to the

lamina-facet joint on the open side

• Perform full-thickness splitting of the lamina in the midline

and create bilateral troughs, and then spread the lamina and

place allograft spacers (double-door laminoplasty)

• Should rigid stabilization be required, lateral mass screws can

be placed. This is best done after drilling and “opening the

door,” but prior to graft insertion.

IV. Complications

Early

- Wound infection (2%)

- Dural tear/CSF leak (<1%)

- Hemorrhage (<1%)

- Spinal cord injury (<1%)

- Nerve root injury

- Delayed C5 nerve root injury (2 to 13.3%)

Late

- Postoperative neck pain (40 to 60%)

- Reduced range of motion (20 to 50%)

- New-onset kyphosis (2 to 15%)

V. Postoperative Care

- Mobilize early with cervical bracing.

- Discharge to home once patient is ambulating and tolerating

full diet—usually 2 to 3 days postoperatively.

VI. Outcomes

- Clinical outcome studies are drawn largely from the Japanese

literature on patients with OPLL and are difficult to compare as

a result of patient heterogeneity and different outcome mea-

sures used.²

36 Cervical Laminoplasty

257

- Long-term (5 to 10 years) outcome studies suggest 50 to 70%

of patients with either OPLL or cervical spondylitic myelopa-

thy show improvement in their neurologic function following

laminoplasty.³

- Limited studies comparing this procedure to its correspond-

ing anterior procedure identify similar clinical outcomes, but

overall there is a suggestion that outcomes are better than with

laminectomy alone.

- Recent studies suggest that clinical outcomes are similar be-

tween (1) laminectomy and fusion and (2) laminoplasty, with

preserved range of motion and overall lower surgical costs for

the latter.

VII Surgical Pearls

- Obtain pre-op x-rays to rule out instability or kyphotic

deformity.

- Ensure the provision of drilling gutters at the lamina-facet

junction (and not lateral to it) and direct drill medial so as not

to disrupt the facet joint

- Lift gently when opening the door and ensure that drilling of the

closed side (through outer cortex and some cancellous bone) is

adequate to avoid creating a true fracture of the lamina. With

a true greenstick fracture some tension should remain in the

opening to help maintain compression on the rib graft to hold

it in place.

- If multiple foraminotomies are required, plan on making the

open side the side where more foraminotomies are required.

- Visually inspect the construct and gently stress it once rib al-

lograft is placed to ensure that you have not compromised the

canal and that it remains stable.

Common Clinical Questions

1. True or false: Patients with kyphotic deformities and symptoms

of myelopathy may benefit from laminoplasty procedures.

2. List three perioperative surgical complications associated with

laminoplasty.

258 IV Surgical Techniques

References

1. Hale JJ, Gruson KI, Spivak JM. Laminoplasty: a review of its role in compres-

sive cervical myelopathy. Spine J 2006;6(6, Suppl):289S-298S

2. Ratliff JK, Cooper PR. Cervical laminoplasty: a critical review. J Neurosurg

2003;98(3, Suppl):230-238

3. Wang MY, Shah S, Green BA. Clinical outcomes following cervical lamino-

plasty for 204 patients with cervical spondylotic myelopathy. Surg Neurol

2004;62(6):487-492, discussion 492-493

Answers to Common Clinical Questions

1. False. Kyphotic deformities are a relative contraindication to

performing this procedure.

2. Delayed C5 nerve root injury (2 to 13.3%), wound infection (2%),

dural tear/CSF leak (<1%), hemorrhage (<1%), spinal cord injury

(<1%)

37 Posterior Cervical Foraminotomy

Matthias Setzer, Nam D. Tran, and Frank D. Vrionis

I. Key Points

- The posterior cervical foraminotomy approach (also referred

to as laminoforaminotomy) allows nerve root decompression

without the need to enter the disc space.

- In contrast to the anterior discectomy approach, posterior cer-

vical foraminotomy is not destabilizing; therefore, there is no

need for fusion/implants or harvesting autograft.

II. Indications and Contraindications

Indications

- Cervical neuroforaminal nerve root compression by a (lateral)

soft disc herniation or spondylosis (osteophyte) with progres-

sive or intractable cervical radiculopathy

- Cervical nerve root decompression if an anterior approach is

not desirable (recurrent surgery, difficult anterior approach,

cervicothoracic levels).

Contraindications

- Primary axial neck pain

- Cervical instability at the involved level

- Cervical myelopathy

- Severe kyphosis

- Large central disc herniation

- Central spinal canal stenosis

III. Technique

Patient Positioning

- After induction of general endotracheal anesthesia the patient

is positioned in a prone position with the head clamped in a

Mayfield head holder (Schaerer Mayfield, Randolph, MA) or in

Gardner-Wells tongs with 5 to 10 pounds of traction. The ad-

vantages of traction are interspace distraction and stability.

- Alternatively, the patient can be positioned in a (semi)sitting

position with the head clamped in a Mayfield head holder. The

sitting position reduces venous pressure and reduces intraop-

erative blood loss. Additionally, the position of the head in rela-

260 IV Surgical Techniques

tion to the cervical spine can be better adjusted than in a prone

position.

- The (semi)sitting position carries the risk of air embolism and

requires the placement of a precordial or intraesophageal Dop-

pler probe and a central venous line for air aspiration in case of

an embolism.

- The (semi)sitting position is contraindicated in patients with a

patent foramen ovale and the possibility of paradoxical arterial

embolism.

Preparation and Draping

- Confirmation and adequate visualization of the correct level

with plain x-ray or fluoroscopy in a lateral position is mandatory.

Incision, Soft-Tissue Dissection, and Spine Exposure

Classical Procedure

- Posterior midline incision approximately 3 to 4 cm in length for

an open microsurgical approach

- Exposure and incision of the nuchal fascia

- Unilateral, subperiosteal dissection of the muscle layers from

the spinous process and lamina to the facet joint with a Bovie

cautery (Bovie Medical Corp., Clearwater, FL) and a Cobb eleva-

tor. Supra- and interspinal ligaments should be preserved.

- Placement of a retractor and radiographic confirmation of the

correct level

Minimally Invasive Procedure

- The proper incision site is marked with a spinal needle and lat-

eral fluoroscopy. The incision is centered slightly rostral to the

intended level of decompression.

- The skin incision is made approximately 2 cm lateral to the

midline.

- If a retractor system is used (small-blade retractor, tubular re-

tractor), only very small incisions are necessary (1.5 to 2 cm).

- Incise the fascia with a Bovie cautery.

- With the use of a bladed retractor, blunt dissection is per-

formed with a finger down to the level of the lamina.

- If a tubular retractor system is used, a K-wire is positioned on

the inferior articular facet of the upper vertebral body under

fluoroscopic guidance. In this situation it is imperative that the

K-wire engage bone at all times.

- Serial dilators are used to bluntly widen the approach through

the muscles, and finally the tubular retractors are placed.

- A final radiographic check is recommended to confirm the cor-

rect level.

37 Posterior Cervical Foraminotomy

261

- The retractor should be placed on the interlaminar space (two-

thirds) and on the facet joint (one-third).

- Bring in the draped microscope.

Foraminotomy and Wound Closure

- Expose and mark the cranial and caudal lamina of the appro-

priate level and check again with fluoroscopy.

- Expose the medial parts of the capsule of the facet joint.

- Perform a laminotomy by removing bone from the lateral parts

of the caudal and cranial lamina with a high-speed drill or with

a small Kerrison rongeur.

- Open the ligamentum flavum with a nerve hook or a dissector,

and resect it with a small Kerrison rongeur.

- Extend the laminotomy cranially and laterally, and expose the

lateral edge of the dura and the nerve root. The nerve root is

generally displaced dorsally.

- Try to remove free disc material under the nerve root with a

nerve hook and a pituitary rongeur.

- If the disc sequestrum is still covered with layers of the pos-

terior longitudinal ligament, it has to be opened with a small

dissector or with bipolar forceps.

- Undercut the superior articular process with 1 and 2 mm Ker-

rison rongeurs until the entire foramen is patent (but preserve

at least 50% of the facet) (Fig. 37.1).

- Epidural bleeding is controlled with Gelfoam (Pfizer, New York)

and Cottonoids (Saramall, Buenos Aires, Argentina).

Fig. 37.1 Foraminotomy. The superior ar-

ticular process can be removed by using a

burr to thin it and a 1 mm Kerrison rongeur

to remove remaining articular process, leav-

ing the nerve root decompressed. (From Vac-

caro AR, Albert TJ, Spine Surgery: Tricks of

the Trade 2nd ed, Thieme; pg. 7, Fig. 2.3D.)

262 IV Surgical Techniques

- Placement of a wound drain (Hemovac [Gohar Shafa, Tehran,

Iran]) is usually not necessary.

- Close fascia with 0 or 2-0 absorbable sutures.

- Use inverted, interrupted 3-0 absorbable sutures for closure of

the subcutaneous layer.

- Close the skin with a running, absorbable intracutaneous su-

ture or with staples.

IV. Complications

- Wound dehiscence

- Wound infection and epidural abscess (1.2%)¹

- Cerebrospinal fluid (CSF) leak (0.6 to 2.5%)^1,2

- Neurologic deterioration due to injury or manipulation of the

nerve root or spinal cord or postoperative epidural hematoma

(1.2 to 2.3%)^1,2

- Air embolism (sitting position) (1.6 to 2.3%)^2,3

- Persistent radiculopathy indicating residual nerve root com-

pression, epidural scarring, early recurrent disk herniation, or

neuropathic pain requiring additional surgery (5.1 to 8%)^1,2

- Recurrent disk herniation (7.6%)²

- Intraoperative hemorrhage caused by epidural veins or as a re-

sult of an inadvertent injury to vertebral artery (very rare and

usually due to a wrong approach)

- Secondary instability due to excessive resection of the facet

joint (4.9%)¹

- Loss of cervical lordosis (18.5%)¹

V. Postoperative Care

- Mobilize patient immediately after surgery.

- There is no need for external bracing; patients typically have

full range of neck motion.

- Pain control is usually achieved with orally administered

opioids.

- Discharge patients when discharge criteria are met (usually on

post-op day 1).

VI. Outcomes

- Large series have reported excellent or good outcomes for

posterior cervical foraminotomy in 90 to 96% of patients with

monoradiculopathy.^1,2,4

37 Posterior Cervical Foraminotomy

263

VII. Surgical Pearls

- Removal of more than 50% of the facet significantly compro-

mises torsional stiffness of the cervical spine.⁵

- The entire length of the foramen can be enlarged safely with

the use of curettes or a high-speed drill with preservation of

more than 50% of the facet by initially working parallel and just

inferior to the nerve root and then, as more room is gained,

removing the rim just dorsal to the nerve root.

- Minimal bone removal (keyhole exposure) is acceptable, but

not at the expense of excessive nerve root retraction or insuf-

ficient exposure of the dura with an increased risk of dural

laceration.

Common Clinical Questions

1. What are the most common indications for a posterior cervical

foraminotomy?

2. What are the two options for performing a posterior cervical

foraminotomy?

3. How much of the facet joint can safely be removed without cre-

ating instability, and how much of the facet joint is usually re-

moved during a posterior cervical foraminotomy?

References

1. Jagannathan J, Sherman JH, Szabo T, Shaffrey CI, Jane JA. The posterior cer-

vical foraminotomy in the treatment of cervical disc/osteophyte disease: a

single-surgeon experience with a minimum of 5 years’ clinical and radio-

graphic follow-up. J Neurosurg Spine 2009;10(4):347-356

2. Jödicke A, Daentzer D, Kästner S, Asamoto S, Böker DK. Risk factors for out-

come and complications of dorsal foraminotomy in cervical disc herniation.

Surg Neurol 2003;60(2): 124-129, discussion 129-130

3. Jadik S, Wissing H, Friedrich K, Beck J, Seifert V, Raabe A. A standardized

protocol for the prevention of clinically relevant venous air embolism dur-

ing neurosurgical interventions in the semisitting position. Neurosurgery

2009;64(3):533-538, discussion 538-539

4. Fehlings MG, Gray RJ. Posterior cervical foraminotomy for the treatment of

cervical radiculopathy. J Neurosurg Spine 2009;10(4):343-344, author reply

344-346

5. Zdeblick TA, Zou D, Warden KE, McCabe R, Kunz D, Vanderby R. Cervical sta-

bility after foraminotomy. A biomechanical in vitro analysis. J Bone Joint

Surg Am 1992;74(1):22-27

264 IV Surgical Techniques

Answers to Common Clinical Questions

1. Cervical neuroforaminal nerve root compression by a (lateral)

soft disc herniation or spondylosis (osteophyte) with progres-

sive or intractable cervical radiculopathy, and the need for cer-

vical nerve root decompression if an anterior approach is not

desirable (recurrent surgery, difficult approach, cervicothoracic

levels)

2. The standard procedure with a midline incision and subperios-

teal dissection from the midline to the facet joint, and the mini-

mally invasive procedure with a paramedian incision about 2 cm

from the midline and blunt dissection through the muscles using

small-blade or tubular retractors and serial dilators

3. Removal of more than 50% of the facet significantly compro-

mises torsional stiffness of the cervical spine. During a posterior

cervical foraminotomy, typically less than 50% of the facet joint

is removed (approximately 30%).

38 Cervical Open Reduction Techniques:

Anterior and Posterior Approaches

Harminder Singh, George M. Ghobrial, and James Harrop

I. Key Points

- Cervical facet dislocations result from high-energy traumatic

forces transmitted through flexion/distraction vectors.

• A flexion, rotational, and lateral force can result in a unilateral

jumped facet.

• If the mechanism of injury involves flexion/compression forc-

es (e.g., diving headfirst into a shallow pool), then facet and

vertebral body fractures may be encountered in the form of

jumped and/or perched facets.

• A severe flexion/distraction injury with a compression com-

ponent is also called a teardrop fracture.

- Rule of thumb: A unilateral jumped facet results in 25% dis-

placement (anterolisthesis) of one vertebral body on another

(as seen on lateral plain radiographs or computed tomography

[CT] scan of the cervical spine); bilateral jumped facets are as-

sociated with a 50% anterolisthesis.

- Acute management usually consists of reduction of the dislo-

cated joints and the realignment of fractured cervical segments,

through either open surgical intervention or axial cervical

traction.

- Re-creating the force vectors of the mechanism of injury can

facilitate reduction of the facets or deformity and realign the

spine. For example, the cervical spine is flexed and distracted

to realign the facets if the mechanism of injury was flexion/

distraction.

- The open anterior approach provides for the removal of extrud-

ed disc prior to reduction of a dislocated facet. This approach

may also be effective for reducing fractures and dislocations.

- Posterior instrumentation reestablishes the posterior tension

band and provides the optimal environment for fusion.

II. Indications

Cervical open reduction can restore spinal alignment, decompress

the neural elements, and establish rigid internal fixation.

- Cervical open reduction is indicated when:

• Decompression of neural elements is required

266 IV Surgical Techniques

• Closed reduction fails

• Contraindications for closed reduction

◦ Patient with altered mental status

◦ Skull fracture precluding tong placement

◦ A relative contraindication is a rigid spine such as in ankylos-

ing spondylitis.

III. Technique

Anterior Approach

- Neuromonitoring (somatosensory evoked potentials [SSEPs],

motor evoked potentials [MEPs]) allows monitoring of spinal

cord function during spinal manipulation.

- Localization of the cervical level is possible using fluoroscopy

or plain radiographs.

• Anatomic localizing

◦ C5-C6 disc space: level of the cricoid cartilage

◦ C3-C4 disc space: 1 cm above level of cricoid cartilage

- If a herniated disc is compressing the neural elements, a com-

plete discectomy is performed prior to anterior reduction.

• Blunt dissection: Retract carotid sheath laterally and trachea/

esophagus medially with retractors to expose anterior spinal

column. The anterior longitudinal ligament (ALL) is typically

disrupted as a result of trauma.

• Dissect longus colli laterally with monopolar cautery to ex-

pose the cervical vertebrae.

• In unilateral dislocations, the superior vertebral body will be

rotated away from the side of dislocation.

• The annulus is incised with a scalpel as far laterally as possible

to the uncovertebral joints.

• The disc and posterior longitudinal ligament (PLL) are re-

moved with curettes and with Kerrison and pituitary ron-

geurs until the dura is visualized. The PLL may be ruptured,

particularly with bilateral dislocation.

- Caspar retractors are placed, with pins one level above and be-

low the subluxed and dislocated segments.

• Angulate pins convergently to place the spine in kyphotic

(flexed) posture for distraction.

• Distract Caspar pins; the superior body will rotate back and

become flush with the inferior body (Fig. 38.1).

- Once the desired spinal alignment is achieved, a tricortical bone

graft harvested from anterior superior iliac crest or allograft is

used for arthrodesis.

38 Cervical Open Reduction Techniques

267

Fig. 38.1

(A,B) Anterior spinal reduction using convergently placed Caspar pins.

Distracting the Caspar pins flexes and distracts the spine, unlocking the facets and

reducing the spine.

- Anterior plate placement: screws anchoring the plate should

be in the middle third of the vertebral body to avoid violation

of end plates.

Posterior Approach

- More commonly used when there is disruption of the posterior

ligamentous complex and associated facet fractures preventing

closed reduction

- Prone position in Mayfield head holder (Schaerer Mayfield,

Randolph, MA) or Gardner-Wells tongs, and make a midline

incision

- Perform subperiosteal dissection during exposure of laminae

and lateral masses.

- Reduction can be performed with direct distraction using two

towel clips in opposite directions on the spinous processes us-

ing a leveraging mechanism (Fig. 38.2).

268 IV Surgical Techniques

Fig. 38.2 Posterior spinal reduction

using two towel clips. The inferior

articulating facet of the superior ver-

tebral body is lifted above and over

the superior articulating facet of the

inferior vertebral body, reducing the

spine.

- Alternatively, the superior articulating process of the inferior

facet can be drilled away to facilitate reduction.

- Once decompression and reduction are achieved, the spine is

locked into place using either lateral mass screws and rods or

posterior wiring techniques.

- Decortication of the facets and supplemental bone graft place-

ment in the lateral gutters help with arthrodesis.

IV. Complications

- Wound infection (increased likelihood in trauma population)

- Graft donor site pain from autograft. Allograft bone is an alter-

native but may have a lower fusion rate.

- Anterior exposure may result in injury to the recurrent laryn-

geal nerve.

- Esophageal perforation

- Carotid artery and vagal nerve injury due to violation of the

carotid sheath

- Horner syndrome: the sympathetic chain lies adjacent and an-

terior to the longus colli muscles.

- Damage to vertebral artery during posterior fixation

- CSF leak (which may be present from original trauma)

- Delayed fusion increases likelihood of screw loosening, plate

migration, graft migration, and ultimately construct breakage.

38 Cervical Open Reduction Techniques

269

V. Postoperative Care

- Immobilization for 6 weeks

- Serial radiographic examination: AP, lateral, swimmer’s views

- Flexion-extension views for assessment of stability

VI. Outcomes

- Kwon et al did a prospective randomized controlled trial com-

paring anterior and posterior fixation for unilateral cervical

facet injuries and reported equal efficacy between the two

techniques.¹

- Johnson et al reported a 13% incidence of loss of postopera-

tive radiographic alignment during follow-up of cervical facet

fracture-dislocations treated with only anterior decompression

and fusion.²

- Reindl et al reported on 41 consecutive patients with unstable

dislocations/subluxations, of whom 8 required anterior reduction

after failure of Gardner-Wells traction; in addition, 2 of those 8

failed, requiring posterior surgery as well.³

- Fehlings et al reported on 44 consecutive patients treated with

posterior cervical fusion for traumatic instability. Long-term

follow-up revealed that the cervical spine was successfully sta-

bilized in 93% of cases.⁴

VII. Surgical Pearls

- Best treated anteriorly: large disc herniation with cord com-

pression such that spinal cord can be decompressed prior to

distraction

- Best treated posteriorly: hyperflexion injury, including PLL in-

jury, unilateral and bilateral facet dislocation without anterior

cervical disc herniation

- Anteriorly, avoid overdistraction of the cervical spine during

placement of the interbody graft. Due to the ligamentous laxity

prevalent in spinal injury, it is easy to overdistract.

- Posteriorly, be mindful of laminar fractures during exposure.

Heat from a Bovie cautery can damage the spinal cord or cause

CSF leaks when transmitted through fractured laminae.

270 IV Surgical Techniques

Common Clinical Questions

1. When should anterior reduction be utilized when closed reduc-

tion is not possible?

2. When should open reduction be performed?

3. Postoperatively after anterior cervical discectomy with fusion,

the patient has a hoarse voice and difficulty swallowing. What

should the clinician be concerned about?

References

1. Kwon BK, Fisher CG, Boyd MC, et al. A prospective randomized controlled trial

of anterior compared with posterior stabilization for unilateral facet injuries

of the cervical spine. J Neurosurg Spine 2007;7(1):1-12

2. Johnson MG, Fisher CG, Boyd MC, Pitzen T, Oxland TR, Dvorak MF. The ra-

diographic failure of single segment anterior cervical plate fixation in

traumatic cervical flexion distraction injuries. Spine

(Phila Pa

1976)

2004;29(24):2815-2820

3. Reindl R, Ouellet J, Harvey EJ, Berry G, Arlet V. Anterior reduction for cervical

spine dislocation. Spine (Phila Pa 1976) 2006;31(6):648-652

4. Fehlings MG, Cooper PR, Errico TJ. Posterior plates in the management of

cervical instability: long-term results in 44 patients. J Neurosurg 1994;

81(3):341-349

Answers to Common Clinical Questions

1. When large anterior disc herniation is present

2. Decompression of neural elements is required. Closed reduction

fails. Closed reduction is contraindicated.

3. Injury to the recurrent laryngeal nerve on exposure

39 Resection of Pancoast Tumors

Jean-Paul Wolinsky and Ziya L. Gokaslan

I. Key Points

- T3N0M0 or T4N0M0 tumors (respectively, tumors with chest

wall or chest wall and vertebral body invasion, negative nodes,

and no metastasis) Pancoast tumors are potentially amenable

to curative surgery if complete resection can be achieved.

- Pancoast tumors can be violated, but in contrast to some pri-

mary spinal tumors (i.e., chordoma and chondrosarcoma), if to-

tal resection is achieved, oncologic goals can still be met.

- Involvement or injury to the C8 and T1 roots or the lower trunk

of the brachial plexus can result in significant pain and loss of

hand function.

II. Indications

- Isolated lung mass with direct extension into the chest wall,

lower trunk of the brachial plexus, and vertebral column

- No evidence of metastatic disease

- Negative mediastinal nodes

- Possibility of complete tumor resection

III. Technique

- Patient is positioned supine and undergoes general endotra-

cheal intubation with a double-lumen tube. Positioning of the

endotracheal tube is confirmed via bronchoscopy.

- Mediastinoscopy is performed, confirming that there is no evi-

dence of positive mediastinal lymph nodes. If positive nodes

are found, procedure is aborted and surgery is no longer a

treatment option.

- If the vertebral artery or subclavian vessels are involved in tu-

mor, they can be bypassed or sacrificed prior to stages 1 and 2

so that they may be resected with the specimen.

272 IV Surgical Techniques

Stage 1

Stage 1 can be performed with patient in the lateral position and combined

with stage 2, eliminating the need to reposition.

- Patient is taken from the supine position and placed prone

on chest rolls and the head secured in a Mayfield head holder

(Schaerer Mayfield, Randolph, MA). The cervical-thoracic re-

gion is cleaned and prepped in the usual sterile fashion. Pro-

phylactic antibiotics are administered.

- The cervical-thoracic spine is exposed using the standard sub-

periosteal technique.

- Cervical lateral mass and thoracic pedicle screw instrumenta-

tion is inserted.

- Laminectomies are performed at the levels of interest. Nerve

roots to be sacrificed are identified, ligated, and sectioned prox-

imal to the dorsal root ganglion.

- Preoperatively, it is determined if the C8 and T1 nerve roots can

be preserved, or if they will need to be sacrificed for oncolog-

ic reasons. If they are to be preserved, they are identified and

traced laterally. The pedicle and the transverse process of T1

are resected. If the chest wall is involved in tumor, but there is

no involvement of the vertebral column, then the rib heads are

disarticulated from the vertebral body. If the vertebral column

is involved in tumor, but the proximal portion of the rib is not,

then the proximal portion of the T1 rib is resected. The C8 and

T1 nerve roots are traced further laterally, identifying where

they come together to form the lower trunk of the brachial

plexus. The lower trunk of the brachial plexus is identified and

protected during tumor resection. Injury to the C8 or T1 roots

or the lower trunk of the brachial plexus can result in signifi-

cant pain and loss of hand function.

- The lateral aspect of the vertebral column to be resected, con-

tralateral to the tumor, is dissected, and the segmental vessels

are ligated and cut.

- The most rostral and caudal disc spaces of the section of the

vertebral column to be resected are identified. A Tomita-saw

(MANI, Inc., Utsunomiya, Japan) is placed ventral to the thecal

sac and posterior to the annulus at both of these disc spaces.

The end of the saw, contralateral to the tumor, is tucked lateral

to the vertebral column (to be retrieved later, during stage 2). If

the most rostral disc space is C7-T1 or higher, this disc will be

cut by means of a separate approach, using a standard anterior

cervical discectomy technique.

- Two rods are contoured to the shape of the spine to span the

cervical and thoracic instrumentation. One rod is secured to

39 Resection of Pancoast Tumors

273

the instrumentation contralateral to the tumor. The second rod

is retained for stage 2. The wound is then temporarily closed.

Stage 2

- The patient is repositioned in the lateral decubitus position

(tumor side up) on a bean bag. After the patient is properly

positioned and secured to the table, the head is secured via a

Mayfield head frame.

- The chest and posterior wound are cleaned, prepped, and draped.

- The posterior wound is reopened.

- The bronchus ipsilateral to the tumor is occluded and the lung

deflated.

- A posterior-lateral thoracotomy is performed at the interspace

below the section of chest wall involved with tumor. The skin

incision is extended medially to intersect with the midline spi-

nal incision. The paraspinous musculature is mobilized off of

the transverse processes and ribs. The rostral aspect of the tho-

racotomy incision is elevated as a myocutaneous flap.

- The chest wall is then cut, starting at the level of the thora-

cotomy and extending rostrally, lateral to the extent of tumor

involvement, until the rostral aspect of the tumor margin is

passed. The intercostal nerves, arteries, veins, and musculature

are sectioned with the chest wall.

- A formal lung lobectomy is performed proximal to the tumor,

isolating the tumor from the lung.

- The contralateral Tomita-saws are retrieved ventral to the ver-

tebral bodies, and using the saws, the discs are cut.

- The specimen is now completely mobilized and can be deliv-

ered en bloc. Pancoast tumors can be violated, and unlike the

case for primary spinal tumors (i.e., chordoma and chondrosar-

coma), if total resection with negative margins is achieved, the

oncologic goals can still be met.

- The vertebral column defect is reconstructed, and arthrodesis is

then performed.

- Two thoracostomy tubes are placed and tunneled out through

separate incisions.

- A thoracoplasty is constructed, and the thoracotomy and poste-

rior incisions are closed in the standard fashion.

IV. Complications

- Cerebrospinal fluid

(CSF) leak and meningopleural fistula:

These should be closed primarily, and the closure should be

reinforced with fibrin glue. Postoperatively, the patient’s tho-

274 IV Surgical Techniques

racostomy should be transitioned to water seal as early as

possible. Postoperative positive airway pressure (BiPAP) may

decrease the chance of a meningopleural fistula. Postopera-

tive lumbar drainage should be considered. Postoperative sus-

pected CSF leaks can be verified by analyzing the pleural fluid

for β₂ transferrin.

- Thoracic duct injury and chyle leak/chylothorax: Primary liga-

tion of the thoracic duct to control the leak should be attempt-

ed. High-volume thoracostomy output suggests the possibility

of a thoracic duct injury.

- Esophageal injury: Primary closure at the time of injury should

be undertaken. Treat an injury in the postoperative period with

a high degree of suspicion as such injuries carry significant

morbidity and mortality.

- Pseudarthrosis

- Instrumentation failure

- C8, T1, lower trunk injury

- Bronchopleural fistula

- Vascular injury

V. Postoperative Care

- Intensive care unit (ICU)

- Thoracostomies to 20 cm H₂O suction until there is no evidence

of pneumothorax, H₂O seal for 24 hours, then discontinue one

thoracostomy every 24 hours.

- Incentive spirometry

VI. Outcomes

- Two-year and 5-year survival rates of patients undergoing com-

plete resection with negative margins are 62% and 40%, respec-

tively, compared with 29% and 12% for patients with positive

margins.^1-3

VII. Surgical Pearls

- Ligate nerves proximal to dorsal root ganglion to decrease the

chances of chronic dysesthetic pain.

- When dissecting around the vertebral body, contralateral to the tu-

mor, stay in the plane between the vertebral body and the segmen-

tal vessels to keep the vasculature protected during the resection.

- Suspected thoracic duct injuries can be better visualized 30 min-

utes after administering cream through a nasogastric tube. The

chyle will become milky rather than clear, and can be seen better.

39 Resection of Pancoast Tumors

275

Common Clinical Questions

1. Lung tumor lesions involving the vertebral column are usually

treated for palliation. Is the Pancoast tumor treated in this way?

2. Is mediastinoscopy an important element in the workup of a

Pancoast tumor?

3. Can the C8 and T1 nerve roots be sacrificed without significant

consequences?

References

1. York JE, Walsh GL, Lang FF, et al. Combined chest wall resection with verte-

brectomy and spinal reconstruction for the treatment of Pancoast tumors. J

Neurosurg 1999;91(1, Suppl):74-80

2. Gandhi S, Walsh GL, Komaki R, et al. A multidisciplinary surgical approach

to superior sulcus tumors with vertebral invasion. Ann Thorac Surg

1999;68(5):1778-1784, discussion 1784-1785

3. Bolton WD, Rice DC, Goodyear A, et al. Superior sulcus tumors with verte-

bral body involvement: a multimodality approach. J Thorac Cardiovasc Surg

2009;137(6):1379-1387

Answers to Common Clinical Questions

1. Pancoast tumors without nodal involvement or metastasis, even

if they demonstrate invasion into the chest wall (T3M0N0) or

vertebral column (T4M0N0), if they can be completely resected,

are associated with a significant improvement in survival.

2. Positron emission tomography (PET), computed tomography

(CT), and bone scans are useful tools for the staging of metas-

tasis. Mediastinoscopy is useful in verifying that a patient does

not have positive lymph nodes. Positive lymph nodes on medi-

astinoscopy will render a patient no longer N0, in which case

surgery for treatment is no longer an option.

3. Sacrifice of the C8 or T1 nerve root will result in significant loss

of hand function and can also be a source of chronic pain.

40 Cervical-Thoracic Junction Technique

Matthew B. Maserati and David O. Okonkwo

I. Key Points

- The cervical-thoracic junction (CTJ) is an anatomically and

biomechanically unique region of the vertebral column that is

particularly susceptible to traumatic injury, intervertebral disk

and zygapophyseal joint degeneration, and iatrogenic (postsur-

gical) deformity.^1,2

- Reconstruction and fixation at the CTJ must be carefully

planned, with key anatomic and biomechanical principles tak-

en into account.

• The CTJ is a transitional zone between the mobile, lordotic

cervical spine and the relatively rigid, kyphotic thoracic spine.

• Posterior element morphology transitions from large lateral

masses and small pedicles in the cervical spine to larger ped-

icles and indistinct lateral masses in the thoracic spine, with

implications for posterior fixation.

- Several surgical approaches exist for accessing pathology at the

CTJ, and the choice of the most appropriate approach requires a

comprehensive preoperative workup.

• Thorough history with attention to pulmonary status, overall

cardiac health, prior neck surgery or radiation therapy (ear,

nose, and throat [ENT]evaluation of vocal cords and recurrent

laryngeal nerve function should be considered for these pa-

tients), and prior thoracic surgery

• Physical examination with attention to signs of myelopathy

but also to body habitus and sagittal balance to identify any

relevant deformity such as thoracic hyperkyphosis

• Multimodality radiographic evaluation

◦ Standing anteroposterior (AP) and lateral radiographs with

swimmer’s view (consider placing a radiopaque marker in

the manubrial notch)

◦ Magnetic resonance imaging (MRI) for assessment of the

neural elements and discoligamentous structures

◦ Computed tomography (CT), especially in trauma and for as-

sessment of posterior element morphology when posterior

fixation is planned (thin cuts and three-dimensional recon-

structions may further aid preoperative planning)

◦ Consider a vascular study (e.g., CT angiography) to delineate

vertebral artery anatomy

40 Cervical-Thoracic Junction Technique

277

- The superior mediastinum is unfamiliar territory for most

spine surgeons. It contains critical structures such as the tho-

racic duct, azygos vein, great vessels and their branches, the

sympathetic chain, and the pleural apices, thus carrying the

potential for catastrophic visceral injury.

II. Indications

- Fractures

• Unstable traumatic fracture/dislocation

• Osteoporotic fracture causing neurologic deficit, deformity, or

persistent pain refractory to less invasive treatments

- Neoplasms

• Vertebral/epidural metastases

• Intradural-extramedullary tumors

• Intramedullary tumors

- Infection

• Osteomyelitis/discitis meeting criteria for surgery

• Spinal tuberculoma (Pott disease)

- Deformity

• Post-laminectomy kyphosis

• Chin-on-chest deformity

• Degenerative kyphoscoliosis

• Posttraumatic kyphosis

- Symptomatic herniated nucleus pulposus in the upper thoracic

spine (C7-T3)

• Radiculopathy (after

6 to 8 weeks of failed conservative

therapy)

• Neurologic deficit from spinal cord compression

III. Technique

- Three principal approaches to the CTJ

• Anterior

• Anterolateral

• Posterior

- Anterior approach^2-4

• Options

◦ Suprasternal

(i.e., conventional low cervical or

“Smith-

Robinson”) approach: use preoperative mid-sagittal cervi-

cal-thoracic MRI or CT to determine the lowest vertebra and

intervertebral disc accessible without sternotomy.

◦ Transclavicular (not discussed here; see Kurz et al⁵)

◦ Transmanubrial/sternal splitting (Fig. 40.1)

278 IV Surgical Techniques

Retract

esophagus

Left recurrent

Longus

laryngeal

coli muscle

nerve

Thyroid

gland

Inferior

thyroid

vessels

Brachial

plexus

Ligate inferior

thyroid artery

Cut

sternal

edge

Left

brachiocephalic

trunk

Fig. 40.1 Sternal splitting ap-

proach and exposure.

(From

Haher R, Merola A, Surgical Tech-

nique for the Spine, Thieme; pg.

74, Fig. 15-2B.)

• Advantages

◦ Permits direct visualization of ventral pathology

◦ Ideal for approaching a midline ventral lesion causing cord

compression, and for performing an anterior release for cor-

rection of deformity

• Disadvantages

◦ Superior mediastinum is unfamiliar anatomy and may re-

quire the assistance of an access surgeon, particularly for

transsternal approach.

◦ Risks injury to recurrent laryngeal nerve, thoracic duct, and

sympathetic chain (Fig. 40.2)

◦ Sternal splitting adds significant morbidity.

- Anterolateral (transthoracic) approach²

• Advantages

◦ Permits visualization of anterior pathology from anterior

vantage point

40 Cervical-Thoracic Junction Technique

279

Fig.

40.2 Surgical anatomy

relevant to an anterior cervical

discectomy. Subclavian artery

(sa), subclavian vein (sv), ca-

rotid artery (ca), jugular vein

(jv), recurrent laryngeal nerve

(rn), thoracic duct

(td), tra-

chea (t), and thyroid cartilage

(tc) (with permission from Bar-

row Neurological Institute).

◦ Permits anterior column reconstruction with less risk to

neural elements

• Disadvantages

◦ Typically requires the assistance of an access surgeon

◦ Violation of thoracic cavity and attendant pulmonary

morbidity

- Posterior approaches^2,6,7

• Options

◦ Straight midline approach (cervical-thoracic laminectomy,

with possible addition of pedicle screw fixation)

◦Lateral extracavitary approach

◦ Transpedicular approach

◦ Costotransversectomy

◦ Pedicle subtraction/Smith-Peterson osteotomy

• Advantages

◦ Does not require the assistance of an access surgeon

◦ Dissection is entirely extrapleural

◦ Single approach allows for both decompression and

stabilization

• Disadvantages

◦ Ventral pathology may be obscured by the spinal cord and

nerve roots.

◦ Does not permit correction of a fixed kyphotic deformity

◦ Muscle atrophy and/or proximal junctional instability may

result from overly aggressive dissection during exposure.

280 IV Surgical Techniques

◦ Anterior column reconstruction through posterior approach

places the neural elements at risk.

- Special considerations in performing posterior fixation at the

CTJ

• Screws in this region are under significant stress and at great-

er risk of pullout or breakage.^1,2,6

◦ Avoid stopping a construct at the CTJ (C6-T2).

◦ Consider bicortical fixation.

• Rods must be carefully contoured with attention to differ-

ences between the patient’s preoperative curvature and the

desired final result.⁶

◦ Ensure that sagittal balance and horizontal gaze are pre-

served or restored.

◦Limit the prominence of the rod ends (particularly in thinner

patients).

• The transition from lateral mass screws in the low cervical

spine to pedicle screws in the thoracic spine complicates rod

contouring and placement.⁶

◦ Consider cervical pedicle screw fixation.

◦ Use polyaxial screws for fixation at—and immediately adja-

cent to—the CTJ.

◦ Dual-diameter rods are available to accommodate the larger

heads of lower thoracic pedicle screws.

◦ For some long constructs and difficult deformity cases,

cross-connectors may be used to connect noncollinear rods.

Anterior (Transmanubrial) Approach^1,2

- Place patient in supine position on radiolucent table.

• Consider electrophysiologic monitoring such as somatosen-

sory and motor evoked potentials (SSEPs, MEPs), particularly

in cases of spinal cord compression and/or myelopathy.

• Preoperative reduction with traction may be beneficial in cas-

es of severe kyphosis (obtain initial baseline SSEPs and MEPs

prior to attempting reduction).

- Sterile prep and drape.

- Incision (Fig. 40.1)

• May use T-shaped incision on the anterior chest wall or an

oblique supraclavicular incision beginning just anterior to the

(left) sternocleidomastoid muscle and extending inferomedi-

ally over the sternum for a variable length depending on the

level of the pathology.

◦ Manubrium typically corresponds to T2-T3 level (correlate

with preop imaging).

40 Cervical-Thoracic Junction Technique

281

◦Left-sided approach may facilitate avoidance of recurrent la-

ryngeal nerve injury.

- Divide platysma and perform sharp dissection to define sterno-

cleidomastoid and strap muscles superiorly.

• Transection of the omohyoid muscle may permit additional

retraction.

- Identify the manubrium inferiorly and perform subperiosteal

dissection posteriorly, taking care to protect the brachiocephal-

ic veins.

- Using a sternal saw or high-speed drill, split the manubrium.

• Take care to preserve muscular attachments.

- Perform blunt dissection of the potential space medial to the

carotid sheath and lateral to the strap muscles, down to the

prevertebral fascia.

• Take care to avoid injury to the thoracic duct (typically on the

left and at C7-T1, but may extend up to C6 in some cases).

- Confirm pathologic level using fluoroscopy or plain radiography.

- Perform decompression

(discectomy, corpectomy) and

stabilization.

• Use long-handled, angled instruments to overcome the long

distance from the anterior chest wall to the anterior thoracic

spine, and to avoid line-of-sight issues.

• Options for anterior column reconstruction

◦ Iliac crest autograft (“gold standard” but associated with donor

site morbidity)

◦ Allograft strut

◦ Polyetheretherketone (PEEK) or titanium cage (avoid tita-

nium in osteoporotic patients due to large discrepancy in

modulus of elasticity and possibility of settling)

◦ Typically supplement with anterior plate fixation

- Fill wound with saline and watch for bubbles (the presence of

bubbles indicates transgression of the apical visceral pleura

and necessitates placement of a chest tube through a separate

incision).

- Leave a drain in the prevertebral space.

- Close in layers (wire manubrium).

IV. Complications

- Minor

• Superficial wound dehiscence

• Injury to strap muscles (exacerbating preexisting respiratory

compromise)

282 IV Surgical Techniques

• Nonunion of the clavicle/manubrium

• Traction injury to the recurrent laryngeal nerve

- Major

• Injury to carotid sheath

• Injury to azygos vein

• Injury to thoracic duct (chyle leak)

• Injury to great vessels in the mediastinum

• Injury to the sympathetic chain (Horner syndrome)

• Injury to pleural apices (hemopneumothorax)

• Perforation of trachea or esophagus

• Deep wound infection

• Cerebrospinal fluid (CSF) leak

• Injury to spinal cord or exiting nerve roots

V. Postoperative Care

- Consider monitoring patient in the intensive care unit, particu-

larly in cases of lengthy operative time, significant blood loss,

and preoperative pulmonary or cardiac compromise.

- Perioperative hypotension should raise concern of great vessel

injury after an anterior approach.

- For anterior approaches, monitor drain output for evidence of

chyle leak.

- Consider maintaining patient in cervical-thoracic orthosis for 8

to 12 weeks in patients with poor bone quality or when fixation

is otherwise felt to be suboptimal.

VI. Outcomes

- No long-term studies or large series have been reported.

- Small series report anterior approach-related mortality of 0 to

40%, but comprise different patient populations with widely

varying pathology and premorbid status.^1,2

- Posterior approaches are probably associated with decreased

morbidity.

VII. Surgical Pearls

- Preoperative workup is critical, with special attention paid to

body habitus and sagittal balance, cardiopulmonary comorbid-

ities, and appropriate imaging, including the anterior chest wall

(when anterior approach is being considered).

40 Cervical-Thoracic Junction Technique

283

- Assistance of an access surgeon is advisable for work in the su-

perior mediastinum.

- Avoid stopping a construct at the CTJ and consider bicortical

screws for greater strength.

- Anterior column reconstruction is essential, since it is respon-

sible for 80% of load bearing.

- Posterior approaches are probably associated with less morbid-

ity but place the neural elements at increased risk when pa-

thology is wholly ventral, or when one is placing an anterior

graft.

Common Clinical Questions

1. What elements of the patient history and physical examination

are uniquely important when one is considering a surgery at the

cervical-thoracic junction?

2. What are the advantages and disadvantages of the anterior ap-

proach to the cervical-thoracic junction?

References

1. An HS, Vaccaro A, Cotler JM, Lin S. Spinal disorders at the cervicothoracic

junction. Spine (Phila Pa 1976) 1994;19(22):2557-2564

2. Mummaneni PV, Lenke L, Haid RW. Fixation options for the cervicothoracic

junction. In Spinal Deformity: A Guide to Surgical Planning and Manage-

ment. St. Louis, MO: Quality Medical; 2007

3. Comey CH, McLaughlin MR, Moossy J. Anterior thoracic corpectomy without

sternotomy: a strategy for malignant disease of the upper thoracic spine.

Acta Neurochir (Wien) 1997;139(8):712-718

4. Sharan AD, Przybylski GJ, Tartaglino L. Approaching the upper thoracic verte-

brae without sternotomy or thoracotomy: a radiographic analysis with clini-

cal application. Spine (Phila Pa 1976) 2000;25(8):910-916

5. Kurz LT, Pursel SE, Herkowitz HN. Modified anterior approach to the cervi-

cothoracic junction. Spine (Phila Pa 1976) 1991;16(10, Suppl):S542-S547

6. Chapman JR, Anderson PA, Pepin C, Toomey S, Newell DW, Grady MS. Pos-

terior instrumentation of the unstable cervicothoracic spine. J Neurosurg

1996;84(4):552-558

7. Fessler RG, Dietze DD Jr, Millan MM, Peace D. Lateral parascapular extrapleu-

ral approach to the upper thoracic spine. J Neurosurg 1991;75(3):349-355

284 IV Surgical Techniques

Answers to Common Clinical Questions

1. Body habitus, sagittal contour at the cervical-thoracic junc-

tion, cardiac and pulmonary status, prior neck or cardiothoracic

surgery, and prior radiation therapy to the neck or superior

mediastinum

2. The advantages include direct visualization of ventral pathol-

ogy, anterior release for correction of kyphotic deformity, and

the ability to reconstruct the anterior column with less risk

to the neural elements. Disadvantages include the need for an

access surgeon due to the unfamiliar anatomy of the superior

mediastinum; potential injury to the recurrent laryngeal nerve,

sympathetic chain, and thoracic duct; and significant additional

morbidity if sternal splitting is required.

41 Thoracic Pedicle Technique

Ryan J. Halpin and Tyler R. Koski

I. Key Points

- Transpedicular instrumentation allows for anterior and poste-

rior column spinal fixation for a more rigid construct that is

biomechanically superior to the use of thoracic hooks.

- Thoracic pedicles are smaller and more variable in size than

pedicles of the lumbar spine.¹

- Sagittal pedicle height gradually increases from upper to lower

thoracic spine.

- Transverse pedicle width decreases from the upper thoracic

spine to the mid-thoracic spine (T5-T6) before gradually in-

creasing through the lumbar spine.

- The transverse pedicle angle decreases from T1 to T12.

- Straightforward screw trajectories are associated with higher

pullout strengths than anatomic trajectories, although anatom-

ic trajectories may allow for a larger pedicle screw diameter.²

- Extrapedicular screws are biomechanically inferior to intrape-

dicular screws but are an excellent alternative when anatomy

dictates their use.³

II. Indications

- Reduction and stabilization of traumatic fractures

- Stabilization for tumor resection, infection, or spinal inflamma-

tory disease (i.e., ankylosing spondylitis)

- Correction of spinal deformity such as kyphosis or scoliosis

III. Technique

- The authors use a free hand technique⁴ and prefer to place the

pedicle screw parallel to the superior end plate with appropri-

ate medial angulation. Fluoroscopy and image guidance may be

used at the discretion of the surgeon.

- Exposure

• Soft tissues are meticulously cleared from the posterior ele-

ments of the levels to be fused, and the levels above and be-

low, including their facet capsules, are spared.

• Exposure extends from the spinous process, lamina, and facet

medially to the tips of the transverse processes laterally.

286 IV Surgical Techniques

- Facetectomy

• The facet capsules are cleared of soft tissue to expose the “pla-

teau” ridge of the thoracic lamina above the “valley” of the su-

perior facet. At the intermediate levels the inferior facet may

be removed with an osteotome to assist with visualization of

the superior facet.

- Starting point (Fig. 41.1)

• Cortical burr holes are made in the thoracic lamina ridge (pla-

teau) 1 to 2 mm lateral to the midpoint of the superior facet

(valley).

• Starting points are generally more lateral at the upper tho-

racic spine and become more medial toward the mid-thoracic

spine (T7) before once again becoming more lateral in the dis-

tal thoracic spine.

• Look for a cortical “blush” after the burring, which suggests

entry into the cancellous portion of the pedicle.

Fig. 41.1 Pedicle screw starting points with 3.5 mm acorn-tipped burr. The poste-

rior elements are burred to create a posterior cortical breach roughly 5 mm in depth.

(From Kim YJ et al, Free hand pedicle screw placement in the thoracic spine: is it safe?

Spine. 2004;29(3):333-342. Reprinted with permission.)

41 Thoracic Pedicle Technique

287

- Pedicle probe

• We use a 35 mm pedicle probe having a blunt 2 mm tip with

a slight curve.

• The probe is initially pointed laterally to avoid medial wall

violation and inserted to a depth of 15 to 20 mm. A hole probe

is then used to assess for a floor, and all four walls (superior,

inferior, medial, and lateral) are assessed for breaches.

• The probe is then reinserted with the curve pointed medially

into the vertebral body at an appropriate depth based on com-

puted tomography (CT) scan (average of 30 mm in the upper

levels and 40 to 45 mm in lower levels). The probe is removed

and the hole probe is inserted to again assess the four walls

and the floor for violations of the cortex.

- Tapping

• The tract is then under-tapped using a tap diameter 1 mm

smaller than that of the planned screw. If the tract is small

or if there is any concern about deviation, the tract may be

tapped using a cannulated tap over a K-wire.

• After the tap is removed, the hole is probed again for breaches.

The depth of the hole probe is measured and compared with

the preoperative length of the planned screw before a deci-

sion is made on the appropriate screw length.

- Screw placement

• The screw is slowly placed into the pedicle tract with close at-

tention paid to make sure it does not deviate from the planned

trajectory.

- Screw confirmation

• Screw placement can be assessed using intraoperative antero-

posterior (AP) and lateral x-ray, fluoroscopy, or CT scanning.

• Triggered electromyography (EMG) from intercostal and ab-

dominal muscles can be used to test screws prior to placing

the rods, although this method is not as reliable as it is for the

lumbar spine

- Salvage techniques

• New tracts in different trajectories can be made using the

same technique as described above. K-wires and cannulated

taps may be used to avoid entry into the original tract, and

care must be taken when placing the tap or screw over the

K-wire to prevent the K-wire’s advancement due to binding.

• Extrapedicular screws can be placed by starting more later-

ally and using a “in-out-in” technique through the transverse

process and then back into the vertebral body.

• Pedicle, infralaminar, and transverse process hooks and sub-

laminar wires can also be utilized if necessary.

288 IV Surgical Techniques

IV. Complications

- Medial breach rates range from 0.04 to 24%. Breaches as great as

2 to 4 mm (similar to the volume taken up by a thoracic hook)

may be tolerated without injury to the spinal cord, which lies 2

to 4 mm medial to the pedicle at some levels.⁴

- Lateral breach rates range from 0.4 to 29% and may result in

injuries to the aorta, segmental vessels, lung parenchyma, or

visceral structures, or pneumothorax.

- Anterior cortical breaches range from 0 to 8% and have the po-

tential to cause injuries to the esophagus, aorta, or vena cava.

- Both proper screw placement and the ability to detect a breach

in the pedicle using a probe have been shown to be dependent

on the level of training of the surgeon. Medial breaches are

more difficult to detect than lateral breaches. Breaches of the

anterior cortex are easiest to detect.

V. Postoperative Care

- Follow-up imaging is done at the discretion of the surgeon.

The authors prefer early postoperative CT scanning to evaluate

placement if an intraoperative CT scan was not performed.

VI. Outcomes

- Multiple clinical and biomechanical studies have shown that

properly placed pedicle screw constructs are superior to hook

or hybrid constructs in terms of rigid fixation, the ability to

correct coronal and sagittal deformities, and preventing loss of

correction.

- Experienced spine surgeons report malpositioning of screws

at rates of 1.5 to 6.2%. CT scans detect pedicle perforation at

higher rates than x-rays.⁴

- Neurologic, vascular, and visceral injuries are rare (<1%) but can

be devastating.

VII. Surgical Pearls

- A thin-cut CT scan is helpful for reviewing the anatomy of tho-

racic pedicles and their relationship to neurovascular struc-

tures prior to surgery.

- Pedicle screws may be augmented by injections of polymeth-

ylmethacrylate (or hydroxyapatite, calcium phosphate, or car-

bonated apatite) in patients who are at risk for screw pullout

(i.e., those with osteoporosis).

41 Thoracic Pedicle Technique

289

- Extrapedicular screws (using the “in-out-in” technique) are a

viable option when the pedicles are too small to accept a screw

or for revision instrumentation cases.

- Limit soft-tissue exposure to the levels being fused and avoid

disrupting the facet capsules at the levels above and below the

fusion.

- Any change in resistance upon insertion of the pedicle probe

should raise suspicion of a tract violation, and the tract should

be probed immediately. Medial breaches are located in the first

10 to 15 mm of the tract.

Common Clinical Questions

1. Extrapedicular thoracic screws (i.e., those that use the “in-out-

in” technique):

A. Are biomechanically stronger than intrapedicular screws

B. Are biomechanically equivalent to intrapedicular screws but

carry a higher risk of injury

C. Are biomechanically weaker than intrapedicular screws

D. Cannot be used as a salvage technique for a missed screw

2. True or false: Tapping the screw tract is not a useful technique in

the thoracic spine due to the small pedicle size.

3. True or false: CT scanning is the most accurate indicator of ap-

propriate screw positioning.

References

1. Gray’s Anatomy 1918 Edition. Public Domain

2. Lehman RA Jr, Polly DW Jr, Kuklo TR, Cunningham B, Kirk KL, Belmont PJ

Jr. Straight-forward versus anatomic trajectory technique of thoracic

pedicle screw fixation: a biomechanical analysis. Spine (Phila Pa 1976)

2003;28(18):2058-2065

3. White KK, Oka R, Mahar AT, Lowry A, Garfin SR. Pullout strength of thoracic

pedicle screw instrumentation: comparison of the transpedicular and extra-

pedicular techniques. Spine (Phila Pa 1976) 2006;31(12):E355-E358

4. Kim YJ, Lenke LG, Bridwell KH, Cho YS, Riew KD. Free hand pedicle screw place-

ment in the thoracic spine: is it safe? Spine (Phila Pa 1976) 2004;29(3):333-

342, discussion 342

42 Lateral Extracavitary Approach

Beejal Y. Amin and Muwaffak Abdulhak

I. Key Points

- The posterolateral approach allows for circumferential neural

decompression under direct visualization with extrapleural/

extravisceral dissection.

- Single-stage ventral and dorsal column support can be achieved

using the same incision.

II. Indications^1,2

- Thoracic disc herniations or osteophytes

- Thoracic fractures

- Anterolateral decompression for neoplasms

- Osteomyelitis with anterior column compromise

- Lesions located between T3 and L2

III. Preoperative Preparation²

- Sagittal magnetic resonance imaging (MRI) should include

“scout radiographs” because of the ability they provide to count

to the precise spinal level of interest.

- Anteroposterior (AP) chest x-ray confirms presence of 12 ribs.

- Spinal angiogram is useful in case of lesions between T6 and L2

to identify the radiculomedullary artery of Adamkiewicz.

- Computed tomography (CT) scan can be helpful for studying the

bony anatomy.

IV. Technique^1-3

- The patient is intubated and general anesthesia is administered.

- Antiembolism stockings and Foley catheter are placed.

- Large-bore peripheral and central catheters are necessary giv-

en the possibility of rapid blood loss during the procedure.

- Patient is placed in the prone position on a spinal table.

• The patient must be well secured to the table to allow for safe

lateral tilting during surgery.

• Arms are tucked at the sides or above the head and all pres-

sure points are padded.

- Spinal cord monitoring is optional.

292 IV Surgical Techniques

- Incision is made in the midline with a “hockey stick”-shaped

curve.

• Incision is carried through the subcutaneous tissue to the tho-

racolumbar fascia.

• Self-retaining retractors are placed, and the fascia is opened

vertically over the spinous processes.

• Exposure of the spinous process, lamina, facets, costotrans-

verse junction, and rib at each level is performed.

- The curved portion of the skin incision is made just caudal to

the last level to be instrumented and is angled 8 cm laterally to

allow adequate soft tissue retraction.

- The fascial incision is curved laterally to expose the lateral bor-

der of the erector spinae muscles.

- The erector spinae muscles are dissected off the ribs and re-

flected medially.

• The muscle group can be tented up with a Penrose drain.

- Reconfirm the spinal level and rib of interest with AP

fluoroscopy.

- Remove the rib 7 to 10 cm lateral to the costovertebral junction.

• Rongeuring the tip of the corresponding transverse process

may facilitate this procedure.

• Special attention should be given to ensure the pleura is not

punctured.

- Identify the neurovascular bundle and follow it medially to the

vertebral foramen.

• If necessary, ligate the intervening intercostal vessels and

nerves.

• The nerve should be sectioned proximal to the dorsal root

ganglion prior to closure to prevent anesthesia dolorosa.

- The sympathetic chain is encountered and displaced ventrally

in a subperiostal fashion.

- A localization radiograph is taken with a spinal needle placed

into the disc space.

- Visualization of the vertebral body and pedicle is enhanced

by tilting the operating table 15 to 20 degrees away from the

surgeon.

- The foramen is enlarged with the use of curettes until the lat-

eral aspect of the thecal sac is exposed.

• Consider starting with a midline laminectomy in case of se-

vere ventral thecal sac compression.

• Epidural bleeding can be controlled with a hemostatic agent

and Cottonoids (Saramall, Buenos Aires, Argentina); electro-

cautery should be avoided adjacent to the thecal sac.

42 Lateral Extracavitary Approach

293

- The rostral portion of the pedicle just inferior to the disc space

is removed.

- The annulus of the disc is incised just ventral to the posterior

longitudinal ligament.

- Disc material and bone ventral to the thecal sac are broken

down into the cavity with the use of curettes or thin, flat

instruments.

- After removal of adjacent discs, corpectomy can be completed

with a high-speed drill.

• The adequacy of ventral decompression is determined by use of

dental mirror.

- Anterior stabilization can be achieved with the placement of an

anterior graft into the corpectomy site.

• The use of expandable cages is recommended to provide an-

terior support.

- The operating table is tilted back to the neutral position.

- AP/lateral x-rays can aid in assessing the position of the ante-

rior graft and facilitate placement of posterior instrumentation.

- The wound is closed in a multilayered fashion (Fig. 42.1).

Fig. 42.1 Lateral view of the retracted

paraspinal muscle bundle medially and

the myocutaneous flap laterally, the lat-

eral dural sac and exiting nerve roots,

and the lateral vertebrae.

294 IV Surgical Techniques

V. Complications^1,2

- Pneumothorax

- Hemothorax

- Pleural effusion

• Significant pleural fluid collections are best treated with tube

thoracostomy rather than thoracentesis.

- Dural tear

- Spinal cord injury

- Anesthesia dolorosa

VI. Postoperative Care

- Aggressive pulmonary toilet is necessary to prevent postopera-

tive pneumonia.

- Surgical drains and chest tubes are typically discontinued at 48

to 72 hours.

- External orthosis is recommended following instrumentation

cases for up to 12 weeks.

VII. Outcomes²

- Reported series showed 70% improvement in myelopathy from

thoracic disc herniation.

- Eighty percent improvement is reported in neurologic condi-

tion from traumatic lesions of thoracic spine.

- Morbidity rate is significant and reported to be as high as 55%

in one series.²

VIII. Surgical Pearls

- The intercostal nerve should be divided proximal to the dorsal

root ganglion to prevent anesthesia dolorosa.

- Meticulous dissection of the rib and rib head to avoid pleural

injury along with gentle retraction of the lung may help mini-

mize pulmonary morbidity.

42 Lateral Extracavitary Approach

295

Common Clinical Questions

1. Where should the nerve be sacrificed in relation to the dorsal

root ganglion?

A. Proximal to the dorsal root ganglion

B. Distal to the dorsal root ganglion

2. The benefits of the lateral extracavitary approach include:

A. Circumferential neural decompression can be achieved un-

der direct visualization.

B. Single-stage ventral and dorsal column support can be

achieved using the same incision.

C. Both A and B

References

1. Larson SJ, Holst RA, Hemmy DC, Sances A Jr. Lateral extracavitary ap-

proach to traumatic lesions of the thoracic and lumbar spine. J Neurosurg

1976;45(6):628-637

2. Resnick DK, Benzel EC. Lateral extracavitary approach for thoracic and thora-

columbar spine trauma: operative complications. Neurosurgery 1998;43(4):

796-802, discussion 802-803

3. Capener N. The evolution of lateral rhachotomy. J Bone Joint Surg Br

1954;36-B(2):173-179

Answers to Common Clinical Questions

1. A (to prevent anesthesia dolorosa)

2. C

43 Transpedicular Approach

Frank La Marca, Paul Park, and Juan M. Valdivia

I. Key Points

- Alternative posterior approach for anterior decompression

avoids the morbidity associated with anterior (i.e., transthorac-

ic, thoracoabdominal) approaches for neural decompression.

- Less extensive dissection required compared with other ante-

rior approaches

- Particularly effective technique for soft thoracic disc hernia-

tions or intrapedicular lesions

- Not ideal for large calcified central thoracic disc herniations

II. Indications

- Soft central or lateral thoracic disc herniations, anterolateral

calcified thoracic disc hernations

- Reduction of retropulsed fragment(s) in vertebral burst fracture

- Resection and/or biopsy of intravertebral/intrapedicular lesions

- Decompression of anterolateral spinal canal in the setting of

tumor

III. Technique

- Patient is in prone position on Jackson table with gel rolls or

frame.

- Neurophysiologic monitoring

(transcranial motor evoked

potentials and somatosensory evoked potentials should be

considered)

- Fluoroscopy: Obtain multiple views for correct localization.

Either count from the sacrum or obtain anteroposterior (AP)

views counting ribs, having confirmed 12 rib-bearing segments

preoperatively. For extremely obese patients, a marker can be

placed preoperatively by interventional radiology with subse-

quent imaging to confirm marker as a viable reference point.

- Midline incision: ipsilateral erector spinae muscles dissected to

expose lamina, facet complex, transverse process

- If instrumentation is required, exposure is increased to encom-

pass the targeted segments.

- In the thoracic spine, the medial portion of the transverse pro-

cess overlies the pedicle.

43 Transpedicular Approach

297

- If necessary, AP fluoroscopy can be used to localize the pedicle

margins.

- The pedicle inferior to the targeted disc space is targeted (i.e.,

the T8 pedicle for a T7-T8 disc herniation).^1,2

- At a minimum, a laminotomy is created adjacent to the targeted

pedicle.

- The posterior cortex of the pedicle is opened with a high-speed

drill. Sequential passage of curettes and/or high-speed drill is

used to create a channel through the cancellous pedicle. The

walls of the pedicle can be thinned to an “eggshell” thickness

with the drill. Once the vertebral body is reached, a down-going

curette can be used to safely fracture the medial wall of the

pedicle laterally, exposing the lateral margins of the dura. The

medial portion of the adjacent facet is resected and the supe-

rior wall of the pedicle is removed to expose the disc space.

- A Woodson elevator is used to carefully palpate the ventral epi-

dural space to identify the lesion.

- For disc herniations, the disc space is entered just lateral to the

dura. Disc material is removed with rongeurs. The high-speed

drill is then used to create a cavity encompassing the disc space

as well as the adjacent vertebral bodies (Fig. 43.1). The drill is

angled to extend the cavity medially, maintaining a thin margin

of disc annulus or posterior vertebral wall between the drill tip

and the ventral dura. A small down-going curette is then used

Fig. 43.1 To allow access to the interior of the vertebral body, it may be necessary

to resect the rib, rib head, and transverse process. (From Vaccaro AR, Albert TJ, Spine

Surgery: Tricks of the Trade 2nd ed, Thieme; pg. 89, Fig. 25.2.)

298 IV Surgical Techniques

to gently push the disc herniation into the cavity, allowing re-

moval with rongeurs.³

- Note that the ventral dura is not well visualized with this tech-

nique. For more centralized masses, an instrument such as a

down-going curette is used to localize the mass by palpation.

The curette is then used to push the mass into the cavity (Fig.

43.1).

- For retropulsed bone or tumor, more of the vertebral body is

removed to create the cavity into which the epidural mass is

pushed.

- For larger masses, a bilateral transpedicular approach can be

used.

- With bilateral approaches, fusion should be considered.

IV. Complications

- Infection

• Discitis

- Durotomy

• Pseudomeningocele formation

- Transient/permanent neurologic injury

• Spinal cord injury if excessive retraction is applied to the dura

during the decompression

- Inadequate visualization of the ventral epidural space, result-

ing in suboptimal anterior decompression

V. Postoperative Care

- Consider neurologic intensive care unit for close monitoring,

particularly for patients with preexisting neurologic deficit or

significant comorbidities.

- Routine postoperative imaging is not required.

- Urgent MRI is needed if new neurologic deficit is present.

VI. Outcomes

- In properly selected patients, neurologic outcomes for symp-

tomatic thoracic disc herniations treated by the transpedicular

approach are similar to outcomes for the transthoracic approach.

VII. Surgical Pearls

- Review axial and sagittal images on computed tomography

(CT) to understand the pedicular anatomy; may use three-di-

mensional reconstruction.

43 Transpedicular Approach

299

- When anatomy is distorted due to prior surgery or fusion mass,

fluoroscopy and pedicle marker may be used to localize the

pedicle as for pedicle screw placement.

- If anterior decompression is unsafe due to scarring with ante-

rior dura or fragment indenting spinal cord, consider opening

dura for adequate visualization of spinal cord in relation to the

anterior pathology.

- Anterior unintended durotomy or cerebrospinal fluid (CSF)

leak can be treated locally with Duragen (Integra Life Sciences

Corp., Plainsboro, NJ) or Dura-Guard (Synovis, St. Paul, MN) and

a sealant agent

- Postoperative lumbar drain should be considered with

durotomy.

Common Clinical Questions

1. What is the main disadvantage of the transpedicular approach

for anterior decompression?

2. A large central calcified disc herniation is best approached via

which technique?

3. Is fusion necessary after a transpedicular approach?

References

1. Vaccaro A, Albert T. Spine Surgery: Tricks of the Trade. New York: Thieme

Medical Publishing; 2009

2. Vanichkachorn JS, Vaccaro AR. Thoracic disk disease: diagnosis and treat-

ment. J Am Acad Orthop Surg 2000;8(3):159-169

3. Bilsky MH. Transpedicular approach for thoracic disc herniations. Neurosurg

Focus 2000;9(4):e3

Answers to Common Clinical Questions

1. Inadequate visualization of the ventral midline dura

2. Transthoracic

3. For a unilateral transpedicular approach, fusion is typically not

necessary.

44 Costotransversectomy

Dean B. Kostov and Adam S. Kanter

I. Key Points

- Conservative management of thoracic disc herniation with ra-

diculopathy is the preferred primary management.

- The presence or progression of myelopathy due to thoracic disc

pathology is accepted as an indication for surgery.

- Costotransversectomy is best suited for ipsilateral noncalcified

central pathology and is contraindicated for contralateral de-

compression and large central calcified disease.

- Costotransversectomy provides a well-tolerated surgical cor-

ridor to address ventral and ventrolateral pathology via a pos-

terior approach, but care must be taken in working around the

neural structures.

- Excellent choice for patients who cannot tolerate anterior ap-

proaches via thoracotomy

II. Indications

- Thoracic disc herniation^1-4

- Drainage of spinal abscess/infections (originally described for

tubercular abscess by Ménard)

- Spinal decompression of ventral and ventrolateral space-occu-

pying lesions^2-4

- Resection of paraspinal nerve sheath tumors^2,3

- Correction of kyphotic deformity²

III. Technique (Fig. 44.1)

- Position patient prone or partial lateral. Incision can be para-

median, T-shaped, straight, or curvilinear with convexity to-

ward the midline to allow for greater access.

- The incision is carried through skin, trapezius, and/or latissi-

mus dorsi (for lower approaches) and erector spinae with me-

dial retraction to expose the ribs and transverse process of the

caudal vertebrae of the level of interest.

- Subperiosteal dissection of the perichondrium around the rib

is performed, protecting the pleura and neurovascular bundle

(use a semisharp subperiosteal dissector such as a Doyen rib

raspatory).

44 Costotransversectomy

301

Fig. 44.1 Cross-section of the costotransversectomy approach. The shaded area

depicts bone that may be removed using this approach to expose the spinal canal.

(From Vaccaro AR, Albert TJ, Spine Surgery: Tricks of the Trade 2nd ed, Thieme; pg.

86, Fig. 24.3.)

- After sharp division of the costotransverse ligament, the trans-

verse process is removed at the junction with the lamina using

rongeurs or a high-speed drill.

- Transection of the rib about 3 to 5 cm (depending on the expo-

sure needed) from the costotransverse junction and disarticu-

lation of the rib from the costovertebral joint is then performed.

- Partial laminectomy and facetectomy are carried out to iden-

tify the lateral margin of the dura using a high-speed drill and/

or small Kerrison rongeurs.

- The pleura may be protected ventrally with a malleable retractor,

and a rib spreader may be used to increase exposure depending on

number of levels indicated.

- Careful dissection along the superolateral border of the pedicle

can be performed to safely expose the vertebral body or iden-

tify the disc space, depending on the goals.

- Discectomy should be performed laterally first, followed by the

creation of a cavity centrally that can be used to push medio-

dorsal pathology inward to facilitate safe removal without ma-

nipulation of the spinal cord. This cavity may be enlarged to

include partial vertebral resection as needed.

- If vertebral column resection is to be performed, then a midline

approach with or without T-shaped extension is best to allow

for safe instrumentation.

- If the spine is to be destabilized due to vertebral column resec-

tion, posterior instrumentation with gradual reduction of ky-

phosis using temporary rods should be done first.

302 IV Surgical Techniques

- During closure, the field should be flooded with irrigation and a

Valsalva maneuver performed to identify any pleural compro-

mise. If pleura is violated, primary repair should be attempted

with or without placement of a chest tube.

- The wound should be closed in layers and drains placed as

needed.

IV. Complications

- Highly dependent on pathology and procedure performed

- Neurologic decline (5.5%), neurovascular bundle compromise,

hemothorax

- Pneumothorax (as high as 25%), injury to pleura, lung contu-

sion, atelectasis^2-4

- Dural tear, symptomatic or asymptomatic pseudomeningocele

- Infection

- Injury to great vessels lying anterior to vertebral body

- Injury to radiculomedullary arterial branches, leading to spinal

cord infarct

V. Postoperative Care

- Chest x-ray should take place in recovery room to evaluate for

pneumothorax.

- Patient should be placed in a monitored unit with continuous

pulse oxymetry performed.

- Incentive spirometry and pulmonary toilet are key in the postop-

erative period.

- Pain should be adequately controlled to prevent guarding and

shallow breathing.

- Early mobilization with standard spinal postoperative care

(e.g., deep vein thrombosis [DVT] prophylaxis)

VI. Outcomes

- Improvement in weakness ranging from 30 to 58%

- Improvement in radiculopathy or local pain ranging from 42

to 91%

- Spasticity and myelopathy improvement has been reported as

high as 95%.

- Comparing costotransversectomy with anterior or combined

approaches for treatment of oncologic disease, the periopera-

tive complication profile is similar, but a posterior approach

may be better tolerated in patients with multiple medical

comorbidities.

44 Costotransversectomy

303

VII. Surgical Pearls

- The spinal cord should never be manipulated to gain exposure.

- If the goal of surgery is anterior column resection, then poste-

rior instrumentation should be placed with a temporary rod

prior to destabilization of the vertebral column

- Following the neurovascular bundle back will lead to the neural

foramen, and the removal of the rib head leads to the disc space

of interest.

- If more exposure is needed one should remove more rib, allow-

ing a greater lateral corridor, rather than trying to work via a

more posterior approach.

Common Clinical Questions

1. With central thoracic disc herniations, what side is preferred for

performing a costotransversectomy approach if indicated?

2. What is the origin of the major arterial supply to the spinal cord

from T8 to the conus, and where is it located?

3. During positioning, what is a useful anatomic landmark for the

T7 vertebral level?

References

1. Greenberg MS. Handbook of Neurosurgery. 6th ed. New York: Thieme Medi-

cal Publishers; 2006:322-323, 516-521

2. Vaccaro AR. Spine Surgery: Tricks of the Trade. 2nd ed. New York: Thieme

Medical Publishers; 2006:83-87

3. McCormick WE, Will SF, Benzel EC. Surgery for thoracic disc disease. Complica-

tion avoidance: overview and management. Neurosurg Focus 2000;9(4):e13

4. Wiggins GC, Mirza S, Bellabarba C, West GA, Chapman JR, Shaffrey CI. Periop-

erative complications with costotransversectomy and anterior approaches

to thoracic and thoracolumbar tumors. Neurosurg Focus 2001;11(6):e4

Answers to Common Clinical Questions

1. The left side is preferred to avoid the great veins (the aorta is much

more resilient).

2. The artery of Adamkiewicz, located on the left in 80% of pa-

tients, and arising between T9 and T12 in 75% of the population

3. The inferior tip of the scapula

45 Thoracoscopic Approach

Timothy D. Uschold and Steve W. Chang

I. Key Points

- Working angles and trajectories to the thoracic spine are com-

parable between the thoracoscopic and open anterolateral

(thoracotomy) approaches. Posterior elements, contralateral

roots, and the contralateral pedicle cannot be accessed.

- Thoracoscopy allows access to the entire thoracic spine (T1 to

T12) and eliminates the need for an approach surgeon. Similar

access may be obtainable with mini-open techniques.

- Thoracoscopy requires a unique skill set, knowledge of anato-

my, and familiarity with unusual instruments. Proficiency typi-

cally requires considerable laboratory preparation.

- Single-lung ventilation via a double-lumen endotracheal tube

is required for thoracoscopic access. Patients with significant

obesity, cardiac dysfunction, and/or pulmonary comorbidities

may require specialist referral for preoperative clearance.

II. Indications

- Microdiscectomy for symptomatic thoracic herniation

- Sympathectomy: primarily utilized for palmar hyperhidrosis

after failure of medical management. Craniofacial hyperhidro-

sis, axillary hyperhidrosis, reflex sympathetic dystrophy, and

palmar ischemic phenomena are less common indications.¹

- Osteomyelitis/discitis, epidural abscess, nerve sheath tumor,

vertebral biopsy, corpectomy, costovertebral joint pain, verte-

bral reconstruction, and spinal deformity²

- Contraindications: malignant tumors requiring en bloc resec-

tion, intradural pathology. Due to high rates of intradural mi-

gration and calcification, open thoracotomy is favored for giant

(occupying >40% of canal diameter) midline herniated discs.³

III. Technique

- The patient is turned to the lateral decubitus position, an ax-

illary roll is placed, and the upper arm is gently raised and

supported via an armboard. After the patient is secured to the

operating table, the bed is rotated to assist gravity retraction

of the lung.

45 Thoracoscopic Approach

305

- Single-lung ventilation ensues after reconfirmation of position

of the endotracheal tube.

- The surgeon stands facing the patient’s chest. Various portal

configurations are acceptable depending on the level of inter-

est. Working portals are biased toward the anterior axillary line

(usually equidistant from the level of interest), and the endo-

scopic portal is biased toward the posterior axillary line.

- A 1 cm incision is made along the superior costal margin. Blunt

dissection with a hemostat and/or finger, as in chest tube place-

ment, is used to pierce the parietal pleura. Working portals are

placed under direct vision with the endoscope. Minor adhesions

are lysed using a combination of blunt and sharp dissection.⁴

- Sympathectomy for palmar hyperhidrosis:

• One or two working portals are required (typically the third

and/or fourth intercostal spaces), and the endoscope is placed

at the fifth intercostal space.

• The second rib is identified inferior to the apical fat pad and

the brachiocephalic and subclavian vessels. The sympathetic

chain is then transected at the second and third rib heads

with bipolar cautery followed by scissors. The ends are gently

dissected and separated.¹

- Discectomy

• Based on the necessary exposure, the parietal pleura overlying

the rib heads and/or bodies is incised with cautery. The pleura

can be reflected with elevators, cautery, or further sharp dis-

section. Segmental vessels are mobilized, ligated, coagulated,

and transected when necessary (Fig. 45.1).

• A dissector is used to separate the neurovascular bundle from

the inferior costal margin and to dissect the superior margin

free from pleura and muscular attachment. The costoverte-

bral joint is disarticulated using a levered Cobb elevator. The

distal rib is transected, and the rib head is removed. The ex-

posed pedicle is resected with Kerrison rongeurs. The dura

and exiting root are now visualized.

• A cavity is drilled into the disc space and adjacent bodies, and

the disc fragment is removed with careful curettage directed

away from the thecal sac.

- Closure

• A chest tube connected to standard suction (-20 cm H₂O) is

directed toward the lung apex through a working portal and

secured in an airtight fashion. The thoracic wall is inspected

with the endoscope. The remaining working portals are closed,

and the atelectatic lung is reinflated under direct vision.

306 IV Surgical Techniques

Fig. 45.1 Thoracic anatomy demonstrating relationship of vertebral bodies to ribs,

sympathetic chain, and segmental vessels (used with permission from Barrow Neu-

rological Institute).

• Chest tubes may be removed before the patient leaves the op-

erating room. Alternatively, chest tubes can be left in place

until output diminishes to less than 100 cc/day, transitioned

to water seal, and removed later.⁴

IV. Complications

- Durotomy: Repair methods include hemoclips or fascial harvest

for onlay graft with fibrin sealant, and temporary lumbar cerebro-

spinal fluid (CSF) diversion. Chest tubes should be placed to water

seal. Occult CSF leaks may be identified with a Valsalva maneuver.

- Wrong-level procedure: Localization can typically be achieved

by identifying anatomic landmarks with the endoscope and

confirmed by fluoroscopy. Ribs articulate with the disc space

above the corresponding vertebral body (e.g., the T5 rib leads to

the T5 pedicle and T4/T5 disc space). A radiopaque fiducial may

be placed preoperatively in the pedicle of interest.

- Persistent pneumothorax or atelectasis

- Miscellaneous complications: neurovascular compression

syndromes (positioning), intercostal neuralgia (typically tran-

45 Thoracoscopic Approach

307

sient), gustatory sweating (sympathectomy), Horner syndrome

(sympathectomy involving stellate ganglion), and chylothorax

V. Postoperative Care

- An upright anteroposterior radiograph is obtained in the re-

covery room and the next morning to evaluate for persistent

pneumothorax.

- Aggressive pulmonary toilet, incentive spirometry, and nebu-

lizer use are promoted to prevent atelectasis.

VI. Outcomes

- Sympathectomy

• Increase of more than 1°C in palmar temperature monitoring,

an indirect marker of vasodilation, is a useful intraoperative

prognostic for success.¹

• Uniform reports of 96 to 100% relief of palmar hyperhidrosis.

Rate of compensatory hyperhidrosis (e.g., legs, back, trunk)

ranges from 50 to 61% in large series. No useful predictors of

compensatory hyperhidrosis.⁴

- Discectomy

• Advantages reported over thoracotomy in terms of pulmo-

nary complications, operative pain, wound complications,

chest tube duration, intercostal neuralgia and rib resection,

and decreased length of hospital stay

VII. Surgical Pearls

- To avoid inadvertent injury to lung parenchyma or to vascular

or neural structures, the working tips of all instruments should

be visualized at all times with the endoscope.

- A larger cavity drilled into the disc and body, if necessary, may

be useful during discectomy. All movements should be directed

away from the thecal sac.

- Disc calcification is not a contraindication to thoracoscopic mi-

crodiscectomy (unless giant) but may require more extensive

drilling (e.g., diamond burr) to protect the thecal sac against

levered resection during curettage.

- Portal incisions should be planned to facilitate conversion to

open thoracotomy if needed.

- Use of an angled endoscope may be useful for confirming de-

compression of the anterior thecal sac and root(s), especially in

the setting of suspected residual disc.

308 IV Surgical Techniques

Common Clinical Questions

1. Describe characteristics of a herniated disc least appropriate for

thoracoscopic microdiscectomy.

2. What are the success rate and most common side effect of tho-

racoscopic sympathectomy for palmar hyperhidrosis at T2/T3?

3. Name three surgical or postoperative strategies to prevent se-

vere complications related to CSF leakage during thoracoscopic

surgery.

References

1. Han PP, Gottfried ON, Kenny KJ, Dickman CA. Biportal thoracoscopic sympa-

thectomy: surgical techniques and clinical results for the treatment of hy-

perhidrosis. Neurosurgery 2002;50(2):306-311, discussion 311-312

2. Han PP, Kenny K, Dickman CA. Thoracoscopic approaches to the thoracic

spine: experience with 241 surgical procedures. Neurosurgery 2002;51(5,

Suppl):S88-S95

3. Hott JS, Feiz-Erfan I, Kenny K, Dickman CA. Surgical management of gi-

ant herniated thoracic discs: analysis of

20 cases. J Neurosurg Spine

2005;3(3):191-197

4. Dickman CA, Rosenthal DJ, Perin NI. Thoracoscopic microsurgical discectomy.

In Dickman CA, Rosenthal DJ, Perin NI. Thoracoscopic Spine Surgery. New

York: Thieme; 1999: 221-244

Answers to Common Clinical Questions

1. Midline, giant, calcified herniated nucleus pulposus

2. Nearly 100% with symptomatic improvement. Compensatory

hyperhidrosis is the most common side effect.

3. Lumbar drain placement, fascial graft repair with fibrin sealant,

attempt primary repair of durotomy with hemoclips and chest

tubes placed to water seal

46 Pedicle Subtraction Osteotomy/

Smith Petersen Osteotomy

Frank La Marca, Paul Park, and Juan M. Valdivia

I. Key Points

- For correction of mainly symptomatic fixed sagittal imbalance

(pedicle subtraction osteotomy [PSO]) and nonfixed sagittal

imbalance (Smith-Petersen osteotomy [SPO])¹

- An asymmetric PSO can also be used for correction of coronal

imbalance.

- Can aid in the correction of coronal balance via posterior col-

umn release (SPO) or three-column release (PSO)

- Can be performed on the thoracic or lumbar spine

II. Indications

- Uncompensated spinal kyphoscoliosis (thoracic and/or lum-

bar) with or without progression

- Correction of fixed kyphosis requiring more than 30 degrees of

correction (PSO) at one spinal segment

- Correction of nonfixed deformity requiring 5 to 10 degrees of

correction (SPO) per spinal segment

III. Technique

Pedicle Subtraction Osteotomy

- 1. Position on Jackson frame with extended chest bolster.

- 2. Neurophysiologic monitoring should be used (transcra-

nial motor evoked potentials, somatosensory evoked poten-

tials, electromyography) to minimize neurologic injury during

correction

- 3. Place two to three levels of bilateral pedicle screws cephalad

and caudal to the target vertebral segment (i.e., commonly L2

or L3 in the lumbar spine).

- 4. Remove transverse process and rib head (if in thoracic spine).

- 5. For 360 degree extrapedicular vertebral body exposure, dis-

sect soft tissues and vascular structures from vertebral body

with placement of malleable retractors to maintain separation.²

- 6. Perform Gill laminectomy of the target vertebral body and

partial laminectomies of the adjacent segments (Fig. 46.1A).

- 7. Decancellate and resect pedicle while contralateral temporary

rod is in place.

310 IV Surgical Techniques

Fused spine

(ankylosing)

35-degree

wedge

to be

resected

Lines of osteotomy

(lateral view)

(posterior view)

Fig. 46.1

(A,B) Pedicle subtraction osteotomy. (From Haher R, Merola A, Surgical

Technique for the Spine, Thieme; pg. 234, Fig. 50-3A,C.)

- 8. Resect (chisel or drill) a posterior wedge out of vertebral

body (Fig. 46.1B).³

- 9. Repeat steps 5 and 6 on the contralateral side.²

- 10. Resect remaining posterior vertebral body cortex; impact

bone into cavity previously created during wedge resection of

vertebral body with angled bone tamp or down-going curette.²

- 11. Use fluoroscopy to confirm adequate resection in addition to

visual inspection.³

- 12. Compress across pedicle screws to close down osteotomy

(Fig. 46.1B).

- 13. Evaluate neurophysiologic monitoring and/or wakeup test

to ensure absence of neurologic compromise.

Smith-Petersen Osteotomy

- 1. Position on Jackson frame with extended chest bolster.

- 2. Consider use of multimodal neurophysiologic monitor-

ing to minimize neurologic complications during deformity

correction.

- 3. Place pedicle screw instrumentation across targeted segments.

46 Pedicle Subtraction Osteotomy/Smith Petersen Osteotomy

311

- 4. Remove interspinous ligaments with rongeur.

- 5. Spinous processes are removed at each targeted segment in a

45 degree angle in addition to removal of the upper and lower

lamina edges.

- 6. Bilateral facetectomies are performed with osteotomes and/

or a high-speed drill⁴ (Fig. 46.2A).

- 7. Remove ligamentum flavum.

- 8. Compress across the screw heads to close the osteotomy⁴

(Fig. 46.2B).

- 9. The patient may be placed in extension to assist in closure of

the osteotomy.⁴

IV. Complications

- Neurologic injury due to iatrogenic spinal stenosis upon closure

of the osteotomy

- Spinal subluxation during osteotomy

- Durotomy

Fused spine

Wedge

to be

resected

Lines

osteotomy

Fig. 46.2

(A,B) Smith-Petersen osteotomy. (From Haher R, Merola A, Surgical Tech-

nique for the Spine, Thieme; pg. 228, Fig. 49-1A,B.)

312 IV Surgical Techniques

- Hypotension due to excessive blood loss during osteotomy; avoid

hypotension especially during correction maneuvers as spinal

cord ischemia may result

- Epidural hematoma

- Vascular injury

- Pseudarthrosis

V. Postoperative Care

- Immediate neurologic evalution upon wakeup

- Admission to neurologic intensive care for close monitoring

- Maintenance of blood pressure

- Consider postoperative computed tomography (CT) scan to

evaluate adequacy of bone resection and juxtaposition of os-

teotomy margins.

VI. Outcomes

- With PSO, average curve improvements are 61 degrees in sco-

liosis cases, 56 degrees in global kyphosis cases, and 51 degrees

in angular kyphosis cases.⁴

- Clinical and radiographic outcomes are superior with PSO in

the lumbar spine rather than in the thoracic. The lower the PSO

is performed, the less angulation is required for sagittal balance

correction.¹

- In properly selected patients, sagittal balance can be restored

with PSO or multiple SPO safely.

VII. Surgical Pearls

- Ensure that bone resection is adequate and wide enough lat-

erally in both PSO and SPO to prevent interference upon oste-

otomy closure or compression of neurologic structures.

- Use thrombin powder or bioabsorbable bone wax to minimize

bleeding during PSO without compromising fusion rates. Apro-

tinin is also an option, although controversy exists over pos-

sible associated complications.

- Do not resect the anterior vertebral wall entirely during PSO, as

it will serve as a hinge during pedicle screw compression and

osteotomy closure and prevent vertebral segment subluxation.

- Posterior laminectomy resection should be complete and in-

clude any epidural scar removal to assess dural sac adequately

after osteotomy closure and ensure there is no spinal canal

compression.

46 PedicleSubtractionOsteotomy/SmithPetersenOsteotomy

313

- During SPO closure, place patient in extension to lengthen the

anterior spinal column and facilitate osteotomy closure and to

minimize strain on the pedicle screw construct.

Common Clinical Questions

1. How many degrees of correction can be achieved with PSO as

opposed to SPO?

2. What is the main advantage of a PSO/SPO procedure?

3. In regard to the anterior and middle columns, what is the main

difference between PSO and SPO?

References

1. Dorward IG, Lenke LG. Osteotomies in the posterior-only treatment of

complex adult spinal deformity: a comparative review. Neurosurg Focus

2010;28(3):E4

2. Bridwell KH, Lewis SJ, Rinella A, Lenke LG, Baldus C, Blanke K. Pedicle sub-

traction osteotomy for the treatment of fixed sagittal imbalance. Surgical

technique. J Bone Joint Surg Am 2004;86-A(Suppl 1):44-50

3. Bridwell KH, Lewis SJ, Lenke LG, Baldus C, Blanke K. Pedicle subtraction os-

teotomy for the treatment of fixed sagittal imbalance. J Bone Joint Surg Am

2003;85-A(3):454-463

4. La Marca F, Brumblay H. Smith-Petersen osteotomy in thoracolumbar defor-

mity surgery. Neurosurgery 2008;63(3, Suppl):163-170

Answers to Common Clinical Questions

1. Up to 30 degrees per level with PSO compared with 10 degrees per

level with SPO

2. Correction of sagittal imbalance and reestablishment of lordosis

or correction of kyphosis

3. PSO is a closing wedge osteotomy involving the three columns,

and thus shortens the middle and posterior columns. SPO, in

contrast, uses the middle column as a pivot, thus lengthening

the anterior column and shortening the posterior column.

47 Transthoracic Approach

Brian Kwon and David H. Kim

I. Key Points

- The transthoracic approach places the major vessels of the tho-

racic cavity at risk and threatens injury to the lungs and heart.

- An injury to the spinal cord at this level may result in paraplegia.

- Mark levels carefully, and make frequent use of radiographs or

fluoroscopy.

II. Indications

- Thoracic myelopathy resulting from spinal cord compression¹

• Herniated nucleus pulposus (HNP), stenosis, or ossification of

the posterior longitudinal ligament (OPLL)

• Cervical and lumbar pathology ruled out

- Infections

• Discitis or osteomyelitis

- Trauma

- Tumors

- Not for axial thoracic spine pain

III. Technique

- Position lateral decubitus.²

- Alert anesthesia staff to use double-lumen endotracheal tube

so that deflation of lung can be performed if necessary.

- Confirm level(s)

• If using open technique, manually palpate ribs (enlist help of

thoracic surgeon).

• Live fluoroscopy: use fixed markers, such as spinal needles

placed into facet joints (to mark pedicles or ribs).

• Count ribs on anteroposterior (AP) view (take note of males

with missing twelfth rib).

• Lower thoracic vertebrae can be counted from sacrum.

• Confirm as many times as necessary (thoracic vertebrae look

alike!).

- Make skin incision over disc or vertebral body based on imaging.

• Semilinear or linear

- Upper thoracic discs (T2 to T5) may require mobilization of

scapula.

47 Transthoracic Approach

315

• Cut latissimus dorsi, serratus anterior, and teres major mus-

cles midsubstance—allows scapula to be deflected cephalad

and dorsally.

- For lower thoracic discs (T9 to T12), hemidiaphragm may need

to be released from the vertebrae.

- Resect rib for visualization (Fig. 47.1A-C).

• Preserve nerve root if possible; otherwise sacrifice by ligating

a segment of nerve to prevent painful neuromas. Tell patient

about post-op paresthesia.

• Excellent source of structural or morselized autograft

- Can get to discs and vertebrae via transpleural or retropleural

approach

• Incise parietal pleura.

• Lifts off lateral side of vertebral body

- Deflate lung.

- Ligate segmental vessels close to azygous vein/aorta.

Fig.

47.1

(A,B) A window is

made through the parietal pleura

over the vertebral body. (C) The

corpectomy is performed all the

way to the contralateral pedicle.

(From Anterior thoracic decom-

pression. In: Spine Surgery: Tricks

of the Trade 2nd ed. Vaccarro AR,

Albert TJ, eds. Thieme; pg. 108,

Figs. 31.2, 31.3.)

316 IV Surgical Techniques

• Necessary for corpectomies

- Follow nerve root into foramen.

- Rib head resection is necessary above T9-T10.³

• May not be necessary at T11 or T12

• Helpful to see pedicle, the primary landmark for performing

discectomy

IV. Complications

- Spinal cord injury

• Spinal neuromonitoring necessary

• Direct spinal cord trauma

• Vascular insufficiency

◦ Note ligation of multiple segmental vessels for multilevel

surgery.

- Lung injury

• From retractors, burr, other equpment

- Vascular injury

- Thoracic duct injury

• On the right in lower thoracic spine (T9 to T12), on the left in

upper thoracic spine (T4 and above)

- Pneumothorax

- Post-op neuritis

V. Postoperative Care

- Chest tube, for transpleural approach

• Placed outside operative incision

- Bracing optional

VI. Outcomes

- Generally good for neurologic outcomes depending on the se-

verity of preoperative myelopathy

• Can use Japanese Orthopedic Association score or Nurick

grade

- Pain outcomes less predictable

VII. Surgical Pearls

- Mark levels carefully with good intra-op imaging.

- Can follow rib, rib head, and nerve root to disc space

47 Transthoracic Approach

317

Common Clinical Questions

1. Which of the following is not an appropriate indication for

transthoracic spine surgery?

A. Infection

B. Tumor

C. Trauma

D. Back pain

2. Complications of transthoracic spine surgery include (choose all

that apply):

A. Spinal cord injury

B. Incisional hernia

C. Neuralgia

D. Chylothorax

3. True or false: Thoracic vertebrae can be easily differentiated

from one another.

References

1. Bohlman HH, Zdeblick TA. Anterior excision of herniated thoracic discs. J

Bone Joint Surg Am 1988;70(7):1038-1047

2. Currier BL, Eismont FJ, Green BA. Transthoracic disc excision and fusion for

herniated thoracic discs. Spine (Phila Pa 1976) 1994;19(3):323-328

3. Moro T, Kikuchi S, Konno S. Necessity of rib head resection for anterior discec-

tomy in the thoracic spine. Spine (Phila Pa 1976) 2004;29(15):1703-1705

Answers to Common Clinical Questions

1. D. Back pain or axial pain is not an appropriate indication. Sur-

gical outcomes for axial pain are less reliable and, given the in-

herent risks of thoracic spine surgery, such pain is not a good

indication for it.

2. A, C, D. Spinal cord injury can occur from direct trauma to the

cord or ischemia due to hypotension or ligation of the segmental

vessel from which the anterior spinal artery arises. Neuralgia

results from ligation of thoracic nerve root. Thoracic duct injury

can occur in lower, right-sided thoracic approaches.

3. False. Thoracic vertebrae look very similar and because of the

overlying rib cage, anatomic differences cannot be used to con-

firm operative level.

48 Retroperitoneal Approaches to the

Thoracolumbar Spine

Camilo A. Molina, Ziya L. Gokaslan, and Daniel M. Sciubba

I. Key Points

- Of utmost importance to performing any ventrolateral approach-

es to the lumbar spine is extensive knowledge of the regional

anatomy, including the abdominal wall, peritoneal contents, ret-

roperitoneal contents, and ventrolateral musculature and neural

elements.

- Conventional open anterior (transperitoneal) approaches to

the lumbar spine require mobilization of the sympathetic

plexus and great vessels, which is associated with a significant

incidence of complications. Retroperitoneal approaches to the

lumbar spine minimize the incidence of such complications by

avoiding mobilization of the large bowel, sympathetic plexus,

and great vessels.

- The indications to perform a particular type of approach are

more dependent on the localization of the pathology, the bal-

ance between advantages and disadvantages, and the surgeon’s

knowledge of the approach than on the pathology itself. For

example, the indications to perform an interbody fusion range

from preoperative segmental instability to iatrogenic instabili-

ty due to wide decompressions, but do not dictate a specific ap-

proach. In other words, the indications for a minimally invasive

interbody fusion are the same as for an open interbody fusion.

However, the relative localization of the instability, the skill of

the surgeon, complication risks, and the health status of the pa-

tient indicate the preferential use of a particular approach over

another (i.e., retroperitoneal versus transperitoneal).

- In general, left-sided approaches are more practical than right-

sided approaches because it is less difficult to separate the aor-

ta from the spine than to separate the more delicate inferior

vena cava, particularly in cases of retroperitoneal fibrosis that

occur in patients previously treated with radiation therapy due

to neoplasms.

II. Conventional Open Retroperitoneal Access

- Indications

• Open retroperitoneal access provides a wide anterior expo-

sure to the spine, allowing for the treatment of spine patholo-

48 Thoracolumbar Spine: Retroperitoneal Approaches

319

gies of degenerative, traumatic, and neoplastic origins. The

most widely used approach is to perform anterior lumbar

interbody fusions to treat a variety of spine pathologies that

develop due to degenerative and neoplastic spine diseases,

such as degenerative disc disease, trauma-related internal disc

disruption, pseudarthrosis, decompression for neural stenosis,

and spine deformity.^1-3This approach can also been employed

to perform anterior access lumbar corpectomies^1,2,4; it is also

a common avenue for treating epidural spinal neoplasms and

cases of complex spine deformity.

- Surgical technique varies with the level accessed.

• Lumbosacral (L2 to S1)¹

◦ A paramedian incision traversing the subcutaneous tissue to

expose the external oblique muscle is made, preferably on

the left to avoid the more prominent common iliac vein on

the right. The external oblique muscle is then incised at the

medial aponeurotic region, after which the rectus sheath is

opened. The rectus muscle is then mobilized mediolaterally

to preserve segmental innervation of the abdominal wall.

◦ Following mobilization of the rectus muscle, the retroperi-

toneal space is developed at the level of the semilunar line.

This is done by dissecting the peritoneum in a lateromedial

direction, freeing it from the superficial posterior rectus

sheath (superior to the semilunar line). The peritoneal sac

is then bluntly dissected off the psoas muscle, allowing for

retroperitoneal access to the lumbar spine (it is important to

identify and follow the ipsilateral ureter to identify the left

iliac vein and artery).

◦ Exposure is then assisted by a self-retaining retractor (Omni-

Retractor, Omni, St. Paul, MN). The left iliac artery and vein

are retracted medially and segmental vessels divided later-

ally. It is crucial to avoid injury to vascular and lymphatic

structures (Fig. 48.1).

◦ Following completion of the procedure, hemostasis should

be confirmed and the self-retractor blades removed one by

one to ensure a dry field. The wound is then irrigated and the

abdominal wall reconstructed in plane-by-plane fashion.

• Thoracolumbar (T12 to L2): thoracoabdominal approach¹

◦The patient is secured in the lateral decubitus position. Ap-

proach is mostly via the left side.

◦ An obliquely oriented thoracoabdominal incision is made

and extended from the tenth or eleventh rib to the abdomi-

nal wall.

◦The rib is dissected free from its bed via division of subcutane-

ous tissues, serratus anterior, latissimus dorsi, and intercostal

320 IV Surgical Techniques

External oblique m.

Internal oblique m.

Transversalis fascia

Ureter

Gonadal vessels

Psoas m.

L3 segmental artery

Inferior vena cava

Genitofermoral nerve

Fig. 48.1 Lateral view of the retroperitoneal approach to the lumbar spine.

muscles. The rib should be exposed at its superior border to

avoid the neurovascular bundle below. The rib dissection is

followed obliquely to the abdominal wall by dividing the ex-

ternal and internal oblique muscles. However, this distance

should be limited to minimize postoperative muscular dys-

function. The transversalis layer is visible deep to the split

costal margin and can be divided to expose the peritoneum.

◦The peritoneum is ventrally dissected of overlying struc-

tures (diaphragm and psoas muscle) to open the retroperi-

toneal space.

◦ The diaphragm is taken down, leaving a distal cuff for repair,

avoiding the more central region to prevent damage to the

phrenic nerve. The lung is gently compressed cranially with a

moist lap pad. The parietal pleura is now visualized and can be

opened to access the anterior thoracolumbar spine.

◦ For access to the anterior disc space, segmental vessels to

the vertebral bodies are dissected and divided. These vessels

must be handled with the utmost care as they pose a signifi-

cant risk for hemorrhage and are a vital supply to both in-

tra- and extraspinal structures. Some advocate preoperative

angiography of the artery of Adamkiewicz to assist surgical

48 Thoracolumbar Spine: Retroperitoneal Approaches

321

approach and diminish the risk of paraplegia. Care should

also be employed to prevent injury to retroperitoneal lym-

phatics (cisterna chyli and thoracic duct) and the develop-

ment of large lymphoceles.

◦ Following completion of the procedure, if the diaphragm

was incised, a large-bore chest tube is applied and the dia-

phragm repaired with nonabsorbable sutures. The thoracic

cavity is then closed by employing rib-approximating su-

tures and repairing the intercostalis musculature. The ante-

rior abdominal wall, serratus anterior, and latissimus dorsi

muscles are reapproximated and reconstructed plane by

plane via running nonabsorbable sutures.

• Management of vascular anatomy

◦ Vascular concerns related to such approaches include man-

aging the aorta, inferior vena cava, iliac vessels, iliolumbar

vein, and segmental vessels.

◦ With regard to the major vessels in the thoracolumbar and

lumbar regions, the aorta usually is more toward the left

side of the spinal column and the inferior vena cava is more

toward the right side. Such anatomy should be reviewed and

confirmed preoperatively. Most surgeons prefer to approach

the patient from the left, as aortic damage is easier to repair

than damage to the vena cava. However, if pathology is ec-

centric to one side, the surgeon should be prepared to ap-

proach from either side.

◦ Iliac vessels, which are the caudal extensions of the aorta

and inferior vena cava, usually are not encountered with a

lateral approach unless L5 is involved with the pathology.

◦ The iliolumbar vein is an important direct tether in a left-sided

dissection at L4-L5 or lower. This lumbar vein crosses from the

inferior vena cava to approximately the level of the L5 body.

Any dissection that exposes L4-L5 to the left of the left common

iliac vein and inferior vena cava requires the identification, liga-

tion, and division of the iliolumbar vein. Start at the L4-L5 disc

and dissect distally to the L5 body until the iliolumbar vein is

visualized.

◦ Segmental arteries and veins lie at the lateral aspect of the

vertebral bodies within the “valleys” of the lateral spine.

Such vessels must be identified and ligated prior to exposure

of the lateral vertebral body with subperiosteal dissection. If

a segmental artery is sectioned with a Bovie cautery device

(Bovie Medical Corp., Clearwater, FL), it may retract toward

the aorta and continue bleeding. Therefore, early identifica-

tion and ligation are paramount with exposure.

322 IV Surgical Techniques

- Complications

• Retroperitoneal fibrosis, rectus muscle hematoma, pancreatitis,

femoral nerve palsy, ureteral injuries, lymphoceles, pseudo-

meningocele, latissimus dorsi rupture, impotence, and retro-

grade ejaculation^2,5,6

• Acutely developing lymphoceles can be remedied by oversew-

ing the lymphatic chain with a nonabsorbable suture.

- Outcomes

• Advantages of a conventional open retroperitoneal approach rel-

ative to a posterior approach include higher rates of fusion due to

the ability to place larger interbody fusion devices, the ability to

perform more complete disc excisions, and a reduced incidence

of nerve damage. Furthermore, this approach is associated with

decreased pulmonary complications and length of hospital stay.

• A conventional retroperitoneal approach is also associated

with better outcomes in comparison with an anterior trans-

peritoneal approach. For example, in addition to avoidance of

large-vessel and bowel injury, the retroperitoneal approach is

associated with a decreased incidence of retrograde ejacula-

tion for exposures of L4-L5.

III. General Postoperative Care for Retroperitoneal

Approaches

- Retroperitoneal approaches do not typically require bowel rest

in the postoperative period, unlike the transperitoneal approach.

Nonetheless, although infrequent, bowel injury can occur via

a retroperitoneal approach and is primarily identified by ileus

and/or peritoneal irritation. Therefore, caution must be taken to

identify and assess patients demonstrating signs of peritoneal ir-

ritation or dysfunction such as an absence of flatus.

- Patients should be monitored for the development of deep vein

thrombosis (DVT) and potential pulmonary embolisms (PEs).

Patients are at high risk for developing DVT or PEs due to the

significant manipulation of the deep veins (particularly the

iliac vein), which commonly leads to the formation of venous

thrombi.

IV. Surgical Pearls

- As a general rule in any spine surgery, segmental vessels ob-

structing the target structure must be ligated on the anterior

portion of the vertebral body to preserve optimal collateral cir-

culation to the neuroforamen and spinal cord.

48 Thoracolumbar Spine: Retroperitoneal Approaches

323

- In mobilizing or traversing the psoas muscle, two things should

be considered. First, it is beneficial to stay on the anterior third of

the psoas muscle to prevent nerve root injury. Second, it is impor-

tant to visualize and protect the genitofemoral nerve running on

the surface of the psoas muscle. This prevents complications such

as retrograde ejaculation or paresthesias of the anterior thigh.

Common Clinical Questions

1. Retroperitoneal approaches are preferentially done on the left

side of the patient for all the following reasons except:

A. It is generally safer to mobilize the aorta than the inferior

vena cava

B. The common iliac vein may be more prominent on the right

side

C. The presence of the liver may minimize exposure

D. The left ureter is less susceptible to injury than the right

ureter

2. Complications of retroperitoneal exposure include all of the fol-

lowing except:

A. Retroperitoneal fibrosis

B. Appendicitis

C. Ureteral injury

D. Femoral nerve palsy

3. To obtain adequate exposure, an essential component of the

thoracoabdominal approach is:

A. Incising the diaphragm along along the costal margin and

leaving a cuff attached to the rib

B. Transecting the psoas to allow full retraction of the muscle

C. Dissection of the lumbar plexus from the overlying psoas

muscle

D. Avoiding sacrifice of segmental arteries

324 IV Surgical Techniques

References

1. Gumbs AA, Bloom ND, Bitan FD, Hanan SH. Open anterior approaches for

lumbar spine procedures. Am J Surg 2007;194(1):98-102

2. Gumbs AA, Shah RV, Yue JJ, Sumpio B. The open anterior paramedian retro-

peritoneal approach for spine procedures. Arch Surg 2005;140(4):339-343

3. McAfee PC, Bohlman HH, Yuan HA. Anterior decompression of traumatic tho-

racolumbar fractures with incomplete neurological deficit using a retroperi-

toneal approach. J Bone Joint Surg Am 1985;67(1):89-104

4. Payer M, Sottas C. Mini-open anterior approach for corpectomy in the thora-

columbar spine. Surg Neurol 2008;69(1):25-31, discussion 31-32

5. Patel AA, Spiker WR, Daubs MD, Brodke DS, Cheng I, Glasgow RE. Retro-

peritoneal lymphocele after anterior spinal surgery. Spine (Phila Pa 1976)

2008;33(18):E648-E652

6. Peng CW, Bendo JA, Goldstein JA, Nalbandian MM. Perioperative outcomes

of anterior lumbar surgery in obese versus non-obese patients. Spine J

2009;9(9):715-720

Answers to Common Clinical Questions

1. D

2. B

3. A

49 Open and MIS Lumbar Microdiscectomy

Ali A. Baaj and Mark S. Greenberg

I. Key Points

- Conservative therapy is the initial and primary treatment mo-

dality for radiculopathy caused by a herniated nucleus pulpo-

sus (HNP) in the lumbar spine.

- Lumbar microdiscectomy is a safe and effective procedure

when the indication is appropriate.

- Cauda equina and conus syndromes caused by HNP in the lum-

bar spine constitute neurosurgical emergencies and require

immediate evaluation.

II. Indications

- Symptomatic HNP

• Radiculopathy (after 6 to 8 weeks of failed conservative therapy)

• Cauda equina syndrome

• Conus syndrome

- Not for isolated axial low back pain

- No instability on preoperative dynamic plain radiographs

III. Technique

Open

- The patient is placed in the prone position.

• Use of a Wilson frame may widen the interlaminar space and

assist in access.

- Fluoroscopy is used for localization.

- A 2 to 3 cm midline incision is made with a number 10 scalpel.

- A subperiosteal dissection of tissue from spinous process and

lamina on the ipsilateral side is performed.

• Supraspinous and interspinous ligaments should be preserved.

- The medial facet joint is the lateral limit of the dissection.

- A retractor (e.g., Williams or Taylor) is placed.

- The inferior lamina of the superior level and superior lamina of

the inferior level are identified and confirmed with fluoroscopy.

- Using a high-speed drill, a laminotomy (usually) is performed

by drilling the inferior part of the superior level.

• For inferior fragment migration, some of the superior lamina

from the inferior level may need to be removed.

326 IV Surgical Techniques

- Ligamentous flavum is removed with curette and Kerrison

punch.

- The operative microscope is brought in.

- The nerve sleeve and dura are gently retracted medially (Fig.

49.1).

- The posterior longitudinal ligament (PLL) and annulus fibrosus

are incised with a number 11 blade, medial to lateral (always

incise away from dura).

- Disc material is removed with a pituitary rongeur.

• The surgeon must have an understanding of where the an-

terior longitudinal ligament (ALL) is to prevent inadvertent

penetration into the retroperitoneal vessels with the pituitary

rongeur.

- The disc space is irrigated and loose disc tissue is removed.

- An instrument (e.g., Woodson or dental dissector) is passed be-

neath the dura to ensure there is no residual fragment.

- A nerve hook is used to probe under the PLL superior and infe-

rior to the disc space to check for residual.

- The fascia is closed with 0 or 2-0 absorbable suture.

- The subcutaneous layer is closed with inverted, interrupted 3-0

absorbable suture.

- The skin is closed with running suture, staples, or skin adhesive.

Fig.

49.1 Dorsal view of lami-

notomy defect showing thecal sac,

traversing nerve root

(retracted

medially), and herniated disc.

49 Open and MIS Lumbar Microdiscectomy

327

Minimally Invasive Technique

- After correct positioning and localization, a 12 to 16 mm inci-

sion is made 10 mm lateral to the midline on the appropriate

side.

- The thoracodorsal fascia is incised with blade or cautery, and

serial dilators are positioned with the use of fluoroscopy.

- The final dilator and working tube should be docked over the

interlaminar space with visualization of the inferior lamina of

the superior level.

- The operative microscope is brought in.

- Soft tissue is dissected and drilling is performed until ligamen-

tum flavum is reached.

• If drilling is done too laterally, the pedicle or facet joint is at

risk; confirm location with fluoroscopy if needed.

- The ligament is removed and discectomy is performed as in the

open approach.

- If a wider decompression is needed, the working tube may be

repositioned to allow access to more lamina, and even the con-

tralateral foramen.

IV. Complications

- Cerebrospinal fluid (CSF) leak (5 to 8%)¹

• Attempt primary repair using nonabsorbable suture (typi-

cally challenging).

• Alternatively, cover with Gelfoam (Pfizer, New York) and/or

fibrin glue.

- Nerve root injury (1%)

- Wound infection (1%)

- Vascular injury (<1%)

• Suspected injury to the iliac vessels anteriorly (e.g., bright red

blood from disc space or sudden, unexplained drop in blood

pressure) requires immediate wound closure, repositioning of

patient to supine, and immediate vascular surgery consult.

V. Postoperative Care

- Mobilize early; no need for bracing.

- Discharge to home when patient meets discharge criteria (typi-

cally, ambulating, tolerating a diet, voiding, and receiving ad-

equate pain control from oral medications—usually same day

or on post-op day 1).

328 IV Surgical Techniques

VI. Outcomes

- There is an 85% chance of a good (minimal symptoms) or excel-

lent (asymptomatic) outcome.²

- First recurrence is usually treated with repeat microdiscecto-

my. Further recurrence may necessitate fusion.

- Multiple randomized trials have been plagued by crossovers

between cohorts, and the most definitive statement that can

be made is that decisions for surgery versus conservative treat-

ment based on symptoms, duration, and patient preference re-

sults in similar good outcomes in both treatment groups.³

VII. Surgical Pearls

- Ensure the HNP is the pain/symptom generator based on exam

and imaging.

- Minimal disruption of medial facet (don’t confuse the facet for

the lamina during the initial approach)

- Overly aggressive drilling of facet may lead to instability.

- Ensure you are not in a nerve root axilla when performing

discectomy.

- Preoperative dynamic films may be necessary to rule out

instability

- May need hemilaminectomy or complete laminectomy if treat-

ing large central disc (e.g., for cauda equina or conus syndrome).

Common Clinical Questions

1. What is the best way to avoid drilling into the facet joint or ped-

icle during MIS discectomy?

2. When evaluating for recurrent lumbar herniated disc, what ra-

diologic examination is most appropriate?

3. When evaluating a recurrent lumbar herniated disc, what radio-

logic exam is helpful in ruling out instability?

49 Open and MIS Lumbar Microdiscectomy

329

References

1. German JW, Adamo MA, Hoppenot RG, Blossom JH, Nagle HA. Perioperative

results following lumbar discectomy: comparison of minimally invasive dis-

cectomy and standard microdiscectomy. Neurosurg Focus 2008;25(2):E20

2. Hoffman RM, Wheeler KJ, Deyo RA. Surgery for herniated lumbar discs: a

literature synthesis. J Gen Intern Med 1993;8(9):487-496

3. Weinstein JN, Tosteson TD, Lurie JD, et al. Surgical vs nonoperative treat-

ment for lumbar disk herniation: the Spine Patient Outcomes Research Trial

(SPORT): a randomized trial. JAMA 2006;296(20):2441-2450

Answers to Common Clinical Questions

1. Obtain anteroposterior/lateral fluoroscopy shots intraoperative-

ly to confirm location.

2. MRI with and without contrast

3. Flexion-extension x-rays

50 Lumbar Foraminotomy (MIS)

Ali A. Baaj and Juan S. Uribe

I. Key Points

- Removing more than one-third of the medial facet joint when

performing a foraminotomy could lead to instability.

- The combination of a high-speed drill and small-caliber Kerrison

rongeur should be utilized to safely perform a foraminotomy.

- Foraminal stenosis and nerve root compression are the result of

hypertrophy/degeneration of the superior articulating facet of

the lower vertebra.

II. Indications

- Focal lateral recess and/or foraminal stenosis

III. Technique

- The patient is placed in the prone position.

• A Wilson radiolucent frame is adequate if no fixation is

planned.

- Fluoroscopy is utilized for localizing the level of the foramen.

- A paramedian 2 to 3 cm incision is made 1 cm lateral to the

midline.

- The fascia is incised with a monopolar cautery.

- Serial dilators and a nonexpandable tube retractor are placed

under fluoroscopic visualization.

• The optimal arrangement is to dock the dilator/tube retractor

on the inferior aspect of the lamina of the superior level. For

example, for a L4/L5 foraminotomy, the tube is positioned on

the inferior aspect of the L4 lamina.

• This approach is similar to that of minimally invasive surgery

(MIS) for microdiscectomy

- The operative microscope is brought over the field.

• This is optional, but the microscope provides for better illumi-

nation and visualization through the tubular retractor.

- The inferior aspect of the lamina is drilled until the underlying

ligamentum flavum is visualized.

- With the use of nerve hooks, curettes, and Kerrison rongeurs,

the ligamentum flavum is resected.

- The traversing nerve root is typically visualized at this point.

50 Lumbar Foraminotomy (MIS)

331

- The medial facet is undermined until the medial pedicle is pal-

pated with a Woodson or ball-ended probe.

- With a number 2 Kerrison, the foramina above and below the

pedicle are widened and hypertrophied ligament is resected

until the shoulder of the exiting root is visualized.

- A ball-ended probe should pass easily in the foramina to con-

firm adequate decompression.

- The space is irrigated and the fascial, subcutaneous, and skin

layers are closed in standard fashion.

• Subfascial drains are not typically used.

IV. Complications¹

- Cerebrospinal fluid (CSF) leak (<5%)

• Technically challenging to repair primarily through the MIS

tube

- Nerve root injury (<1%)

- Wound infection (<1%)

V. Postoperative Care

- Mobilize early without brace.

- Discharge to home when patient meets discharge criteria.

• Typically same day or postoperative day 1

VI. Outcomes

- The presumed benefits of MIS foraminotomy include reduced

blood loss, less tissue damage, and shorter hospital stays. How-

ever, no randomized trial has compared traditional open with

MIS foraminotomy.

VII. Surgical Pearls

- Leaving the ligamentum flavum intact until all the “bony work”

is completed protects the dura during drilling and when the

Kerrison punches are in use.

- Aggressive drilling of the facet to remove more than one-third

may lead to facet joint instability.

- Patients whose history and exam findings of radiculopathy cor-

relate with the foraminal stenosis seen on imaging will likely

have the best outcomes from this procedure.

51 Lumbar Laminectomy

Armen Deukmedjian, Ali A. Baaj, and Juan S. Uribe

I. Key Points

- An adequate lumbar laminectomy affords good central decom-

pression and lateral gutter decompression, and sets the stage

for foraminotomies at the corresponding spinal levels.

- Removing more than one-third of the medial facet joints during

a laminectomy could accelerate degeneration and cause insta-

bility, necessitating a subsequent fusion.

II. Indications

- Focal or multilevel lumbar central and lateral recess stenosis

III. Technique

- Place patient in the prone position.

• A Wilson frame is adequate if no instrumentation is planned;

otherwise an OSI table is generally used.

- Localize with fluoroscopy.

- Make a midline incision at the appropriate level and perform a

subperiosteal dissection to detach the erector spinae muscles

from the lamina.

- Stop at the medial aspect of the facet joint. Do not disturb the

facet joint capsule.

- Use a Horsley or Leksell rongeur to remove the spinous

process(es).

- Use a drill with an AM-8 bit to complete the laminectomy; al-

ternatively, use Kerrison and Leksell rongeurs.

• The facets are often hypertrophied, and the medial one-third

can be drilled or removed with Kerrison rongeurs.

- Know your landmarks and be careful to avoid drilling the facet

joint, pedicle, or pars.

- Remove the ligamentum flavum with Kerrison rongeurs to

complete the decompression.

- Use a ball-ended probe to inspect the foramina (Fig. 51.1).

• Use the number 2 Kerrison if necessary to perform the

foraminotomy.

- Use a subfascial drain if the wound is extensive.

- Ensure a tight fascial closure and close the skin in the standard

fashion.

334 IV Surgical Techniques

Fig. 51.1 Dorsal view of lumbar spine show-

ing decompressed thecal sac and nerve roots

with laminectomy taken to the medial facets

laterally.

IV. Complications

- Cerebrospinal fluid leak (CSF) leak (0.3 to 13%; increases to

about 18% in redo operations)¹

• Should be repaired using nonabsorbable suture

- Neurologic deficit (0.3%)¹

- Wound infection (1 to 5%)²

- Spondylolisthesis³

- Death (0.06%)¹

V. Postoperative Care

- Mobilize early without brace.

- Remove drain when output drops below 50 ml per 8-hour shift

(typically postoperative day 1).

- Discharge home when patient meets discharge criteria.

VI. Outcomes

- Review of literature reveals 60 to 70% with good to excellent

results.^1-4

- Reoperation in 10 to 30% for recurrent/adjacent-level stenosis,

spondylolisthetic stenosis, or instability^1,3-5

VII. Surgical Pearls

- With advanced degenerative disease, obtain preoperative dy-

namic films to rule out a dynamic spondylolisthesis.

51 Lumbar Laminectomy

335

- Leaving the ligamentum flavum until all the “bony work” is

completed protects the dura during drilling and use of the Ker-

rison punches.

Common Clinical Questions

1. Why are preoperative dynamic x-rays sometimes obtained be-

fore a lumbar laminectomy?

2. During lumbar laminectomy, what location is associated with

the highest likelihood of a CSF leak?

References

1. Greenberg M. Handbook of Neurosurgery. 7th ed. New York: Thieme Medical

Publishers; 2010:448-450

2. Turner JA, Ersek M, Herron L, Deyo R. Surgery for lumbar spinal stenosis.

Attempted meta-analysis of the literature. Spine (Phila Pa 1976) 1992;

17(1):1-8

3. Caputy AJ, Luessenhop AJ. Long-term evaluation of decompressive surgery for

degenerative lumbar stenosis. J Neurosurg 1992;77(5):669-676

4. Tuite GF, Stern JD, Doran SE, et al. Outcome after laminectomy for lumbar spi-

nal stenosis. Part I: Clinical correlations. J Neurosurg 1994;81(5):699-706

5. Katz JN, Lipson SJ, Larson MG, McInnes JM, Fossel AH, Liang MH. The outcome

of decompressive laminectomy for degenerative lumbar stenosis. J Bone

Joint Surg Am 1991;73(6):809-816

Answers to Common Clinical Questions

1. To rule out spondylolisthesis

2. The superior aspect of the lamina, or in the lateral recess if there

is significant stenosis

52 Posterior and Transforaminal Lumbar

Interbody Fusion (PLIF/TLIF) (Open)

Devin Vikram Amin and Adam S. Kanter

I. Key Points

- Arthrodesis across one or more vertebral disc spaces is indi-

cated in conditions that produce spinal instability.

- Bilateral posterior lumbar interbody fusion (PLIF) may be per-

formed at L5-S1 with less potential for neural injury due to the

enlarged capacity of the neural canal at this level.

- A primary advantage of the transforaminal lumbar interbody

fusion (TLIF) procedure over PLIF is the reduction in nerve root

retraction, and thus in neural complications.

II. Indications

- Spondylolisthesis grade I or II

- Reoperation for pseudarthrosis

- Degenerative disc disease causing discogenic low back pain

- Recurrent disc herniation with mechanical back pain, or recurrent

radiculopathy

- Lumbar deformity with coronal or sagittal plane imbalance

- Neural foraminal stenosis from disc space collapse

III. Technique

Transforaminal Lumbar Interbody Fusion

- Exposure of the disc space

• Expose the vertebral spinous process and lamina of the levels

above and below the operative disc space using lateral x-ray

to confirm the anatomic level. In the case of a L4-L5 TLIF, the

medial facet joint (inferior articular process) of the L4/L5 in-

terspace on the primary symptomatic side is removed.

• This is performed with a high-speed drill or osteotome to cre-

ate a sagittal cut in the lamina and a transverse cut through

the pars interarticularis directly over the exiting nerve root at

the inferior aspect of the pedicle of the index neural foramen.

• The joint capsule and ligamentum flavum can be detached

with monopolar electrocautery. A Leksell rongeur is used to

remove the medial facet, which is morselized for fusion auto-

graft. The superior (or lateral) facet of the caudal level is then

52 Posterior and Transforaminal LIF

337

removed with a Kerrison rongeur until the superior aspect of

the next pedicle is encountered. Care must be taken to avoid

injury to the exiting nerve root within the foramen at this level.

• The shoulder of the traversing nerve root is visualized exit-

ing the thecal sac at the level of the disc space. The medial

and superior borders of the caudal pedicle limit the amount of

the superior facet that can be removed. A high-speed drill can

be used to shave bony osteophytes to optimize the trajectory

into the disc space and minimize nerve root retraction during

interbody graft placement.

- Discectomy

• The discectomy is performed by incising the annulus with

a scalpel and then using curettes and pituitary rongeurs to

remove the nucleus pulposus and cartilaginous end plates,

thus exposing the bony surface of the vertebral end plates for

fusion.

• Preservation of the bony end plates will serve to prevent graft

subsidence into the cancellous portion of the vertebral body.

- Interbody grafting

• An interbody graft of the appropriate size is packed with au-

tograft or other fusion substrate¹ and carefully impacted into

the disc space.¹ A nerve retractor is placed against the travers-

ing nerve root shoulder to protect it during graft placement.

• The interbody graft should not protrude beyond the dorsal as-

pect of the adjacent vertebrae.

- Pedicle screw placement

• The pedicle screw entry point is indicated by the mamillary

process: the junction of the transverse process, superior facet,

and pars interarticularis. The lateral to medial trajectory var-

ies generally from 5 to 20 degrees from L1 to L5 (i.e., 5 degrees

at L1 and increasing at 5 degree increments per caudal level).

• The rostral to caudal trajectory should parallel the pedicle as

directed by palpation with a Woodson-Adson or similar in-

strument if a decompression has been performed, or alterna-

tively, using intraoperative fluorscopy or image guidance.

• Once the pedicle screws have been placed, a lordotic rod is

inserted and the cap screws are tightened with compression

across the screw heads. This restores lordosis and compresses

the interbody graft to prevent graft migration and facilitate

fusion.

- Closure

• A multilayer closure is performed using absorbable sutures in

the lumbodorsal fascia and subdermis. Staples or nylon su-

ture is used to close the skin.

338 IV Surgical Techniques

• If a surgical drain has been left in the wound, it is secured to

the skin with suture and the wound is covered with an ap-

propriate dressing.

Posterior Lumbar Interbody Fusion

- The PLIF procedure is similar to TLIF with respect to exposure,

discectomy, and closure.

- The key difference is that the approach to the disc space is more

medial and a portion of the facet remains, necessitating neural

element retraction for discectomy and interbody graft place-

ment (Fig. 52.1).²

- Laminectomy is routinely performed with a high-speed drill

and rongeurs, following which the ligamentum flavum is re-

sected to expose the thecal sac. Bilateral foraminotomies are

routinely performed with a Kerrison rongeur to ensure ad-

equate nerve root decompression, but the distal aspects of

the roots themselves are not typically exposed as in the TLIF

procedure.

- Once visualization has been accomplished, a dural retractor is

used to medialize the neural elements and expose the underly-

ing disc space.

- The discectomy, graft placement, and pedicle screw construct

techniques are similar to those for the TLIF technique. Careful

attention must be paid during intervertebral work to limit me-

dial retraction of the neural elements. ³

Fig. 52.1 An implant filled with cancellous bone graft is inserted into the rectangu-

lar channel. Note the teeth of the cage that engage the vertebral bone. (From Fessler

R, Sekhar L, Atlas of Neurosurgical Techniques, Thieme; pg. 686, Fig. 95-3B.)

52 Posterior and Transforaminal LIF

339

IV. Complications

- Dural tear (5 to 14%) can occur at any stage of the procedure,

but most commonly occurs during the thecal sac and nerve

root exposure.⁴

- Nerve root injury secondary to retraction has been reported

in up to 13% of cases, with resultant radiculopathy, typically

transient.

- Vascular injury during the discectomy, typically from breach of

the anterior longitudinal ligament, requires packing of the disc

space, emergency closure, and vascular consult for laparotomy

and/or interventional repair of the injured vessel.

- Infection (1 to 5%), typically with skin flora

V. Postoperative Care

- Mobilize early; consider deep vein thrombosis (DVT) prophy-

laxis if patient is not ambulating on post-op day 1.

- Pain management with patient-controlled administration of

narcotics augmented with muscle relaxants, and transition

early to oral medications

- Discontinue wound drain based on output (e.g., less than 100

ml in 24 hours).

VI. Outcomes

- Clinical success rate is typically 75% for relief of mechanical

back pain and radiculopathy.

- Fusion rates around 90% have been reported in multiple series.⁵

VII. Surgical Pearls

- Strict dissection along the periosteum minimizes blood loss.

- PLIF procedures may be more suited to the L5 to S1 disc space.

- Nerve root retraction can be reduced or eliminated with the

more lateral to medial trajectory of the TLIF procedure.

- The introduction of pedicle screw and rod constructs has re-

duced the incidence of pseudarthrosis from TLIF and PLIF

procedures.

340 IV Surgical Techniques

Common Clinical Questions

1. A patient with known tethered cord would be better suited for

which lumbar interbody fusion procedure?

2. The pars interarticularis is transected completely in which lum-

bar interbody fusion procedure?

3. The lateral to medial trajectory is greatest for pedicle screws

inserted at which lumbar level?

References

1. Mummaneni PV, Rodts GE Jr. The mini-open transforaminal lumbar inter-

body fusion. Neurosurgery 2005;57(4, Suppl):256-261

2. Khoo LT, Palmer S, Laich DT, Fessler RG. Minimally invasive percutaneous pos-

terior lumbar interbody fusion. Neurosurgery 2002;51(5, Suppl):S166-S1

3. Cole CD, McCall TD, Schmidt MH, Dailey AT. Comparison of low back fusion

techniques: transforaminal lumbar interbody fusion (TLIF) or posterior

lumbar interbody fusion (PLIF) approaches. Curr Rev Musculoskelet Med

2009;2(2):118-126

4. Greenberg MS. Handbook of Neurosurgery. 6th ed. New York: Thieme Medi-

cal Publishers; 2006:744-748.

Answers to Common Clinical Questions

1. TLIF. The degree of neural element retraction is less with the

TLIF procedure, which reduces the risk of traction on the conus

medullaris.

2. TLIF. A complete medial facetectomy is part of the TLIF technique.

3. L5. The angle increases from 5 to 20 degrees as the lumbar level

increases from L1 to L5.

53 Minimally Invasive Transforaminal Lumbar

Interbody Fusion (MIS TLIF)

Michael Y. Wang

I. Key Points

- Minimally invasive transformational lumbar interbody fusion

(MIS TLIF) can be utilized to achieve lumbar spinal decompres-

sion, fixation, and fusion.

- The intent behind this approach, which is still unproven, is to

reduce soft-tissue injury, blood loss, recovery time, and length

of hospital stay associated with open TLIF.

- It is important to recognize the anatomic landmarks at the

interpedicular space, referred to as a Kambin triangle: me-

dial (traversing root), lateral (exiting root), and base (inferior

pedicle)

II. Indications

Harms first described the transforaminal lumbar interbody fusion

(TLIF) technique for circumferential fusion in 1982 using an in-

terbody spacer and a supplemental pedicle screw construct.¹ This

procedure was a departure from the traditional posterior lumbar

interbody fusion (PLIF) in that the TLIF required only a unilateral

facetectomy and a single interbody cage. TLIF then became popular

due to the lower rates of nerve root injury given the reduced surgical

manipulation of neural elements, and it was also found to be effec-

tive for revision surgery because the midline dural sac did not have

to be exposed.

A minimally invasive approach for accomplishing the TLIF pro-

cedure was subsequently developed.² This technique utilized the

advantages of expandable working tubes and percutaneous pedicle

screw technology to reduce the soft-tissue injury that has been doc-

umented to result from open surgery.³ Although no class I evidence

exists to demonstrate the superiority of MIS TLIF over open TLIF,

comparative studies suggest a trend toward reduced postoperative

pain, hospital length of stay, infection rates, and blood loss.⁴ MIS TLIF

can generally be applied in all situations where an open TLIF can be

used.

- Single- or two-level degenerative disc disease with correlative

clinical symptoms

- Spondylolisthesis less than Meyerding grade III

342 IV Surgical Techniques

- Recurrent lumbar disc herniation

- Spondylosis with radiculopathy and back pain

- Focal spinal deformity concentrated at less than three interseg-

mental levels

- Synovial cysts exhibiting spinal instability

III. Technique

There are several variations of the MIS TLIF technique. Here a stan-

dard approach is described that has been successfully utilized by

numerous surgeons.

- The patient is positioned prone on a Jackson operating room

table, which offers several advantages. The location of the inci-

sion is targeted under fluoroscopy, and two paramedian skin

incisions are made between 3 and 4 cm lateral to the midline.

Sharp incision of the fascia allows for blunt finger dissection

between the longissimus and multifidus muscles along a modi-

fied Wiltse plane (Fig. 53.1).⁵ This not only minimizes trauma

to muscular tissues but also minimizes intraoperative bleeding

and creates a natural plane that allows for efficient maintenance

of the trajectory of the retractors. The approach, if unilateral, is

taken from the side where decompression is most necessary.

Fig. 53.1 Axial magnetic resonance image (MRI) showing the modified Wiltse plane

between the longissimus and multifidus muscles. High MRI signal can be seen along

this plane between the muscles, giving direct access to the facet joints.

53 Minimally Invasive Transforaminal LIF

343

- Tubular dilator retractors are then placed through this plane

and the level confirmed with fluoroscopy. Monopolar cautery

is then used to clear any muscle tissue over the facet joint, mak-

ing sure to expose the lateral aspect of the joint.

- Once the surgeon has confirmed the location of the pars and

the lower pedicle, a quarter-inch osteotome or high-speed burr

is used to remove the facet joint. Either a partial or complete

facetectomy can be performed, with greater bone removal for

cases with more medial compression. Care must be taken not

to drill into the pedicle. After facet removal the lateral aspect of

the ligamentum flavum is visualized. This is resected until the

lateral thecal sac is seen (Fig. 53.2). Autograft bone is saved for

later grafting purposes.

- Further decompression can then be performed as needed,

with removal of ipsilateral ligamentum flavum, decompression

under the pars, or contralateral decompression. This is best

achieved by angling the retractors more medially. Alternative-

ly, bilateral decompression can be accomplished through dual

ports placed on each side.

- After palpation of the caudal pedicle and confirmation of the

location of the exiting and traversing nerve roots, the annulus

is incised, followed by aggressive intervertebral disc removal

and end plate preparation, as with the open technique. This is

followed by intervertebral cage placement.

- The neural elements are reinspected. If a posterolateral fusion

is desired, the dura is covered with Gelfoam (Pfizer, New York)

Fig. 53.2 A Kambin triangle.

344 IV Surgical Techniques

and the lateral facets and transverse processes are decorticated

with a drill. This is followed by bone graft application.

- Supplemental pedicle screw placement can then be accom-

plished either using a mini-open technique (through the re-

tractor with visualization) or percutaneously before or after the

decompression. For the mini-open method, the screw place-

ment is very similar to open TLIF. Various methods are used

for percutaneous targeting, including (1) AP only, (2) the owl’s-

eye en face approach, (3) biplanar fluoroscopy, and (4) image

guidance. All percutaneous methods involve placement of a

joshed needle into the pedicle, followed by the use of a can-

nulated awl and tap to create a screw entry tract. Finally, screw

placement and rod tunneling are used to connect the construct

components.

- A drain is not typically used.

IV. Complications

- Cerebrospinal fluid (CSF) leakage is uncommon with these pro-

cedures because the dural exposure is limited to those areas

that are to be decompressed directly. Dural repair can be dif-

ficult. Some surgeons have advocated leaving the durotomy

unrepaired and applying a collagen sponge locally, which sug-

gests that the limited dead space reduces the risk of CSF leakage

postoperatively.

- Incomplete neural decompression is more problematic than in

open surgery given the small working corridor. Care must be

taken to visualize critical landmarks to ensure that any com-

pression (such as at a far lateral disc) is adequately addressed.

The critical landmarks include the caudal pedicle, pars interar-

ticularis, and lateral ligamentum flavum.

- Nerve root injury is best avoided by maintaining an appre-

ciation of the medial-lateral location in which the surgeon is

working. Careful identification and control of the exiting and

traversing nerve roots prior to discectomy is critical.

- Cage misplacement occurs most frequently when inadequate

disc material has been removed or the bony end plate has been

violated. Care in end plate preparation is essential to minimize

graft settling. In addition, it is desirable that the cage cross the

midline, and this can be confirmed with fluoroscopy.

- Screw misplacement is most commonly the result of poor tar-

geting technique. Thus, close familiarity with one technique

53 Minimally Invasive Transforaminal LIF

345

for ensuring that the pedicle is not breached is essential. The

anteroposterior (AP) targeting techniques are excellent for pre-

venting neural injuries.

- Pseudarthrosis can be minimized but never totally prevented.

Proper end plate preparation, cage sizing, and the use of os-

teobiologic adjuvants will limit this complication. In addition,

attention to postoperative nutrition, bracing, and external elec-

trical bone stimulation are helpful.

V. Postoperative Care

Care after surgery is the same as with open TLIF. Patients should be

rapidly mobilized with physical therapists, with external bracing as

a treatment option. Muscle spasm occurs more commonly with MIS

procedures and is best treated with muscle relaxants and benzodi-

azepines, as opposed to narcotics.

VI. Outcomes

Proper patient selection is vital for achieving excellent outcomes.

Although MIS TLIF has not been conclusively shown to be superior

to open TLIF, several reports suggest this pattern. In a well-selected

population, radiculopathy will show meaningful improvement in 80

to 95% of cases; axial back pain will improve in 70 to 85% of cases.

VII. Surgical Pearls

- In cases where substantial muscle creeps under the edges of

the retractor, consider pharmacologic paralysis. Also consider

removing the retractor and making a longer fascial opening,

followed by placement of a deeper retractor.

- When performing a contralateral neural decompression, leave

the ipsilateral ligamentum flavum intact at first. This will push

the thecal sac ventrally, keeping it out of the way while the con-

tralateral work is being performed.

- Intervertebral disc can be removed efficiently using an insert-

and-rotate scraper. These devices allow entry into collapsed

disc spaces and also effectively remove any disc herniations

causing neural compression.

- Self-distracting cages, usually with a “bulleted” nose, will allow

the placement of larger interbody cages, as it is difficult to use

pedicle screw manipulation of a laminar spreader to open the

disc space in MIS surgery.

346 IV Surgical Techniques

Common Clinical Questions

1. MIS TLIF is utilized because it is believed to result in all of the

following except:

A. Decreased soft-tissue damage

B. Higher fusion rates

C. Shorter hospital stays

D. Reduced blood loss

2. One of the critical maneuvers to reduce neural injury is:

A. Remove more facet bone so that less nerve retraction is

needed

B. Use of intraoperative intravenous steroids

C. Stronger pedicle screw fixation

D. Repair of dural tears

3. When placing intervertebral cages in a MIS TLIF it is important

to:

A. Make sure the cage is higher than 13 mm

B. Make sure the cage is longer than 27 mm

C. Use only nondegradable interbody devices

D. Cross the midline

References

1. Harms J, Rolinger H. A one-stager procedure in operative treatment of spon-

dylolistheses: dorsal traction-reposition and anterior fusion

(author’s

transl). Z Orthop Ihre Grenzgeb 1982;120(3):343-347

2. Schwender JD, Holly LT, Rouben DP, Foley KT. Minimally invasive transforami-

nal lumbar interbody fusion (TLIF): technical feasibility and initial results. J

Spinal Disord Tech 2005;18(Suppl):S1-S6

3. Kawaguchi Y, Matsui H, Tsuji H. Back muscle injury after posterior lumbar

spine surgery. Part 2: Histologic and histochemical analyses in humans.

Spine (Phila Pa 1976) 1994;19(22):2598-2602

4. Dhall SS, Wang MY, Mummaneni PV. Clinical and radiographic comparison

of mini-open transforaminal lumbar interbody fusion with open transfo-

raminal lumbar interbody fusion in 42 patients with long-term follow-up. J

Neurosurg Spine 2008;9(6):560-565

5. Wiltse LL, Bateman JG, Hutchinson RH, Nelson WE. The paraspinal sacro-

spinalis-splitting approach to the lumbar spine. J Bone Joint Surg Am

1968;50(5):919-926

54 Percutaneous Pedicle Screw Placement

Michael Y. Wang

I. Key Points

- Numerous methods can be used for implanting percutaneous

pedicle screws, such as image guidance, en face targeting, and

biplanar fluoroscopy.

- Percutaneous screws can be safely placed in the thoracolumbar

spine using a simple method based primarily on anteroposte-

rior (AP) x-rays.

- Percutaneous screw-rod constructs are a truly minimally inva-

sive surgical (MIS) technique for segmental fixation.

II. Indications

Percutaneous placement of transpedicular screws with connect-

ing rods can find application in virtually any setting where open

screw fixation might be utilized in the thoracolumar spine. For a

fusion setting, this can be employed in conjunction with interbody

fusion for stabilization,¹ such as after an anterior lumbar inter-

body fusion (ALIF), lateral interbody fusion, transforaminal lum-

bar interbody fusion (TLIF), or transsacral fusion. In addition, a

speculum retractor can be used to expose the lateral masses for

posterolateral fusion bed preparation in conjunction with percu-

taneous fixation. Also, percutaneous fixation can be used for stabi-

lization or “internal bracing” in the absence of a bony arthrodesis.²

Thus, whether a fusion is intended or not, percutaneous screw-

rod fixation can be used to confer spinal stability for degenerative,

traumatic, neoplastic, and infectious pathologies.

III. Technique

There are various methods for targeting the pedicles of the lumbar

or thoracic spine. These include (1) frame-based or frameless image-

guided navigation,³ (2) biplanar fluoroscopy in the AP and lateral

views, (3) “en face” or “direct down the pedicle” imaging,⁴ (4) a mini-

open technique with tactile feedback, and (5) an AP-based targeting

method.⁵ This chapter will describe the AP-based targeting method.

- 1. The patient is positioned prone on a radiolucent operating

table. Care is taken to ensure that there are no obstructions to

the fluoroscopic image at the level(s) of interest, as the tech-

nique is heavily dependent on intraoperative imaging.

54 Percutaneous Pedicle Screw Placement

349

- 2. An absolutely precise AP view is registered at the level of

screw placement. This is done by first ensuring that the axial

rotation of the fluoroscope aligns the spinous process equidis-

tant between the right and left pedicles (Fig. 54.1). Either the

fluoroscope can be moved or the bed rotated to register this

image, but the surgeon must compensate for any rotation de-

pending on the method used. The sagittal (Ferguson) angle is

then adjusted so that the anterior and posterior cortical rims

of the upper end plate of the vertebral body are superimposed

into a single line. This ensures that the x-ray beam is complete-

ly aligned with the sagittal plane of the pedicles (and thus an

ideal screw trajectory).

- 3. The skin is then marked so that a cutaneous entry point can

be made 1 to 2 cm lateral to the lateral border of the pedicle.

A Jamshidi needle (MedSurge, Chennai, India) is then inserted

through the skin and directed slightly medially to contact the

bone surface. The needle is then docked at the junction of the

transverse process and facet joint near the mamillary process

(the attachment of the multifidus muscle).

- 4. Once the Jamshidi needle has been docked on this ideal ped-

icle screw starting point, the needle is marked 2 cm above the

skin surface with a surgical marker (Fig. 54.2). The needle is

then hammered into the pedicle to a depth of 2 cm (where the

marking meets the skin surface). The trajectory will be medi-

alized to match the patient’s anatomy (10 to 30 degrees). If a

proper AP image has been obtained, making the Jamshidi nee-

dle parallel to the horizon and parallel to the upper end plate

will place the needle in the proper sagittal orientation.

- 5. So long as the medial wall of the pedicle is not breached at a

depth of 2 cm, there will be no medial pedicle wall violation;

the needle will have passed the depth of the pedicle (and spinal

Fig. 54.1 AP projection on the L5 ver-

tebral body. Note that the upper end

plate of the L5 body is visualized as a

single line and that the spinous pro-

cess is equidistant between the two

pedicles.

350 IV Surgical Techniques

Fig. 54.2

(A) AP view targeting the lower vertebral body. Note the rotation in rela-

tion to the body above (where the spinous process is not in the midline). Docking at

the junction of the facet joint and transverse process is followed by 2 cm of medial

needle advancement. (B) The needle is confirmed on lateral fluoroscopy as having

passed the spinal canal, ruling out pedicle wall violation. (C) An insulating sheath is

used to minimize soft-tissue trauma while an awl and tap are advanced over the K-

wire. (D) Final screw positioning with extension tabs attached to guide rod insertion.

Final construct as visualized on (E) lateral and (F) AP views.

54 Percutaneous Pedicle Screw Placement

351

canal) following 2 cm of advancement. Once the Jamshidi nee-

dle has been placed, the inner stylet is removed and a Kirschner

wire (K-wire) is inserted into the vertebral body.

- 6. The procedure is then conducted at other vertebral levels

with adjustments in fluoroscopic targeting for each level. After

all of the K-wires have been placed, the fluoroscope is moved to

a lateral position. The K-wires are then used to guide an awl and

tap for pedicle preparation as with open surgery. Final pedicle

screw placement is then performed followed by K-wire removal.

- 7. During the procedure, care is taken to ensure that the K-

wires do not violate the anterior vertebral body and enter the

retroperitoneum, which could cause vascular or hollow viscus

injury. In addition, care must be taken not to lose control of the

wires or have them pull out prematurely.

- 8. Following screw placement a percutaneous rod is advanced

subfascially through the screw extensions to connect the seg-

mental levels (Fig. 54.3). Rod insertion can occur through one

of the end screw incisions or through a separate incision distal

to the screws.

- 9. It is helpful to have at least some bend in the rod, as “steer-

ing” the rod medially or laterally is made easier by rotating

the rod along its long axis to turn the tip medially or laterally.

Fig. 54.3 Jamshidi needles and K-wires in place. Note the use of

a long skin incision with placement of instrumentation through

the exposed fascia and the use of a needle driver to control the

K-wire during manipulation.

352 IV Surgical Techniques

Finally, set screws are placed through the screw extensions to

lock the rod to the individual screws.

IV. Complications

The complications associated with percutaneous screw placement

are akin to those encountered with open surgical instrumentation

procedures. In addition, there are risks associated with loss of con-

trol of the K-wires, which can result in inadvertent entry into the

retroperitoneum.

Difficulties can be encountered with initial pedicle cannulation

or with rod passage and screw-rod connection. Use of the AP-based

technique results in a low rate of pedicle violation as long as high-

quality fluoroscopic images are utilized for targeting the Jamshidi

needles. Rod passage and connection techniques are often specific

to the implant manufacturers and the instruments available for rod

and screw manipulation, so they are not described here.

V. Postoperative Care

Care after surgery is the same as with open instrumentation. Pa-

tients should be rapidly mobilized with physical therapists, with

external bracing as a treatment option. Muscle spasm occurs more

commonly with MIS procedures and is best treated with muscle re-

laxants and benzodiazepines as opposed to narcotics.

VI. Surgical Pearls

- In many instances all of the surgery can be accomplished by a

single surgeon standing on the side opposite the fluoroscope.

This improves surgical workflow and minimizes the risk of

contaminating the sterile field. Because of the highly imaging-

dependent nature of the method described here, standing on

the same side as the pedicle screw insertion (which is typical

for open surgery) is much less important.

- When a rod is passed across the thoracolumbar junction it is

usually preferable to pass the rod from cranial to caudal.

- Because the screw head heights and orientation are not imme-

diately visible, the surgeon should be prepared to pass a pre-

pared rod initially, and then remove it and recontour or resize

the implant to achieve the optimal construct. Forcing the screw

and rod to mate may result in screw pullout.

54 Percutaneous Pedicle Screw Placement

353

Common Clinical Questions

1. Percutaneous pedicle screws can be safely inserted using all of

the following techniques except:

A. AP-guided imaging

B. Pure freehand technique

C. Biplanar fluoroscopy

D. Image guidance

2. When using the AP-based technique for percutaneous pedicle

cannulation, how far is the Jamshidi needle advanced before

passing the medial pedicle wall?

A. 1 cm

B. 2 cm

C. 3 cm

D. 4 cm

3. Bending the rod allows what to be accomplished more easily?

A. Cutting the rod to size

B. Reducing spondylolistheses

C. Rod-screw mating

D. Medial and lateral maneuvering

References

1. Schwender JD, Holly LT, Rouben DP, Foley KT. Minimally invasive transforami-

nal lumbar interbody fusion (TLIF): technical feasibility and initial results. J

Spinal Disord Tech 2005;18(Suppl):S1-S6

2. Jeanneret B, Jovanovic M, Magerl F. Percutaneous diagnostic stabilization for

low back pain. Correlation with results after fusion operations. Clin Orthop

Relat Res 1994;304(304):130-138

3. Wang MY, Kim KA, Liu CY, Kim P, Apuzzo ML. Reliability of three-dimensional

fluoroscopy for detecting pedicle screw violations in the thoracic and lum-

bar spine. Neurosurgery 2004;54(5):1138-1142, discussion 1142-1143

4. Magerl F. Verletzungen der Brust- und Lendenwirbelsaule. Langenbecks Arch

Chir 1980;352:428-433

5. Harris EB, Massey P, Lawrence J, Rihn J, Vaccaro A, Anderson DG. Percutane-

ous techniques for minimally invasive posterior lumbar fusion. Neurosurg

Focus 2008;25(2):E12

Answers to Common Clinical Questions

1. B

2. B

3. D

55 Minimally Invasive Lateral Retroperitoneal

Trans-Psoas Interbody Fusion (e.g., XLIF, DLIF)

Edwin Ramos, Ali A. Baaj, and Juan S. Uribe

I. Key Points

- Success with this technique relies heavily on¹

• Careful patient positioning

• Gentle retroperitoneal dissection

• Meticulous psoas splitting with electromyographic (EMG)

monitoring

• Fusion bed preparation with release of contralateral annulus

• Appropriate-size interbody implant placement

II. Indications²

- Axial low back pain caused by

• Degenerative disc disease

• Spinal stenosis (mild to moderate only) with significant back

pain component

• Grade 1 to 2 spondylolisthesis

• Adjacent-segment disc degeneration

• Interbody fusion as stand-alone or adjunct in treatment of de-

generative scoliosis

- Postdiscectomy space collapse with neuroforaminal stenosis

(indirect decompression)

- Total disc replacement

- Thoracolumbar corpectomies

• Burst fractures

• Tumors

• Treatment of deformity with sagittal plane imbalance

III. Technique

- Patient positioning

• The patient is placed on a radiolucent bendable table in true 90

degree lateral decubitus position with the top of the crest just

inferior to the table break.

• Usually the left side is up, unless the crest is higher on that

side or there has been previous surgery on that side.

• Flex the table to increase the distance between the iliac crest

and the ribs. This allows access to the disc space (important at

L4-L5 to clear the crest and above L3 to clear the lower ribs).

55 Minimally Invasive Retroperitoneal Trans-Psoas IF

355

• Localize the skin incision with lateral fluoroscopy by center-

ing crossed K-wires over the disc’s mid-position. For multilev-

el approaches, a single longitudinal incision with individual

transverse fascial openings for each level is adequate.

- Retroperitoneal access (single skin/fascia incision technique)

• Work perpendicular to the floor while dissecting through the

muscle fibers to avoid entry into the peritoneal cavity, which

is anteriorly displaced in the lateral position.

• Entry into the retroperitoneal cavity is confirmed by the appear-

ance of bright yellow fat and a loss of resistance by the muscle

tissues. Finger dissection is then performed so that the surgeon

can feel the psoas muscle deep in the cavity and the transverse

processes posteriorly.

- Trans-psoas approach and retractor placement

• A series of tubular dilators are placed with EMG monitoring.

Directional EMG monitoring (Neurovision, NuVasive, San Di-

ego, CA) allows not only proximity to motor nerves but also the

location of these nerves in relation to the dilator (Fig. 55.1). It

is essential to guide the dilators with the finger to the psoas

muscle to avoid inadvertent entry into the peritoneal cavity.

• Lateral fluoroscopy will guide dilator placement into the mid-

dle (or just posterior to the middle) of the disc space while

bluntly splitting the fibers of the psoas. A K-wire is placed

through the initial dilator and into the disc space to hold it in

place. EMG monitoring is performed with each dilator prior to

the introduction of a larger dilator.

Fig. 55.1 Lateral view of the lum-

bar plexus. Understanding this

anatomy is critical for successful

implementation of the lateral trans-

psoas approach. (From Uribe JS et al.

Defining the safe working zones us-

ing the minimally invasive lateral ret-

roperitoneal transpsoas approach:

an anatomical study, Journal of

Neurosurgery Spine, Aug 2010. Re-

printed with permission.)

356 IV Surgical Techniques

• The retractor is then placed and a shim needle is introduced

to the disc space under AP fluoroscopy to secure it.

- Preparation of the disc space

• The disc space is incised with a knife just anterior to the shim,

with a small rim of disc kept just in front of it to keep the re-

tractor from sliding anteriorly.

• A Cobb elevator is passed along both end plates and through

the contralateral annulus under fluoroscopic guidance.

• A series of instruments (curettes, pituitaries, rasps) are used

to clean the space and prepare the end plates.

- Interbody spacer and instrumentation are then placed.

- The retractor is removed slowly in the open configuration to

allow the psoas muscle to be inspected for bleeding.

- The external oblique fascia is closed with interrupted absorb-

able suture and the skin is closed in a subcuticular fashion.

IV. Complications^1,3,4

- Hip flexor weakness, thigh numbness, quadriceps weakness,

genitofemoral neuralgia

- Abdominal viscera perforation

- Rupture of anterior longitudinal ligament

- Great vessel injury

- Kidney-ureteral injury

- Graft subsidence

- Psoas/retroperitoneal hematoma

- Abdominal wall paresis

- Rhabdomyolysis

V. Postoperative Care

- For single-level lumbar cases the patient is mobilized in the im-

mediate post-op period without a brace. No drains are placed.

- The patient is usually discharged on postoperative day 1 for

single-level cases.

- In case of significant leg weakness or a drop in hematocrit, a

computed tomography (CT) or magnetic resonance imaging

(MRI) scan is indicated to rule out a psoas hematoma.

VI. Outcomes

- If thigh numbness (12 to 75%) occurs (from retraction against

the femoral nerve—anterior femoral cutaneous), it usually

resolves by the time of the 3-month follow-up without treat-

55 Minimally Invasive Retroperitoneal Trans-Psoas IF

357

ment. This is more common at L4-L5 level due to the proximity

of the femoral nerve to the surgical field.¹

- Hip flexor weakness correlates with trauma to the psoas mus-

cle. It is rarely a neurogenic injury. Gentle placement of the di-

lators and retractor limits the incidence of this.

- Quadriceps weakness is likely due to injury of the femoral

nerve.

- Arthrodesis rates and clinical outcomes are similar to those for

other interbody techniques^1-4; however, since the technique is

in its infancy, long-term outcomes are still uncertain.

VII. Surgical Pearls

- Do not proceed with surgery unless perfect AP and lateral pro-

jections of the disc space have been prepared. This is best ac-

complished by careful patient positioning, not by adjusting the

fluoroscopy machines.

- Minimize the amount of lateral flexion of the patient and flex

the ipsilateral hip during positioning. This may decrease the

amount of tension on the lumbar plexus.

- Guide the initial dilator with finger dissection through the ret-

roperitoneal space to prevent visceral injury.

- Ideally no nerves will be encountered during EMG stimulation.

In other than ideal situations, place the nerve posterior to the

retractor, where it can be safely retracted away from the surgi-

cal field without the risk of root avulsion or stretch injury.

Common Clinical Questions

1. Which nerve runs over the psoas muscle and is likely to be af-

fected by a lateral approach at L2-L3?

2. What is the most likely explanation for post-op hip flexor

weakness?

3. Retraction against which nerve at the L4-L5 level is responsible

for post-op anterior thigh numbness?

358 IV Surgical Techniques

References

1. Dakwar E, Cardona RF, Smith DA, Uribe JS. Early outcomes and safety of the

minimally invasive, lateral retroperitoneal transpsoas approach for adult de-

generative scoliosis. Neurosurg Focus 2010;28(3):E8

2. Ozgur BM, Aryan HE, Pimenta L, Taylor WR. Extreme Lateral Interbody Fu-

sion (XLIF): a novel surgical technique for anterior lumbar interbody fusion.

Spine J 2006;6(4):435-443

3. Knight RQ, Schwaegler P, Hanscom D, Roh J. Direct lateral lumbar interbody

fusion for degenerative conditions: early complication profile. J Spinal Dis-

ord Tech 2009; 22(1):34-37

4. Tormenti MJ, Maserati MB, Bonfield CM, Okonkwo DO, Kanter AS. Compli-

cations and radiographic correction in adult scoliosis following combined

transpsoas extreme lateral interbody fusion and posterior pedicle screw in-

strumentation. Neurosurg Focus 2010;28(3):E7

Answers to Common Clinical Questions

1. The genitofemoral nerve

2. Psoas muscle bruising as opposed to damage to femoral nerve

branches to the psoas

3. The femoral nerve (sensory fibers via the anterior femoral cu-

taneous nerve)

56 Anterior Lumbar Interbody Fusion (ALIF)

Krzysztof B. Siemionow and Kern Singh

I. Key Points

- Anterior lumbar interbody fusion (ALIF) offers several potential

advantages over other surgical approaches.

• The ability to perform a complete or subtotal discectomy

• Large surface area for fusion and structural grafting

• Favorable fusion environment (compression)

• Effective for anterior releases, particularly in the setting of

high-grade deformity

• Posterior muscle sparing

• Indirect foraminal decompression

II. Indications

- Spondylolisthesis (typically grade I or II)

- Degenerative disc disease causing mechanical low back pain

- Postdiscectomy collapse with neural foraminal stenosis

- Treatment of posterior pseudarthrosis

- Treatment of post-laminectomy kyphosis

- Treatment of coronal and/or sagittal imbalance

III. Technique

- Place the patient supine on a regular operating table or a flat

Jackson table.

- A bump under the sacrum will allow for increased lumbar

lordosis.

- Slight Trendelenburg position will allow the abdominal con-

tents to displace cephalad away from the surgical field.

- The operative level is identified with lateral fluoroscopy. This

localizes the skin incision (critical for mini-ALIF approaches).

- A left transverse or longitudinal paramedian incision is made.

- The anterior rectus sheath is identified and divided in line with

the skin incision.

- Blunt dissection is used to mobilize the rectus and to identify

its lateral border.

- The lateral edge of the rectus abdominis muscle is retracted to-

ward the midline, exposing the posterior rectus sheath (above

the arcuate line) or, less commonly, the arcuate line and the

preperitoneal space (below the arcuate line).

360 IV Surgical Techniques

- The posterior rectus sheath-arcuate line is carefully divided

in a superior-to-inferior direction and the preperitoneal space

identified.

- Using blunt dissection, the peritoneum is mobilized off of the

anterior and lateral abdominal wall and retroperitoneal blunt

dissection is used to identify the psoas muscle.

- Hand-held retractors are advanced.

- The ureter, peritoneum, and abdominal contents are mobilized

across the midline.

- The psoas muscle is released and then retracted laterally, al-

lowing direct visualization into the disc space.

- With blunt dissection medial to the psoas muscle, the in-

dex disc space is identified and confirmed with a marker and

fluoroscopy.

- Retractors are placed around the lateral annulus, first on the

right side, retracting the abdominal contents and the iliac vein

(Fig. 56.1).

Fig. 56.1 Key anterior retro-

peritoneal structures.

56 Anterior Lumbar Interbody Fusion (ALIF)

361

- Once the disc space is confirmed, an annulotomy is made with

either a knife or electrocautery.

- A Cobb elevator and curette are used to remove the cartilagi-

nous end plates, carefully preserving the subchondral bone/

end plate.

- Pituitary rongeurs are used to remove the disc fragments.

- An interbody graft (allograft, titanium, or polyetheretherketone

[PEEK]) is appropriately sized to gently distract the disc space

and contact the ring apophysis.

- The anterior rectus sheath is closed with nonabsorbable sheath.

The posterior sheath does not require repair.

IV. Complications^1,2

- Iliac vein injury

- Ileus

- Retrograde ejaculation occurs secondary to injury to the su-

perior hypogastric plexus (sympathetic chain). The superior

hypogastric plexus provides innervation to the internal vesical

sphincter. The reported incidence of retrograde ejaculation af-

ter ALIF varies widely in the literature, ranging from 0.4 to 5.9%

of male patients.^3,4

- Ureteral injury

- Deep vein thrombosis

- Abdominal hernia

- Rectus muscle paresis

V. Postoperative Care

- Patients are mobilized on the first postoperative day.

- Diet is advanced as tolerated starting on the first postoperative

day.

- Discharge to home when patient meets discharge criteria (typi-

cally, ambulating, tolerating a diet, voiding, and adequate pain

control on oral medications).

VI. Outcomes

- Satisfactory clinical outcomes can be anticipated in 70% of

patients.⁵

- Fusion rates vary from 85 to 95% in most series and depend on

whether autograft or bone morphogenetic protein (BMP) is used.⁶

- Interbody subsidence is an expected phenomenon and occurs

in as many as 85% of cases, particularly stand-alone grafts.⁷

362 IV Surgical Techniques

VII. Surgical Pearls

- Localize with fluoroscopy prior to making a skin incision.

- Trendelenburg position allows the abdominal contents to move

cephalad out of the operative field. This position also decreases

venous bleeding.

- Avoid the use of monopolar cautery around the sympathetic

chain prior to the annulotomy.

- Take care not to violate the subchondral end plates.

Common Clinical Questions

1. What is retrograde ejaculation and how can the risk be

minimized?

2. At what level does the aorta bifurcate, and why is that important

for anterior spinal procedures?

3. List four indications for anterior lumbar interbody fusion.

References

1. Jarrett CD, Heller JG, Tsai L. Anterior exposure of the lumbar spine with and

without an “access surgeon”: morbidity analysis of 265 consecutive cases. J

Spinal Disord Tech 2009;22(8):559-564

2. Brau SA. Mini-open approach to the spine for anterior lumbar interbody

fusion: description of the procedure, results and complications. Spine J

2002;2(3):216-223

3. Sasso RC, Burkus JK, LeHuec JC. Retrograde ejaculation after anterior lumbar

interbody fusion: transperitoneal versus retroperitoneal exposure. Spine

(Phila Pa 1976) 2003;28(10):1023-1026

4. Tiusanen H, Seitsalo S, Osterman K, Soini J. Retrograde ejaculation after ante-

rior interbody lumbar fusion. Eur Spine J 1995;4(6):339-342

5. Madan SS, Boeree NR. Comparison of instrumented anterior interbody

fusion with instrumented circumferential lumbar fusion. Eur Spine J

2003;12(6):567-575

6. Burkus JK, Transfeldt EE, Kitchel SH, Watkins RG, Balderston RA. Clinical

and radiographic outcomes of anterior lumbar interbody fusion using re-

combinant human bone morphogenetic protein-2. Spine (Phila Pa 1976)

2002;27(21):2396-2408

7. Choi JY, Sung KH. Subsidence after anterior lumbar interbody fusion using

paired stand-alone rectangular cages. Eur Spine J 2006;15(1):16-22

56 Anterior Lumbar Interbody Fusion (ALIF)

363

Answers to Common Clinical Questions

1. Retrograde ejaculation occurs secondary to injury to the supe-

rior hypogastric plexus, a part of the sympathetic chain, which

provides innervation to the internal vesical sphincter. Avoid us-

ing monopolar cautery around the sympathetic chain. Consider

using a posterior approach in young males. When it occurs, ret-

rograde ejaculation results in a normal sexual climax followed

by the lack of ejaculate. Sperm typically is not propelled forward

and ends up in the bladder.

2. In two-thirds of cases, the aorta bifurcates at L4/L5. Approaches

to the L4/L5 intervertebral disc are more challenging and re-

quire mobilization of the iliac vessels.

3. Spondylolisthesis (usually grade I or II), treatment of pseudar-

throsis, postdiscectomy collapse with neuroforaminal stenosis,

and treatment of lumbar deformity with coronal and/or sagittal

imbalance

57 Axial Lumbar Interbody Fusion (AxiaLIF)

Elias Dakwar and Juan S. Uribe

I. Key Points

- Minimally invasive presacral approach for intervertebral dis-

cectomy and fusion

• Originally described for L5-S1 and extended to include L4-L5

• Relies on indirect decompression

• Not intended to be used as a stand-alone, requires supple-

mental fixation such as transfacet pedicle screws or pedicle

screw-rod fixation

II. Indications

- Degenerative disc disease

- Radiculopathy

- Spondylolisthesis (grade I or II)

- Revision

• Pseudarthrosis

• Extension of long fusion to sacrum

III. Contraindications

- Aortic bifurcation below L5-S1 or aberrant midline vessel an-

terior to S1

- Previous pelvic or retroperitoneal surgery

- Inflammatory bowel disease

- Sacral agenesis

- Severe sacral lordosis

- Spondylolisthesis exceeding grade II

IV. Preoperative Management

- Imaging

• Magnetic resonance imaging (MRI) of the lumbar spine (com-

puted tomography [CT] if MRI is contraindicated) including

the tip of the coccyx to evaluate the trajectory, aberrant or

anomalous vascular structures, and presacral fat pad

- Bowel prep performed the day before surgery

• GoLYTELY (Braintree Laboratories, Braintree, MA), 4 L

• MiraLax (Merck, Whitehouse Station, NJ), 64 oz

57 Axial Lumbar Interbody Fusion (AxiaLIF)

365

• Mag Citrate (Metagenics, San Clemente, CA)

- Antibiotics

• Make sure to include anaerobic and gram (negative) coverage.

V. Technique¹

- Setup: biplanar fluoroscopy and radiolucent bed

- Position: prone with the knees below the level of the hips us-

ing Jackson table or OSI table (Mizuho OSI, Union City, CA) with

sling for the legs

- A 20 French catheter is inserted into the rectum and 10 ml of

air is insufflated to improve visualization of the rectum during

fluoroscopy.

- The anus is isolated with an occlusive dressing and the sacro-

coccygeal region is prepped and draped in the usual sterile

fashion.

- A 15 mm skin incision is made 1 cm lateral to the tip of the

coccyx and 2 cm caudal to the left or right paracoccygeal notch.

Be sure to continue the incision through the underlying fascia

(Fig. 57.1).

- Blunt finger dissection is used to develop the presacral space

and push the rectum anteriorly.

Fig. 57.1

(A,B) Schematic diagram depicting the optimal trajectory and entry point

for presacral access to the L5-S1 axial lumbar interbody fusion.

366 IV Surgical Techniques

- A dissecting tool is advanced along the anterior midline of the

sacrum using an oscillating movement to sweep the presacral

fat away from the floor of the pelvis, and it is then docked at the

S1-S2 junction.

- Once the trajectory is confirmed by fluoroscopy, a guide pin is

placed into the sacrum (Fig. 57.1).

- A series of dilators are then carefully placed until the working

cannula is securely docked into the sacrum.

- The guide pin is then removed and a drill is passed into the

sacrum and disc space.

- A series of disc space cutters and wire brushes are used to per-

form the discectomy.

- Once the discectomy is performed, bone graft material is in-

serted into the disc space through the cannula. It is important

to place the bone graft prior to drilling into the body of L5 so

that bone graft material is not packed into that defect.

- An appropriate-size three-dimensional (3D) axial titanium rod

is placed through the sacrum into the disc space and into the L5

vertebral body. The axial rod has a differential pitch that creates

distraction across the disc space as it is rotated.

- Once satisfactory placement of the axial rod is achieved, the

working cannula is removed, and the wound is irrigated and

closed in the standard fashion. Dermabond liquid dressing

(Ethicon, a Johnson & Johnson company, New York) is placed

over the incision as an occlusive dressing.

VI. Postoperative Care

- Mobilize patient early with or without brace, according to sur-

geon preference.

- No procedure-related restrictions

- Discharge to home when patient meets discharge criteria, in-

cluding tolerating regular diet, ambulating, voiding, and ade-

quate pain control on oral medications.

VII. Potential Complications

- Bowel perforation²

- Vascular injury

• Transverse sacral veins or middle sacral artery

- Infection

57 Axial Lumbar Interbody Fusion (AxiaLIF)

367

VIII. Outcomes

- Limited outcomes

- Fusion rate, 91%; Oswestry Disability Index (ODI), decrease of

26 points; Visual Analogue Scale (VAS), decrease of 7 points at

one-year follow-up^3,4

IX. Surgical Pearls

- True anteroposterior (AP) and lateral fluoroscopy images with

continuous imaging throughout the procedure to ensure prop-

er trajectory and safe access

Common Clinical Questions

1. True or false: Axial lumbar interbody fusion relies on indirect

decompression.

2. True or false: Axial lumbar interbody fusion is safe to perform in

patients with a grade III or IV spondylolisthesis.

References

1. Marotta N, Cosar M, Pimenta L, Khoo LT. A novel minimally invasive presacral

approach and instrumentation technique for anterior L5-S1 intervertebral

discectomy and fusion: technical description and case presentations. Neu-

rosurg Focus 2006;20(1):E9

2. Botolin S, Agudelo J, Dwyer A, Patel V, Burger E. High rectal injury during

trans-1 axial lumbar interbody fusion L5-S1 fixation: a case report. Spine

(Phila Pa 1976) 2010; 35(4):E144-E148

3. Aryan HE, Newman CB, Gold JJ, Acosta FL Jr, Coover C, Ames CP. Percu-

taneous axial lumbar interbody fusion (AxiaLIF) of the L5-S1 segment:

initial clinical and radiographic experience. Minim Invasive Neurosurg

2008;51(4):225-230

4. Asgarzadie F. Khoo L, Cosar M, Marotta N, Pimenta L: One Year Outcomes

of Minimally-Invasive Presacral Approach and Instrumentation Technique

for Anterior Lumbosacral Intervertebral Discectomy and Fusion, in 22nd An-

nual CNS mtg, 2007

Answers to Common Clinical Questions

1. True

2. False

58 Facet Screw Fixation/Fusion

Ben J. Garrido and Rick C. Sasso

I. Key Points

- Pedicle screw fixation historically has been the gold standard

for lumbar fusion stabilization. However, criticisms of the pedi-

cle screw construct—including higher complication rates, bulky

hardware, increased pain, and excessive wide soft-tissue dis-

section—have led to a more innovative, minimally invasive fixa-

tion technique. Translaminar facet screws have been found to

be biomechanically advantageous, significantly increasing the

stiffness and stability in compression, extension, flexion, bend-

ing, and torsion of spinal motion segments.^1,2

- Facet screws were first described by King in 1948 as short screws

placed horizontally across the facet joint. Boucher’s modifica-

tions in 1959 included an increased screw length directed more

vertical into the pedicle. Today’s technique includes Magerl’s

1984 modification, involving a longer screw with an entry point

at the base of the contralateral spinous process, increasing its

effective fixation strength by expanding the working length at

both sides of the facet.³

- This technique involves a minimally invasive approach without

significant soft-tissue dissection. Improved outcomes—including

biomechanical stability, decreased complication rates, reduced

reoperation rates, lower operative times, minimal blood loss, and

improved patient-perceived outcomes—have been demonstrated.⁴

- The use of image navigation with this posterior stabilization

technique has been validated as a safe, feasible, economical and

efficient method associated with low screw misplacement rates

and excellent operative field viewing.⁴

II. Indications

- In conjunction with anterior interbody fusion for symptomatic

discogenic pain unresponsive to at least 6 months of aggressive

nonoperative treatment where posterior elements are present,

intact

- Primary circumferential lumbar fusion with less than grade II

spondylolisthesis

- Repair of pseudarthrosis after stand-alone anterior lumbar in-

terbody fusion (ALIF)

58 Facet Screw Fixation/Fusion

369

III. Technique

- The patient is placed in the prone position on a radiolucent

Jackson table frame.

- Image navigation rather than fluoroscopy used to localize

incision.

- A small posterior midline incision is made at the appropriate

level.

- A subperiosteal dissection along the spinous process and lam-

ina to the targeted facet is performed bilaterally. The cephalad

juxtalevel facet joint is not exposed. Supraspinous and interspi-

nous ligaments should be preserved.

- The facet joint is the lateral limit of the dissection.

- A retractor is placed, allowing visualization of both the start

point and contralateral caudal facet joint.

- A small, 2 cm incision is made lateral to the midline incision

to allow a blunt bullet or drill guide to obtain the appropri-

ate trajectory. Dock at the spinolaminar junction and target the

contralateral facet/pedicle.

- Create a pilot hole with a starting awl, leaving enough room for

the contralateral translaminar facet screw along the width of

the spinolaminar junction. Place the first screw at the cephalad,

superior aspect of the spinolaminar confluence and the second

contralateral screw caudal to it in line with the lamina.

- Using a high-speed drill with a long 2.85 mm bit and image

navigation (if available), drill to the contralateral facet/pedicle

using tactile progression through the anatomical bony trajec-

tory. Take care not to breach ventrally into the canal, and ide-

ally stay within the lamina. Measure for screw length off the

calibrated drill.

- While maintaining the drill guide in fixed position, use power

to insert a 4.0 mm screw along the same drilled hole.

- Complete the tightening off power. Avoid overtightening the

screw or fracturing the spinous process.

- Repeat the preceding steps for the contralateral translaminar

facet screw.

- Obtain final imaging studies (Fig. 58.1).

- Decorticate posterior bony elements/lamina and add bone

graft substitute.

- Close the fascia with 0 absorbable suture.

- Close the subcutaneous layer with inverted, interrupted 2-0

absorbable suture.

- Close the skin with running suture or skin adhesive.

370 IV Surgical Techniques

Fig.

58.1 Anteroposterior and lateral views demonstrating

facet screw trajectory.

IV. Complications

- Spinous process fracture

- Ventral trajectory breach with either screw or drill

- Nerve root injury

- Wound infection

- Pseudarthrosis

V. Postoperative Care

- Mobilize early without bracing.

- Discharge home when patient meets discharge criteria (typi-

cally, ambulating, tolerating a diet, voiding, and adequate pain

control on oral medications).

VI. Outcomes

- Reported reoperation rate is 5%, versus 24 to 37.5% for pedicle

screw constructs, a statistically significant difference.⁴

- Operative time and blood loss have been shown to be signifi-

cantly lower in the translaminar facet screw cohort compared

with the pedicle screw population.⁴

- Patient-recorded outcomes include a significant decrease in

postoperative Visual Analogue Scale (VAS) pain scores for both

translaminar facet screw and pedicle screw constructs.⁴

58 Facet Screw Fixation/Fusion

371

VII. Surgical Pearls

- Obtain adequate visualization of the starting point, trajectory,

and contralateral caudal facet joint.

- Plan accordingly for the placement of both screws and the ideal

position prior to drilling.

- Establish an appropriate starting point at the confluence of the

spinous process and lamina. Do not start high on the spinous

process.

- Perform final screw tightening off power and do not overtight-

en or strip the screw, or fracture posterior bony elements.

Common Clinical Questions

1. Which of the following is a characteristic of the translaminar

facet screw?

A. Requires a wide soft-tissue dissection

B. Not a minimally invasive technique

C. Combines an increased working length with greater fixation

strength

D. Can be used with bilateral pars defects

2. Translaminar facet screws have been associated with:

A. Longer operative times

B. Lower rates of reoperation compared with pedicle screws

C. Greater operative blood loss

D. Inferior biomechanical properties relative to pedicle screws

References

1. Heggeness MHO, Esses SI. Translaminar facet joint screw fixation for lumbar

and lumbosacral fusion. A clinical and biomechanical study. Spine (Phila Pa

1976) 1991;16(6, Suppl):S266-S269

2. Ferrara LA, Secor JL, Jin BH, Wakefield A, Inceoglu S, Benzel EC. A biome-

chanical comparison of facet screw fixation and pedicle screw fixation: ef-

fects of short-term and long-term repetitive cycling. Spine (Phila Pa 1976)

2003;28(12):1226-1234

3. Magerl FP. Stabilization of the lower thoracic and lumbar spine with external

skeletal fixation. Clin Orthop Relat Res 1984;189(189):125-141

4. Best NM, Sasso RC. Efficacy of translaminar facet screw fixation in circum-

ferential interbody fusions as compared to pedicle screw fixation. J Spinal

Disord Tech 2006;19(2): 98-103

59 Interspinous Process Decompression

Ravi Ramachandran and Peter G. Whang

I. Key Points

- Lumbar stenosis refers to compression of the thecal sac, which

may result in lower extremity pain/numbness (i.e., neurogenic

claudication).

- Interspinous devices (ISDs) are designed to perform an “indi-

rect” decompression by maintaining flexion of a stenotic seg-

ment, which increases the dimensions of the spinal canal and

foramina.

- Appropriate candidates for ISD should experience clear relief of

their claudication with lumbar flexion (i.e., sitting).

- This technique may give rise to reduced surgical morbidity and

more rapid rehabilitation compared with laminectomy with or

without arthrodesis.

II. Indications

- Symptomatic neurogenic claudication secondary to spinal ste-

nosis with or without spondylolisthesis (confirmed by comput-

ed tomography [CT] or magnetic resonance imaging [MRI]) that

has failed to respond to conservative treatments (e.g., physical

therapy, medications, or epidural injections)

- Limiting lumbar extension may also target various sources of

low back pain by unloading the posterior disc and facet joints.¹

- Contraindications

• Significant spinal deformities (spondylolisthesis >grade I, sco-

liosis >25 degrees)

• Bony ankylosis

• Severe osteoporosis

• Critical stenosis/cauda equina syndrome

- The X-Stop spacer (Medtronic, Memphis, TN) is FDA-approved

for use at one or two levels of the lumbar spine (Fig. 59.1).

III. Technique

- Preoperative planning

• Radiographs: evaluate for presence of spinal deformity (scoli-

osis on anteroposterior (AP), spondylolisthesis on lateral) and

anklyosis (no segmental motion on flexion/extension views).

374 IV Surgical Techniques

Fig. 59.1 Photograph of X-Stop device, Medtron-

LLC).

• CT/MRI: confirm diagnosis of stenosis.

• Dual x-ray absorptiometry (DEXA): assess risk for osteopo-

rotic fractures.

- Anesthesia: general, monitored anesthesia care (MAC), or local

- Positioning: lateral decubitus or supine on a radiolucent table;

make sure that the lumbar spine is maintained in flexion

- A vertical midline incision centered over the affected segment(s)

is made through the skin and fascia, with care taken to avoid at-

tenuating the supraspinous/interspinous ligaments.

- After the levels are confirmed using fluoroscopy or intraopera-

tive x-rays, a subperiosteal exposure of the spinous processes

and laminae is performed without disrupting the facet capsules.

- The interspinous space is distracted so that the ISD may be in-

serted between two adjacent spinous processes (depending on

the surgical protocol for each specific implant).

- May also be combined with a microdecompression (e.g.,

laminotomies)

- The wound is closed in layers, and a drain may or may not be

used.

IV. Complications

- Intraoperative

• Spinous process (SP) fracture

• Malpositioning of implant

• Inability to safely place the implant (e.g., attenuation of liga-

ments, excessively small interspinous space secondary to

“kissing” SP or facet hypertrophy)

- Postoperative

• SP fracture

59 Interspinous Process Decompression

375

• Device migration/dislocation

• Persistent/recurrent symptoms (same- versus adjacent-segment

degeneration)

- In the series of Barbagallo et al, the incidence of complications

was 10.1% (primarily spinous process fractures and device dis-

locations) with a reoperation rate of 7.2%.²

V. Postoperative Care

- May be performed in ambulatory setting as opposed to in-

patient admission

- Immediate postoperative ambulation

- No bracing typically required

- Gradual return to normal activities

VI. Outcomes

- Kuchta et al published the 2-year results of 175 consecutive X-

Stop procedures performed at a single center.³

• X-Stop brought significant improvement in clinical outcome

measures.

• Reoperation rate of 4.6% (removal of implant with posterior

decompression)

- Zucherman et al reported the results of a multicenter, prospec-

tive, randomized trial comparing X-Stop and nonoperative mo-

dalities for spinal stenosis (191 patients).⁴

• At 2 years, clinical outcomes of patients receiving X-Stop were

significantly improved compared with those undergoing con-

servative treatments.

• No device-related complications, but 6% of X-Stop cohort re-

quired subsequent laminectomy

- There continues to be a paucity of data on other ISDs.

VII. Surgical Pearls

- Appropriate candidates for this technique should experience

clear relief of their claudicatory symptoms with lumbar flexion

or sitting.

- Flexion-extension lateral x-rays may identify the presence of

bony ankylosis at the stenotic level(s), which may preclude the

implantation of an ISD.

- The lumbar spine should be maintained in flexion to facilitate

intraoperative distraction of the stenotic segments

376 IV Surgical Techniques

- Hypertrophic facet joints may need to be partially excised to

allow successful placement of the ISD.

- Care must be taken when inserting the ISD in osteoporotic pa-

tients, who may be at greater risk for spinous process fractures.

Common Clinical Questions

1. Which of the following patients is best suited for placement of

an ISD?

A. Patient with severe low back pain and minimal extremity

symptoms

B. Patient with claudication secondary to moderate stenosis

and a grade II spondylolisthesis at L4-L5

C. Patient with moderate stenosis at L3-L4 whose symptoms

improve with sitting

D. Patient with severe stenosis between L2 and L5 who com-

plains of perianal numbness and bladder dysfunction

2. What is the primary mechanism by which ISD relieves claudica-

tory symptoms?

A. Decreases facet joint forces

B. Unloads posterior disc tissue

C. Eliminates redundant ligamentum flavum and other com-

pressive lesions

D. Increases the dimensions of the spinal canal

3. Which is not a typical characteristic of neurogenic claudication?

A. Pain is worse when walking uphill

B. Symptoms improve with sitting

C. Pain/numbness is worse with lumbar extension

D. Symptoms do not change when riding a bicycle

59 Interspinous Process Decompression

377

References

1. Bono CM, Vaccaro AR. Interspinous process devices in the lumbar spine. J

Spinal Disord Tech 2007;20(3):255-261

2. Barbagallo GM, Olindo G, Corbino L, Albanese V. Analysis of complications

in patients treated with the X-Stop Interspinous Process Decompression

System: proposal for a novel anatomic scoring system for patient selection

and review of the literature. Neurosurgery 2009;65(1):111-119, discussion

119-120

3. Kuchta J, Sobottke R, Eysel P, Simons P. Two-year results of interspinous spacer

(X-Stop) implantation in 175 patients with neurologic intermittent claudi-

cation due to lumbar spinal stenosis. Eur Spine J 2009;18(6):823-829

4. Zucherman JF, Hsu KY, Hartjen CA, et al. A multicenter, prospective, random-

ized trial evaluating the X STOP interspinous process decompression system

for the treatment of neurogenic intermittent claudication: two-year follow-

up results. Spine (Phila Pa 1976) 2005;30(12):1351-1358

Answers to Common Clinical Questions

1. C

2. D

3. A

60 Lumbar Arthroplasty

Ishaq Y. Syed, Barrett I. Woods, and Joon Y. Lee

I. Key Points

- Lumbar arthroplasty has recently been approved in the United

States as an alternative treatment strategy to spinal arthrod-

esis in the treatment of refractory symptomatic discogenic back

pain.

- Etiology of low back pain remains unclear, with numerous pos-

sible pain generators.

- Goals: preserve physiologic spinal motion, prevent facet ar-

thropathy, prevent adjacent-segment disease, restore disc

height, and provide long-term pain relief¹

- The prosthesis should approximate the size and motion of the

physiologic disc, avoid distracting the facet joints, and, ideally,

reproduce the normal biomechanics (Fig. 60.1).

- No independent long-term, randomized, prospective study on

any artificial disc has been published to date that clearly delin-

eates the safety and efficacy of lumbar arthroplasty.

II. Indications

- Patient refractory to a minimum of 6 months of conservative,

nonoperative treatment

- One- or two-level symptomatic degenerative disc disease in pa-

tients of age 18 to 60 years

- Correlative objective radiographic findings including disc des-

iccation, vacuum disc, high-intensity zone signal, and Medic

signal changes

Fig. 60.1 Photograph of the Charite ar-

tificial disc (with permission from DePuy

Spine, Inc.).

60 Lumbar Arthroplasty

379

- Postdiscectomy axial back pain or juxtafusion disc degeneration

- Absence of central or lateral recess stenosis that may require

posterior decompression to address concomitant radicular leg

pain

- Provocative discography may demonstrate concordant pain re-

production and confirm diagnosis.

III. Contraindications

- Compromised structural integrity of bone

• Tumor, osteoporosis

(T-score

<-2.5), osteomalacia, acute

fracture

- Potential compromise of stability or alignment of implant

• Scoliosis, spondylolysis, spondylolisthesis (>grade I), incom-

petent posterior elements

- Conditions that may compromise clinical outcome of disc

replacement

• Significant facet arthrosis, disc herniation with predominant

radicular symptoms, central or lateral recess stenosis, disc

height less than 5 mm

- Miscellaneous

• Obesity (BMI >40), local or systemic presence of tumor or in-

fection, pregnancy, intraspinal neoplasm

IV. Technique²

- Positioning

• The patient is placed in the supine position on a radiolucent

table with all bony prominences padded after institution of

general anesthesia and Foley insertion to decompress the

bladder.

• C-arm fluoroscopy is used to identify the approach angle and

location of the disc space and to verify that clear anteroposte-

rior and lateral images can be attained.

- Standard sterile preparation and draping are performed and

prophylactic intravenous antibiotics are administered.

- Exposure

• The majority of prostheses are implanted by means of an open

anterior approach similar to that used for anterior lumbar in-

terbody fusion (ALIF).

• A general or vascular surgeon can obtain access to the spine

through either an anterior retroperitoneal approach (most

preferred) or a midline transperitoneal approach.

380 IV Surgical Techniques

• A left-sided approach is preferred between L3 and L5 due to

the relative resilience of the aorta and ease of mobility com-

pared with the vena cava.

• In accessing L5-S1 in male patients a right-sided approach is

recommended to reduce the rate of injury of the superior hy-

pogastric plexus, which can cause retrograde ejaculation.

• The retroperitoneal space is entered deep to the rectus sheath

and the peritoneum, with the ureter retraced medially.

• Blunt dissection reveals the lateral edge of the psoas, and vas-

cular structures are carefully mobilized and elevated off the

anterior spine.

- Procedure

• Fluoroscopic images are used to confirm the disc level and

identify the midline.

• A subtotal discectomy is performed by excising the anterior

longitudinal ligament, annulus, and nucleus pulposus, leaving

the lateral portion of the annulus intact.

• The cartilaginous end plate is debrided from the osseous end

plate. The integrity of the end plate is preserved to ensure im-

plant fixation and avoid subsidence.

• If necessary, the posterior longitudinal ligament (PLL) is re-

leased and posterior osteophytes debrided.

• Special instruments are used to measure the footprint, lor-

dotic angle, and core height.

• Based on preoperative templating and intraoperative sizing,

the appropriate trial is inserted.

• The appropriately sized prosthesis is implanted after device-

specific preparation of the end plate.

• If the device has a polyethylene core, it is trialed and inserted

after confirming on lateral fluoroscopy the restoration of de-

sired disc height and lordosis.

- Fluoroscopy confirms the central position of the implant on the

anteroposterior view. Ideally, the center of rotation of the de-

vice is 2 mm posterior to the sagittal midline of the vertebral

body on the lateral view.

- Final confirmatory radiographs are obtained and the wound is

closed in routine fashion.

- The approach varies according to the lumbar level accessed as

well as device-specific modifications to the general technique.

60 Lumbar Arthroplasty

381

V. Complications

- Approach-related complications (10 to 13%): vascular injury,

phlebitis, pulmonary embolism, sexual dysfunction, and retro-

grade ejaculation.

- Postoperative retroperitoneal scarring makes revision surgery

more difficult.

- Failure of the prosthesis primarily involves facet joint degener-

ation, subsidence, device migration, and adjacent-level disease.

- Cases of vertebral body fractures have been reported.

- Heterotopic ossification has been reported in varying degrees

in 1.4 to 15.2% of patients.

- A prospective, randomized, multicenter Food and Drug Admin-

istration (FDA)-regulated clinical trial reported on complica-

tions of 589 patients.³

• The disc replacement group was found to have an 8.8% reop-

eration rate, compared with 10.1% in the lumbar fusion con-

trol group. Mean time to reoperation was 9.7 months.

• The primary reason for removal of the implant was device mi-

gration (75%).

• A higher incidence of vascular injury occurred in the reopera-

tion group (16.7%) compared with the primary group (3.4%).

• Fourteen patients required posterior instrumented fusion for

persistent low back pain (2.4%).

VI. Postoperative Care

- Patients bear weight as tolerated and are mobilized on the first

postoperative day.

- A brace is typically not needed.

- Standing radiographs are obtained as soon as feasible postop-

eratively to document the position of the implant in the weight-

bearing position.

- A gentle low back and abdominal strengthening program is

implemented starting with the first postoperative day.

- The patient is given postoperative restrictions including avoid-

ance of substantial extension, bending, twisting, or heavy lift-

ing for the first 6 weeks.

- Progressive unrestricted activity is allowed after 6 weeks.

382 IV Surgical Techniques

VII. Outcomes

- Results of a prospective, randomized, multicenter FDA-regulat-

ed trial conducted to assess the safety and efficacy of the pro-

cedure were recently published.⁴

• The study reported on 160 patients who completed 5-year

follow-up.

• Patients were randomized to total disc replacement (TDR) or

anterior interbody fusion using Bagby and Kuslich (BAK) cages

with iliac crest autograft.

• Overall success was 57.8% in the TDR group versus 51.2% in

the BAK group.

• Oswestry Disability Index (ODI), Visual Analogue Scale (VAS)

pain scores, patient satisfaction, and SF-36 questionnaires

were similar across the two groups.

• The mean range at the index level was 6 degrees for the TDR

patients and 1 degree for the BAK patients. Changes in disc

height were similar for the two.

• The authors concluded there is no statistical difference in

clinical outcomes between the groups.

• The TDR patients did reach a statistically higher rate of em-

ployment and lower rate of long-term disability compared

with the BAK patients.

- The clinical efficacy, long-term durability, and potential com-

plications need to be more clearly elucidated with the use of

unbiased prospective randomized studies with long-term

follow-up.

VIII. Surgical Pearls

- The lumbar spine is positioned in the neutral position to mini-

mize tension on retroperioteneal vessels.

- Sympathetic and parasympathetic nerves must be carefully

preserved to prevent erectile dysfunction and retrograde ejacu-

lation in male patients.

- The integrity of end plates must be preserved to ensure good

implant fixation and avoid subsidence.

- The implant must restore appropriate lordosis, have adequate

end plate coverage, and avoid distraction of more than 3 mm to

apply proper tension to the posterior ligaments.

60 Lumbar Arthroplasty

383

Common Clinical Questions

1. All of the following are contraindications to total disc arthro-

plasty except:

A. The presence of significant lateral recess stenosis

B. Facet arthrosis

C. Degenerative spondylolisthesis

D. Smoking

E. Obesity (BMI >40)

2. Which of the following statements is true with regard to total

disc arthroplasty?

A. Randomized prospective control trials have illustrated the

efficacy of lumbar disc arthroplasty, establishing that it

preserves normal biomechanics and reduces the incidence of

adjacent-segment degeneration.

B. A right-sided approach to the L5/S1 disc space is recom-

mended in male patients undergoing total disc arthroplasty.

C. The PLL is essential to the appropriate tensioning of the disc

replacement and should not be excised.

D. Heterotopic ossification is not a confirmed potential compli-

cation of total disc arthroplasty.

E. A significant portion of the cranial and caudal end plate must

be removed prior to placement of the implant for proper set-

ting of the prosthesis.

References

1. Gamradt SC, Wang JC. Lumbar disc arthroplasty. Spine J 2005;5(1):95-103

2. Tropiano P, Huang RC, Girardi FP, Cammisa FP Jr, Marnay T. Lumbar total disc

replacement. Surgical technique. J Bone Joint Surg Am 2006;88(Suppl 1 Pt

1):50-64

3. McAfee PC, Geisler FH, Saiedy SS, et al. Revisability of the CHARITE artificial

disc replacement: analysis of 688 patients enrolled in the U.S. IDE study of

the CHARITE Artificial Disc. Spine (Phila Pa 1976) 2006;31(11):1217-1226

4. Guyer RD, McAfee PC, Banco RJ, et al. Prospective, randomized, multicenter

Food and Drug Administration investigational device exemption study of

lumbar total disc replacement with the CHARITE artificial disc versus lum-

bar fusion: five-year follow-up. Spine J 2009;9(5):374-386

Answers to Common Clinical Questions

1. D

2. B

61 Lumbosacroiliac Fixation

Amit R. Patel, Alexander R. Vaccaro, and Ravi K. Ponnappan

I. Key Points

- Lumbosacroiliac

(LSI) fixation provides the strongest bio-

mechanical construct for sacral fractures and lumbopelvic

dissociations.¹

- The construct spans the sacrum and allows for relatively normal

load transfer from the lumbar spine through the sacroiliac (SI)

joints to the pelvis, permitting early post-op weight bearing.

- In long constructs, including L5-S1, iliac (pelvic) fixation im-

proves fusion rates of vertebrae.²

- Iliac screws must remain in bone throughout their length to

prevent injury to pelvic viscera and neurovascular structures.³

- Sacropelvic relationships should be measured and taken into

account in performing long-segment fixation extending into

the sacrum/ilium (Table 61.1 and Fig. 61.1).

II. Indications

- Complex sacral fractures with or without pelvic discontinuity

- Adult scoliosis patients with L5-S1 spondylolisthesis

Table 61.1 Commonly Measured Pelvic Parameters

Sacral slope

An angle subtended by a horizontal reference line and the

sacral end plate

Normal around 40 degrees (varies with patient’s position)

Pelvic tilt

Angle formed by a vertical line from the center of the

femoral heads and the line from the femoral heads to the

middle of S1 end plate

Measures 11.9 to 10.3 degrees (varies with patient’s position)

Pelvic incidence Angle between a line drawn perpendicular to the sacral

plate at its midpoint and a line connecting the midpoint

of the middle axis of the femoral heads

Mean normal value is 48 to 53 degrees

Low: flattened lumbar lordosis, low shear stress at lumbo-

sacral junction, low risk of progression of spondylolisthesis

High: high sacral slope, high pelvic tilt, increased lordosis,

high shear stress at lumbosacral junction, high risk of

progression of spondylolisthesis

61 Lumbosacroiliac Fixation

385

Fig.

61.1 Sacropelvic radiographic mea-

surements.

- Revision lumbosacral fusion

- Adult isthmic spondylolisthesis

- High-grade dysplastic spondylolisthesis

III. Technique

- A subperiosteal dissection is made to the lumbar transverse

processes, sacral ala, and posterior superior iliac spine (PSIS).³

• While exposing the sacrum, stay extraperiosteal and avoid

falling into the dorsal sacral foramina.

- Using blunt and sharp elevators, lift the musculature off of the

inner and outer aspects of both iliac wings to help establish the

direction for iliac screw placement.

- S1 pedicle screw: Placement begins by identifying the region

where the ala and lateral S1 facet meet; a high-speed bur can

be used to mark the starting point (Fig. 61.2).³

• This point is typically 1 cm cephalad to and slightly lateral to

the S1 foramen.

- S2 pedicle screw: Placement begins by identifying the inferior

medial aspect of the dorsal S1 foramen and the superior me-

dial aspect of the dorsal S2 foramen; the starting point is the

middle of an imaginary line connecting the two points, which

can be marked with a high-speed bur (Fig. 61.2).³

- Use a gearshift probe to create a path from this starting point to

the anterior cortex of the sacrum; gently tap the gearshift with

a mallet to perforate the anterior cortex.³

386 IV Surgical Techniques

• S1 screw: typically 6.5 mm in diameter and 40 to 45 mm in

length; should be aimed medially for the sacral promontory

• S2 screw: typically 6.5 mm in diameter and 50 to 60 mm in

length; should aim 30 to 35 degrees laterally and tilt cephalad

15 to 20 degrees (parallel to the SI joint)

- Iliac (pelvic) screw: placement begins by identifying the inferi-

omedial aspect of the PSIS (Fig. 61.2)

- Using a high-speed bur or a rongeur at the PSIS, find cancellous

bone and then use the gearshift probe to develop a screw path

that runs between the inner and outer cortex of the ilium.

- The path, directed toward the anterior inferior iliac spine (AIIS),

should not be forced and should be produced easily; if resis-

tance is met, consider a larger soft-tissue exposure and/or the

use of fluoroscopy to guide the gearshift along a more appro-

priate path.³

• The combination obturator-outlet view best shows the proper

starting point and path of the iliac screw.¹

• The combination obturator-inlet view confirms that the screw

has not violated the inner or outer iliac cortex (Fig. 61.3).¹

• A true lateral oblique view of the pelvis or iliac ensures that

there is no sciatic notch or acetabular encroachment of the

iliac screws and confirms full accommodation of the screw

length (Fig. 61.4).

• A simplified method of iliac screw insertion is to place one’s

finger within the sciatic notch along the outer table of the

ilium and use this landmark as a guide in probe and screw

insertion, without the need for intraoperative fluoroscopy or

Kirschner wire (K-wire) guidance.

Fig. 61.2 Posterior view of

pelvis. Note starting points

for the sacral and iliac

screws.

61 Lumbosacroiliac Fixation

387

Fig.

61.3 Lateral lumbopelvic x-ray

demonstrating appropriately positioned

pelvic fixation. Note position of pelvic

screws in relation to the sciatic notch.

- Using a K-wire and tap, the final iliac screw is placed; it is typi-

cally 7.5 to 8 mm in diameter and 65 to 90 mm in length.

• In revision cases where iliac crest bone was harvested for

grafting for the index procedure, iliac screw placement can be

more challenging and longer screws may be used.³

• Iliac screws must stay entirely within bone given the proxim-

ity of various pelvic structures.

- A rod is used to connect the sacral screw, the iliac screw, and

the construct.

Fig. 61.4 Lateral view of pelvis show-

ing anatomic landmarks and direction

of safe placement of the iliac screws.

388 IV Surgical Techniques

IV. Complications

- Infection and wound rates approach 20%.⁴

- Symptomatic hardware requiring removal³

- A formal SI joint arthrodesis is generally not performed; as a

consequence, the implant may fracture due to fatigue failure.⁴

- Superior gluteal artery injury from sciatic notch violation⁴

- Wound breakdown due to disruption of the distal erector spi-

nae musculature attachment. When elevating the posterior

paraspinal muscles to expose the medial border of the ilium,

be careful not to disrupt the distal attachment of the erector

spinae muscles as that may lead to wound problems.

V. Postoperative Care

- Early patient mobilization

- External orthosis (if utilized) must include leg extension (to im-

mobilize hip).¹

VI. Outcomes

- L5-S1 fusion rates approach 92% with utilization of sacropelvic

fixation.⁴

- Iliac screw placement is possible in revision cases; in one se-

ries, 34 of 36 patients had successfully placed iliac screws de-

spite previous iliac crest graft harvesting.⁴

- Iliac screw loosening is reportedly as high as 52%, although this

did not correlate with pseudarthrosis; the rate of iliac screw

breakage is considerably lower (5.3%).²

- Nearly half of patients report being able to feel their

instrumentation.²

- The infection rate is reported at 3.7%.⁴

VII. Surgical Pearls

- The site of iliac crest bone grafting should be made more supe-

riorly along the crest to maintain adequate bone stock for iliac/

pelvic bolt fixation.³

- LSI fixation can be combined with iliosacral screws (triangu-

lar osteosynthesis) to stabilize the weight-bearing axis and the

pelvic ring.⁵

- In the placement of bicortical S1 screws, medial screw angula-

tion is necessary to avoid traversing the L5 nerve root.¹

- Separate (accessory) incisions can be utilized for iliac fixation

with the use of subcutaneous tunneling to connect to lumbo-

sacral fixation.³

61 Lumbosacroiliac Fixation

389

Common Clinical Questions

1. Which pelvic view best confirms that the iliac screw has not

violated the inner or outer cortex of the ilium?

A. Lateral

B. Anteroposterior

C. Iliac oblique

D. Obturator-inlet

E. Obturator-outlet

References

1. Schildhauer TA, Bellabarba C, Nork SE, Barei DP, Routt ML Jr, Chapman JR. De-

compression and lumbopelvic fixation for sacral fracture-dislocations with

spino-pelvic dissociation. J Orthop Trauma 2006;20(7):447-457

2. Kuklo TR, Bridwell KH, Lewis SJ, et al. Minimum 2-year analysis of sacropelvic

fixation and L5-S1 fusion using S1 and iliac screws. Spine (Phila Pa 1976)

2001;26(18):1976-1983

3. Bradford DS, Zdeblick TA. Master Techniques in Orthopaedic Surgery: The

Spine. 2nd ed. Philadelphia, PA: Lippincott; 2004:336-345

4. Herkowitz HH, Garfin SR, Eismont FJ, et al. The Spine. 5th ed. Philadelphia, PA:

Elsevier; 2006:1180-1183.

5. Kim JH, Horton W, Hamasaki T, Freedman B, Whitesides TE Jr, Hutton WC.

Spinal instrumentation for sacral-pelvic fixation: a biomechanical com-

parison between constructs ending with either S2 bicortical, bitriangulated

screws or iliac screws. J Spinal Disord Tech 2010;23(8):506-512

Answers to Common Clinical Questions

1. D. Refer to Fig. 61.3. The obturator-inlet view best confirms that

the iliac screw has remained intracortical, which is of critical

importance given the proximity of the pelvic contents to the ilia.

The obturator-oblique view is used to confirm the chosen start-

ing point and the iliac screw path. The lateral view can show

if a screw has violated the sciatic notch. The iliac oblique view

confirms that the screw has not advanced into the acetabulum.

The anteroposterior view does not have a significant role in iliac

screw placement.

62 Sacrectomy

Ioannis Papanastassiou, Mohammad Eleraky, and Frank D. Vrionis

I. Key Points

- A posterior and combined approach to and instrumentation for

total sacrectomy are feasible.

- Try to obtain wide margins and consider the use of intraopera-

tive adjuvants (cryotherapy, phenol, brachytherapy, etc.).

- Use adjuvant radiation therapy (preferably intensity-modulat-

ed radiation therapy (IMRT) or proton beam) for contaminated

margins.

II. Indications

- Aggressive benign tumors of the sacrum (giant cell tumors,

osteoblastoma)

- Malignant primary sacral tumors (chordoma, Ewing’s sarcoma/

primitive neuroepithelial tumor [PNET], osteosarcoma, etc.)

- Selected cases of metastatic tumors/multiple myeloma (fre-

quently located in the sacrum)

- Pelvic tumors invading sacroiliac joint and sacrum (chondro-

sarcoma, Ewing sarcoma, osteosarcoma, etc.)

III. Technique

- Sacrectomy can be total or subtotal, a stand-alone operation or

performed in the context of more complex sacropelvic resec-

tions (extended internal/external hemipelvectomies).

- Subtotal resections can be categorized according to the resec-

tion plane.

- Transverse/axial resection: usually done between sacral seg-

ments (S1/S2, S2/S3, below S3)

- Sagittal resection: can be in the midline

(hemisacrecto-

my) or located more laterally (e.g., through or lateral to the

neuroforamens)^1,2

- Approach: depending on the location and tumor type, the ap-

proach could be posterior (longitudinal or transverse) or com-

bined anteroposterior.

62 Sacrectomy

391

Posterior Approach

- It is generally accepted that sacrectomies at the S2/S3 level and

not extending to the rectum can be performed via a posterior-

only approach. For S1/S2 resections controversy exists; for to-

tal sacrectomies (L5-S1 level), most authorities recommend a

combined approach, although there are reports describing total

sacrectomy through a posterior approach alone.

- The type of posterior (transverse or longitudinal) incision may

be indicated from a previous biopsy or from the tumor location.

A longitudinal approach is typically employed, sometimes with

a transverse component (T-type, Fig. 62.1): after the skin inci-

sion (with the biopsy tract incorporated), the gluteus maximus

is dissected laterally and the erector spinae are detached from

the midline and posterolateral aspect of the sacrum and flaps

elevated in an upward fashion; this maneuver greatly facilitates

surgical exposure.

- Subsequently, a laminectomy is done in the desired level and

the cauda equina is ligated with double silk sutures and cut in

the axilla of the most caudal nerve roots to be preserved (Fig.

62.2).

- The sacrum is freed from its attachment to surrounding struc-

tures (pelvic floor-anococcygeal ligament, sacrotuberous/sa-

crospinous ligaments, piriformis muscles). Piriformis resection

should be as wide as possible as this has been found to decrease

local recurrence.

- Finally, sacrectomy is completed using osteotomes; caution is

recommended to the whole surgical team at this point because

massive hemorrhage may commence.

Combined Approach (Anteroposterior)

- Typically, the anterior resection comes first. The surgery is pref-

erably performed in a staged fashion (anterior → supine, pos-

terior → prone) with an interval of 2 to 3 days between stages;

this is believed to reduce morbidity. However, there are advo-

cates of a single-stage operations either in the lateral position

or in the supine/prone position.

- The anterior approach could be open, laparoscopic, intraperi-

toneal, or extraperitoneal. Involvement of the rectum makes

the anterior intraperitoneal approach mandatory (typically by

a general surgeon); if there is a clear plane between rectum and

tumor, especially if the tumor is located eccentrically, a retro-

peritoneal approach may be used.^1,2

62 Sacrectomy

393

Fig. 62.2 Relationship of the ventral surface of the sacrum to the major pelvic struc-

tures, arteries, veins, and neural structures. (From Dickman, Fehlings, Gokaslan, Spi-

nal Cord and Spinal Column Tumors, Thieme; pg. 635, Fig. 44-2.)

- At the end of the anterior stage, complete mobilization of the

rectum is accomplished or a colostomy is performed; ligation of

the internal iliac vessels is done with discectomy or osteotomy

at the desired level and anterior osteotomy of the sacroiliac (SI)

joints (or more laterally if needed). A radiopaque marker may

be left at the discectomy/osteotomy level to facilitate localiza-

tion at the second stage.

- It is widely believed that the use of a vertical rectus abdominis

myocutaneous flap reduces the risk of wound infection/break-

down. This should be done at the first stage and the flap left in

the wound to be utilized at the end of the posterior operation.

394 IV Surgical Techniques

Reconstruction

- If the sacrectomy is performed below the S1/S2 level, recon-

struction in general is not needed; however, a higher chance of

sacral insufficiency fractures has been reported. Indications for

instrumentation include total sacrectomy, partial sacrectomy

involving more than 50% of SI joints, or sagittal hemisacrecto-

my that obliterates the SI joint unilaterally or bilaterally. How-

ever, even for total sacrectomies, some authorities believe that

any stabilization is unwarranted, since this typically prolongs

the operation and increases morbidity and risk of infection. To-

tal sacrectomy is believed to create a flail axial skeleton, leading

to pain or mechanical kinking of neurovascular structures or

viscera and significantly affecting ambulation, a set of condi-

tions favoring reconstruction.

- Reconstruction began in the 1980s with Harrington rods, moved

to the Galveston-Luque wire technique in the 1990s, and now

consists of a two-to-four-rod construct interconnected with

sacral bars; pedicle screws are placed from L2-L3 caudally and

the pelvis is anchored with long iliac screws (two to four).

- Cortical strut grafts (e.g., fibular or femoral diaphysis) can be

used to bridge the osseous gap between the SI joints or iliac

wings. They provide a more biologic fixation and the ability

to form an osseous bridge and maintain continuity with the

disrupted ring. This may prove very important in long-term

survivors.^1,2

- A newer and more technically challenging technique has been

described by the Mayo group. Two fibular grafts are placed be-

tween L5 and the supra-acetabular region bilaterally along the

force transmission lines, providing triangulation and increasing

resistance to failure by two times.³ Experience indicates that it

may be easier to insert the strut grafts in the posterior inferior

iliac spine.

IV. Complications

- Hemorrhage (injury of internal iliac, iliolumbar, and median

sacral vessels, eg), which may be life threatening

- Visceral damage (rectum, ureters)

- Wound healing problems/infection (may be as high as 50%)

- Sensorimotor, bowel, bladder, and sexual dysfunction. The high-

er the resection level, the greater the morbidity. As a general

rule, preservation of at least one S3 nerve leads to the preserva-

tion of function in two-thirds of patients, unilateral sacrectomy

62 Sacrectomy

395

has good results in 90%, and S1/S2 resections or total sacrecto-

mies result universally in loss of function (Table 62.1).⁴ Saddle

anesthesia is common; motor loss is encountered only in cases

of S1 root resection.

- Sacral insufficiency fractures

- General medical complications (pneumonia, ileus, deep vein

thrombosis (DVT), etc.). Generally, the morbidity and mortal-

ity are high (5% perioperative deaths in Sloan Kettering series).⁵

V. Postoperative Care

- Stabilization of the patient is crucial in the first postoperative

days (typically in the intensive care unit).

- Ambulation may be commenced immediately for low resec-

tions, or in a delayed fashion, depending on the level of stability

and fixation quality, with walking aids.

- Keep wound clean, with frequent dressing changes to prevent

contamination from rectum.

- Give stool softeners and high-volume food supplements. Pa-

tients may need to manually disimpact stools. Gradually at-

tempt bladder training, with the possible need for patients to

self-catheterize.

VI. Outcomes

- Survival is greatly dependent on the type of the tumor, pre-

vious operations, and tumor location. For sacral chordomas,

which are the most common tumors warranting sacrectomy,

5-year and 10-year survival are 68% and 40%, respectively (SEER

database). Local recurrence occurs in about 40% (28% for wide

versus 64% for intralesional in one series of 64 chordomas). Dis-

tant metastasis occurs in one-third of patients.⁵

Table 62.1 Bladder and Bowel Function after Sacrectomy

Resection level

Spared nerve roots Normal

Normal bladder

bowel

S1/S2

Both S1

S2/S3

Both S2

40%

25%

S3/S4

Both S3

100%

69%

Variable

Unilateral

67%

60%

Hemisacrectomy Unilateral S1 to S5

87%

89%

396 IV Surgical Techniques

VII. Surgical Pearls

- The posterior-only approach is useful for S1/S2 resections and the

combined anteroposterior approach (in a staged fashion) is prac-

ticed for higher resections.

- Use of the rectus abdominis flap in combined procedures re-

duces wound complications.

- Anticipate and prepare the surgical team for blood loss when

initiating a posterior osteotomy (ensure good hydration, give

aminocaproic acid, make PRBCs and FFPs available).

- For total sacrectomies use a two- (or four-) rod construct with

interconnecting sacral bars. Strut allografts (either transverse

or in a triangular fashion) are desirable to promote fusion.

- Wide resection is crucial to prevent local recurrence and sig-

nificantly affects survival. Try to obtain negative margins in the

sacrospinal canal and wide surgical margins posteriorly, by ex-

cising parts of the piriformis, gluteus maximus, and sacroiliac

joints.

Common Clinical Questions

1. Which nerve roots are critical for bladder/bowel function and

should be preserved if possible?

2. What is the incidence of local recurrence after wide and intra-

lesional resection of sacral chordomas? Does it affect survival?

3. Which level of resection can be performed safely via a posterior

approach only, and when is a combined approach mandated?

References

1. Mavrogenis AF, Patapis P, Kostopanagiotou G, Papagelopoulos PJ. Tumors of

the sacrum. Orthopedics 2009;32(5):342

2. Fourney DR, Rhines LD, Hentschel SJ, et al. En bloc resection of primary sacral

tumors: classification of surgical approaches and outcome. J Neurosurg

Spine 2005;3(2):111-122

3. Dickey ID, Hugate RR Jr, Fuchs B, Yaszemski MJ, Sim FH. Reconstruction after

total sacrectomy: early experience with a new surgical technique. Clin Or-

thop Relat Res 2005; 438:42-50

4. Todd LT Jr, Yaszemski MJ, Currier BL, Fuchs B, Kim CW, Sim FH. Bowel

and bladder function after major sacral resection. Clin Orthop Relat Res

2002;(397):36-39

5. Schwab JH, Healey JH, Rose P, Casas-Ganem J, Boland PJ. The surgical manage-

ment of sacral chordomas. Spine (Phila Pa 1976) 2009;34(24):2700-2704

63 Vertebral Body Augmentation

Mohammed Eleraky and Frank D. Vrionis

I. Key Points

- Vertebral augmentation is commonly employed in treating

compression fractures in patients with osteoporosis or spine

tumors.

- Two different percutaneous vertebral augmentation methods

for cement application into the vertebral body have been docu-

mented: vertebroplasty and kyphoplasty.

- In vertebroplasty, polymethylmethacrylate (PMMA) cement is

injected percutaneously into the collapsed vertebral body.

- Kyphoplasty involves placing inflatable bone tamps percutane-

ously into a vertebral body. The inflation of the bone tamp al-

lows some restoration of vertebral height. After deflation, the

cavity that has been produced is filled by injection of PMMA.

- Two randomized clinical trials showed that improvement in pa-

tients with painful osteoporotic vertebral fractures was similar

between those treated with vertebroplasty and those treated

with a simulated procedure, at one month follow-up.^1,2

- Compared with nonsurgical management, balloon kyphoplasty

resulted in improvements in quality of life and disability mea-

sures and reduction of back pain in patients with acute painful

vertebral fractures.²

II. Indications

- Severe pain or progressive collapse due to vertebral body com-

pression fractures in patients with osteoporosis (primary or

secondary).

- Severe pain or progressive collapse due to vertebral body me-

tastasis or multiple myeloma. Treatment algorithm for painful

thoracic or lumbar vertebral body fractures in cancer patients

(Fig. 63.1).

- Contraindications to vertebral augmentation include asymp-

tomatic lesions, patients who are improving on conservative

care, ongoing local or systemic infection, retropulsed bone

fragment or epidural tumor causing myelopathy, and allergy to

bone cement.

63 Vertebral Body Augmentation

399

Fig. 63.1 Treatment algorithm for painful thoracic or lumbar vertebral body frac-

tures in cancer patients. See text for details. VB = vertebral body; RT = radiation

therapy. (Reproduced with permission from Fourney DR, Schomer DF, Nader R, Ch-

lan-Fourney J, Suki D, Rhines LD, Ahrar K, Gokaslan ZL. Percutaneous vertebroplasty

and kyphoplasty for painful vertebral body fractures in cancer patients. SCSCT; pg.

624, Fig. 43-3.)

Diagnosis

- Magnetic resonance imaging (MRI) scan of the spine (T1 and

short T1 inversion recovery [STIR] sequences) to detect verte-

bral body edema and associated impending fractures

- Computed tomography (CT) scan of the fractured vertebral

body with sagittal reconstruction to evaluate posterior verte-

bral wall integrity

- Bone scan in some cases to assess acuity of fracture and ex-

clude metastasis in different levels

III. Technique

- Procedures can be performed under general or local anesthesia.

- Patient is placed in prone position on Jackson radiolucent table,

with postural reduction of kyphosis if present.

400 IV Surgical Techniques

- Biplanar fluoroscopy is used.

- Both techniques start with the percutaneous insertion of (11

gauge) Jamshidi needle or guide pin into the fractured vertebra

and end with the injection of PMMA.

- This can be achieved through a transpedicular approach in

nearly every case.

- In the thoracic spine the needle can be inserted extrapedicular-

ly, between the rib head and lateral aspect of the pedicle (Fig.

63.2).

- Single or bilateral injection can be performed (it is important to

fill the center of the vertebral body).

Vertebroplasty

- After correct positioning of the needle, the inner stylet is

removed.

- Contrast material is then injected to ensure that the needle is

not positioned in the venous flow path (optional).

- Cement, in thin liquid form, is injected into the vertebra using

multiple small syringes.

- The flow of the cement should be followed on the image

intensifier.

Kyphoplasty

- After proper needle positioning, a series of tools (drill, curette)

are used to create a working channel. Once inserted, the bal-

loons are inflated using volume and pressure controls (digital

manometer) to create a cavity within the vertebra.

- Once this has been achieved, the balloons are deflated and

removed.

- Thick cement can be fed through the cannula under low pres-

sure to fill the cavity created by the balloon tamp.

- In cases involving the upper thoracic spine, the shoulders can

interfere with the lateral view, so a stack of pillows of appro-

priate height should be placed under the chest to lower both

shoulders. Alternatively, the arm and the shoulder are left

hanging down parallel to the trunk.

IV. Complications

- Procedure-related: cement leakage can result from fracture

clefts or improper instrument position and can occur in the

spinal canal, neuroforamen, or disc space.

- Medical: pulmonary embolism, hemo- or pneumothorax, soft-

tissue hematomas

63 Vertebral Body Augmentation

401

Fig. 63.2 Entry points and trajectories for the transpedicular approach during ky-

phoplasty. (Courtesy of Medtronic.)

- New adjacent vertebral fracture due to leakage of cement into

the disc

- Pedicle fracture

V. Postoperative Care

- Mobilize early with no need for bracing.

- Clinical evaluation and plain spinal radiographs

- Discharge home when patient meets discharge criteria (usually

same day or on postoperative day 1).

VI. Outcomes

- All studies reported significant improvements in pain score and

functional outcome.^1,3

- The risk of neurologic sequelae ranges from 0.4 to 4.0% accord-

ing to various reports.^2-4

- The complication rate is considerably higher for spinal metas-

tasis due to lytic areas involving the vertebral cortex.

402 IV Surgical Techniques

- A recent study by Kallmes et al,¹ however, showed that im-

provements in pain and pain-related disability associated with

osteoporotic compression fractures in patients treated with

vertebroplasty were similar to those for the control group,

without treatment.

VII. Surgical Pearls

- The possibility of cement leakage can be overcome through the

use of high-quality imaging and slow application of PMMA in

a viscous state.

- In cases of focal kyphosis due to index fracture, the levels above

and below the fracture should also be considered in the treat-

ment plan. No more than three levels should be treated at one

setting. This policy minimizes the risk of microembolization

(cement and fat emboli).⁴

Common Clinical Questions

1. Contraindications to vertebral augmentation include all of the

following except:

A. Asymptomatic lesions

B. Retropulsed bone fragment

C. Epidural tumor causing myelopathy

D. Severe pain due to vertebral body compression fractures in

patients with osteoporosis

2. Procedure-related complications include all of the following

except:

A. Cement leakage

B. Pulmonary embolism, hemo- or pneumothorax

C. New adjacent vertebral fracture

D. Three levels attempted at one setting

63 Vertebral Body Augmentation

403

References

1. Kallmes DF, Comstock BA, Heagerty PJ, et al. A randomized trial of vertebro-

plasty for osteoporotic spinal fractures. N Engl J Med 2009;361(6):569-579

2. Wardlaw D, Cummings SR, Van Meirhaeghe J, et al. Efficacy and safe-

ty of balloon kyphoplasty compared with non-surgical care for verte-

bral compression fracture (FREE): a randomised controlled trial. Lancet

2009;373(9668):1016-1024

3. Lee MJ, Dumonski M, Cahill P, Stanley T, Park D, Singh K. Percutaneous treat-

ment of vertebral compression fractures: a meta-analysis of complications.

Spine (Phila Pa 1976) 2009;34(11):1228-1232

4. Mendel E, Bourekas E, Gerszten P, Golan JD. Percutaneous techniques in the

treatment of spine tumors: what are the diagnostic and therapeutic indica-

tions and outcomes? Spine (Phila Pa 1976) 2009;34(22, Suppl):S93-S100

Answers to Common Clinical Questions

1. D

2. D

64 Spinal Cord Tumor Resection

Michelle J. Clarke and Timothy F. Witham

I. Key Points

- Intradural tumor resection has the potential for significant

neurologic morbidity.¹

- Prognosis and outcome are highly variable and dependent on

pathology.^1,2

II. Indications

- Diagnosis or treatment of a contrast-enhancing intradural le-

sion in a symptomatic patient

• Sensory or motor deficits and sphincter dysfunction

• Localized pain, especially nonmechanical pain exacerbated by

recumbency

• Not indicated for transverse myelitis, multiple sclerosis, or

drop metastases

• In malignant lesions, consider biopsy and adjuvant therapy to

avoid neurologic morbidity.

III. Technique

- Place patient in prone position with Mayfield clamp (Integra

LifeSciences, Plainsboro, NJ).

- Preoperative corticosteroids and broad-spectrum antibiotics

are routinely administered.

- Neuromonitoring is required.

• Continuous somatosensory evoked potentials (SSEPs)

• Pre-positioning motor evoked potentials (MEPs) provide a

baseline that can be used throughout the case.

- Standard midline incision with subperiosteal dissection of the

paraspinal muscles.

- Laminectomy or laminoplasty is performed one level above

and one level below the rostral and caudal poles of the tumor.

• Immaculate hemostasis and placement of moist Cottonoids

(Saramall, Tandil, Argentina) in the epidural space will pre-

vent the accumulation of blood in the operative cavity.

- Midline durotomy is performed just rostral to the tumor and

extended caudal to the tumor (Fig. 64.1).

• Ultrasound prior to the dural opening may help define the lo-

cation of the tumor.

64 Spinal Cord Tumor Resection

405

Fig. 64.1 The durotomy is completed and

the arachnoid is incised. (From Vaccaro AR,

Albert TJ, Spine Surgery: Tricks of the Trade

2nd ed, Thieme; Fig. 4.2.)

• Use tack-up sutures to tent the dura laterally to the paraspinal

muscles.

• The arachnoid is preserved and opened separately under mi-

croscopic guidance.

• The arachnoid can be clipped to the dural edges using small

vascular clips.

- Locate midline to minimize neurologic morbidity.

• The tumor may distort the cord; thus, the posterior median

sulcus may be estimated by inspecting the bilateral dorsal

root entry zones or identifying the convergence of small ves-

sels in the midline.

• Dorsal column mapping by monitoring SSEPs and directly

stimulating the cord may be helpful.

- A midline myelotomy is started in the area of maximum cord

enlargement.

• Extend the incision superiorly and inferiorly to expose the tu-

mor in its entirety.

- Begin dissecting the tumor at the area of maximal enlargement

(Fig. 64.2).

• Carefully spread the posterior columns with a micro-dissector.

• Pial sutures may be used at the edge of the incision to provide

gentle traction.

- Once the tumor is exposed, send a specimen for frozen section

pathology.

• High-grade tumors are debulked; postoperative adjuvant

therapy is required.

• Low-grade glial tumors and ependymomas are more aggres-

sively approached

- En bloc resection is recommended when possible.²

• Reduces tumor spillage

406 IV Surgical Techniques

Fig. 64.2 Tumor dissection is initiated in

the middle portion of the tumor, which is

the bulkiest. (From Vaccaro AR, Albert TJ,

Spine Surgery: Tricks of the Trade 2nd ed,

Thieme; Fig. 4.3.)

• Reduces intralesional bleeding and maintains a better surgi-

cal plane

- Large tumors may require piecemeal resection.

- To resect, gently push the spinal cord away from the lesion us-

ing micro-instruments.

• Minimize movement of the intact spinal cord to prevent

injury.

• An ultrasonic aspirator may be useful.

- Note: dissection/resection along the median raphe may be

difficult.

• Beware of coagulating the anterior spinal artery or its

branches.

- Post-resection ultrasound may be valuable in determining the

extent of resection.

- Irrigate inside the thecal sac to remove all blood products.

- Immaculate watertight dural closure is needed.

• Consideration can be given to dural patches/grafts to enlarge

the diameter of the thecal sac in patients with expansible le-

sions and local swelling.

- Dural sealant should be considered.

- If a laminoplasty is called for, replace the lamina using pre-

drilled mini-plates.

• This may decrease the incidence of cerebrospinal fluid (CSF)

leak.

- Irrigate and close the incision in a watertight fashion.

64 Spinal Cord Tumor Resection

407

IV. Complications

- Neurologic injury

• Significant motor morbidity

• Significant proprioceptive morbidity

• Sphincter dysfunction (can be minimized if the conus is

avoided)

- CSF leak

- Wound infection

• Increases with adjuvant cytotoxic agents

- Post-laminectomy kyphosis

• Greatest risk: children <3 years, patients with preoperative

deformity, patients with preoperative neurologic deficit

• Laminoplasty may reduce this risk.

V. Postoperative Care

- Place patient supine and require bed rest for 24 to 48 hours as

a CSF leak precaution.

- Patient can be weaned from steroids over 2 to 4 weeks.

- Consider postoperative magnetic resonance imaging (MRI)

with and without contrast within 48 hours of surgery.

• Consider reoperation for residual tumor (depending on pa-

thology and neurologic status).

- Gradually mobilize the patient with the assistance of physical

therapy.

• Most patients will have sensory changes that will make am-

bulation difficult.

- Leave Foley catheter in place until patient is ambulatory.

• Straight catheterization is needed for sphincter dysfunction.

- Patient can be discharged to home or rehab facility depend-

ing on functional status once discharge criteria are met (typi-

cally, tolerating diet, having adequate pain control on oral

medications, and, depending on functional status, voiding and

ambulating).

- Depending on the pathologic findings, the patient should have

a consultation with radiation oncology and neurologic oncol-

ogy personnel to discuss adjuvant therapy.

• No radiation or chemotherapy should be given until the

wound is healed, which typically requires 3 to 4 weeks.

408 IV Surgical Techniques

VI. Outcomes

- Highly dependent on tumor pathology and the availability of

adjuvant therapies

- A large proportion of patients require inpatient rehabilitation.

- In the event of recurrence, consider further surgery.

VII. Surgical Pearls

- Detailed preoperative discussion of risks is mandatory.

• Postoperative neurologic deficit is common and unpredictable.

• Dorsal column dysfunction is expected.

- Neurologic monitoring is mandatory.

• Epidural MEPs can help prevent neurologic injury.

- Laminoplasty may decrease the risk of postoperative CSF leak

and kyphosis.

• Place mini-plates on lamina and drill pilot holes before per-

forming the laminectomy to ease repair.

- Begin dissection at the midpoint of the lesion, where it is the

bulkiest, to reduce injury.

- In lesions with associated cysts, the laminectomy need not ex-

tend beyond the solid tumor.

• Cyst walls are typically nonneoplastic, and complete tumor

resection results in cyst resolution.

Common Clinical Questions

1. Where and in what direction should the myelotomy be

performed?

2. If the tumor has a cystic component, does this need to be

resected?

3. What type of neuromonitoring is appropriate?

64 Spinal Cord Tumor Resection

409

References

1. Constatini S, Siomin V, Epstein F. Surgical management of intramedullary

spinal cord tumors. In Fessler RG and Sekhar L, eds. Atlas of Neurosurgical

Techniques: Spine and Peripheral Nerves. New York: Thieme; 2006

2. Hanbali F, Fourney DR, Marmor E, et al. Spinal cord ependymoma: radical

surgical resection and outcome. Neurosurgery 2002;51(5):1162-1172, dis-

cussion 1172-1174

3. Yang S, Yang X, Hong G. Surgical treatment of one hundred seventy-four intra-

medullary spinal cord tumors. Spine (Phila Pa 1976) 2009;34(24):2705-2710

Answers to Common Clinical Questions

1. Longitudinally in the midline of the spinal cord. With splitting of

the dorsal columns, proprioceptive deficit is minimized.

2. No. The cyst wall is usually nonneoplastic and the cyst will

resolve.

3. Continuous intraoperative SSEPs and MEPs are required.

65 Surgical Resection of Spinal Vascular Lesions

Timothy D. Uschold, Alim P. Mitha, and Steve W. Chang

I. Key Points

- The natural history of spinal vascular lesions is usually malig-

nant. Given the eloquence of local tissue, early definitive treat-

ment is favored whenever feasible.

- All arteriovenous

(AV) lesions require preoperative spinal

angiography.

- Preservation of the anterior spinal artery (ASA) is paramount

during attempts at surgical treatment or embolization.

- The optimal trajectory for the resection of spinal cavernous

malformations is determined by the two-point method. A line

connecting the center of the lesion with its most accessible

margin determines the approach. Some lesions without pial

contact may still be resected.

- Timing of surgical intervention after hemorrhage is controver-

sial, although the presence of acute hemorrhage may aid in early

resection of some cavernomas.

II. Indications

- Cavernous malformations: Surgery is recommended for all ac-

cessible lesions that reach a pial surface. Small, deep-seated

asymptomatic lesions can be followed. Deep lesions with evi-

dence of repeated hemorrhage or expansion should be consid-

ered for surgery.¹

- Extradural-intradural AV malformations (AVMs): Palliative at-

tempts at flow reduction and/or selective targeting of high-risk

features are appropriate in the setting of progressive symptoms

related to steal, repeated hemorrhage, mass effect, or congestion.

- Intramedullary and conus AVMs: Surgical resection, typically

with preoperative embolization, is recommended if gross total

excision can be achieved. Embolization alone for cure has been

demonstrated but remains more controversial.

- Intradural-dorsal and intradural-ventral AV fistula (AVF): all

require definitive treatment with either surgery or nonpar-

ticulate embolization. If clinical history and imaging findings

suggest an intradural-dorsal AVF despite a negative angiogram,

surgical exploration is warranted.

- Extradural AVF: all require definitive treatment; endovascular

intervention is favored.

65 Surgical Resection of Spinal Vascular Lesions

411

III. Technique

- Posterior or posterolateral approach via laminectomy or

laminoplasty

• Added costotransversectomy or facetectomy may allow fur-

ther lateral exposure.

• The dura is opened in a linear fashion and the arachnoid is

tacked to the dura.

• If additional anterolateral visualization is necessary, the den-

tate ligaments may be transected and tacked contralaterally

with 6-0 Prolene suture to facilitate gentle rotation of the spi-

nal cord. This may be done across several levels for maximum

effect (Fig. 65.1).

- Cavernous malformations

• When necessary, myelotomy is made sharply with a linear pial

opening. Appropriate zones for entry into the cord include the

dorsal midline and the lateral dorsal sulcus at the dorsal root

entry zone. This trajectory enters the substantia gelatinosa. A

third entry option is the lateral trajectory behind the dentate

ligaments and between the dorsal and ventral spinocerebellar

tracts (Fig. 65.2).

• The lesion is dissected circumferentially. Coagulation of the

cavernoma may be necessary to shrink and debulk the lesion’s

Fig.

65.1 Gentle spinal cord rotation is facilitated by retraction of dentate

ligament(s) (used with permission from Barrow Neurological Institute).

412 IV Surgical Techniques

Fig. 65.2 Alternative posterior and posterolateral zones of entry for myelotomy

(used with permission from Barrow Neurological Institute).

interior. The associated venous anomaly should be preserved.

Surrounding hemosiderin-stained spinal cord is not taken.¹

- Intradural-dorsal AVFs: Following dural opening, the arterial-

ized vein is followed to its intradural interface along the root

sleeve, where the radicular artery pierces the dura. The intra-

dural fistulous connection is clipped, bipolared, and transected.

- Extradural AVF: transarterial endovascular coil embolization is

typically the preferred modality of treatment, although trans-

venous routes have been described.

- Intradural-ventral AVFs: Anterior and posterolateral trajec-

tories have been described. The fistula is bipolared and tran-

sected such that arterial supply to the ASA and normal venous

drainage is preserved. Venous varices can be further excised.

Nonparticulate embolization may be useful in selected cases,

although surgery remains the gold standard.

- Intramedullary spinal AVMs: Arterial rather than venous feeders

should be sharply dissected circumferentially, cauterized, and

transected first. The largest draining vein is typically cauterized

and transected last for removal of the specimen.

- Extradural-intradural AVMs: Embolization may be the primary

palliative modality for the setting of symptomatic steal, repeat-

ed hemorrhage, or vascular congestion. Surgery is typically re-

served for relief of persistent, symptomatic mass effect.

65 Surgical Resection of Spinal Vascular Lesions

413

IV. Complications

- Cerebrospinal fluid leak, wound complications.

- Delayed or acute neurologic decline: May be attributable to

progressive venous thrombosis, especially in the setting of em-

bolization for intradural-dorsal AVFs. Routine postprocedural

heparinization is considered in these patients. Blood pressure

control is strict, and judicious use of steroids is advised before

intervention.

V. Postoperative Care

- Postprocedural angiography and/or magnetic resonance imag-

ing (MRI) is essential to verify treatment effect, especially in

the setting of new neurologic deficits.

VI. Outcomes

- Cavernous malformations: Subtotal resection offers nominal

benefit. Initial postoperative deterioration has been reported

in 24 to 50%, but long-term follow-up data suggest improved

neurologic function in as many 46 to 58%.

- Intradural-dorsal AVFs: The primary benefit of surgery over en-

dovascular treatment remains risk of recurrence (as high as 98%

initial success for surgery vs. 46 to 85% for embolization).² En-

dovascular abilities are improving. Motor improvements have

been reported in approximately 60% of patients compared with

40% showing improvements in sphincter dysfunction (Aminoff-

Logue [AL] Scale, Table 65.1), irrespective of treatment modal-

ity. Numerically, improvements in AL scores are typically mod-

est (about one point).

- Intradural-ventral AVFs: Available series are mostly small, but

neurologic improvement or stabilization following surgery has

been reported to range from 87.5 to 95%. Preoperative emboli-

zation may be useful in limiting flow rate (and in some cases for

cure), but incomplete occlusion has resulted in more modest

improvements compared with surgery.³

- Extradural AVFs: Outcomes reported in numerous case reports

have been favorable in terms of fistula obliteration and clinical

improvement. In the setting of acute hematoma, surgical evac-

uation within 12 hours is an important prognostic.

- Extradural-intradural AVMs: Most multimodality attempts are

purely palliative. Rare cases may be amenable to embolization

followed by operative resection.

414 IV Surgical Techniques

Table 65.1 Aminoff-Logue Scale

Gait dysfunction

1. Leg weakness or gait change without significant activity impairment

2. Restricted walking but no DME assist required

3. Cane for ambulation

4. Crutches or walker for ambulation

5. Bed-bound, does not stand, confined to wheelchair

Urinary dysfunction

1. Hesitancy, urgency, and/or frequency

2. Intermittent incontinence or retention

3. Full incontinence or retention

Abbreviation: DME, durable medical equipment.

Source: Modified from Aminoff MJ and Logue V. The Prognosis of Patients with Spinal

Vascular Malformations. Brain 1974;(97):211-218.

- Intramedullary AVMs: Clinical improvement rates of 33 to 67%

have been reported for surgery, compared with rates of 8 to

20% for clinical decline. Rates of postsurgical angiographic cure

have ranged from 59 to 100%. Further endovascular data using

Onyx is anticipated. The most appropriate and definitive strat-

egy remains preoperative embolization (when technically ap-

propriate) followed by microsurgical excision.

- Conus AVMs: Little published experience. Aggressive multimo-

dality treatment can result in clinical improvement or stabiliza-

tion in addition to angiographic cure.

VII. Surgical Pearls

- Intraoperative electrophysiologic monitoring of somatosensory

evoked potentials (SSEPs) and motor evoked potentials (MEPs) is

essential for all cases. In the setting of AV lesions, serial indocya-

nine green angiography (ICG) and/or intraoperative spinal angio-

graphic runs before and during resection are often useful.

- Anterior or anterolateral approaches to the resection of spinal

vascular lesions are seldom advised due to the risk of ASA com-

promise and poor dural closure.⁴

- Sharp rather than blunt dissection is favored when possible.

- If required, myelotomy should expose the entire cranial-caudal

extent of the lesion to minimize parenchymal retraction and aid

in visualizing feeding pedicles.

65 Surgical Resection of Spinal Vascular Lesions

415

- Pressure measurements in the arterialized veins of intradu-

ral dorsal AVFs can be transduced using a small-gauge needle.

Pressure should more closely approximate central venous pres-

sure following fistula obliteration.

Common Clinical Questions

1. Name the primary advantage of surgery (in terms of outcome)

over embolization for intradural-dorsal AVFs.

2. Name three zones of entry for myelotomy from a posterior

approach.

3. Name three intraoperative tools or strategies useful in guiding

and confirming treatment for AVMs and AVFs.

References

1. Vishteh AG, Sankhla S, Anson JA, Zabramski JM, Spetzler RF. Surgical resection

of intramedullary spinal cord cavernous malformations: delayed complica-

tions, long-term outcomes, and association with cryptic venous malforma-

tions. Neurosurgery 1997;41(5):1094-1100, discussion 1100-1101

2. Steinmetz MP, Chow MM, Krishnaney AA, et al. Outcome after the treatment

of spinal dural arteriovenous fistulae: a contemporary single-institution se-

ries and meta-analysis. Neurosurgery 2004;55(1):77-87, discussion 87-88

3. Cho KT, Lee DY, Chung CK, Han MH, Kim HJ. Treatment of spinal cord peri-

medullary arteriovenous fistula: embolization versus surgery. Neurosur-

gery 2005;56(2):232-241

4. Connolly ES Jr, Zubay GP, McCormick PC, Stein BM. The posterior approach to

a series of glomus (Type II) intramedullary spinal cord arteriovenous mal-

formations. Neurosurgery 1998;42(4):774-785, discussion 785-786

Answers to Common Clinical Questions

1. Decreased risk of recurrence with surgery

2. Dorsal midline, dorsal lateral sulcus, lateral between the nerve

roots

3. Intraoperative monitoring, ICG, intraoperative spinal angiogra-

phy, intravascular pressure transduction

Positioning

Tien V. Le, Juan S. Uribe, and Fernando L. Vale

Topic

Positioning

Prone

•

Patient initially supine on radiolucent imaging top of the

positioning

Jackson table

on Mizuho

•

Pad bony prominences appropriately (see below).

OSI

•

Temporarily tuck arms with thin sheet.

“Jackson”

•

Place the Jackson Spinal Surgery Table Top over patient and

Spinal Table

temporarily hold in place with pins for adjustment of pads.

•

Position rigid plastic head rest directly over Prone View

headrest or other soft head rest.

•

Thoracic pad to be positioned between sternal notch and

xyphoid

•

Center the hip and thigh pads for appropriate support.

•

Leg pads centered over rest of legs, leaving room for both

feet once turned prone

•

Place a bed sheet folded to width of ~2 feet and centered

over the lower half of the arms for later use in tucking.

•

Attach four seatbelts, one for upper thorax, one at hips,

one at thigh, and one at lower leg.

•

Remove pin and compress Jackson frame until there is

some resistance at caudal end, then replace pin in new slot.

•

Remove pin and compress Jackson frame until there is firm

resistance rostrally, then replace pin in new slot

•

Refasten all four seatbelts tightly.

•

Count for four seatbelts and four pins both rostrally and

caudally.

•

Loosen resistance at head of bed.

•

Discuss which side to turn patient with partner at caudal

end and the anesthesiologist.

•

Turn in brisk, smooth fashion 180° into prone position.

•

Remove seatbelts and remove pins securing the posterior

bed and remove the posterior bed.

•

Double-check positioning of all padding and confirm

adequacy.

•

Check foley position and be sure genitals in males are free

of compression.

•

Abdomen should be decompressed, allowing for diaphrag-

matic excursion.

•

Check for neutral position of cervical spine and reposition

Prone View as needed.

420 Appendices

Topic

Positioning

Padding and • Pad all bony prominences to prevent postoperative neuropathies.

prophylaxis

•

May use egg-crate foam padding or any other soft material

such as gel pads or Tempur-Pedic foam.

•

Wrists should be padded to decrease risk of median

neuropathy.

•

Elbows should be padded to decrease risk of ulnar neuropathy.

•

Knees/fibular head should be padded to decrease risk of

common peroneal neuropathy.

•

The pelvis anterior superior iliac spine should be padded to

decrease risk of lateral femoral cutaneous neuropathy.

•

An axillary roll can be placed at the upper chest wall when

in a lateral decubitus position to decrease risk of brachial

plexopathy.

•

Eye goggles and slight reverse trendelenburg position may

help decrease undo pressure on eyes when in prone posi-

tion, which decreases risk of postoperative blindness.

•

Supine position

cervical

•

Place intrascapular shoulder roll.

approach

•

Head midline placed in chin strap and with 5-10 lbs of traction

•

Neck in neutral position

•

Pad all bony prominences appropriately.

•

Tape shoulders with 3” silk tape and pull to caudal end of

operating table to maximize view of caudal cervical spine.

•

Tuck arms to side in secure fashion, make sure thumbs

point up.

•

May use soft wrist ties using unrolled KERLIX roll for later

use by circulator for more visualization of caudal levels in

extreme cases

•

Slight reverse trendelenburg

Posterior

•

Place in prone position using Jackson spinal table as above.

cervical

•

Gardner-Wells tongs may be placed in neutral position (3-4

approach

cm directly above the pinna and inferior to superior tempo-

ral line) prior to flipping for additional axial cervical traction

and reduction if needed.

•

Likewise, some may opt to use a Mayfield skull clamp for rigid

fixation for certain cases (e.g., severe kyphotic deformities).

•

Tuck arms using preplaced sheet by wrapping sheet around

the arms and onto the thoracolumbar region.

•

Secure with multiple towel clamps.

•

Be sure thumbs are facing down.

•

Tape shoulders with 3” silk tape and tape to caudal end of

Jackson table.

•

Tape the skin overlying the trapezius with 3” silk tape

bilaterally, and tape to caudal end of Jackson table until

posterior skin of neck is taught.

•

Place in slight reverse trendelenburg.

I Positioning

421

Topic

Positioning

Posterior

•

Place in prone position using Jackson table as above.

cervical

•

Gardner-Wells tongs may be placed in neutral position (3-4

approach

cm directly above the pinna and inferior to superior tempo-

for occipital

ral line) prior to flipping for additional axial cervical traction

cervical

and reduction if needed.

fusion

•

Likewise, some may opt to use a Mayfield skull clamp for

rigid fixation prior to fusion.

•

Tuck arms using preplaced sheet by wrapping sheet around

the arms and onto the thoracolumbar region. Secure with

multiple towel clamps.

•

Be sure thumbs are facing down.

•

Tape shoulders with 3” silk tape and tape to caudal end of

Jackson table.

•

Tape the skin overlying the trapezius with 3” silk tape

bilaterally and tape to caudal end of Jackson table until

posterior skin of neck is taught.

•

Place in slight reverse trendelenburg.

•

Slightly flex the cervical spine and place chin in military

tuck position to allow for better exposure of occiput and

occipital-cervical junction, keeping the neck neutral.

Posterior

•

For unstable fractures or when manipulation of lumbar

lumbar

spine is to be kept to a minimum, position patient with

approach

Jackson table as above.

•

For operations without instability (e.g., microdiskectomy),

may use a “Wilson frame” or positioning on two large

parallel, longitudinally oriented gel rolls with enough

room to allow for diaphragmatic excursion and abdominal

decompression.

•

Failure to allow for abdominal decompression leads to

increased pressure transmitted to epidural veins, compli-

cating surgery with increased bleeding.

•

For kyphoplasty/vertebroplasty, may use two large gel

rolls, with one spanning the width of the chest and one

spanning the width of the pelvis.

•

Regardless of specific procedure, for lumbar operations,

arms should be abducted and forearms forward, resting on

a soft pillow which is positioned on top of an armrest.

•

The arms should not be abducted more than 90° and the

elbows should not have any direct pressure on them to

minimize ulnar neuropathy.

•

Axillary padding should be used to minimize brachial

plexus injuries.

•

Keep patient in slight reverse trendelenburg.

422 Appendices

Topic

Positioning

•

Patient is supine on an operating table with arms tucked to

lumbar

the side.

approach

•

All bony prominences appropriately padded

•

May use additional roll in lumbosacral region for increased

lordosis.

Lateral

•

C-Max table or other table capable of flexion/extension at

transpsoas

the hip to be used

approach

•

Patient is placed in lateral decubitus position depending on

which side is approached for procedure.

•

An axillary roll should be placed.

•

The superior iliac crest should be positioned just past the

“break” in the table.

•

A moderately sized roll may then be placed at the break,

especially for an L4/5 disc space, this is not as important if

operating at L2/3 or higher.

•

Hips are flexed with knees bent, allowing for more relaxed

iliopsoas muscles.

•

Fluoroscopy is used to establish a “true” AP view with the

C-arm in its most neutral position.

•

Once established, 3” silk tape is used to secure the patient

at the iliac spines.

•

More tape is used to secure the thoracic cavity. Be sure to

protect the nipples with foam when applying the tape.

•

The legs must be taped down to secure the patient in this

fixed position.

•

An arm board is used to support the lower arm.

•

An additional arm board is used to support the upper arm,

or stacked pillows may be used to support the upper arm.

Lateral

•

The same basic positioning is done for transpsoas ap-

thoracic

proach, but be sure to leave enough room for operating at

approach

the appropriate thoracic level(s).

Class

Example

Benefits

Limitations

Uses

Cervical:

Soft collar

• Light

• Minimal purchase of

• Cervical sprains

Cervical orthoses (CO)

• Inexpensive

occiput & mandible

• Post-op support

• Comfortable

• Still permits up to 80%

• Proprioceptive reminder

• High compliance

of motion

limiting extremes of

neck movement

• Not for patients with

bony instability

Cervical:

Thomas

• More rigid than CO

• No caudal fixation

• Temporary immobilizer

Occipital-mandibular

collar

• Better purchase of

• Poor lateral bending &

in acute trauma

cervical orhoses (OMC)

occiput & mandible

rotation control

• Not for patients with

• Better restriction of

• Still no significant

bony instability

flexion-extension

restriction of motion

Class

Example

Benefits

Limitations

Uses

Cervical:

Miami J

•

Most effective of

•

Parallelogram effect

•

Long term immobilizer for

Occipital-mandibular high

collar

high thoracic CTO’s in

severely unstable injury

thoracic orthoses (OMHT)

stabilizing all planes

•

Postop support

(73% flexion/extension,

High thoracic cervico-

51% lateral bending,

thoracic orthoses (CTO)

65% rotation)

• More effective at upper cer-

•

Relatively low occipital &

vical spine (C0-C3) versus

mandibular skin pres-

mid & lower segments

sure, reduces risk of skin

• Primarily restricts

ulceration

flexion-extension

• Poor restriction of lateral

bending & rotation

• Occipital-mandibular &

better upper thoracic

purchase (above sternum

anteriorly & above T3 spi-

nous process posteriorly)

Class

Example

Benefits

Limitations

Uses

Aspen collar

•

Less restricting than

•

Parallelogram effect

•

Long term immobilizer for

Miami J but more so than

cervical instabilities

Philadelphia

•

Postop support

•

Relatively low skin pres-

sure, reduces risk of skin

ulceration

•

Cleanable and replaceable

liners

•

Large anterior and poste-

rior openings for better

airflow

Philadelphia

•