Handbook of Spine Surgery E-Book

• Herausgeber: Thieme Medical Publishers
• Kategorie: Fachliteratur
• Sprache: Englisch

Veröffentlichungsjahr: 2015

Beschreibung

<p><strong><em>An updated edition of the most comprehensive guide to spine surgery</em></strong></p><p><cite>Handbook of Spine Surgery, Second Edition</cite>, is a completely updated and comprehensive reference that distills the basic principles of contemporary spine surgery. Its coverage of both principles and techniques makes it an excellent refresher before surgery or a valuable daily companion for residents and surgeons caring for patients with spinal disorders.</p><p>Key Features of the Second Edition:</p><ul><li>New chapters on adult degenerative deformity, pediatric scoliosis and radiographic principles of deformity</li><li>Expanded spinal trauma section now includes separate chapters on cervical, thoracolumbar, and sacropelvic injuries</li><li>Common clinical questions (with answers) at the end of each chapter highlight topics frequently encountered in the operating room and on board exams</li><li>Easy-to-read bulleted format</li></ul><p>The second edition of this handbook is the go-to guide for all those involved in spine surgery.</p>

Leseprobe

Handbook of Spine Surgery

Second Edition

Ali A. Baaj, MD

Assistant ProfessorDepartment of Neurological SurgeryWeill Cornell Medical CollegeAdult and Pediatric Spine SurgeryNew York Presbyterian HospitalNew York, New York

Praveen V. Mummaneni, MD

Professor and Vice-ChairmanDepartment of NeurosurgeryUniversity of California–San FranciscoCo-Director, UCSF Spine CenterSan Francisco, California

Juan S. Uribe, MD

Associate ProfessorDirector, Spine SectionDepartment of NeurosurgeryUniversity of South FloridaTampa, Florida

Alexander R. Vaccaro, MD, PhD, MBA

Richard H. Rothman Professor and ChairmanDepartment of Orthopaedic SurgeryProfessor of NeurosurgeryCo-Chief of Spine SurgerySidney Kimmel Medical Center at Thomas Jefferson UniversityCo-Director, Delaware Valley Spinal Cord Injury CenterPresident, Rothman InstitutePhiladelphia, PennsylvaniaMark S. Greenberg, MDAssociate ProfessorDepartment of Neurosurgery and Brain RepairUniversity of South FloridaTampa, Florida

196 illustrations

ThiemeNew York • Stuttgart • Delhi • Rio de Janeiro

Executive Editor: Timothy HiscockManaging Editor: Sarah LandisDirector, Editorial Services: Mary Jo CaseyEditorial Assistant: Nikole ConnersProduction Editor: Kenneth L. ChumbleyInternational Production Director: Andreas SchabertVice President, Editorial and E-Product Development: Vera SpillnerInternational Marketing Director: Fiona HendersonInternational Sales Director: Louisa TurrellDirector of Sales, North America: Mike RosemanSenior Vice President and Chief Operating Officer: Sarah VanderbiltPresident: Brian D. Scanlan

Library of Congress Cataloging-in-Publication DataHandbook of spine surgery/[edited by] Ali A. Baaj, Praveen V. Mummaneni, Juan S. Uribe, Alexander R. Vaccaro, Mark S. Greenburg.—2nd edition.      p.; cm. Includes bibliographical references and index. ISBN 978-1-62623-163-4 (alk. paper)—ISBN 978-1-62623-164-1 (eBook)I. Baaj, Ali A., editor. II. Mummaneni, Praveen V., editor. III. Uribe, Juan S., editor. IV. Vaccaro, Alexander R., editor. V. Greenburg, Mark S., editor. [DNLM: 1. Spine—surgery—Handbooks. 2. Neuro-surgical Procedures—methods—Handbooks. 3. Orthopedic Procedures—methods—Handbooks. 4. Spinal Cord—surgery—Handbooks. WE 39]RD533617.4’71—dc23                                                         2015033555

© 2016 Thieme Medical Publishers, Inc.Thieme Publishers New York333 Seventh Avenue, New York, NY 10001 USA+1 800 782 3488, [email protected]

Thieme Publishers StuttgartRüdigerstrasse 14, 70469 Stuttgart, Germany+49 [0]711 8931 421, [email protected]

Thieme Publishers DelhiA-12, Second Floor, Sector-2, Noida-201301Uttar Pradesh, India+91 120 45 566 00, [email protected]

Thieme Publishers Rio de Janeiro, Thieme Publicações Ltda.Edifício Rodolpho de Paoli, 25o andarAv. Nilo Peçanha, 50 – Sala 2508Rio de Janeiro 20020-906, Brasil+55 21 3172 2297

Cover design: Thieme Medical PublishersTypesetting by Prairie Papers

Printed in China by Everbest      Printing Company                               5 4 3 2 1

ISBN 978-1-62623-163-4

Also available as an e-book:eISBN 978-1-62623-164-1

Important note: Medicine is an ever-changing science undergoing continual development. Research and clinical experience are continually expanding our knowledge, in particular our knowledge of proper treatment and drug therapy. Insofar as this book mentions any dosage or application, readers may rest assured that the authors, editors, and publishers have made every effort to ensure that such references are in accordance with the state of knowledge at the time of production of the book.

Nevertheless, this does not involve, imply, or express any guarantee or responsibility on the part of the publishers in respect to any dosage instructions and forms of applications stated in the book. Every user is requested to examine carefully the manufacturers’ leaflets accompanying each drug and to check, if necessary in consultation with a physician or specialist, whether the dosage schedules mentioned therein or the contraindications stated by the manufacturers differ from the statements made in the present book. Such examination is particularly important with drugs that are either rarely used or have been newly released on the market. Every dosage schedule or every form of application used is entirely at the user's own risk and responsibility. The authors and publishers request every user to report to the publishers any discrepancies or inaccuracies noticed. If errors in this work are found after publication, errata will be posted at www.thieme.com on the product description page.

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.

This book, including all parts thereof, 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, mimeographing or duplication of any kind, translating, preparation of microfilms, and electronic data processing and storage.

To my parents, Abdulwahab and Hana, to my wife, Gabriela, to all my mentors of spine surgery, especially Juan Uribe and Ziya Gokaslan, and to the residents and fellows who give us the reason to do all this.AAB

For Valli, Nikhita, Nkihil, and Neel for all their love and support.For the fellows and residents whom I have had the pleasure to help teach.PVM

I would like to dedicate this book to the birth of my child, Christian John Vaccaro, and to my beautiful wife, Lauren. Lauren's gift of caring and love has only added to the joy of our family life.ARV

To my family.MSG

To my wife, Catalina, my son, Sebastian, my daughter, Camila, my parents, Carlos Santiago and Maria Cecilia, and my parents-in-law, Ivan and Maria Cecilia, for their love and unconditional support.JSU

Contents

Foreword

Foreword

Preface

Acknowledgments

Contributors

I Anatomy

1 Embryology of the Spine

Eric Momin, Jared Fridley, and Andrew Jea

2 Craniovertebral Junction

Jonathan Hobbs and Edwin Ramos

3 Cervical Spine

William J. Readdy, Eric Sribnick, and Sanjay S. Dhall

4 Thoracic Spine

Whitney S. James, Jens R. Chapman, and Rod J. Oskouian Jr.

5 Lumbar Spine

Hormuzdiyar H. Dasenbrock, Rafael De la Garza-Ramos, and Ali Bydon

6 Sacral–Iliac Spine

Amit R. Patel, Matthew Chin, Amrit Khalsa, and Ravi K. Ponnappan

II Clinical Spine Surgery

7 Physical Examination

Mark S. Greenberg

8 Spinal Imaging

David Minges and Joon Y. Lee

9 Radiation Exposure in Spine Surgery

Alexander Tuchman and Patrick C. Hsieh

10 Electrodiagnostic Testing in Spine Surgery

Kamakshi Patel and Holli A. Horak

11 Intraoperative Neurophysiological Monitoring in Spine Surgery

Colin R. Bamford

12 Bedside Procedures

Daniel C. Lu and Praveen V. Mummaneni

13 Pharmacology

Mark S. Greenberg

14 Radiation Therapy in Spine Surgery

Alexander Tuchman and Patrick C. Hsieh

15 Spinal Radiosurgery Therapy

Benjamin M. Zussman, Edward A. Monaco III, and Peter Carlos Gerszten

16 Spinal Navigation

Roger Härtl and José A. Corredor

17 Spine Biologics

Zorica Buser, Rahul Basho, and Jeffrey C. Wang

III Spinal Pathology

18 Congenital Anomalies

Jared Fridley, Eric Momin, and Andrew Jea

19 Cervical Trauma

Gregory D. Schroeder and Alexander R. Vaccaro

20 Thoracolumbar Trauma

Wyatt L. Ramey, Jesse Skoch, and Ali A. Baaj

21 Sacropelvic Trauma

Kelley Banagan, Salman Abbasifard, Ali A. Baaj, and Steven C. Ludwig

22 Infection

Arya Giri Varthi, William D. Long III, Jason O. Toy, and Peter G. Whang

23 Spinal Column and Spinal Cord Tumors

C. Rory Goodwin, Camilo Molina, and Daniel M. Sciubba

24 Cervical and Thoracic Spine Degenerative Disease

Clinton J. Burkett and Mark S. Greenberg

25 Degenerative Lumbar Spine Disease

Michael Y. Wang

26 Congenital and Neuromuscular Scoliosis

Marie Roguski, Amer F. Samdani, and Steven W. Hwang

27 Scheuermann's Kyphosis

Jahangir Asghar, Paul D. Kiely, and Harry L. Shufflebarger

28 Adolescent Idiopathic Scoliosis

Lawrence G. Lenke and Todd M. Chapman Jr.

29 Adult Degenerative Deformity

Salman Abbasifard and Ali A. Baaj

30 Radiographic Parameters of Spinal Deformity

Khoi D. Than, Andrei Fernandes Joaquim, and Praveen V. Mummaneni

31 Vascular Pathology of the Spine

Timothy D. Uschold and Steven W. Chang

32 Spondyloarthropathies

Amir A. Ahmadian and Fernando L. Vale

33 Spinal Emergencies

Puya Alikhani, Andreas K. Filis, and Frank D. Vrionis

IV Surgical Techniques

34 Occipitocervical Fusion

Gisela Murray, Edwin Ramos, and Juan S. Uribe

35 Chiari I Decompression

Mark S. Greenberg

36 Transoral Odontoidectomy

Steven M. Presciutti, Martin Quirno, Colin B. Harris, and Frank M. Phillips

37 C1–C2 Techniques

Jau-Ching Wu, Khoi D. Than, and Praveen V. Mummaneni

38 Direct Fixation of Odontoid Fractures

Rajiv Saigal and Dean Chou

39 Cervical Arthroplasty

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

40 Anterior Cervical Corpectomy

Colin B. Harris and Frank M. Phillips

41 Anterior Cervical Diskectomy

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

42 Cervical Laminectomy with and without Fusion

Shyam M. Shridharani and F. Andrew Rowan

43 Cervical Laminoplasty

Glen R. Manzano and Allan D. Levi

44 Posterior Cervical Foraminotomy

Andreas K. Filis and Frank D. Vrionis

45 Cervical Open Reduction Techniques: Anterior and Posterior Approaches

Harminder Singh, George M. Ghobrial, and James S. Harrop

46 Anterior Cervical–Thoracic Junction Technique

Muhammad M. Abd-El-Barr, Viren S. Vasudeva, and Michael W. Groff

47 Freehand Thoracic Pedicle Screw Placement Technique

Sheri Palejwala, Jesse Skoch, and Ali A. Baaj

48 Transpedicular Approach

Vinko Zlomislic and Steven R. Garfin

49 Costotransversectomy

Hasan A. Zaidi and U. Kumar Kakarla

50 Lateral Extracavitary Approach

Marco Ferrone and Christopher M. Bono

51 Pedicle Subtraction Osteotomy/Smith-Petersen Osteotomy

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

52 Thoracoscopic Approaches to the Spine

Meic H. Schmidt and Ricky Kalra

53 Lateral Approaches to the Thoracolumbar Spine

Jay Rhee, C. Rory Goodwin, and Jean-Paul Wolinsky

54 Open and Minimally Invasive Spinal Lumbar Microdiskectomy

Ali A. Baaj and Mark S. Greenberg

55 Lumbar Foraminotomy

Ali A. Baaj and Juan S. Uribe

56 Posterolateral Endoscopic Diskectomy

Christopher Yeung and Anthony T. Yeung

57 Lumbar Laminectomy

Benjamin D. Elder and Timothy F. Witham

58 Posterior and Transforaminal Lumbar Interbody Fusion

Zachary J. Tempel, Hazem A. Mashaly, and Adam S. Kanter

59 Minimally Invasive Transforaminal Lumbar Interbody Fusion

Michael Y. Wang

60 Percutaneous Pedicle Screw Placement

Michael Y. Wang

61 Minimally Invasive Lateral Retroperitoneal Transpsoas Interbody Fusion

Gisela Murray, Ali A. Baaj, and Juan S. Uribe

62 Anterior Lumbar Interbody Fusion

Junyoung Ahn, Krzysztof Siemionow, Dustin H. Massel, Benjamin C. Mayo, William D. Long III, Krishna D. Modi, and Kern Singh

63 Facet Screw Fixation/Fusion

Justin W. Miller and Rick C. Sasso

64 Interspinous Process Decompression

Jason O. Toy, Ravi Ramachandran, Arya Giri Varthi, and Peter G. Whang

65 Lumbar Arthroplasty

Keith Jackson and Joon Y. Lee

66 Lumbosacroiliac Fixation

Phillip Horne, William D. Long III, and Andrew A. Sama

67 Iliosacral Percutaneous Fixation (Iliosacral Screws)

Jonathan G. Eastman and Eric O. Klineberg

68 Sacroiliac Joint Fusion

Kornelis Poelstra and Jessica Sosio

69 Sacrectomy

Thomas Kosztowski, Mohamad Bydon, C. Rory Goodwin, and Ziya L. Gokaslan

70 Vertebral Body Augmentation

Andrey Alex Volkov, Ioannis Papanastassiou, and Frank D. Vrionis

71 Spinal Cord Tumor Resection

Mari L. Groves and George I. Jallo

72 Surgical Resection of Spinal Vascular Lesions

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

Appendices

I Positioning

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

II Selected Spinal Orthoses

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

III Outcome Scales

Index

Foreword

In this exciting second edition of the Handbook of Spine Surgery, editors Ali A. Baaj, Praveen V. Mummaneni, Juan S. Uribe, Alexander R. Vaccaro, and Mark S. Greenberg have configured a virtual step-by-step “cookbook” of all the common and uncommon surgical spine procedures utilized around the globe, with chapters authored by highly recognized spinal surgeons. This task has been expertly accomplished by the overall organization of the chapters into sections: Anatomy, Clinical Spine Sur gery, Spinal Pathology, and Surgical Techniques. Specific topics are thoroughly covered within and across sections, such as “Thoracolumbar Trauma” (Chapter 21 in the Spinal Pathology section), “Freehand Thoracic Pedicle Screw Placement Technique” (Chapter 47 in the Surgical Techniques section), and specific surgical procedures, such as “Sacrectomy” (Chapter 69 in the Surgical Techniques section). A common template is followed in which each chapter logically proceeds from Key Points to Indications, Techniques, Complications, Postperative Care, Outcomes, Surgical Pearls, Common Clinical Questions and Answers (as is seen in current CME formats), and Key References. This structure is very effective and ideal for quick and easy review the evening before, or even the morning of, conferences and surgical procedures. Trainees still trying to master these topics, as well as more senior surgeons needing a quick refresher, will benefit. The organizational style is direct and compact but thorough, appropriately illustrated when helpful, and perfectly suited to a busy clinical schedule where essential information and details need to be gleaned in rapid fashion, whether in print, on a phone, tablet, or computer. The organizational consistency of the chapters also aids in quick dissemination and retention, which is critical to our training environment.

I can envision this text being extremely useful to a wide range of individuals: from a third-year medical student performing his or her initial surgical rotation while assigned to the spine service, to a spine physician assistant helping out during surgery, to a spinal surgery fellow gaining technical confidence during the most important year of fellowship training. Those residents, fellows, and attendings utilizing this text will probably find the greatest “bang for their buck” in the pearls and tips, which are written to optimize safety and maximize efficiency during various specific spinal surgery procedures. I also found the Q and A sections a nice refresher for keeping up on the myriad of spine surgery techniques that have rapidly advanced over the past decade, as spine surgery itself continues down a subspecialization pathway distinct from orthopedic surgery and neurosurgery. In that regard, this book would also serve as an excellent review for those studying for board certification or recertification for the American Board of Orthopaedic Surgery or the American Board of Neurological Surgery exams.

I congratulate the editors and contributing authors for this important piece of work. Any “handbook” should, by definition, be able to concisely provide essential details of a condition and various remedies and solutions—as well as obstacles encountered along the way—to best educate the intended audience. I am confident that the Handbook of Spine Surgery has more than accomplished these objectives and will have an enduring and important impact on those fortunate enough to benefit from the assembled information provided.

Lawrence G. Lenke, MDProfessor and Chief of Spinal SurgeryDepartment of Orthopaedic SurgeryColumbia University Collegeof Physicians and SurgeonsSurgeon-in-ChiefThe Spine Hospital atNew York-Presbyterian/Allen HospitalNew York, New York

Foreword

The second edition of the Handbook of Spine Surgery, edited by Dr. Ali A. Baaj, Dr. Praveen V. Mummaneni, Dr. Juan S. Uribe, Dr. Alexander R. Vaccaro, and Dr. Mark S. Greenberg, is an outstanding distillation of the current knowledge of the evaluation and surgical management of spinal disorders. The book is divided into four well-organized sections: a detailed synopsis of spinal anatomy, an evaluation of the techniques used for clinical evaluation of spinal surgery, a detailed description of spinal surgical pathology, and a step-by-step description of surgical techniques. In addition, there are appendices on patient positioning, selected spinal orthoses, and commonly used outcome scales.

The Handbook of Spine Surgery particularly excels as a quick reference for almost any type of spinal surgical condition or surgical procedure, from occipitocervical fusion to spinopelvic fixation. Each of the chapters is written by a world-renowned physician. The surgical chapters are authored by experts from the field of orthopaedic or neurosurgical spinal surgery; every chapter has introductory key points and detailed descriptions of indications for each of the surgical procedures. A step-by-step description of instrumentation techniques, frequently asked questions, and surgical pearls are provided by experts in the field.

This book will be an invaluable resource for orthopaedic and neurosurgical residents in training, spinal surgical fellows, and practicing orthopaedic surgeons and neurosurgeons who deal with spinal pathology. The book covers an exhaustive set of topics in a succinct manner, but sufficient information is provided to serve as a surgical atlas. I feel that this will become the standard resource for surgeons in training, early in practice, those preparing for board examinations, and experienced spine surgeons needing a refresher. I am positive that in its electronic form this book will be used as a quick reference on a daily basis by most practicing spine surgeons. I congratulate the editors on this outstanding resource and look forward to having it available to use in my own practice.

Christopher I. Shaffrey, MD, FACSJohn A. Jane Professorship of NeurologicalSurgeryDivision Head Spine SurgeryProfessor of Orthopaedic SurgeryUniversity of Virginia Medical CenterCharlottesville, Virginia

Preface

We are delighted to present the second edition of the Handbook of Spine Surgery. As with the previous edition, our goal is to provide a comprehensive yet portable and compact text that distills the basic principles of contemporary spine surgery. We have once again been fortunate to receive contributions from dozens of reputable surgeons representing acclaimed orthopedic and neurosurgery programs.

Whereas the highly popular format of the first edition is once again adopted, we have significantly enhanced the text with several new chapters addressing topics like pediatric scoliosis and adult deformity principles. We have also expanded the spinal trauma section to include dedicated chapters on cervical, thoracolumbar, and sacropelvic injuries. Surgical pearls and board-style questions at the end of each chapter emphasize the salient points of each topic.

We are confident that this text will continue to be an excellent resource for surgeons and trainees alike as we all strive to improve spine education and training and the clinical care of our patients.

Ali A. Baaj, MDPraveen V. Mummaneni, MDJuan S. Uribe, MDAlexander R. Vaccaro, MD, PhDMark S. Greenberg, MD

Acknowledgments

The editors would like to thank all the chapter authors for contributing to this second edition. We also thank the team at Thieme Publishers for their assistance in the preparation and publication of this text.

Contributors

Salman Abbasifard, MDSurgery DepartmentNeurosurgery DivisionUniversity of Arizona Medical Health CenterTucson, Arizona

Muhammad M. Abd-El-Barr, MD, PhDDepartment of SurgeryBrigham and Women's HospitalBoston, Massachusetts

Amir A. Ahmadian, MDNeurosurgeonDepartment of NeurosurgeryUniversity of South FloridaTampa, Florida

Junyoung Ahn, BSDepartments of Surgery, Orthopedic Surgery, and Biological PsychologyUniversity of Texas SouthwestDallas, Texas

Puya Alikhani, MDDepartment of NeurosurgeryUniversity of South FloridaTampa, Florida

Jahangir Asghar, MDPediatric Orthopedic Spine SurgeonNicklaus Children's HospitalMiami, Florida

Ali A. Baaj, MDAssistant ProfessorDepartment of Neurological SurgeryWeill Cornell Medical CollegeAdult and Pediatric Spine SurgeryNew York Presbyterian HospitalNew York, New York

Colin R. Bamford, MDAssociate ProfessorDepartment of NeurologyUniversity of ArizonaTucson, Arizona

Kelley Banagan, MDAssistant ProfessorDepartment of OrthopaedicsUniversity of Maryland Medical CenterBaltimore, Maryland

Rahul Basho, MDDirector of Spine SurgeryHannibal Regional HospitalMidwest Orthopedic SpecialistsHannibal, Missouri

Christopher M. Bono, MDChief, Orthopaedic Spine ServiceDepartment of Orthopaedic SurgeryBrigham and Women's HospitalBoston, Massachusetts

Clinton J. Burkett, MDNeurosurgeonNeurological Surgery AssociatesFort Lauderdale, Florida

Zorica Buser, PhDSenior Research AssociateDepartment of Orthopaedic SurgeryKeck School of MedicineUniversity of Southern CaliforniaLos Angeles, California

Ali Bydon, MDAssociate Professor of NeurosurgeryThe Johns Hopkins UniversityBaltimore, Maryland

Mohamad Bydon, MDAssistant Professor of Neurologic SurgeryDepartment of Orthopedic Surgeryand Health Sciences ResearchMayo ClinicRochester, Minnesota

Steven W. Chang, MDAttending PhysicianBarrow Neurological InstituteBarrow Neurosurgical AssociatesPhoenix, Arizona

Jens R. Chapman, MDComplex Spine SurgerySwedish Neuroscience InstituteSeattle, Washington

Todd M. Chapman Jr., MDDepartment of Orthopaedic SurgeryWashington UniversitySt. Louis, Missouri

Matthew Chin, MDDepartment of Orthopaedic SurgeryDrexel University College of MedicinePhiladelphia, Pennsylvania

Dean Chou, MDProfessorDepartment of NeurosurgeryUniversity of California-San Francisco Spine CenterSan Francisco, California

José A. Corredor, MDWeill Cornell Brain and Spine CenterDepartment of Neurological SurgeryWeill Cornell Medical CollegeNew York-Presbyterian HospitalNew York, New YorkCirujano de ColumnaeBogotá, Colombia

Hormuzdiyar H. Dasenbrock, MDDepartment of NeurosurgeryBrigham and Women's HospitalBoston, Massachusetts

Sanjay S. Dhall, MDAssociate ProfessorDepartment of Neurological SurgeryUniversity of California-San FranciscoDirectorSpinal Neurotrauma ProgramSan Francisco General HospitalSan Francisco, California

Jonathan G. Eastman, MDAssistant ProfessorDepartment of Orthpaedic SurgeryDivision of TraumatologyUniversity of California-Davis Health SystemSacramento, California

Benjamin D. Elder, MD, PhDDepartment of NeurosurgeryThe Johns Hopkins University School of MedicineBaltimore, Maryland

Marco Ferrone, MDInstructor of Orthopaedic SurgeryDepartment of Orthopaedic OncologyBrigham and Women's Hospital/Dana Farber Cancer InstituteBoston, Massachusetts

Andreas K. Filis, MDDepartment of Orthopedics and Oncological SciencesUniversity of South Florida College of MedicineTampa, Florida

Kevin T. Foley, MD, FACS, FAANSProfessor of Neurological Surgery, Orthopaedic Surgery, and Biomedical EngineeringUniversity of Tennessee Health Science CenterChairman, Semmes-Murphey ClinicMemphis, Tennessee

Jared Fridley, MDDepartment of NeurosurgeryBaylor College of MedicineHouston, Texas

Steven R. Garfin, MDDistinguished Professor and ChairDepartment of Orthopaedic SurgeryUniversity of California-San DiegoSan Diego, California

Rafael De la Garza-Ramos, MDDepartment of NeurosurgeryThe Johns Hopkins UniversityBaltimore, Maryland

Peter Carlos Gerszten, MD, MPH, FACSPeter E. Sheptak Professor and Vice-ChairmanDepartments of Neurological Surgery and Radiation OncologyUniversity of Pittsburgh Medical CenterPittsburgh, Pennsylvania

George M. Ghobrial, MDDepartment of Neurological SurgeryThomas Jefferson UniversityPhiladelphia, Pennsylvania

Ziya L. Gokaslan, MD, FAANS, FACSGus Stoll, MD Professor and ChairDepartment of NeurosurgeryThe Warren Alpert Medical School of Brown UniversityNeurosurgeon-in-ChiefRhode Island Hospital and The Miriam HospitalClinical Director, Norman Prince Neurosciences InstitutePresident, Brown Neurosurgery FoundationRhode Island HospitalDepartment of NeurosurgeryNorman Prince Neurosciences InstituteProvidence, Rhode Island

C. Rory Goodwin, MD, PhDDepartment of NeurosurgeryThe Johns Hopkins UniversityBaltimore, Maryland

Mark S. Greenberg, MDAssociate ProfessorDepartment of Neurosurgery and Brain RepairUniversity of South FloridaTampa, Florida

Michael W. Groff, MDDirector of Spinal NeurosurgeryDepartment of NeurosurgeryBrigham and Women's HospitalBoston, Massachusetts

Mari L. Groves, MDDepartment of NeurosurgeryThe Johns Hopkins HospitalBaltimore, Maryland

Colin B. Harris, MDAttending Spine SurgeonSyracuse Orthopedic SpecialistsCrouse Hospital and St. Joseph's Hospital Health Care CenterSyracuse, New York

James S. Harrop, MD, FACSProfessorDepartments of Neurological and Orthopedic SurgeryDirector, Division of Spine and Peripheral Nerve SurgeryNeurosurgery Director of Delaware Valley SCI CenterThomas Jefferson UniversityPhiladelphia, Pennsylvania

Roger Härtl, MDProfessor of Neurological SurgeryDirector of Spinal SurgeryCo-Director, Spine CenterWeill Cornell Brain and Spine CenterNew York, New York

Jonathan Hobbs, MDDepartment of NeurosurgeryUniversity of ChicagoChicago, Illinois

Holli A. Horak, MDAssociate ProfessorDepartment of NeurologyUniversity of ArizonaTucson, Arizona

Phillip Horne, MD, PhDAssistant Professor of SurgeryDepartment of Orthopaedic SurgeryDuke Orthopaedics of RaleighDuke Raleigh HospitalRaleigh, North Carolina

Patrick C. Hsieh, MD, MScAssociate ProfessorDirector of Minimally Invasive Spine Program and Spinal OncologyDepartment of NeurosurgeryUSC Spine CenterUniversity of Southern California Keck School of MedicineLos Angeles, California

Steven W. Hwang, MDChiefDivision of Pediatric NeurosurgeryDepartment of NeurosurgeryTufts Medical Center and Floating Hospital for ChildrenBoston, Massachusetts

Keith Jackson, MDStaff SurgeonDepartment of Orthopaedics and RehabilitationWomack Army Medical CenterFort Bragg, North Carolina

George I. Jallo, MDProfessor of Neurosurgery, Pediatrics, and OncologyDirectorInstitute Brain Protection ServicesAll Children's Hospital-Johns Hopkins MedicineSt. Petersburg, Florida

Whitney S. James, MD, MHSDepartment of NeurosurgeryUniversity of Arizona Medical CenterTucson, Arizona

Andrew Jea, MDAssociate ProfessorDepartment of NeurosurgeryBaylor College of MedicineHouston, Texas

Andrei Fernandes Joaquim, MD, PhDNeurosurgeonDepartment of NeurologyState University of CampinasCampinas-SP, Brazil

U. Kumar KakarlaAttending PhysicianBarrow Neurological InstituteBarrow Neurosurgical AssociatesPhoenix, Arizona

Ricky Kalra, MDDepartment of NeurosurgeryUniversity of UtahSalt Lake City, Utah

Adam S. Kanter, MDChiefDivision of Spine SurgeryAssociate ProfessorDepartment of Neurological SurgeryUniversity of PitttsburghPittsburgh, Pennsylvania

Amrit Khalsa, RN, IBCLCConsultantLabor of Love Lactation ServicesMeta Midwifery in the Bay AreaOakland, California

Paul D. Kiely, MCh, FRChIntegrated Spine Research DepartmentHospital for Special SurgeryNew York, New York

Eric O. Klineberg, MD, MSAssociate ProfessorDepartment of Orthopaedic SurgeryUniversity of California-Davis Health SystemSpine CenterSacramento, California

Thomas Kosztowski, MDDepartment of NeurosurgeryThe Johns Hopkins HospitalBaltimore, Maryland

Frank La Marca, MDClinical Associate ProfessorDepartment of NeurosurgeryUniversity of MichiganAnn Arbor, Michigan

Tien V. Le, MDNeurological SurgeonTampa Bay Neurosurgery and Spine SpecialistsTampa, Florida

Joon Y. Lee, MDAssociate ProfessorDirector of Clinical ResearchDepartment of Orthopaedic SurgeryUniversity of Pittsburgh Medical CenterPittsburgh, Pennsylvania

Lawrence G. Lenke, MDProfessor and Chief of Spinal SurgeryDepartment of Orthopaedic SurgeryColumbia University College of Physicians and SurgeonsSurgeon-in-ChiefThe Spine Hospital at New York-Presbyterian/Allen HospitalNew York, New York

Allan D. Levi, MD, PhD, FACSProfessor and ChairmanDepartment of Neurological SurgeryUniversity of MiamiMiami, Florida

William D. Long III, MDPrivate PracticePremier OrthopaedicsBergen County, New Jersey

Daniel C. Lu, MD, PhDAssociate ProfessorDepartment of NeurosurgerySpinal Cord Rehabilitation CenterRonald Reagan UCLA Medical CenterUCLA Medical CenterDirector, NeuroplasticityComprehensive Spine CenterSanta Monica, California

Steven C. Ludwig, MDChief of Spine SurgeryDirector of Spine FellowshipHead of the Division of Spine SurgeryUniversity of MarylandDepartment of OrthopaedicsBaltimore, Maryland

Glen R. Manzano, MDAssistant Professor of Clinical NeurosurgeryDepartment of Neurological SurgeryUniversity of Miami Health SystemUniversity of Miami HospitalMiami, Florida

Hazem A. Mashaly, MDDepartment of NeurosurgeryAin Shams UniversityCairo, Egypt

Dustin H. Massel, BSResearch CoordinatorDepartment of Orthopaedic SurgeryRush University Medical CenterChicago, Illinois

Benjamin C. Mayo, BAResearch CoordinatorDepartment of Orthopaedic SurgeryRush University Medical CenterChicago, Illinois

Justin W. Miller, MDOrthopaedic Spine SurgeonIndiana Spine GroupCarmel, Indiana

David Minges, MDOrthopaedic Spine SurgeonAdvanced Bone and JointSt. Peters, Missouri

Alim P. Mitha, MDCerebrovascular/Endovascular/Skull Base NeurosurgeonDepartment of Clinical NeurosciencesFoothills Medical CentreUniversity of CalgaryCalgary, Alberta, Canada

Krishna D. Modi, BSResearch AssistantDepartment of Orthopaedic Surgery Rush University Medical CenterMidwest Orthopaedics at RushChicago, Illinois

Camilo Molina, MDDepartment of NeurosurgeryThe Johns Hopkins UniversityBaltimore, Maryland

Eric Momin, MDDepartment of NeurosurgeryBaylor College of MedicineHouston, Texas

Edward A. Monaco III, MD, PhDAssistant ProfessorDepartment of Neurological SurgeryUniversity of Pittsburgh Medical CenterPittsburgh, Pennsylvania

Praveen V. Mummaneni, MDProfessor and Vice-ChairmanDepartment of NeurosurgeryUniversity of California-San FranciscoCo-Director, UCSF Spine CenterSan Francisco, California

Gisela Murray, MDNeurosurgeonSan Juan, Puerto Rico

Rod J. Oskouian Jr., MDChief of Spine DivisionDepartment of Neurological SurgerySwedish Neuroscience InstituteSeattle, Washington

Sheri Palejwala, MDDepartment of NeurosurgeryUniversity of ArizonaTucson, Arizona

Ioannis Papanastassiou, MD, PhDOrthopedic DepartmentGeneral Oncological Hospital Kifisias ‘Agioi Anargyroi’Athens, Greece

Paul Park, MDAssociate ProfessorDepartment of NeurosurgeryUniversity of MichiganAnn Arbor, Michigan

Amit R. Patel, MDOrthopaedic Spine SurgeonOrthopaedic and Spine SpecialistsYork, Pennsylvania

Kamakshi Patel, MD, MPHAssistant Professor of NeurologyUniversity of Texas Medical BranchGalveston, Texas

Frank M. Phillips, MDProfessorDepartment of Orthopaedic SurgerySpine Fellowship Co-DirectorRush University Medical CenterChicago, Illinois

Kornelis Poelstra, MD, PhDChairmanDepartment of SurgerySacred Heart Hospital on the Emerald CoastPresident, The Spine Institute on the Emerald CoastMiramar Beach, Florida

Ravi K. Ponnappan, MDClinical Associate ProfessorDepartment of Orthopaedic SurgeryDrexel University College of MedicinePhiladelphia, Pennsylvania

Steven M. Presciutti, MDMidwest Orthopaedics at RushRush UniversityChicago, Illinois

Martin Quirno, MDMidwest Orthopaedics at RushRush UniversityChicago, Illinois

Ravi Ramachandran, MDSpine SurgeonSacramento, California

Wyatt L. Ramey, MDDivision of NeurosurgeryDepartment of SurgeryUniversity of ArizonaTucson, Arizona

Edwin Ramos, MDAssistant ProfessorDepartment of NeurosurgeryUniversity of ChicagoChicago, Illinois

William J. Readdy, BSRobert Wood Johnson Medical SchoolNew Brunswick, New Jersey

Jay Rhee, MDDirector of Spine SurgeryDepartment of NeurosurgeryHoly Cross Health SystemSilver Spring, Maryland

Marie Roguski, MD, MPHDepartment of NeurosurgeryTufts Medical CenterBoston, Massachusetts

F. Andrew Rowan, MD, MSDepartment of OrthopedicsUniversity of ArizonaTucson, Arizona

Rajiv Saigal, MD, PhDDepartment of Orthopedic SurgeryScripps Health, San Diego Spine FoundationSan Diego, California

Andrew A. Sama, MDAssociate ProfessorDepartment of Orthopaedic Spine SurgeryHospital for Special Surgery Weill Cornell School of MedicineNew York, New York

Amer F. Samdani, MDChief of SurgeryShriners Hospitals for Children-PhiladelphiaPhiladelphia, Pennyslvania

Rick C. Sasso, MDProfessorChief of Spine SurgeryDepartment of Orthopaedic SurgeryIndiana University School of MedicineIndiana Spine GroupIndianapolis, Indianapolis

Meic H. Schmidt, MD, MBA, FAANS, FACSProfessor of Neurosurgery and OrthopaedicsRonald I. Apfelbaum Endowed Chair for Spine SurgeryVice Chair for Clinical AffairsDepartment of NeurosurgeryChief Value Officer, University Hospital, Neurosurgery ServiceProgram Director, Neurosurgery Spine FellowshipDirector, Spinal Oncology Service, Huntsman Cancer InstituteClinical Neurosciences CenterUniversity of UtahSalt Lake City, Utah

Gregory D. Schroeder, MDDepartment of Orthopaedic SurgeryRothman Institute at Thomas Jefferson UniversityPhiladelphia, Pennsylvania

Daniel M. Sciubba, MDAssociate Professor of Neurosurgery, Oncology, and Orthopaedic SurgeryDepartment of NeurosurgeryThe Johns Hopkins UniversityBaltimore, Maryland

Shyam M. Shridharani, MDAssistant ProfessorDepartment of Orthopaedic SurgeryThe University of ArizonaTucson, Arizona

Harry L. Shufflebarger, MDChiefDivision of Spinal SurgeryDepartment of Orthopedic SurgeryNicklaus Children's HospitalMiami, Florida

Krzysztof Siemionow, MDChief of Spine SurgeryAssistant Professor of Orthopaedicsand NeurosurgeryUniversity of Illinois-ChicagoChicago, Illinois

Harminder Singh, MD, FACS, FAANSAssistant ProfessorDepartment of NeurosurgeryStanford University School of MedicineStanford, California

Kern Singh, MDAssociate ProfessorDepartment of Orthopaedic SurgeryRush University Medical CenterChicago, Illinois

Jesse Skoch, MDDepartment of SurgeryDivision of NeurosurgeryBanner University Medical CenterTucson, Arizona

Jessica Sosio, BSDepartment of BiologyFlorida State UniversityTallahassee, Florida

Eric Sribnick, MD, PhDAssistant ProfessorDepartment of NeurosurgeryThe Ohio State UniversityColumbus, Ohio

Zachary J. Tempel, MDDepartment of Neurological SurgeryUniversity of Pittsburgh Medical CenterPittsburgh, Pennsylvania

Khoi D. Than, MDAssistant ProfessorDepartment of Neurological SurgeryOregon Health & Science UniversityPortland, Oregon

Jason O. Toy, MDDepartment of Orthopaedics and RehabilitationYale University School of MedicineNew Haven, Connecticut

Alexander Tuchman, MDDepartment of Neurological SurgeryKeck School of MedicineUniversity of Southern CaliforniaLos Angeles, California

Juan S. Uribe, MDAssociate ProfessorDirector, Spine SectionDepartment of NeurosurgeryUniversity of South FloridaTampa, Florida

Timothy D. Uschold, MDNeurological and Spine SurgeonSouthern Oregon Neurosurgical and Spine AssociatesMedford, Oregon

Alexander R. Vaccaro, MD, PhD, MBARichard H. Rothman Professor and ChairmanDepartment of Orthopaedic SurgeryProfessor of NeurosurgeryCo-Chief of Spine SurgerySidney Kimmel Medical Center at Thomas Jefferson UniversityCo-Director, Delaware Valley Spinal Cord Injury CenterPresident, Rothman InstitutePhiladelphia, Pennsylvania

Juan M. Valdivia, MD, FAANSNeurosurgeonBay Care Medical GroupTampa, Florida

Fernando L. Vale, MDProfessor and Vice-ChairmanDepartment of Neurosurgery and Brain RepairUniversity of South FloridaTampa, Florida

Arya Giri Varthi, MDDepartment of Orthopaedic Surgery and RehabilitationYale New Haven HospitalNew Haven, Connecticut

Viren S. Vasudeva, MDDepartment of NeurosurgeryBrigham and Women's HospitalHarvard Medical SchoolBoston, Massachusetts

Andrey Alex Volkov, DODepartment of NeurooncologyMoffitt Cancer CenterTampa, Florida

Frank D. Vrionis, MD, PhDChief of NeurosurgeryH. Lee Moffitt Cancer CenterProfessor of NeurosurgeryDepartment of Orthopedics and Oncological SciencesUniversity of South Florida College of MedicineTampa, Florida

Jeffrey C. Wang, MDChief, Orthopaedic Spine ServiceCo-Director, University of Southern California Spine CenterProfessor of Orthopaedic Surgery and NeurosurgeryUSC Spine CenterLos Angeles, California

Michael Y. Wang, MD, FACSProfessorDepartments of Neurological Surgery and Rehab MedicineUniversity of Miami Miller School of MedicineMiami, Florida

Peter G. Whang, MD, FACSAssociate Professor, Spine ServiceDepartment of Orthopaedics and RehabilitationYale University School of MedicineNew Haven, Connecticut

Timothy F. Witham, MD, FACSAssociate Professor of Neurosurgery and Orthopaedic SurgeryDirector, The Johns Hopkins Bayview Spine ProgramDirector, The Johns Hopkins Neurosurgery Spinal Fusion LaboratoryCo-Program Director, Johns Hopkins Neurosurgery ResidencyBaltimore, Maryland

Jean-Paul Wolinsky, MDAssociate Professor of Neurosurgery and OncologyDepartment of NeurosurgeryThe Johns Hopkins UniversityBaltimore, Maryland

Jau-Ching Wu, MD, PhDConsultant, Assistant ProfessorDepartment of NeurosurgeryNeurological InstituteTaipei Veterans General HospitalSchool of Medicine National Yang-Ming UniversityTaipei City, Taiwan

Anthony T. Yeung, MDOrthopedic Spine SurgeonDesert Institute for Spine CarePhoenix, Arizona

Christopher Yeung, MDPresidentDesert Institute for Spine CarePhoenix, Arizona

Hasan A. Zaidi, MDBarrow Neurological InstituteBarrow Neurosurgical AssociatesPhoenix, Arizona

Vinko Zlomislic, MDAssistant Clinical ProfessorDepartment of Orthopaedic SurgeryUniversity of California-San DiegoSan Diego, California

Benjamin M. Zussman, MDDepartment of NeurosurgeryUniversity of Pittsburgh Medical CenterPittsburgh, Pennsylvania

I

Anatomy

1 Embryology of the Spine

Eric Momin, Jared Fridley, and Andrew Jea

1.1 Key Points

• Vertebral body development: Gastrulation gives rise to paraxial mesoderm, which forms somites, which differentiate into sclerotomes, which surround neural tissue then resegment, and ossify into vertebral bodies.

• Vertebral body shape is determined by several homeobox (Hox) genes.1

• Posterior element development: Cells adjacent to the neural tube form vertebral arches (or neural arches).

• Epiblast cells migrate to form the primitive groove, which in turn forms the notochord.

• The anterior neuropore closes on day 25 and the posterior neuropore 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 differentiation and relative ascension of the conus.

1.2 Bony Development

• Vertebral body:

– Somatogenesis: Paraxial mesoderm gives rise to 42 to 44 somites. Somites give rise to ventromedial sclerotomes and dorsolateral dermomyotomes. In week 4, cells of the sclerotomes move to surround the spinal cord and notochord.2

– Resegmentation: Each sclerotome is at first separated by mesenchyme. Sclerotomes undergo resegmentation, which occurs when the caudal half of each sclerotome separates and fuses with the cephalic half of the next sclerotome.

• Posterior elements: Cells adjacent to the neural tube form vertebral arches (or neural arches) that give rise to the posterior elements.

• Disk: Cells from the caudal portion of the sclerotome form the annulus fibrosus. Notochord remnants form the nucleus pulposus.

• Ossification: An ossification center is a cartilaginous “model” that is ossified into bone.

– Three primary ossification centers for each vertebrae: One for the vertebral body and one for each half of the vertebral arches. Five secondary ossification centers for subaxial vertebrae: One for the superior and inferior endplates of the body, one for the spinous process, and one at the tip of each transverse process.

– C2 develops from five primary ossification centers: Two for the body of the dens, one for the vertebral body, and one for each neural arch.3 The tip of the dens represents a secondary ossification center.

– Hox genes: The shape of vertebral bodies is regulated by Hox genes that code for transcription factors.1

• Spinal curves: Thoracic and sacral curves are present during the fetal period. Cervical lordosis develops when the child learns to hold up the head. Lumbar lordosis develops with walking.

1.3 Neural Development

• Primitive pit: The bilaminar disk consists of epiblast and hypoblast layers. Some epiblast accumulates at each side of the dorsal midline to form the primitive streak and, subsequently, the primitive groove. At the rostral edge of the primitive groove is a pit, the primitive node.

• Genesis of notochord: After gastrulation occurs, epiblast migrates rostrally from the primitive node, which is called the notochordal process. (This phenomenon can be compared to pushing one's finger into an inflated balloon.) The tube is formed exactly between the ectoderm and endoderm, and it divides the mesoderm. Thus, it is bordered laterally by mesoderm, superiorly by ectoderm, and inferiorly by endoderm.

• Induction of neural plate: At 3 weeks’ gestation, the edges of the neural plate begin to elevate to form neural folds that begin to fuse in the cervical region, forming the neural tube (Fig. 1.1).2

– Anterior neuropore closes on the 25th day.

– Posterior neuropore closes on the 27th day.

Neural crest cells detach from the neural folds and migrate to form glia, arachnoid, pia, melanocytes, chondrocytes, chromaffin cells, osteocytes, Schwann cells, and enteric ganglia.

• Mantle layer: Neuroblasts form a 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). The boundary between the plates is called sulcus limitans.

– At the thoracic (T1–T12) and upper lumbar (L1–L2) region, the intermediate horn contains sympathetic neurons of the autonomic nervous system.

Fig. 1.1(a) 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. (b) The fused neural tube then continues to close both rostrally and caudally.

Fig. 1.2(a) Cross-section of the developing spinal cord demonstrates how the migrating neuroblasts from the neuroepithelial layer form dorsal and ventral mantle layers. These ultimately become the gray matter of the spinal cord. (b) In addition, note the development of the dorsal root ganglion, as well as the outward growth of the motor axons.

• Marginal layer: 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 28–42).

• From day 43 to day 48, the ventriculus terminalis (a cystic structure at the caudal neural tube end) undergoes retrogressive differentiation, which is completed postnatally at 2 months.2

– This results in relative ascension of the conus to its final level of L1/L2 and formation of the cauda equina and filum terminale (Fig. 1.3).

Fig. 1.3 The relative ascension of the conus and formation of the filum terminale via retrogressive differentiation.

1.4 Clinical Correlates

• The conus ascends to L1 to L2 by 2 months of age and may be lower in a neonate (keep in mind for lumbar punctures).

• Complete fusion of the ossification centers of C2 does not occur until age 12 (synchondroses between ossification centers can be mistaken for fractures).

• Incomplete closure of

– Anterior neural tube (22 days) → occipital encephalocele

– Anterior neuro pore (24 days) → anencephaly

– Anterior neuro pore + anterior neuro tube → craniorachischisis (brain and upper spinal cord remain open)

– Posterior neuro pore (26 days) → spina bifida/spinal dysraphism below L1/L2

– Neural tube (defect of secondary neurulation, 28 to 35 days) → spinal dysraphism above L1/L2

– Ventriculus terminalis → terminal myelocystocele (cyst lined with ependymal cells, communicates with the central canal)

Common Clinical Questions

1. Which structures border the notochordal process?

2. Why is the dorsal midline devoid of vascular structures?

3. Why do most mammalian species have seven cervical vertebrae?

Answers to Common Clinical Questions

1. Mesoderm laterally, ectoderm superiorly, endoderm inferiorly.

2. Mesoderm does not cross the dorsal midline in development, so the vascular structures derived from mesoderm are not present on the dorsal midline.

3. The Hox genes are highly conserved between species.

References

1. Wellik DM. Hox genes and vertebrate axial pattern. Curr Top Dev Biol 2009;88: 257–278

2. Sadler TW. Langman's Medical Embryology. 8th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2000

3. Greenberg MS. Handbook of Neurosurgery. 6th ed. New York, NY: Thieme; 2005

2 Craniovertebral Junction

Jonathan Hobbs and Edwin Ramos

2.1 Key Points

• The craniovertebral junction (CVJ) is composed of the occiput (O), occipital condyles, atlas (C1), and axis (C2) and represents the transition between the cranium and mobile cervical spine.

• CVJ is composed of osseous structures articulated with synovial joints, muscles, ligaments and membranes.

• The principal motion segment of the O–C1 joint is flexion extension; the C1 to C2 motion segment is the most flexible of the cervical spine in respect to axial rotation.

• The unique ligament and membrane configuration of the CVJ provide stability and permit movement without compromising the traversing neural elements (Fig. 2.1).

Fig. 2.1 CVJ ligamentous structures. (From Thieme Atlas of Anatomy, General Anatomy and Musculoskeletal System, © Thieme 2005, illustration by Karl Wesker.)

2.2 Bony Anatomy

• The CVJ consists of the base of the occiput, the atlas (C1), and the axis (C2).

• The boundaries of the foramen magnum are the basion anteriorly, the opisthion posteriorly, and the occipital condyles inferolaterally.

• The atlas (C1) has no vertebral body or spinous process. It is comprised of an anterior arch, a posterior arch, and two lateral masses. The superior facets are concave and accommodate the convex occipital condyles, allowing for flexion-extension motion segments (Fig. 2.2).

• The C1 anterior tubercle (C1 “button”) is the attachment site of the anterior longitudinal ligament (ALL) and the longus colli muscle.

Fig. 2.2(a) Superior and (b) lateral view of the atlas. (From Thieme Atlas of Anatomy, General Anatomy and Musculoskeletal System, © Thieme 2005, illustration by Karl Wesker.)

• The vertebral artery and C1 nerve run along the superior lateral groove on C1 (sulcus arteriosus). In less than 15% of the population, the groove is roofed, forming the arcuate foramen.

• The axis (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 spinous process (Fig. 2.3).1

• The C2 odontoid (Gr. “tooth”) process projects superiorly and has multiple, overlapping ligamentous attachments to C1 and the occiput.

Fig. 2.3(a) Superior and (b) lateral view of the axis. (From Thieme Atlas of Anatomy, General Anatomy and Musculoskeletal System, © Thieme 2005, illustrations by Karl Wesker.)

2.3 Neural Anatomy

• Cervical nerve roots exit above their corresponding level (e.g., the C2 nerve root exits above the C2 pedicle).

• C1 nerve root: The posterior division (suboccipital nerve) is more prominent than the anterior division. It innervates suboccipital 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.

2.4 Vascular Anatomy

• The vertebral artery (VA) leaves the C2 transverse foramen (becoming V3), takes a 45° 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 atlantooccipital 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 the 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).

2.5 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

– 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 vertebrae to nuchal ligament and occipital bone; superficial to suboccipital muscles

Table 2.1 Principal craniovertebral junction ligaments: Their attachments and modes of action3,4

Ligament

Attachments

Action

Apical

Odontoid tip (superiorly) to basion in apical cave

No significant function

Alar (paired)

Occipital–alar: Odontoid tip to occipital condyles

Atlantoalar: Odontoid tip to lateral masses of atlas

Limit axial rotation and lateral bending on contralateral side and may limit anterior displacement of atlas. If transverse ligament ruptures, becomes primary ligament preventing atlantoaxial subluxation.

Cruciate

Superior: Posterior odontoid to upper clivus

Inferior: Posterior odontoid to posterior surface of C2 body

Transverse component: Medial tubercles of C1 lateral masses to posterior dens

Transverse component is the primary stabilizing ligament of the AAJ by keeping odontoid locked against anterior ring of C1, preventing anterior subluxation of atlas on axis. Permits axial rotation.

Superior and inferior limbs offer minimal stability.

Tectorial

Posterior aspect of vertebral bodies, superiorly to IAC; continuation of PLL

Function debated: Limit extension versus limit flexion versus little to no impact on stability. Prevents odontoid from compression ventral cervical spinal cord.

ALL

Anterior aspect of vertebral bodies

Limits hyperextension, distraction.

Accessory atlantoaxial

C2 body laterally to medial C1 lateral masses

No biomechanical studies available. May mimic alar ligament function.

Capsular

O–C1 and C1–C2 articulating facets

Stabilizes natural motion of facet joints.

Anterior and posterior atlantooccipital membranes

Anterior: Anterior C1 tubercle to anterior rim of foramen magnum

Posterior: C1 posterior arch to posterior rim of foramen magnum

AAO: May limit extension of AOJ. Limited studies.

PAO: No significant role in stability.

Lateral atlantooccipital ligament

Anterolateral aspect of C1 transverse process to jugular process of occipital bone

No biomechanical studies available. May limit lateral flexion of contralateral side.

Barkow ligament

Horizontal band attaching anteromedial aspect of the occipital condyles to the attachment of the alar ligaments

May limit extension of O–C1 joint. May inhibit lateral displacement of a unilateral occipital condyle fracture. The transverse ligament must be intact for the Barkow ligament to function properly.

Atlantodental ligament

Horizontal band attaching anterior base of the dens to internal aspect of anterior arch of the atlas

Helps maintain predental space (along with transverse and alar ligaments). Limits axial rotation before alar ligaments. Limits posterior displacement of dens before transverse ligament.

Nuchal ligament

Cephalic extension of the supraspinous ligament extending from C7 spinous process to inion

Restricts hyperflexion of the cervical spine.

Abbreviations: AAJ, atlanto-axial joint; AAO, atlantooccipital joint; ALL, anterior longitudinal ligament; IAC, internal auditory canal; O, occiput; PAO, posterior atlantooccipital membrane; PLL, posterior longitudinal ligament.

Fig. 2.4 Muscles of the suboccipital triangle. (From Thieme Atlas of Anatomy, General Anatomy and Musculoskeletal System, © Thieme 2005, illustration by Karl Wesker.)

– Longissimus capitis: Similar to semispinalis, but runs and attaches more laterally to the occiput

2.6 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 undertaking any CVJ stabilization procedure.

• 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 before C1/C2 fixation to verify route and patency of the vertebral arteries, as well as dimensions of the pars interarticularis and/or pedicle.

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 ligament (PLL) at the CVJ?

3. What persistent carotid–vertebrobasilar anastomoses may be encountered in the CVJ?

Answers to Common Clinical Questions

1. Superior part: Apical branch of hypoglossal artery; base: Branches of the vertebral artery.

2. Tectorial membrane.

3. Proatlanto intersegmental artery and persistent hypoglossal artery.

References

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

3. Tubbs RS, Hallock JD, Radcliff V, et al. Ligaments of the craniocervical junction. J Neurosurg Spine 2011;14(6):697–709

4. Debernardi A, D'Aliberti G, Talamonti G, Villa F, Piparo M, Collice M. The craniovertebral junction area and the role of the ligaments and membranes. Neurosurgery 2011;68(2):291–301

3 Cervical Spine

William J. Readdy, Eric Sribnick, and Sanjay S. Dhall

3.1 Key Points

• The subaxial cervical spine includes C3 to C7.

• The cervical spine, like the lumbar spine, normally demonstrates a lordotic curvature.

• Posterior instrumentation often uses lateral mass screws because the pedicles are narrower than in the thoracic and lumbar spine, increasing the risk of neurovascular injury.

• The size and volume of lateral masses decrease from the upper to lower subaxial cervical spine.

• The primary blood supply to the cervical spine is via the anterior spinal artery (ASA) and two posterior spinal arteries (PSA).

3.2 Bony Anatomy

• Radiographic landmarks:1 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.

• In the coronal plane, uncovertebral joints are noted at the anterolateral aspect of the vertebral body (Fig. 3.1).

• The spinal canal is triangular and has a greater lateral than anteroposterior (AP) dimension.

• Lateral masses of the subaxial spine are composed of the superior and inferior articulating processes (the facet) (Fig. 3.2).

• 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 wider, than in C3 to C6.

• The AP diameter of the spinal canal decreases caudally:2 17 mm at C3, 15 mm at C7.

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

• The normal lordotic curvature of the cervical spine is 16 to 25°.3

• Cervical disk herniation occurs most frequently at C5/C6 and C6/C7.

• Biomechanical studies show maximal flexion–extension at C4/C5 and C5/C6 and maximal lateral bending at C2/C3, C3/C4, and C4/C5.

• The least mobile segment is C7/T1.

Fig. 3.1 Cervical vertebrae (a) superior and (b) oblique views.

Fig. 3.2(a) Anterior and (b) posterior views of the bony anatomy of the cervical spine.

3.3 Neural Anatomy

• C3 to C7 nerve roots exit above their corresponding level (e.g., C7 exits above the C7 pedicle).

• Cervical disk herniation is most frequently posterior–lateral and compresses the nerve associated with that level (e.g., C5–C6 herniation impinges on the C6 nerve).

• The C8 nerve root exits above the T1 pedicle.

• The cervical spinal cord enlarges caudally and reaches a maximal cross-sectional area at C6.

• Nerve roots enter the intervertebral foramina laterally, occupy approximately a third of the foramina, and are covered by epidural fat and venous plexus above.

• Nerve roots exit the spine at a point anterolateral to the superior joint facet.

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

• The phrenic nerve is formed by the anterior rami of C3 to C5 and innervates the diaphragm

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

• The cervical plexus gives rise to (1) the ansa cervicalis (supplies 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.

• Three major sympathetic ganglia rest outside the cervical column, behind the carotid sheath: (1) The superior cervical ganglia lies along the sympathetic trunk from C1 to C4 and carries the sympathetics for the head and neck traversing along the carotid artery. (2) The middle cervical ganglia is located at C5 to C6 (also targeting the head and neck). (3) The stellate ganglia extends from C7 to T1.

3.4 Vascular Anatomy

• Vertebral arteries usually originate from the subclavian artery 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 (preforaminal), origin to transverse foramen entrance; V2 (foraminal), C6 to C2; V3, C2 to dura; V4, intradural segment to basilar artery.

• The transverse foramen is lateral to the vertebral body and anterior to the nerve root groove.

• At C3 to C5, the lateralmost aspect of the transverse foramen is often anteromedial to the midpoint of the lateral mass.

• At C6 to 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 just prior to the formation of the basilar artery at the pontomedullary junction.

• The anterior spinal artery is found in the ventral median fissure.

• The posterior spinal arteries most commonly originate from the vertebral arteries but can also arise from posterior inferior cerebellar arteries (PICA).

• The posterior spinal arteries are found in the posterolateral sulci of the spinal cord.

• 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.

3.5 Ligamentous and Muscular Anatomy

• The anterior longitudinal ligament covers anterior vertebral bodies and resists hyperextension.

• The posterior longitudinal ligament covers posterior vertebral bodies and resists hyperflexion.

• The interspinous and supraspinous ligaments run between adjacent 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 landmark for anterior approaches, formed laterally by sternocleidomastoid, superiorly by dorsal portion of the digastric, and anteriorly by omohyoid.

• The carotid triangle contains the carotid sheath (common carotid artery, internal jugular vein, and vagus nerve). The artery is anteromedial, the vein is anterolateral, and the nerve runs posteriorly between the artery and vein.

• After bifurcation of the common carotid, the external branch exits the sheath, whereas the internal brain continues within.

• Longus colli muscles lie anterolateral to vertebral bodies and are elevated during anterior spinal procedures (Fig. 3.3).

Fig. 3.3 Cross-section of the neck and spine at the C5 level.

3.6 Surgical Pearls

• Uncovertebral joints provide several surgical landmarks: They define the lateral borders for corpectomy or discectomy, and they define the midline for cervical plate placement.

• The Magerl technique for lateral mass screw placement is used to avoid injuring the vertebral artery or nerve root. The drill is placed 1 mm medial to the midpoint of the lateral mass and is angled 25° laterally and 30° superiorly.

• During anterior procedures, instruments are most safely inserted into the lateral aspect of the canal.

• During posterior cervical procedures, the patient can be placed in a slight reverse Trendelenburg position to reduce venous engorgement.

• C7 is a transitional-level vertebra. For a posterior fusion involving C7, some surgeons advocate extending the fusion to T1 to reduce adjacent-level disease.

Common Clinical Questions

1. At what level does cervical disk 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?

Answers to Common Clinical Questions

1. C5/C6 and C6/7C.

2. The cervical spine normally has a lordotic curvature between 16 and 25°.

3. The spinal cord is supplied by the anterior spinal artery (from the vertebral arteries), two posterior spinal arteries (from either the vertebral arteries or PICA), and segmental medullary arteries.

References

1. Clark CR, Benzel EC, Currier BL, et al, eds. The Cervical Spine. 4th ed. Philadelphia, 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 1986;11(6):521–524

4. Ebraheim NA, Xu R, Yeasting RA. The location of the vertebral artery foramen and its relation to posterior lateral mass screw fixation. Spine 1996; 21(11):1291–1295

4 Thoracic Spine

Whitney S. James, Jens R. Chapman, and Rod J. Oskouian Jr.

4.1 Key Points

• Twelve rib-bearing vertebral segments make up the normal thoracic spine; anatomical variants include 11 and 13 rib-bearing vertebral segments.

• Motion in the thoracic spine is limited by its osteoligamentous relationship with the rib cage.

• Average thoracic kyphosis ranges from 10 to 40°. The apex of kyphosis typically occurs at T7.1

• Vascular supply in the thoracic spinal cord is tenuous and at great risk for ischemia during and after surgical procedures.

4.2 Bony Anatomy (Fig. 4.1 and Fig. 4.2)2

• The vertebral bodies of the thoracic spine increase in size from the upper to the lower thoracic spine.3

Fig. 4.1 Lateral view of thoracic vertebra. (From Thieme Atlas of Anatomy, General Anatomy and Musculoskeletal System, © Thieme 2005, illustration by Karl Wesker.)

Fig. 4.2 Superior view of thoracic vertebra. (From Thieme Atlas of Anatomy, General Anatomy and Musculoskeletal System, © Thieme 2005, illustration by Karl Wesker.)

• Thoracic vertebral bodies are wedge-shaped, with shorter anterior aspects than posterior aspects. This results in a smooth kyphotic curvature of the thoracic spine.1,3

• The thoracic facets from T1 to T10 are oriented in a coronal plane compared with the more axially oriented cervical facets and the more sagittally oriented T11, T12, and lumbar facets, providing stability in flexion and extension.1,3

• The superior articular facet is anterior and inferior to the inferior articular facet of the level above.

• Pedicle height increases from the upper to lower thoracic spine.3

• Pedicle width decreases from the T1 to T5 to T6, then gradually increases from T5 to T6 to T12.1,3

• Thoracic pedicles join the thoracic vertebral bodies at an acute angle with the superior aspect of the pedicle at the level of the disk space above the vertebral body and the inferior aspect of the pedicle at the midpoint of the vertebral body. The transverse pedicle angle decreases from T1 to T12.3

• The diameter of the thoracic spinal canal ranges from 20.3 mm at T1 to 15.9 mm at T5 to 22.3 mm at T12.4

• The vertebral bodies from T2 to T8 or T9 articulate with two ribs at bilateral demifacets, two superiorly and two inferiorly. The thoracic costotransverse facets from T1 to T10 are located on the transverse process and articulate with the same-level rib (e.g., T7 rib articulates with T6 and T7 vertebral bodies at the demifacets and the T7 transverse facet).

• The T1, T10, T11, and T12 (and sometimes T9) ribs have a full facet for articulation with the corresponding vertebra.

• The 11th and 12th ribs do not articulate with the transverse processes of the vertebral body at the corresponding level.

4.3 Neural Anatomy

• Nerve roots in the thoracic spine exit below the pedicle of the corresponding vertebral level (e.g., T1 nerve root exits below the T1 pedicle).

• Nerves of the thoracic spine innervate the trunk and abdomen. The T4 dermatome is at the nipple line, the T6 dermatome at the base of the sternum, and the T10 dermatome at the level of the umbilicus.

• Preganglionic sympathetic neurons are located in the intermediolateral cell columns from T1 to L2 or L3 and project axons to the sympathetic chain ganglia located on each side of the thoracolumbar vertebrae.

• The spinal cord typically runs through the entire length of the thoracic spinal canal, usually terminating in the conus medullaris at the L1 or L2 level.

4.4 Vascular Anatomy

• The anterior spinal artery runs in the anterior median fissure of the spinal cord and arises from vertebral and radicular arteries.

• The paired posterior spinal arteries run lateral to the posterior intermediate sulci of the spinal cord and usually arise from the posterior inferior cerebellar arteries and radicular arteries.