Atlas-of-Neurosurgical-Techniques-Spine-and-Peripheral-Nerves

Atlasof Neurosurgical Techniques
Spineand Peripheral Nerves
I Thieme

Atlasof Neurosurgical Techniques
SpineandPeripheralNerves
RichardG.Fessler,M.D.,Ph.D.
JohnHarperSeeley Professor and Chief
Sectionof Neurosurgery
Department of Surgery
TheUniversity of Chicago Hospitals
Chicago,Illinois
LaligamSekhar, M.D., F.A.C.S.
Professorand Vice Chairman
Department of Neurosurgery
Universityof Washington
HarborviewMedical Center
Seattle,Washington

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Library of Congress Cataloging-in-Publication
Data
Atlas of neurosurgical
techniques:
spine and peripheral
nerves I [edited
by] Richard C. Fessler, Laligam Sekhar.
p. ;cm.
Includes bibliographical
references.
ISBN0-86577-987-2
(TMP : alk. paper) --ISBN 3-13-127531-6
(CTV : alk. paper)
1.Nervous system--Surgery--Atlases.
I. Fessler, Richard C.
II.Sekhar, Laligam N.
[DNLM: 1.Spinal Nerves--surgery--Atlases.
2. Neurosurgical
Procedures--Atlases.
3. Peripheral
Nerves--surgery--Atlases.
WL 17 A8839 2006]
RD593.A82 2006
617.4'8'00222--dc22
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Dedication
Thisbook isdedicated to those surgeons. scientists. and surgeon-scientists for whom
perfection of surgical technique
is not only a daily pursuit. but who also strive to create
evenbetter means of caring for our patients.
Acknowledgments
Volumesof this magnitude and complexity take years of
preparation. and the participation
of many. many hard
workers. First. I would like to thank my friend Laligam
Sekharfor agreeing to this huge undertaking. and for shep-
herdingthe cranial volume to its impending completion. I
wouldlike to extend my sincere thanks to all of the sur-
geons.fellows. residents. nurses. students. and administra-
tiveassistantswho havecontributed to the Atlasoverthe
years. In addition to performing many of the finishing
touchesto edited chapters. my previous fellows. Drs. Larry
Khoo.Daniel Laich.Robert Isaacs.MickPerez-Cruet. Faheem
Sandhu.Paul Santiago. Trent Tredway, Bong-Soo Kim.John
Song.Sean Christie. John O'Toole.and Kurt Eichholz. wrote
manyof the chapters contained in this text. Nurses Pam
Martin.Laurie Rice.and LoriLoftis and research assistants
Dr.RobinWellington. Melody Hrubes. and Apazra Burks
spent many hours reading manuscripts. organizing draw-
ings. checking manuscripts for completeness. and reviewing
galley proofs prior to publication. My administrative assis-
tants Donna Davisand Diane Torrey carried the responsibil-
ity of maintaining correspondence with the numerous au-
thors represented in the text. Finally.particular thanks are
due to LaceyBresnahan for completion of this book. It was
her determined pursuit of authors and editors alike which
maintained the momentum that resulted in the organized
completion of each chapter. and thus. eventually of the text
itself. Toall of you. my sincere thanks for a remarkable ac-
complishment and ajob well done.
Richard G.Fessler,M.D.
Chicago. lllinois
v

Contents
Acknowledgments
v
Contents
vii
Preface
xvii
Foreword
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ".. . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Contributors
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
SectionI.Occipitocervical Junction
A.Pathologyof the OccipitocervicalJunction
Chapter1. Abnormalities of the Craniocervicaljunction
3
ArnoldH.Menezes
Chapter2. Degenerative and Rheumatologic Diseases of the Occipitocervicaljunction
13
Peter J. Lennarson,
Vincent C. Traynelis, and Arnold H. Menezes
Chapter3. Tumors of the Occipitocervicaljunction
23
Chinyere
Obasi, J. Patrick Johnson,
Michael S. Hahn, and Rinaldo F. Canalis
Chapter4. Trauma of the Occipitocervicaljunction
31
Curtis A. Dickman
B.Anterior Approach
Chapter5. Transoral Approaches to the Craniocervicaljunction: General Principles
48
DavidChoiand H.Alan Crockard
Chapter6. Transoral Odontoidectomy
.60
DavidChoiand H.Alan Crockard
Chapter7.
Extended Transoral Procedures and Midline Intradural Tumor Resection . .. . . . . . .. . . . . .. .64
David Choi and H. Alan Crockard
vii

viii
Contents
Chapter 8. TransoralClosure
73
David Choi and H. Alan Crockard
Chapter
9.
Extended
Maxillotomy
Approach
for High Clinical Pathology.
. . . . . . . . . . . . . . . . . . . . . . . . . . .79
Raj P.TerKonda and Lawrence J. Marentette
C.Anterolateral Approach
Chapter 10. Retropharyngeal Approach to the Occipitocervicaljunction .. . .. . .. . .. . .. . . .. . . . .. . . . . .89
DennisE.McDonnelland Steven]. Harrison
Chapter 11. Closure ofthe Retropharyngeal Approach to the Occipitocervicaljunction
.103
DennisE.McDonnelland Steven]. Harrison
D. Posterior Approach
Chapter 12.
Posterior Suboccipital and Upper Cervical Exposure of the Occipitocervical]unction
... .110
Gary L. Rea and Vijay G.R.Kumar
Chapter 13.
Suboccipital Craniectomy and Cervical Laminectomy for Chiari Malformation..
.115
Vijay G.R. Kumar, Edward Kosnik, and Gary L. Rea
Chapter 14. Posterior OccipitocervicalFusion and Stabilization Using Bent Titanium
Rods
and
Cables.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118
Vijay G.R.Kumar and Gary L. Rea
Chapter 15.
Occipitocervical Encephaloceles:
Surgical Treatment.
.122
]. Parker Mickle
Chapter 16.
Posterior Atlantoaxial Fusion: Surgical Anatomy and Technique Options
.128
Indro Chakrabarti, Trent L. Tredway, and Larry T.Khoo
Chapter 17.
(1-C2 Brooks Fusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .139
Prithvi Narayan, Gerald E.Rodts, and Regis W.Haid
E.Posterolateral Aproach
Chapter 18. Extreme LateralTranscondylar Transtubercular Approach to the
Anterior Craniocervicaljunction
.144
Sean McNatt, Larry T.Khoo,Steven Giannotta, and John Diaz Day
Section II. Midcervical Spine
A. Pathology
of the Midcervical
Spine
Chapter 19.
Congenital Osseous Anomalies of the Mid- to Lower Cervical Spine. . . . . . . . . . . . . . . . . . . .155
JamesT.Guilleand Henry H.Sherk
Chapter 20.
Cervical Spine Degenerative Disease and Cervical Stenosis
.164
Kirk Wayne lobe
Chapter 21.
Intramedullary
Tumors of the Spinal Cord
.169
Keith ¥.c. Gob and Fred]. Epstein
Chapter 22.
Trauma of the Mid- and Lower Cervical Spine. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .176
Bernie W. Chiles IIIand Paul R. Cooper

Contents
ix
B.Anterior Approach
Chapter23.
Cervical Spine: Anterior Approach
.193
Peter M. Klara
Chapter24.
An Anterior Microforaminotomy
(Transuncal) Approach to the Cervical Spine. . . . . .. . . .207
Hae-Dongjho and john Y.Lee
Chapter25.
Odontoid Screw Placement.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218
Julie E. York and Ronald I.Apfelbaum
C.Posterior Approach
Chapter26.
Posterior Approaches to the Cervical Spine
.225
Nitin Tandon and Dennis G. Vollmer
Chapter27.
Cervical Laminectomy
.233
Nitin Tandon and Dennis G.Vollmer
Chapter28.
Cervical Laminoplasty
.239
Nitin Tandon and Dennis G. Vollmer
Chapter29.
Posterior Cervical Foraminotomy
.247
Noam Y.Stadlan
Chapter 30.
Posterior
Cervical
Diskectomy
.. . . . .. . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . .. .250
Noam Y.Stadlan
Chapter31. Posterior Stabilization Using the Bohlman Triple-Wire Technique
.254
Paul K. Maurer
Chapter 32.
Posterior
Stabilization
Using the Titanium
Rectangle
Technique.
. . . . . . . . . . . . . . . . . . . . . .258
Paul K. Maurer
Chapter33.
Posterior Exposure and Release of Locked/Perched Facets
.263
Kirk Wayne lobe
Chapter 34.
Posterior Subaxial Cervical Spine Stabilization Using Sublaminar Cables .. . .. . . . .. . .. . .267
Matthew T.Mayr, Barry D. Birch, and Regis w: Haid,jr.
Chapter 35.
Posterior Cervical Spine Stabilization Using Interfacet Wires . .. . . . .. . . . .. . . . .. . . .. . .. .271
Matthew T.Mayr, Barry D. Birch, and Regis W. Haid,jr.
Chapter 36.
Posterior Cervical Spine Stabilization Using Lateral Mass Plates
.274
Matthew T.Mayr, Barry D. Birch, and Regis w: Haid,jr.
Chapter 37.
Surgical Management
of Intramedullary
Spinal Cord Tumors
.279
Shlomo Constantini, Vitaly Siomin, and Fredj. Epstein
Chapter 38.
Posterior Approach for Resection of Intradural Extramedullary
Tumors.
. . . . . . . . . . . . . . .289
Richard w: Byrne and Mina Foroohar
SectionIII: Cervicothoracic Junction
A.Pathology of the Cervicothoracic Junction
Chapter39.
Tumors of the CervicothoracicJunction
.297
Arthur L.Jenkins IIIand NoelI.Perin

x
Contents
8. AnteriorApproach
Chapter 40.
SupraclavicularApproach to the Cervicothoracicjunction
.306
SooHoChoiand Srinath Samudrala
Chapter 41.
The Transsternal Approach to the Cervicothoracic junction.
. . . . . . . . . . . . . . . . . . . . . . . . . . .312
Sanjay Ghosh and Srinath Samudrala
Chapter 42.
Transmanubrial
Transclavicular Approach to the Cervicothoracic junction
.318
Lany T.Khoo and Srinath Samudrala
Chapter 43.
Vertebrectomy
following Anterior Approaches
.326
Mark A. Liker, Lany T.Khoo, Lacey Bresnahan, and Srinath Samudrala
Chapter 44.
Anterior Reconstruction
following Decompression
via Anterior Approaches
.330
Srinath Samudrala and Lany T.Khoo
C.Anterolateral Approach
Chapter 45.
Transthoracic Approach to the Thoracic Spine
.335
Anthony K.Frempong-Boadu and Richard G.Fessler
D. Posterolateral Approach
Chapter 46.
Lateral Parascapular Extrapleural Exposure of the Upper Thoracic Spine
.343
Richard G.Fessler
Section IV.Thoracicand ThoracolumbarSpine
A.Pathology of the Thoracicand ThoracolumbarSpine
Chapter 47.
Congenital Abnormalities
of the Thoracic and Thoracolumbar
Spine . .. . . . .. . . . .. . . .. . .353
MichaelJ.Rauzzino, Christopher I. Shaffrey, Russ P.Nockels, Mark Abel, and
Richard Ellenbogen
Chapter 48.
Disk Disease of the Thoracic and Thoracolumbar
Spine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .378
Nicholas Post and Anthony K.Frempong-Boadu
Chapter 49.
Tumors of the Thoracolumbar
Spine
.383
Ashok Modha, Ehud Mendel, and Bernard H. Guiot
Chapter 50.
Trauma of the Thoracic and Thoracolumbar
Spine
.396
Danyl DiRisio and Edward C.Benzel
B.Antero/Anterolateral Aproach
Chapter 51.
Lateral Transthoracic Approach to the Spine
.405
David Hart, Lany T.Khoo, and Srinath Samudrala
Chapter 52.
Thoracoabdominal
Approach and Closure
413
Faheem A. Sandhu
and Juan Jimenez
Chapter 53. Retroperitoneal Approach and Closure
.417
JuanJimenez and FaheemA.Sandhu
Chapter 54. ThoracicSympathectomy
.421
Robert E. Isaacs

Contents
xi
Chapter 55.
Transthoracic
Diskectomy
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
Robert E. Isaacs
Chapter 56.
Transthoracic
Vertebrectomy.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .431
Robert E. Isaacs
Chapter57. Anterolateral Graftand Plate Reconstruction
.436
RobertE.Isaacs
C.Posterolateral Approach
Chapter 58.
Costotransversectomy
.441
Sean
T. O'Leary,
Aruna
Ganju,
Michael J.Rauzzino,
Christopher
I. Shaffrey,
and
Russ P.Nockels
D.Posterior Approach
Chapter 59.
Thoracic Laminectomy.
. . . . . . . . . . .. . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. .448
Anantha Kishan and Mitchell R. Gropper
Chapter 60.
Thoracic Laminoplasty
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .452
MitchellR.GropperandAnantha Kishan
.
Chapter 61.
Thoracic Epidural Abscess.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . .456
Milind Deogonkhar and Mitchell R. Gropper
Chapter 62.
Thoracic Extension Osteotomy
.463
Mitchell R. Gropper
Chapter 63.
Diagnosis and Management
of Thoracic Disk Herniation and the
Transpedicular
Decompression
for Thoracic Disk Herniation
.469
Ehud Mendel, Bernard H. Guiot, Robert E.Isaacs, Laurence D. Rhines,
Richard G. Fessler, and Oran Aaronson
Chapter 64.
Spinal Arteriovenous
Malformations.
. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .478
Edward H. Oldfield
Chapter65.
Intradural Extramedullary Tumor Resection in the Thoracic Spine
.489
DonaldA.Smith and ThomasB.Freeman
Chapter66. OpenAnterolateralCordotomy
.. . . . .. . . . .. . . . .. . . .. .. .495
Dennis E. Bullard and Blaine S. Nashold, Jr.
Chapter67. Commissural Myelotomy
.498
Dennis E. Bullard and Blaine S. Nashold, Jr.
Chapter68.
The DREZOperation
...........................503
Dennis E. Bullard and Blaine S. Nashold, Jr.
Chapter 69.
The Caudalis
DREZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .515
Dennis E. Bullard and Blaine S. Nashold, Jr.
Chapter70.
Syringopleural Shunting
.521
Jean-PierreFarmerand GillesBertrand
Chapter71. Syringosubarachnoid Shunting
.530
Jean-PierreFarmerand GillesBertrand

xii
Contents
Chapter 72.
Syringoperitoneal Shunting
.534
Jean-PierreFarmerand GillesBertrand
Chapter 73.
Posterior Approach and In Situ Fusion of the Thoracic Spine
.538
TrentL.Tredwayand RichardG.Fessler
Chapter
74.
Pedicle Screw Instrumentation
of the Thoracic
Spine . . .. . . .. . . . .. . .. . . .. . . . . . .. . . .. . .542
Trent L. Tredway
and Richard
G. Fessler
Section V.Lumbar and Lumbosacral Spine
A. Pathology of the Lumbosacral Spine
Chapter 75.
Spondylolisthesis
in Children
.549
Paul A. Grabb, Michael P.B.Kilburn, Brenda C. Grabb, and Mark N. Hadley
Chapter 76.
Lumbar Degenerative DiskDisease
.555
MickJ.Perez-Cruetand DinoSamartzis
Chapter 77. Tumors of the Lumbar and LumbosacralSpine
......567
Daryl
R. Fourney
and Ziya L. Gokaslan
Chapter 78.
Trauma of the Lumbar Spine
.580
Patricia B. Raksin
B.Anterior Approach
Chapter
79.
Computer-Assisted
Lumbosacral
Fusion.
.. . . . .. . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . .. .590
Lacey Bresnahan and Michael MacMillan
Chapter 80.
Anterior Transperitoneal Approachto the LumbosacralJunction
.596
Anthony K. Frempong-Boadu
C.Anterolateral Approach
Chapter 81.
Anterolateral
Retroperitoneal
Approach to the Lumbosacral Spine. . . . . . . . . . . . . . . . . . . . .604
H.Louis Harkey III, Timothy M. Wiebe, and Michael P.Schenk
D. Posterior Approach
Chapter 82.
Approach to the Lumbar Spine
.612
Richard K. Osenbach
Chapter
83.
Lumbar
Laminectomy.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .618
Richard K. Osenbach
Chapter
84:
Hemilaminectomy
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .625
Richard K. Osenbach
Chapter 85.
Foraminotomy
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .630
Richard K.Osenbach
Chapter 86.
Microdiskectomy
.634
Richard K. Osenbach
Chapter 87. Far-LateralMicrodiskectomy
..638
EmilyFriedman

Contents
xiii
Chapter 88.
Repair of a Cerebrospinal
Fluid Leak
.644
Emily Friedman
Chapter 89.
Lumboperitoneal
Shunt. . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . .. . . .. . . . . . . . . . . . . . . . . . . . . .648
Emily Friedman
Chapter90.
Rhizotomy of the Lumbosacral Nerve Roots. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .651
Frederick A. Boop
Chapter91. Resection of Cauda Equina Ependymomas
.657
R. Shane Tubbs and W.Jerry Oakes
Chapter
92.
Release
of the
Tethered
Spinal
Cord
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .661
W.Jerry Oakes
Chapter93.
Resection of Lumbosacral Lipomas
.666
W.Jerry Oakes
Chapter94.
Transverse Process Fusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .675
Steven D. Wray, David S.Jones, and Charles L.Branch, Jr.
Chapter95.
Posterior Lumbar Interbody Fusion and Transpedicular Screw Fixation
.681
David S.Jones, Steven D. Wray, and Charles L. Branch, Jr.
Chapter96.
Posterior Fusion with Hook-Rod Instrumentation
.690
Eldan Eichbaum, CaryAlberstone, and Bruce McCormack
Chapter97.
Posterior Fusion with Luque Instrumentation
. .. . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . .. . .697
Eldan Eichbaum, Cary Alberstone, and Bruce McCormack
Chapter98.
Placement of Morphine or Baclofen Pumps.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .704
Richard D. Penn
Chapter99. Repair of Myelomeningoceles
.712
Trent L. Tredway
Chapter100. Excision of a Spinal Congenital Dermal Sinus/Dermoid
.715
]. Gordon McComb
Chapter101. Resection of Sacrococcygeal Teratoma.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .723
Sigmund H. Ein
Chapter102. Surgical Management
of Spinal Dysraphism
.729
Dachling Pang
Chapter 103. Repair of Diastematomyelia
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .759
David F.Jimenez and Eric w: Nottmeier
Chapter 104. Sacral Agenesis. .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . .. .. . . . . . . .765
Natarajan Muthulwmar
Chapter 105. Selective Dorsal Rhizotomy of the Lumbosacral Spinaf Cord for
Spasticity in Cerebral Palsy
.771
]. Parker Mickle
Chapter 106. Iliac Crest Bone Grafting
.776
Sanjay Dhall and Larry T. Khoo

xiv
Contents
..
Section VI. Minimally Invasive Spine Procedures
A.Cervical
Chapter 107. CervicalEndoscopicForaminotomy
.785
LarryT.Khoo,LaceyBresnahan,and RichardG.Fessler
Lumbar
Chemonucleolysis
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .811
Manucher].
Javid and Eugene J. Nordby
Arthroscopic
and Endoscopic
Microdiskectomy
via Posterolateral
Access.
. . . . . . . . . . . . .816
Parviz Kambin
Foraminal Epidural Endoscopic Diskectomy
.826
Hallett H. Mathews and Brenda H. Long
Percutaneous
Spinal Cord Stimulator Implantation.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .831
Gregory N. Arends and Robert E. Windsor
Retroperitoneal
Exposure of the Lumbar Spine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .837
Anthony K.Frempong-Boadu
Microendoscopic
Diskectomy
.846
Robert E.Isaacs, Richard G.Fessler,and Lacey Bresnahan
Microendoscopic
Decompression
for Lumbar Stenosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .852
Robert E.Isaacs, Richard G.Fessler,and Lacey Bresnahan
Microendoscopically
Assisted Tranforaminal
Lumbar Interbody Fusion
.859
Robert E.Isaacs, Richard G.Fessler,and Lacey Bresnahan
Vertebroplastyand Kyphoplasty
. . .. . . . . .. . . .. . . . .. .866
Sean D. Christie,John K.Song, and Richard G.Fessler
Section VII.Peripheral Nerve
B.Thoracic
Chapter 108.
Chapter 109.
C.Lumbar
Chapter 110.
Chapter 111.
Chapter 112.
Chapter 113.
Chapter 114.
Chapter 115.
Chapter 116.
Chapter 117.
Chapter 118.
Thoracic Endoscopic Sympathectomy
..
.793
Curtis A. Dickman, Jonathan
J. Baskin, and Nicholas Theodore
ThoracoscopicallyAssisted Spinal Surgery
799
Daniel T. Laich, John K. Song, and Fred H. Geisler
A. Pathology of the Brachial Plexus
Chapter 119.
Neoplasms of Peripheral Nerves
.879
Allan J. Belzberg and Michael J. Dorsi
Chapter 120. Evaluationand Treatment ofTraumatic Peripheral Nerve Injuries. . ... . .. . . . . . .. .. .. .888
Gerald A. Grant, Robert Goodkin, and Michel KHot
Chapter 121. CompressiveLesionsofthe Peripheral Nerve
.895
LisaL.Guyotand Setti S.Rengachary

Contents
xv
B.Brachial Plexus
Chapter 122.
Supraclavicular
Approach to Brachial Plexus Surgery.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .907
Daniel H. Kim, Steven D. Chang, and David G.Kline
Chapter
123.
Infraclavicular
Approach
to Brachial
Plexus Surgery
. .. . .. . .. .. .. . .. . . . .. . . . . . . . . . . ..914
Daniel H. Kim, Steven D. Chang, and David G.Kline
Chapter 124.
Surgical Approach to the Spinal Accessory Nerve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .919
Steven D. Chang, Daniel H. Kim, and David G.Kline
Chapter 125.
Surgical Approach to the Axillary Nerve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .923
Steven D. Chang, Daniel H. Kim, and David G.Kline
Chapter 126.
The Musculocutaneous Nerve
.928
RobertTiel
Chapter
127.
The Median
Nerve
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .932
Robert Tiel
Chapter 128.
Radialand Ulnar Nerves
.937
R. Patrick Jacob and David A. Peace
C.Pathology of the Lumbosacral Plexus
Chapter 129.
Trauma to the Lumbrosacral Plexus. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .944
Yong-Jun Cho,Daniel H. Kim, and David G.Kline
Chapter 130.
Tumors of the Lumbrosacral Plexus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .950
Yong-Jun Cho,Daniel H. Kim, and David G.Kline
D.Lumbosacral Plexus
Chapter 131. Approach to Nerves of the LowerExtremity
.953
Allan H.Friedman
Chapter 132.
Sural Nerve
.966
RajivMidha
E.Other Nerves
Chapter 133.
Intercostal Nerve
.974
Andrew
D. Fine
Chapter134.
SurgicalManagement of Ilioinguinal Neuralgia
.979
HarsimranS.Brara
Chapter135.
SurgicalManagement of Genitofemoral Neuralgia
.983
HarsimranS.Brara
Chapter136.
Lateral Femoral Cutaneous Nerve and Intercostal Nerve
.986
Andrew D.Fineand WesleyFaunceIII
Chapter137. Nerve Graft Harvesting and RepairTechniques
.990
R. Patrick Jacob and David A. Peace
Index
995

Preface
Perhaps the most useful text I recall from my residency
yearswas OperativeNeurosurgeryby Dr.LudwigKempi.Asa
rapid review of surgical technique, it was invaluable and
unequalled by any other text. The step-by-step drawings
whichaccompanied the descriptive text provided a photo
catalogof the sequence of steps in each procedure. Its major
drawback,however, even years ago, was that the number of
procedures shown was limited and somewhat outdated.
Theidea of updating and expanding this rich text, therefore,
seemed to be a very worthwhile endeavor. However, upon
creating the proposed table of contents, the magnitude of
thisundertaking was overwhelming. Since the publication
OperativeNeurosurgery,the numberofneurosurgicalproce-
dures which would need to be included in such a text had
become impressively large. Thus, it became apparent early
onthat this text would need to be more than one volume. A
twovolume text dividing procedures into cranial in one vol-
umeand spine and peripheral nerve in the other was cho-
sen.This volume on spine and peripheral nerves is the first
installment of this text, and will be followed shortly by the
secondvolume emphasizing cranial procedures.
The organization of the overall book and of each individ-
ual chapter is uniform and consistent. First, two types of
chapters are included. Each section begins with a series of
chapters which discuss the pathologies seen in those re-
gions. Forexample, Section Ion the occipitocervical junc-
tion, has four chapters describing congenital abnormalities,
rheumatic diseases, tumors, and trauma. These are "text"
chapters and, as such, are similar to chapters which will be
found in most other textbooks. Each of the chapters that
follow the text chapters, however, emphasizes
surgical
technique with accurate sketches of the procedure accom-
panied by concise descriptions of the surgical maneuvers.
Furthermore, each procedure is accompanied by clearly
delineated indications. contraindications, advantages, and
disadvantages of the technique. This format was selected
for several reasons. First, the text chapters were separated
from the technique chapters to enable the reader to rapidly
access the key points of the procedure, without having to
wade through lengthy discussions of disease processes,
etiologies, differential diagnoses, etc. Thus, the student or
resident who wants to quickly review a surgical technique
before going to the operating room will be able to do so
easily. Furthermore. by limiting the text in the technique
chapters to only that directly describing the actual maneu-
vers of the operation,
redundancy
between chapters is
minimized.
Another method was utilized in this text to minimize re-
dundancy. Many of our operations begin and end in a very
uniform manner, with only the middle of the operation be-
ing distinct. Youwill note, therefore, that in many instances,
the opening and closing are described only once (as specific
chapters) between which are several independent chapters
detailing different operations which utilize these same
openings and closings. Forexample, Chapter 5 describes the
"TransoralApproaches to the CraniocervicalJunction" and is
followed by Chapter 6 on the "Transoral Odontoidectomy",
Chapter 7 on "Extended Transoral Procedures", and Chapter
8 on the "Transoral Closure". Thus, several operations are
shown without repeating the same opening and closing
techniques and diagrams.
Finally, the overall organization follows the spine from
cephalad to caudad, and covers anterior, anterolateral, pos-
terior, and posterolateral
approaches
separately and in
sequence. Minimally invasive procedures are discussed sep-
arately, but follow the same pattern. Finally, peripheral
nerves are covered by approaches to the brachial plexus.the
lumbosacral plexus, and individual peripheral nerves.
It is hoped that this organization provides the reader with
an easy-to-use text that minimizes redundancy, clearly de-
tails surgical technique in both focused text and ample
drawings, list indications and advantages, yet also provides
specific chapters which thoroughly discuss pathology, etiol-
ogy,and differential diagnosis.
Richard G.Fessler, M.D.
Chicago, Illinois
xvii

Foreword
It is not surprising that Dr.Fessler's primary reference as a
neurosurgical resident was the Kempitextbook. Forthe res-
idents and young neurosurgeons of our generation. Kempi
wasthe source. This surgical text assumes the mantle of the
source.This first volume, focusing on spinal and peripheral
nerve pathologies and surgical techniques. is comprehen-
sive,well-organized, and accurately illustrated. Aldous Hux-
leywrote that "experience is not what happens to a man, it
iswhat a man does with what happens to him," The authors
ofeach chapter are experienced surgeons, and we, the read-
ers,greatly benefit from their collective knowledge.
The pathologies are well described and are presented in a
standard reference pattern. Each chapter is concise but
thorough, directing the reader to the appropriate clinical
solution. However, the true unique worth of this treatise is
thefollowing:
This is the textbook that the surgeon opens the night be-
fore, recapitulating in his or her mind the surgical steps,
thus creating a "flow"to be followed the next day.
This will stand the test of time. The value of the illustra-
tions, diagrams, and schematics of the surgical maneuvers
cannot be overestimated.
The listing of the indications, contraindications, and pros
and cons of the distinct procedures are based upon an ac-
cumulation of wisdom only attained via experience. The
authors selected by Dr. Fessler were by necessity chosen
with this in mind. Niels Bohr postulated what these au-
thors have discovered, that "an expert is a man who has
made all the mistakes which can be made in a very narrow
field,"
With this in mind, we can learn from the experience of
the authors of this text and better serve our patients.
Regis Haid. M.D.
Atlanta.
Georgia
xix

Contributors
Oran Aaronson, M.D.
Assistant Professor
Neurological Surgery
Vanderbilt University Medical Center
Nashville, Tennessee
Edward C. Benzel, M.D.
Chairman
The Cleveland Clink Spine Institute
The Cleveland Clinic Foundation
Cleveland, Ohio
Mark Abel, M.D.
Gilles Bertrand, OC,M.D., MSc, FRCS
Senior Neurosurgeon
&Associate Professor
McGill University Health Center
The Montreal Children's Hospital
Montreal, Quebec
CANADA
Chang Ahn, M.D.
Cary Alberstone,
M.D.
Oxnard, California
Gregory N. Arends, M.D.
Chicago Institute of Neurosurgery
and Neuroresearch
Chicago, Illinois
Barry D. Birch, M.D.
Assistant Professor of Neurosurgery
Department
of Neurosurgery
Mayo Clinic
Scottsdale, Arizona
Ronald I. Apfelbaum, M.D.
University of Utah Medical Hospital
Salt Lake City, Utah
Daniel Barrow, M.D.,MBNA
Professor & Chair; Chief of Neurological Surgery
Department
of Neurological Surgery
Emory University School of Medicine
Atlanta, Georgia
Frederick A. Boop, M.D.
Associate Professor of Neurosurgery
Department
of Neurosurgery
University ofTennesee
Health Sciences Center
Semmes-Murphey
Neurologic and Spine Institute
Memphis, Tennessee
Jonathan
J. Baskin, M.D.
Attending
Neurological Surgeon
St.Jospeh's
Hospital
Phoenix, Arizona
Lawrence Borges, M.D.
Division of Neurological Services
Massachusettes
General Hospital
Boston, Massachusetts
AllanJ.Belzberg, M.D.
Johns Hopkins Medical Center
Baltimore, Maryland
Charles L.Branch, Jr., M.D.
WFU Baptist Medical Center
Medical Center Boulevard
Winston-Salem,
North Carolina
xxi

xxii
Contributors
-,
Harsimran S. Brara, M.D.
Kaiser Foundation
Hospital
Los Angeles, California
Lacey Bresnahan, M.S.
Section of Neurosurgery
The University of Chicago
Chicago, Illinois
Dennis E. Bullard, AB,M.D., FACS
Associate Clinical Professor
Department
of Surgery-Neurosurgery
University of North Carolina
Triangle Neurosurgery
PA
Raleigh, North Carolina
Richard W. Byrne, M.D.
Associate Professor of Neurosurgery
Department
of Neurosurgery
Rush University Medical Center
Chicago, Illinois
Robert Campbell, M.D.
Indiana University Medical Center
Indianapolis,
Indiana
Rinaldo F.Canalis, M.D.
Department
of Head &Neck Surgery
University of California at Los Angeles Medical Center
Los Angeles, California
Indro Chakrabarti, M.D.
Clinical Instructor
Department
of Neurological Surgery
Keck School of Medicine
University of Southern California Medical Center
Los Angeles, California
Steven D. Chang, M.D.
Stanford Medical Center
Stanford, California
Randall Chestnut, M.D.
Department
of Neurosurgery
Oregon Health and Sciences University
Portland, Oregon
Bernie W. Chiles III,M.D.
New York Medical College
Valhalla, New York
Yong-Jun Cho
David Choi, M.A.,M.B.,Ch.B.,FRC(SN),Ph.D.
Consultant Neurosurgeon
Department
of Neurosurgery
The National Hospital for Neurology and Neurosurgery
London, United Kingdom
SooHo Choi, M.D.
Division of Neurological and Spinal Surgery
Senta Clinic
San Diego, California
Sean D. Christie, M.D., FRCSC
Fellow in Spinal Surgery
Section of Neurosurgery
The University of Chicago
Chicago, Illinois
Shlomo Constantini,
M.D., M.5c.
Director
Department
of Pediatric Neurosurgery
Tel-Aviv Sourasky Medical Center
Tel Aviv,ISRAEL
Paul R.Cooper, M.D.
New York University Medical Center
New York, N ew York
H. Alan Crockard, D.5c., FRCS(SN),FDS, FRCP
Professor of Neurosurgery
Department
of Neurosurgery
The National Hospital for Neurology and Neurosurgery
London, ENGLAND
Brian Cuddy, M.D.
Department
of Neurosurgery
Medical University of South Carolina
Charleston, South Carolina
Sanjay Dhall
John Diaz Day
Pittsburgh,
Pennsylvania
Milind Deogonkhar, M.D.
Department
of Neurosciences
Cleveland Clinic Foundation
Cleveland, Ohio
Curtis A. Dickman, M.D.
Associate Chief, Spine Section
Director of Spine Research
Department
of Neurological Surgery
St.Joseph Hospital
Phoenix, Arizona
Darryl DiRisio, M.D.
Department
of Neurosurgery
Albany Medical Center
Albany, New York
Michael J. Dorsi
Richard Douglas, M.D.
Pittsburgh,
Pennsylvania
Ann-Christine
Duhaime, M.D.
Department
of Neurosurgery
Children's Hospital of Pennsylvania
Philadelphia,
Pennsylvania

Contributors
xxiii
EldanEichbaum,M.D.
NorthbayNeurosurgical
SantaRosa,California
Thomas B.Freeman,M.D.
Associate Professor
Division of Neurosurgery
Tampa, Florida
SigmundH.Ein,B.A.,M.D., eM., FRCS,FMP, FACS
AssociateProfessor,
Facultyof Medicine
UniversityofToronto
Departmentof Surgery
Divisionof General Surgery
Hospitalfor SickChildren
Toronto,Ontario
Canada
Anthony K. Frempong-Boadu, M.D.
Assistant Professorof Neurological Surgery
Department of Neurosurgery
New York Univeristy Medical Center
New York, New York
RichardEllenbogen,M.D.
Chairman,Department of Neurosurgery
Universityof Washington
Seattle,Washington
Allan H. Friedman, M.D.
Duke University Hospital
Durham, North Carolina
Emily Friedman, M.D.
Pinnacle Neuro Care,Inc.
Oklahoma City, Oklahoma
FredJ.Epstein,M.D.
NeurosurgeryDepartment
BethIsraelHospital
NewYork,NewYork
William Friedman, M.D.
Department of Neurosurgery
University of Florida Collegeof Medicine
Gainesville, Florida
Jean-PierreFarmer,M.D.,CM,FRCS
PediatricNeurosurgeon,AssociateProfessor
Departmentof Neurology and Neurosurgery
McGillUniversityHealth Center
TheMontrealChildren's Hospital
Montreal,Quebec
Canada
ArunaGanju,M.D. .
Assistant Professor
Department of Neurosurgery
Northwestern University
Feinberg School of Medicine
Chicago,Illinois
WesleyFaunceIll, M.D.
SouthwestFloridaNeurological Associated
CapeCoral,Florida
Fred H. Geisler, M.D.,PhD
Illinois Neuro-Spine Center
Aurora, Illinois
MichaelFehlings,M.D.
Divisionof Neurosurgery
UniversityofToronto: Toronto Hospital
WesternDivision
Toronto,OntarioM5T 2S8
Canada
SanjayGhosh,M.D.
Neurosurgeon
Division of Neurological Surgery
Senta Clinic
SanDiego,California
RichardG.Fessler,M.D.,PhD
JohnHarperSeeleyProfessorand Chief
Universityof Chicago
Sectionof Neurosurgery
Chicago,Illinois
StevenGiannotta,M.D.
LAC-Universityof SouthernCaliforniaMedicalCenter
LosAngeles,California
Mark Giovannini, M.D.
Department of Neurosurgery
University of Florida Collegeof Medicine
Gainesville, Florida
AndrewD.Fine,M.D.
Neurosurgeon
NeurosurgeryandSpineSpecialists
Sarasota,Florida
MinaForoohar
Chicago,Illinois
Keith Y.e Goh,FRCSEd
Department of Neurosurgery
Singapore General Hospital
Singapore
DarylR.Fourney,M.D.
Departmentof Neurosurgery
M.D.AndersonCancerCenter
Houston,Texas
ZiyaL.Gokaslan,M.D., FACS
Associate Professor,Chief, Section of Spine
Department of Neurosurgery
University ofTexas
M.D. Anderson CancerCenter
Houston, Texas

xxiv
Contributors
Robert Goodkin
University of Washington
Seattle, Washington
David Hart, M.D.
University Neurosurgeons
of Cleveland, Ine.
Cleveland, Ohio
Brenda C.Grabb, M.D.
Clinical Instructor
Department
of Pediatric Imaging
University of Alabama at Birmingham
Andrea Herbert, M.D.
Department
of Neurosurgery
University of Florida College of Medicine
Gainesville, Florida
Paul A.Grabb, M.D.
Associate Professor
Division of Neurosurgery
University of Alabama at Birmingham
Children's Hospital of Alabama
Birmingham, Alabama
Children's Hospital of Alabama
Birmingham, Alabama
Robert E. Isaacs, M.D.
Director of Spine Surgery
Duke University Medical Center
Durham, North Carolina
Gerald A.Grant, M.D.
Harborview Medical Center
Seattle, Washington
R. Patrick Jacob, M.D.
Department
of Neurosurgery
University of Florida College of Medicine
Gainesville, Florida
Mitchell R.Gropper, M.D.
CINN
Munster, Indiana
George Jallo, M.D.
Division of Pediatric Neurosurgery
Institute for Neurology & Neurosurgery
Beth Israel Medical Center
New York, New York
James T.Guille,M.D.
Shriners Hospital for Children
Philadelphia, Philadelphia
Manucher J. Javid, M.D.
Madison Wisconsin
Bernard H. Guiot, M.D.,FRCSC
Associate Professor
Department
of Neurosurgery
University of South Florida
Tampa, Florida
Arthur L.Jenkins III,M.D.
Assistant Professor of Neurosurgery
Department
of Neurosurgery
Mount Sinai School of Medicine
New York, New York
MarkN.Hadley,M.D.
Universityof Alabamaat Birmingham
Birmingham,Alabama
JorgJerosch, M.D.
Orthopedic Department
Westfalischen Wilhelms University
Munster
Germany
Lisa L.Guyot, M.D., Ph.D.
Detroit, Michigan
Michael S. Hahn. M.D.
Kingston, New York
Hae-DongJho,
M.D., PhD
Professor of Neurosurgery
Jho Institute for Minimally Invasive Neurosurgery
Allegheny General Hospital
Pittsburgh,
Pennsylvania
Regis W. Haid, Jr., M.D.
Atlanta Brain and Spine Care
Atlanta, Georgia
H. Louis Harkey III,M.D.
Professor
Department of Neurosurgery
University of Mississippi Medical Center
Jackson, Mississippi
David F.Jimenez, M.D.
Director and Professor
Center for Neurological Sciences
University of Texas Health Science Center at San antonio
San Antonio, Texas
Juan Jimenez, M.D.
Wheaton,
Illinois
StevenJ. Harrison, MS, CMI
Chairperson and Associate Professor
Department
of Medical Illustration
Medical College of Georgia
Augusta, Georgia
Kirk Wayne Jobe, M.D.
Professor of Neurosurgery
Department
of Neurosurgery
Bayfront Medical Center
St. Petersburg, Florida

r
I
Contributors
xxv
I
J. Patrick johnson,
M.D.
Division of Neurosurgery
University of California at Los Angeles
LosAngeles, California
David S.jones, M.D.
Carolina Neurosurgery
and Spine Associates
Concord, North Carolina
Parviz Kambin, M.D.
Professor
Department
of Orthopaedic
Surgery
Drexel University College of Medicine
Devon, Pennsylvania
LarryT. Khoo, M.D.
Clinical Instructor
Department
of Neurosurgery
LA/Univerisy of Southern California Medical School
LosAngeles, California
Michael P.B.Kilburn, M.D.
Fellow,Spinal Surgery Program
Division of Neurosurgery
University of Alabama at Birmingham
Children's Hospital
Birmingham, Alabama
Daniel H. Kim, M.D.
Assistant Professor, Director
Spinal Neurosurgery
& Reconstructive
Peripheral
Nerve
Surgery
Stanford University Medical Center
Department of Neurosurgery
Stanford, California
Anantha Kishnan
PeterM. Klara, M.D., PhD
Assistant Professor
of Clinical Neurosurgery
and Assistant
Professor of Pathology and Anatomy
EasternVirginia Medical School
Norfolk,Virginia
DavidG. Kline, M.D.
BoydProfessor and Chairman
Department of Neurosurgery
LSHSC
NewOrleans, Louisiana
MichelKliot, M.D.
VeteransAffairs Medical Center
Seattle,Washington
JohnKnightly, M.D.
Chatham, New jersey
Edward Kosnick
VijayG.R. Kumar,
MBBs, FRCS(ENG), FRCS(Neurosurgery)
Consultant Neurosurgeon
West Bank Hospital
Calcutta
India
Daniel T. Laich, D.O.
Chicago Institute of Neurosurgery
and Neuroresearch
Chicago, Illinois
john Y.Lee, M.D.
Department
of Neurological Surgery
University of Pittsburgh
University of Pittsburgh Medical Center Presbyterian
Pittsburgh,
Pennsylvania
Peter J. Lennarson, M.D.
Wright- Patterson Air Force Base
Fairborne, Ohio
Mark A. Liker, M.D.
Department
of Neurological Surgery
University of Southern California University Hospital
University of Southern California
Los Angeles, California
Brenda H. Long, MSRN
Mid-Atlantic Spine Specialists
Richmond, Virginia
Brenda H. Long
Michael MacMillan, M.D.
Associate Professor of Orthopeadic
Surgery
Department
of Orthopaedics
University of Florida
Ortho/Sports
Institute
Gainesville, Florida
Allen Maniker,M.D.
Assistant Professor
Department of Surgery
University of Medicine and Dentistry at Newjersey
Newark,Newjersey
LawrenceJ. Marentette, M.D.,FACS
Professor, Director, Cranial Base Program
Department
of Otolaryngology-Head
and Neck Surgery
University of Michigan Health System
Ann Arbor, Michigan
Hallett H. Mathews, M.D.
Mid Atlantic Spine Specialists
Richmond, Virginia
Paul K.Maurer, M.D.
Associate Professor of Neurological Surgery
University of Rochester Medical Center
Rochester, New York
Matthew T. Mayr, M.D.
Staff Neurosurgeon
Midatlantic
Spine Specialists
Richmond, Virginia
J. Gordon McComb, M.D.
Division of Neurosurgery
University Children's Medical Group
Children's Hospital Los Angeles
Los Angeles, California

xxvi
Contributors
Bruce McCormack, M.D.
San Francisco, California
Paul McCormick, M.D.
Neurological Institute
New York, New York
Dennis E. McDonnell, M.D.
Department
of Neurosurgery
Gunderson Lutheran Medical Hospital & Clinic
LaCrosse, Wisconsin
Blaine S. Nashold,jr.,
M.D.
Duke University Medical Center
Durham, North Carolina
Russ P.Nockels, M.D.
Vice Chair
Department
of Neurological Surgery
Loyola University Medical Center
Maywood, Illinois
Sean McNatt
Eugene j. Nordby, M.D.
Associate Clinical Professor
Department
of Orthopaedic
Surgery
University of Wisconsin
Madison, Wisconsin
Ehud Mendel, M.D.
Associate Professor; Co-Director
Spinal Program
Department
of Neurosurgery
M.D.Anderson Cancer Center
Houston, Texas
Eric W. Nottmeier, M.D.
Instructor
of Neurosurgery
for Mayo Medical School
Department
of Neurosurgery
Mayo Clinic
jacksonville, Florida
Arnold H. Menezes, M.D.
Professor and Vice Chairman
Department
of Neurosurgery
University of Iowa Hospitals &Clinics
Iowa City, Iowa
W.jerry Oakes, M.D.
Professor of surgery and Pediatrics
Department
of Surgery
Division of Neurosurgery
Children Hospital
University of Alabama at Birmingham
Birmingham. Alabama
J. Parker Mickle, M.D.
Department
of Neurosurgery
University of Florida College of Medicine
Gainesville, Florida
Rajiv Midha, M.D. MSc, FRCS(C)
Professor
Department
of Clinical Neurosciences
University of Calgary
Foothills Medical Center
Calgary, Alberta
Canada
Chinyere Obasi, M.D.
Arrowhead Regional Medical Center
Colton, California
Edward H. Oldfield, M.D.
Chief Surgical Neurology Branch
National Institute of Neurological Disorders and Stroke
National Institutes
of Health
Bethesda, Maryland
Ashok Modha, M.D.
Division of Neurosurgery
University of Ottawa
Ottawa, Ontario
Canada
Shaun T. O'Leary, M.D.,PHD
Assistant Professor of Neurological Surgery
Department
of Neurosurgery
Northwestern
University-Evanston
Hospital
Evanston, Illinois
Lorenzo Munoz, M.D.
CINN!Rush Clinic
Chicago, Illinois
Natarajan Muthukumar,
M.Ch, M. N.A.M.S.
Assistant Professor of Neurosurgery
Department
of Neurosurgery
Madurai Medical College
Tamil Nadu
India
Richard K.Osenbach, M.D.
Assistant Professor
Division of Neurosurgery
Duke University and Medical Center
Durham, North Carolina
Prithvi Narayan, M.D.
Assistant Professor
Department
of Neurosurgery
Mount Sinai School of Medicine
New York, New York
DachlingPang,M.D.
Department of Pediatric Neurosurgery
KaiserPermanente MedicalCenter
Oakland, California
DavidA.Peace, MS
Medical Illustrator
Department of Neurosurgery
Universityof Floridaat Gainesville
Gainesville,Florida

Contributors
xxvii
RichardD.Penn,M.D.
Professorof Neurosurgery
Department of Neurosurgery
TheUniversity of Chicago Medical Center
Chicago,Illinois
Mickj. Perez-Cruet, M.D., M.s.
Director,Minimally Invasive Spine Program
MichiganHead and Spine Institute, PLLC
Southfield, Michigan
Dino Samartzis, Dsc, Msc, MA, Dip. EBHC
Graduate Divisions Erasmus Unive
Rotterdam, The Netherlands
University of Oxford
Oxford, England
Harvard University
Cambridge, Massachussetts
Noell. Perin, M.D.,FRCS(Ed), FACS
AssociateClinical Professor
Divisionof Neurosurgery
St.Luke's/ Roosevelt & Beth-Israel Hospitals
NewYork,New York
Srinath Samudrala, M.D.
Assistant Professor
Department of Neurological Surgery
Univeristyof Southern CaliforniaUniversityHospital
Universityof Southern California
LosAngeles,California
Nicholas Post
Faheem A. Sandhu, M.D., Ph.D.
Assistant Professor of Neurosurgery
Georgetown
University
Washington,
DC
PatriciaB.Raksin, M.D.
Department of Neurosurgery
RushPresbyterian-St.
Luke's Medical Center
Chicago,Illinois
Michael P.Schenk, M.S. CMI(F)
Director, Biomedical Illustration
Services
University of Mississippi Medical Center
jackson, Mississippi.
Michael J. Rauzzino, M.D.
Hampton, Virginia
Christopher I.Shaffrey,M.D.
Department of Neurosurgery
Universityof Virginiain Charlottesville
Charlottesville,Virginia
GaryL Rea, M.D.,PhD
OhioState University East
Grant Hospital
Columbus, Ohio
Henry H. Sherk, M.D.
Department
of Orthopedics
Allegheny University Hospital MCP
Philadelphia,
Pennsylvania
John Regan, M.D.
Director of Research
and Education
Cedars-Sinai Institute
for Spinal
Disorders
LosAngeles, California
Vitaly Siomin, M.D.
Department
of Neurosurgery
Dana Children's Hospital
Sackler Faculty of Medicine
Tel Aviv, Israel
Setti S. Rengachary,
M.D.
Department
of Neurosurgery
WayneState University
University Health
Center
Detroit, Michigan
Donald A. Smith, M.D.
Tampa General Hospital
University of Southern FIordia College of Medicine
Tampa, Florida
Laurence D. Rhines,
M.D.
Assistant Professor
Department
of Neurosurgery
The University
ofTexas
M,D.Anderson
Cancer
Center
Houston, Texas
Maurice Smith, M.D.
Memphis, Tennessee
Gerald E. Rodts, M.D.
Emory Clinic/Neurosurgery
Atlanta, Georgia
john K.Song, M.D.
Section of Neurosurgery
The University of Chicago
Chicago, Illinois
DanielRosenthal, M.D.
Oberartzder Klinik fur Neurochirurgie
Klinikumder johann Wolfgang Goethe Universitat
Frankfurtam Main
Germany
Noam Y.Stadlan, M.D.
Director of Spine Surgery
Chicago Institute of Neuroresearch
and Neurosurgery
Assistant Professor
Department
of Neurosurgery
Rush University
Chicago, Illinois

xxviii
Contributors
john Steck, M.D.
Culicchia Neurological Clinic
Marrero, Louisiana
Nitin Tandon, M.D.
Department
of Neurosurgery
Universty ofTexas-HSC Houston
Houston, Texas
Dennis G.Vollmer, M.D.
Professor and Chairman
Department
of Neurosurgery
University of Texas Health Science Center-Houston
Houston, Texas
Raj P.TerKonda, M.D., FACS
Longmont Clinic
Longmont, Colorado
Timothy M. Wiebe, M.D.
Owen and Krawchenko, M.D.'s, P.c.
Watertown,
New York
Nicholas Theodore, M.D.
Director of NeuroTrauma
Neurological Surgeon
St.joseph's
Hospital
Phoenix, Arizona
Robert E.Windsor, M.D.
Georgia Pain Physicians, P.c.
Marietta, Georgia
Eric Woodard, M.D.
Department
of Neurosurgery
Brigham &Women's Hospital
Boston, Massachusetts
Robert Tiel, M.D.
Department
of Neurosurgery
Louisiana State Univeristy Medical Center
New Orleans, Louisiana
Steven D.Wray
Lake Forest University
Winston-Salem,
North Carolina
Vincent C.Traynelis, M.D.
Division of Neurosurgery
University of Iowa Hospitals and Clinics
Iowa City, Iowa
julie E.York, M.D.
Assistant Professor
Department
of Neurosurgery
Loyola University Medical Center
Maywood, Illinois
Trent L Tredway, M.D.
Assistant Professor of Neurosurgery
Department
of Neurosurgery
University of Washington
Seattle, Washington
R.Shane Tubbs, MS, PA-C,PhD
Assistant Professor of Cell Biology and Neurosurgery
Department
of Surgery
Division of Neurosurgery, Cell Biology
Children's Hospital
University of Alabama at Birmingham
Birmingham, Alabama

Section I
Occipitocervical Junction
A. Pathologyof the Occipitocervical
Junction
. 1. Abnormalities of the Craniocervical
junction
. 2. Degenerative and Rheumatologic
Diseasesof the Occipitocervical
junction
. 3. Tumorsof the Occipitocervical
junction
. 4. Traumaof the Occipitocervical
junction
B.AnteriorApproach
. 5. Transoral Approaches to the
Craniocervical junction: General
Principles
. 6. Transoral Odontoidectomy
. 7. Extended Transoral Procedures and
MidlineIntradural Tumor Resection
. 8. Transoral Closure
. 9. Extended Maxillotomy Approach
for High ClinicalPathology
C.AnterolateralApproach
. 10. Retropharyngeal Approachto the
Occipitocervicaljunction
.
11. Closure of the Retropharyngeal
Approach to the Occipitocervical
junction
D. Posterior Approach
.
12. Posterior Suboccipital and Upper
Cervical Exposure of the
Occipitocervical junction
.
13. Suboccipital Craniectomy and
Cervical Laminectomy for Chiari
Malformation
.
14. Posterior Occipitocervical Fusion
and Stabilization Using Bent
Titanium Rods and Cables
.
15. Occipitocervical Encephaloceles:
Surgical Treatment
.
16. Posterior Atlantoaxial Fusion:
Surgical Anatomy and Technique
Options
.
17. Cl-C2 Brooks Fusion
E. Posterolateral Aproach
.
18. Extreme Lateral Transcondylar
Transtubercular Approach to the
Anterior Craniocervical Junction

I
1
Abnormalities of the Craniocervical Junction
ArnoldH. Menezes
.
Classification
. Diagnosis
. Radiological Evaluation
. Treatment
Earlyanatomicaldescriptionsofcraniocervicaljunctionab-
normalitiesdate back to the second quarter of the 19th cen-
tury.!Therewere detailed anatomicaland autopsy studies
inreferenceto bony and, later, neural abnormalities in the
regionPNeurological dysfunction relating to intradural tu-
morsat the craniocervical border was well recognized in
theearlypart of the 20th century. However,the clinical sig-
nificanceof radiographic osseous abnormalities should be
ascribedto Chamberlain in 19394and subsequently to Carl
Listin1941.5It wasListwho pointed out that cranialtrac-
tionreduced even longstanding cervical dislocations. Fang
andOng,in 1962, published the initial results of the direct
transoralapproach to the upper cervical spine.6 Due to the
highmortality,the interest in this surgicaltechniquewas
minimaluntil Greenberg published the classification of at-
lantoaxialabnormalities in 1968.7It was then that interest
inthisregion increased despite the relatively poor success
andtreatment of such entities.
Untilthe mid-1970s, treatment of abnormalities at the
craniocervicalborder consisted of posterior decompression
andenlargement of the foramen magnum with removal of
theposterior arch of the atlas vertebrae and at times a fu-
sion.sHowever, the morbidity and mortality associated
withsuchtreatment was high for patients with irreducible
lesionswith ventral cervicomedullarycompression.The
firsttreatment algorithm utilizing a surgical physiological
approachto the craniocervical region was published in 1980
bythisauthor and colleagues.9 The surgical approach has
beenbased on an understanding of the craniocervical dy-
namics,the site of encroachment, and the type of lesion as
wellasthe stability of the craniocervicaljunction.
Thepathology of these abnormalities
is complex and
extensive.Between 1977 and 1999, 3800 symptomatic pa-
tientswith abnormalities
of the craniocervical junction
hadbeen evaluated by the author. Awide variety of con-
genital,developmental, and acquired abnormalities exist
atthe craniocervical junction and may occur individually
or as more than one anomaly in the same patient.IO.11
Thereare a significant number of individuals who have
both an osseous as well as a neural abnormality.
The
pathology encountered at the foramen magnum requiring
surgical treatment
in 3800 patients
is enumerated
in
Table 1-1.10
.
.
Classification
The classification of craniocervical junction abnormalities
has been divided for practical purposes into the separate
categories under congenital, developmental, and acquired
disorders. The reader must appreciate that there is overlap-
ping within any classification (Table 1-2).
.
Diagnosis
Themost interestingfeatureof craniocervicaljunction
abnormalities is the diversity of their presentation. Acon-
stellation of symptoms and signs may occur as a result of
compromise of the lower brain stem, upper cervical spinal
cord, lower cranial nerves, as well as the cervical nerve
roots and the vascular supply to the previously named
structures.
Each step of the pathological
progression
of
hindbrain
herniation
syndromes,
hydrocephalus,
hydromyelia, and foramen magnum constriction presents
with its own characteristic features. Alist of the patholog-
ical states affecting the craniocervical junction is exten-
sive and these abnormalities
may vary in the magnitude
of neurological dysfunction and in the pattern of associa-
tion with abnormal
findings exclusive of the nervous
system.
The symptoms of craniocervical junction
dysfunction
may be insidious and at times may present with false local-
izing signs. Arapid neurological progression occurs in rare
instances and may be followed by sudden death. There is
frequently a history of minor trauma, which sets off a
/
3

4
Occipitocervical Junction: Pathology of the Occipitocervical Junction
~.
Table 1-2
Classification of Craniocervical Junction Abnormalities
A. Congenital
Anomalies and Malformations
of the
Craniocervical
Junction
I. Malformations of occipital bone
A. Manifestations of occipital vertebra
a. Clivussegmentations
b. Remnants around foramen magnum
c. Atlas variants
d. Dens segmentation
anomalies
B. Basilarinvagination
C. Condylar hypoplasia
D. Assimilation of atlas
II. Malformations of atlas
A. Assimilation of atlas
B. Atlantoaxial fusion
C. Aplasia of atlas arches
III. Malformations of axis
A. Irregular atlantoaxial segmentation
B. Dens dysplasias
a. Ossiculum terminale persistens
b. Os odontoideum
c. Hypoplasia-aplasia
C. Segmentation failure of C2/C3
B. Developmental
and Acquired Abnormalities
of the
Craniocervical
Junction
I. Abnormalities at foramen magnum
A. Secondary basilar invagination (e.g., Paget's disease,
osteomalacia, rheumatoid cranial settling, renal
resistant rickets)
B. Foraminal stenosis (e.g.. achondroplasia)
II. Atlantoaxial instability
A. Errors of metabolism (e.g., Morquio's syndrome)
B. Down syndrome
C. Infections (e.g., Grisel's syndrome)
D. Inflammatory (e.g., rheumatoid arthritis)
E. Traumatic occipitoatlantal and atlantoaxial dislocation;
os odontoideum
F. Tumors (e.g., neurofibromatosis,
syringomyelia)
G. Miscellaneous (e.g., fetal warfarin syndrome, Conradi's
syndrome)
Table 1-1
Pathology
Encountered
at Foramen
Magnum
and Upper Cervical Spinal Canal Requiring
Surgical
Treatment
Primary
Secondary
Neural
Location
Congenital
Acquired
Neoplastic
Neoplastic
Extra/intradural
Tumors
Clivusand
Occipital
Basilar invagination
Eosinophilic
Metastasis
Neurofibroma
Brain stem and
foramen
sclerotome
Basilar impression
granuloma
Nasopharyngeal
Meningioma
cerebellar tumors
magnum
segmentation
(Paget's, rickets,
Fibrous dysplasia
malignancy
Chordoma
Aneurysms
failures
osteogenesis
imperfecta,
Chordoma
Ectopic pituitary
Glomus tumor
Arachnoid and
Neurenteric
acro-osteolysis,
Chondroma
Rhabdomyosarcoma
ependymal cysts
cysts
rheumatoid arthritis)
Chondrosarcoma
Chiari malformation
Paramesial invagination
Plasmacytoma
as in achondroplasia
Atlas
Assimilation
Stenosis as in
Chordoma
Metastasis
Neurofibroma
Glioma of spinal
vertebra
with
achondroplasia;
Chondroma
Plasmacytoma
Meningioma
cord
segmentation
secondary to chronic
Giant cell tumor
Local
Chordoma
Syringohydromyelia
failures
dislocations in Morquio's
Osteoid osteoma
malignancy
Chiari malformation
syndrome, Down
Osteoblastoma
extensions
syndrome, rheumatoid
arthritis, and
arthropathies,
etc.
Axis
Segmentation
Basilar invagination
Aneurysmal bone
Metastasis
Meningioma
Glioma of spinal
vertebra
failure
Basilar impression
cyst
Localtumor
Neurofibroma
cord
Os odontoideum
(e.g., osteogenesis,
Plasmacytoma
extension
Syringohydromyelia
Neurenteric
Paget's, skeletal
Chordoma
cysts
dysplasias, rheumatoid
Giant cell tumor
arthritis,
Osteoblastoma
hyperparathyroidism,
Chondroma
arthropathies)
Chronic dislocation
Osteomyelitis

1
Abnormalitiesof the CraniocervicalJunction
5
At
Figure 1-1
(A) Composite of lateral cervical
spine radiograph in the flexed (left) and the ex-
tended position (right) in a 7-year-old child with
Down syndrome. Note the atlantoaxial disloca-
tion, possible osodontoideum, and the anterior
atlantal
arch
sliding
forward
in extension.
(B) Composite of lateral three-dimensional (3D)
view of the craniocervical junction (left) and a
midsagittal
section of the 3D reconstruction
(right). There is an atlantoaxial dislocation with
bifid anterior and posterior archesto the atlas,as
well as an os odontoideum.
(e) Lateral radi-
ograph made 3 months following adorsal occipi-
tocervical fixation utilizing custom-contoured,
threaded titanium loop instrumentation with au-
tologous rib graft. The craniocervical alignment
ismaintained.
B
c

6
OccipitocervicalJunction: Pathology of the Occipitocervical Junction
Table 1-3
Signsand SymptomsofCraniovertebral
Anomalies(Insidiousor RapidOnset of
SymptomsandSigns)
. Headtilt
.
Short neck, low hairline, limitation of neck motion
. Webneck
. Scoliosis
.
Features of skeletal dysplasias
.
Neck pain and posterior occipital headache
.
Basilarmigraine
.
Hand or foot isolated weakness
.
Quadriparesisfparaparesisfmonoparesis
.
Sensory abnormalities
.
Nystagmus-usually
downbeat and lateral gaze
.
Sleep apnea
.
Repeat aspiration pneumonia. dysphagia
.
Tinnitus and hearing loss
. Vertigo
pattern of symptoms and signs that may progress rapidly.
Table 1-3 enumerates the symptoms and signs of the cran-
iocervicaljunction anomalies that were encountered by this
author.
. Radiological Evaluation
The factors that have been considered in treatment of the
craniocervical junction
osseous and soft tissue lesions
include9.1O.12:
(1) the reducibility; (2) the direction and the
mechanics of compression; (3) the etiology of associated
lesionssuchas vascular abnormalities. the Chiarimalforma-
tion, and syringohydromyelia; and (4) the presence of
abnormal ossification centers and anomalous growth and
development ofthe craniocervical border.
The term reduciblerefers to the ability to achieve normal
osseous alignment and thereby relieve compression on
neural structures.lO.nFor this. maneuvers such as flexion
and extension as wel1 as traction and disimpaction are
utilized (Fig. 1-lA-C).ln
regard to direction of encroach-
ment of neural structures, the lesion is either ventral to the
cervicomedul1aryjunction or dorsal and may be superior as
wel1 as lateral in relation to the foramen magnum (Fig.
1-2A-D). It is important to consider possible association
with neural abnormalities, such as the hindbrain herniation
syndrome. when planning the primary treatment
(Fig.
1-3A,B).
Plain
craniocervical
radiographs
must
include
a
lateral view of the skul1 showing the spine. the anterior
open-mouth view. and oblique views of the cervical spine.1O
Supplementary
views such as a Towne's view and the
anteroposterior
projection into the foramen magnum are
done as necessary. Thin-section
multi planar computed
tomography (CT) with reformatted
two- and preferably
three-dimensional
(2D. 3D) imaging clearly defines the
relationship
and the dimensions
of the craniocervical
junction. Both these studies can be done in the flexed and
extended position to get an understanding of the biome-
chanics. Magnetic resonance imaging in its different modes
in the frontal, sagittal. and axial planes with the flexed and
extended positions is the ideal imaging study to start. How-
ever. the bony anatomy must be precisely outlined with IT
and 3D CTscanning (Fig. 1-4A,B). In al1the techniques of
investigation. dynamic studies are necessary
to assess
the stability and the osseous-angular
relationships to the
neural structures. This provides information regarding the
reducibility as wel1 as the position of fixation should this
be essential (Fig. l-SA-C). The effects of cervical traction
must be documented not only with plain radiographs but
also with magnetic resonance imaging to confirm the relief
of neural compromise and restoration of relationships of
the craniocervical complex. Magnetic resonance angiogra-
phy as wel1as CTangiography may identify obstruction to
the vertebral vessels with the rotated head position or asa
result of deformity and malignancy. Anyunexplained neu-
rological symptom or sign that cannot be accounted forby
the previously mentioned studies requires formal angiogra-
phy. In basilar invagination in children with atlas assimila-
tion and a rotary luxation of the atlas and the axis vertebrae.
vertebral artery distortion and occlusions are not uncom-
mon. Information about the location of these vessels and
the possible kinks that occur with position change must be
available prior to embarking on surgical therapies.
A
c

T'"
1
Abnormalitiesof the CraniocervicalJunction
7
A
Figure1-2
(A) Plainlateralradiographof posterior
fossa and cervicalspine in a 68-year-old individual.
The patient
presented
with difficulty swallowing,
slurred speech. nasal regurgitation.
and poor hand
and leg coordination. She carried a diagnosis of basilar
migraine. The anterior arch of (1 is not visible and the
odontoid process iswellabove a linejoining the hard
palate and the posterior rim of the foramen magnum.
There isa marked thinning of the squamous-occipital
bone.
(8)
Midsagittal
T2-weighted
gadolinium-
enhanced
magnetic resonance
imaging (MRI)of the
posterior fossa and cervical spine. There is atlas assim-
ilation with marked foreshortening
of the true clivus.
The clivus-odontoid angle is less than 90 degrees.
There is indentation of the medulla and the basilar
artery. (e) Axial T1-weighted MRIwith gadolinium en-
hancement through the plane of the lowermedulla.
Note the flattening of the medulla in the anteroposte-
rior dimension.
(

...
D
Rgure 1-2 (Continued)
(D) Composite of midsagittal Tl- and T2-weighted MRIafter ventral decompression
of the lower clivus. the anterior atlas,
and the odontoid and axis body. Posterior decompression
and dorsal occipitocervical fixation have been achieved. There is significant decompres-
sion of the pons and medulla as well as the hindbrain herniation.
A
Figure 1-3
(A) Midsagittal Tl-weighted
magnetic resonance imaging (MRI) in a
12-year-old individual with osteogenesis
imperfecta. There is a secondary basilar
invagination (basilar impression) with the
pontomedullary flexure being less than
90 degrees. The clivusand upper cervicalar-
ticulationisacute inangulation indenting the
pontomedullaryjunction. Asecondary aque-
ductal stenosis has led to significant hydro-
cephalus.Theverticalheight of the posterior
fossaisreduced byan upward invaginationof
the squamous-occipital bone. Note the ac-
quired hindbrain herniation with cerebellar
tonsilsat the C3vertebrallevel.(B)Composite
of axialT2-weightedMRIthrough the planeof
the upper clivus(left) and above the dorsum
sellae (right). There isan invagination of the
upper cervical spine and skull base into the
cranium.Thebasilarartery ishorizontaland is
visualizedinitsentirety. The hydrocephalusis
obvious.
B
-

1
Abnormalitiesof the CraniocervicalJunction
9
A
(
B
Figure1-4
(A)Compositeof midsagittalT2-weightedmagnetic resonance imagingofthe posteriorfossaand upper cervicalspine(left)and three-
dimensional(3D) midsagittal reconstruction
of the posterior fossa and upper cervical spine (right). This child had undergone a Cllaminectomy
with
adorsal occiput-C4
fusion with progressive quadriparesis.
It appears that the dorsal occipitocervical
fusion is complete.
However, there is a fixed
atlantoaxial dislocation with an upward migration of the body of C2 indenting
into the ventral cervicomedullary
junction.
(8) Composite of 3D
computedtomographic
scan of the skull base and upper cervical spine viewed from the frontal and basal position (left) and dorsally (right). Note the
atlantoaxialdislocation with the absence of the anterior atlantal arch components. The dorsal occipitocervical fusion is complete.

.....
10
Occipitocervical Junction: Pathology of the Occipitocervical Junction
A
c
B
Figure 1-5
(A) Composite of lateral cervical spine radiographs
in the neutral and extended
position.
This 13-year-old
male with
Down syndrome
underwent
a failed dorsal atlantoaxial
arthrodesis
a year previously.
There is evidence of os odontoideum
with an unstable
atlantoaxial
articulation.
(8) Midsagittal
section of three-dimensional
computed
tomographic
scan of the craniocervical
junction.
Note the os odontoideum.
(e) Lateral cervi-
cal radiograph
made 6 weeks following
transarticular
C2-C1 screw fixation
(one side) with dorsal occipitocervical
fixation
and utilizing
titanium
loop
and rib grafts. This patient had gross occipitoatlantoaxial
instability.

. Treatment
The factors taken into consideration
for treatment
of
craniocervicaljunction abnormalities have been enumer-
ated.Theneurodiagnostic imaging should have defined the
reducibilityas well as the mechanics of compression and
theassociatedabnormalities. Reducible osseous pathology
needs primary stabilization.12.14.15
Ligamentous reducible
pathology such as with inflammatory states or recent
trauma must be given a trial of immobilization. Fusions
are rare in these circumstances. The reader is referred to
Table1-4 regarding the treatment algorithm for problems
in this region. Irreducible ventral pathology is decom-
pressed via the transoral or transmaxillary
or a lateral
extrapharyngealroute. This is most often accompanied by a
dorsalcraniocervicalstabilization. The author has utilized a
Table1-4
Management Protocol: Treatment of Cranioverte-
bral Abnormalities
Reducible
I
I
I
Acute
Chronic
I
Immobilization
I
t
I
Stable
Unstable
decompression
I
Fusion
Irreducible
I
Encroachment
I
I
I
Ventrolateral
Dorsal
Transorlal/transmaxillary
Dorlal
decompression
or lateralextrapharyngeal
I
decompression
~
I
I
I
Stable
Unstable
Unstable Stable
~/Fusion
References
1. Giacominie. Sull' esistenza dell' "os odontoideum" nell' uomo. Gior
AccadMed Torino 1886;49;24-28
2. Gladstone J, Erickson-Powell
W. Manifestation
of occipital
vertebra
and fusion of atlas with
occipital
bone. J Anat Physiol 49; 190-199,
1914-1915
3. Menezes AH. Surgical approaches
to the craniocervical
junction.
In:
Frymoyer J, ed. The Adult Spine:
Principles
and Practice.
Vol 2. New
York:Raven Press; 1991 :967-986
4. Chamberlain WE. Basilar
impression
(platybasia).
Yale J Bioi Med
1938/39;11
:487
5. ListCF.Neurologic syndromes
accompanying
developmental
anom-
.
alies of occipital bone, atlas and axis. Arch Neurol Psychiatry
1941;45:577-616
6. Fang HSY,Ong AB. Direct anterior
approach
to the upper
cervical
spine.J Bone Joint Surg Am 1962;44:1588-1604
7. Greenberg AD. Atlantoaxial
dislocations.
Brain 1968;91 :655-684
8. Barucha EP, Dastur
HM. Craniovertebral
anomalies.
Brain
1964;
87:469-480
1
Abnormalities of the CraniocervicalJunction
11
custom-contoured, threaded titanium loop for occipitocer-
vical fixation with autologous rib graft for the osseous
construct. Postoperative immobilization is essential for os-
seous integration and success. Table 1-5 enumerates the
surgical approaches to the foramen magnum. Avariety of
"skull base approaches" have been expanded from the basic
anterior,
lateral, and posterior routes to the foramen
magnum.3 Irreducible dorsal or lateral encroachment is
approached
dorsally or laterally, respectively. In either
circumstance, if instability is present it is very likely that a
fusion must accompany the procedure.
Table 1-5
SurgicalApproachesto the ForamenMagnum
Anterior
Transbasal
Transsphenoidal
LeForteI "drop down maxillotomy"
Transoropharyngeal
Medianmandibulotomy
Transfacial
Lateral
Lateral extrapharyngeal
with or without
mandibular
resection
Far "lateral transcondylar"
Lateral infratemporal
approaches (preauricular
and postauricular)
Presigmoid
transpetrosal
Posterior
Posterolateral transcondylar
Posteriordorsal midline
9.
Menezes
AH, Graf CJ, Hibri N. Abnormalities
of the craniovertebral
junction
with
cervicomedullary
compression.
Childs
Brain
1980;7:15-30
10.
Menezes AH. Congenital
and acquired
abnormalities
of the craniover-
tebral
junction.
In: Youmans
J, ed. Neurological
Surgery.
4th
ed.
Philadelphia:
WB Saunders;
1995:1035-1089
11.
VanGilder JC, Menezes
AH, Dolan K. Craniovertebral
Junction
Abnor-
malities.
Mt. Kisco, NY: Futura;
1987:1-255
12.
Menezes
AH, Ryken Te. Instrumentation
of the craniocervical
region.
In: Benzel E. ed. Spinal Instrumentation.
Park Ridge: American
Asso-
ciation of Neurological
Surgeons;
1994:47-62
13.
Jirout J. Changes
in the atlas-axis
relationships
on lateral
nexion of
the head and neck. Neuroradiology
1973;6:215-218
14. Dickman CA,Sonntag VK. Papadopoulos SM,et al. The interspinous
method
of
posterior
atlantoaxial
arthrodesis.
J
Neurosurg
1991 ;74: 190-198
15.
Hensinger
RN.Osseous
anomalies
of the craniovertebral
junction.
Spine 1986;11 :323-333

2
Degenerative and Rheumatologic Diseases
ofthe Occipitocervical Junction
PeterJ.Lennarson,
VincentC.Traynelis,and
ArnoldH. Menezes
. RheumatoidArthritis
Epidemiology
NaturalHistory
ClinicalPresentation
Pathogenesis
BasilarInvagination
AtlantoaxialSubluxation
Theoccipitocervical junction comprises the occiput, the at-
las,theaxis,and their intervening joints and ligaments. This
chapterprimarily
focuses on the effects of rheumatoid
arthritis in the occipitocervical
junction,
spontaneous
atlantoaxial rotary fixation,
and other miscellaneous in-
flammatoryconditions. A host of inflammatory
conditions
canafflict this complex and crucial region, with devastating
consequences.The best described of these diseases is
rheumatoidarthritis.
. Rheumatoid
Arthritis
Epidemiology
Rheumatoidarthritis (RA) is a chronic, systemic, inflamma-
torydisorder affecting multiple joints, including
those of
thecervical spine and craniovertebral
junction.
The term
rheumatoidarthritis was coined by A.B.Garrod! in 1854, but
itwashis son A.E.Garrod, in 1890, who first described the
predilection of this disease for the cervical spine.2 The
prevalenceof RA in adults over the age of 15 is -1%, with
thepeakincidence occurring in the fourth through sixth
decadesof life. Studies demonstrate
a female predomi-
nance,with females being affected twice as often as men.3
Involvementof the cervical spine, and more specifically the
craniovertebraljunction (CVJ),is second in incidence only
tothatof the hands and feet.4Various studies estimate that
59to 88%of patients with RA develop cervical disease.4.5
Theabnormalities most frequently described are atlantoax-
ial subluxation (AAS)and basilar invagination (BI). In a
meta-analysisof 1749 patients in the published literature,
Posterior Atlantoaxial
Subluxation
Atlantoaxial
Rotatory Subluxation
Outcomes
.
Spontaneous Atlantoaxial
Rotatory Fixation
.
Miscellaneous Inflammatory
Conditions Affecting
the Occipitocervical Junction
Casey and Crockard found that 32% (range 5.5-73%) had
AASwhereas 4.2%(range 1.2-32%)had BI.4Over half of
those affected in this analysis (17%) had neurological
symptoms or signs. Although significant subaxial cervical
disease does occur, it is less common than, and usually
foundinassociationwith,diseaseaffectingthe CVJ.
Natural History
Ina prospectivestudy of 100patients with RA,Winfieldet
al found MS to be an early complication.6 At 5-year follow-
up, 12 patients had documented AAS > 7 mm whereas
three individualshad evidenceof BI.Morethan 80%of the
patients with AAShaddevelopedit within 2 yearsof diag-
nosis of RA.Pellicci et al reported on 106 patients over
5 years and found that, of patients with MS, 80%worsened
over the follow-up period.? This same study reported a
mortality rate of 17%for patients with RAcomparedwith
9%for an age-matched cohort. In a postmortem study of
104 patients with RA,Mikulowski et al found AASwith
cervicomedullary compression in 11.8Seven of these 11pa-
tients had experienced sudden death. In a report of 31 pa-
tients with RAand myelopathy, 19 patients died, with 15 of
those deaths occurringwithin 6 months of presentation.9
All 19 patients were either untreated or managed conserva-
tively in a cervical collar. Only fusion provided a reasonable
chance for survival. These studies and others strongly sug-
gest that, once cervical myelopathy is established in pa-
tients with rheumatoid cervical spine disease, the natural
history without surgical intervention is grave and mortality
is more common than previously believed. Additionally, the
incidenceof cervicalmyelopathyand therefore mortality
from myelopathy is likelyunderestimated in rheumatoid pa-
n

14
Occipitocervical Junction: Pathology of the Occipitocervical Junction
tients. Progressivepain, immobility, and weakness are often
attributed to exacerbation of the systemic disease process
rather than to neural compression.
Ahistory of corticosteroid use, seropositivity for rheuma-
toid factor, the finding of rheumatoid subcutaneous nod-
ules, and the presence of mutilating peripheral articular
disease are all predictive of greater progression of cervical
instability and neurological injury.1OSimilarly,in a prospec-
tive study, Corbett et al have clearly documented that the
development of AASis a predictor of eventual poor func-
tional outcome.lI
ClinicalPresentation
The clinical manifestations
of RA include constitutional
symptoms, arthritis, and, in some individuals,extra-articular
complications.The systemic manifestations include subcuta-
neous rheumatoid nodules, ocular inflammatory conditions,
pericarditis,
pleural effusions, pulmonary
nodules, and
Felty'ssyndrome (neutropenia and splenomegaly).Fatigue is
common and may be severe. Arthritis is characteristically
accompanied by morning stiffness.joint involvement is gen-
erally symmetrical and polyarticular. joints that ultimately
develop severe destruction usually become symptomatic
within the first year ofdisease onset,t2Additional neurologi-
cal involvement not referable to the cervical spine includes
compression neuropathies such as carpal tunnel syndrome,
diffuse sensorimotor neuropathies, and mononeuritis multi-
plex. Amild inflammatory myopathy may occur as well. Pre-
sentation of patients as related to specific CVjpathology is
discussed in the followingsections.
Pathogenesis
Although the etiology of RAis unknown, it is postulated to
develop following an environmental exposure, such as an
infection, in genetically predisposed people. In fact, there is
an association between RAand the class IIhuman leukocyte
antigen, HLA-DR4.Despite an extensive search for an infec-
tious agent, none has been found.3
The abnormalities seen in the cervical spine and CVjare
the direct result of rheumatoid destruction of bone, carti-
lage, and supporting ligaments of the involvedjoints. These
changes are due to the same host of inflammatory cells and
mediators
that causes destruction
in the appendicular
skeleton. Although the inciting cause of inflammation is
unclear, the inflammatory process itself is well described.
Initially, lymphocytes proliferate in the synovium, and
polymorphonuclear leukocytes (PMNs)predominate in the
synovial fluid. The PMNs release hydrolytic enzymes,
oxygen radicals, and arachidonic acid metabolites that in-
duce inflammation and cause tissue damage. Lymphokines,
secreted by mononuclear cells, stimulate antibody produc-
tion and the release of additional degradative products. The
influx of combined
fluid and inflammatory
mediators
producesthe pain, swelling, and erythema that characterize
rheumatoid synovitis.s
Granulation tissue known as rheumatoid pannus then
forms in the affected joint as a result of proliferating
fibroblasts and inflammatory cells. The pannus produces
collagenase and other proteolytic enzymes, resulting in
damage to adjacent cartilage,tendons, and bone. The ensuing
destruction leads to cartilage loss, bony erosions, cranial set-
tling, tendon ruptures, and ligamentous laxity.sSubsequent
neurological injury secondary to compression of the spinal
cord, nerve roots, or vertebral arteries can result from direct
impingement by the proliferating synovitic pannus or from
repetitive bony compression due to vertebral subluxation
and instability.
The cervicalspine and CVjare at high risk for involvement
with the rheumatoid process because of the large number of
synovial joints present. Asopposed to osteoarthritis, in the
rheumatoid process, lesions from the joints of Luschka ex-
tend into the disk spaces and vertebral bodies without os-
teophytosis. Thus mobility is retained and subluxations are
common. Because there is a strong correlation between the
severity of cervical disease and that of peripheral erosive
disease, cervical subluxation is more likely in those patients
withprogressiveperipheralperiarticularerosions.to
BasilarInvagination
In addition to atlantoaxial dislocation, vertical penetration
of the odontoid process into foramen magnum or BI may
occur. This process, also termed basilar impression, vertical
subluxation, cranial settling, upward migration of the odon-
toid, and atlantoaxial impaction, results from erosion of
bone and compression of the lateral mass of the atlas verte-
brae with subsequent rostral migration of the axis verte-
brae. The lateral atlantal mass may fracture, with lateral
displacement of the bone fragments. Additional destructive
changes are often severe. The occipital condyles may com-
pletely erode through the lateral masses of the atlas, sepa-
rating them into anterior and posterior pieces. The anterior
component may migrate caudally over the axis body
whereas the posterior component usually shifts upward.
Rheumatoid cranial settling is also accompanied by exces-
sive proliferation of granulation tissue, which, together with
the invaginated odontoid process, produces ventral cervi-
comedullary compression (Fig.2-1 ).13
Cranial settling, like AAS,most frequently presents with
occipital or suboccipital pain, often with radiation toward
the vertex. In the large series compiled by Menezes, such
pain was present in 90%of cases, whereas progressive diffi-
culty with ambulation associated with cervical myelopathy
was present in 76%.Limbparesthesias, vertigo, diplopia, and
transient blackout spells were complaints in 55%of patients
with cranial settling. Abnormal neurological signs such as
hyperreflexia and Babinski responses were present in 80%
of individuals. Acentral cord-like syndrome was found in
30%, and a similar number had a neurogenic bladder.
Evidence of brain stem dysfunction such as internuclear
ophthalmoplegia, facialdiplegia, downbeat nystagmus, and
sleep apnea was found in 20%.The cranial nerves most af-
fected were the hypoglossal,glossopharyngeal, and trigemi-
nal nerves.s Iflower cranial nerve impairment is seen, swal-
lowing and
vocal cord
function
should
be formally
evaluated.
In adults, the upper tip of the odontoid process normally
lies 1 em below the anterior
margin of the foramen
magnum. Several methods exist to evaluate vertical translo-
cation of the dens on lateral cervical radiographs (Fig.2-2).
.
--
-
---
"
~==-_-:-=...,..,--
p-
...

2
Degenerative and Rheumatologic Diseases of the Occipitocervical Junction
15
Figure2-1
Sagittal and axial T2-weighted and coronal Tl-weighted
magnetic resonance imaging sequences
displaying basilar invagination with
ventral cervicomedullary
compression.
Solid arrow
points
to the medulla,
outline
arrow points
to the dens.
Note also the displaced
lateral mass of (1
next to the C3 vertebral
body.
McRae'slineconnectsthe anterior and posterior margins of
the foramen magnum (basion to opisthion). The dens
shouldnot project above this line. Chamberlain's line is
drawnfromthe posterior margin of the hard palate to the
opisthion.The tip of the odontoid process commonly lies
belowor just tangent to Chamberlain's line. The dens
shouldnot projectmore than 3 mm above this line and
6mmispathological.The margins of the foramen magnum
maybedifficultto identify precisely on plain radiographs,
however,making these measurements
often inaccurate.
McGregor'sline,which connects the posterior margin of the
hardpalateto the most caudal point of the occiput, may
beeasierto draw and thus may be more reliable. The tip of
the dens should not project more than 4.5 mm above
Hard palate
';';1 ":"1r
.
Redlund-] ohnell
McGregor's line. Fishgoldalso described a measurement, on
an open-mouth
anteroposterior
(AP) radiograph of the
dens, in which the tip of the dens should be 1 cm or more
below the digastriCline.
Because the tip of the odontoid process may be difficult
to identify in rheumatoid
patients, another method, in
which the tip is not used as a landmark, was described by
Redlund-]ohnell. This method calculates the perpendicular
distance from the central part ofthe end plate of the C2ver-
tebral body to McGregor's line. Vertical migration of the
dens is present if this measurement is less than 34 mm in
men and 29 mm in women.
Ifcranial settling is suspected on plain radiographs, mag-
netic resonance imaging (MRI),including flexion/extension
McGregor
Figure2-2
Lateral view of the occipitocervical junction demonstrating
the common methods used to determine the presence of basilar invagina-
tion.The posterior atlantodental
interval
(PADI) is also shown.

16
Occipitocervical Junction: Pathology of the Occipitocervical Junction
views, should be used to further assess the vertical migra-
tion of the odontoid process, possible craniovertebral insta-
bility, as well as neural compression. Breedveld et al have
shown that distortion of the spinal cord on MRIevaluation
correlates with the signs of myelopathy,
14 and Bundschuh et
al have shown that a brain stem cervicomedullary angle of
less than 135 degrees (normal 135-175 degrees) on MRI
also correlates with cervical myelopathy.
IS
Cranialsettling implies occipitoatlantoaxial instability.s
Conservativetreatment of this entity in patients with signs
and symptoms of neural compression carries the risk of
progressiveneurological impairment and sudden death and
is usually contraindicated. Age,severity of disease, and the
overall medical condition of the patient, including nutri-
tional status, are all factors that are important for deciding
whether surgery should be performed.
The surgical treatment
of rheumatoid
cranial settling
should be determined using the algorithm developed by
Menezes for management of CVJpathology.12This scheme
focuseson the reducibility of the lesion as well as the site of
major compression. Reducibility refers to whether the bony
abnormality can be "reduced" to a normal position and
thereby relieve the compression of the cervicomedullary
junction.
Preoperative halo traction is used to reduce subluxations
and pull the odontoid out of the foramen magnum. Acrown
halo should be used to apply the traction and initially 7 Ib
weight is used. This is gradually increased as needed to a
maximum of 12 Ib over 4 to 5 days. One may expect accept-
able reduction in 4 to 5 days unless the odontoid process
is initially greater than 15 mm above the foramen magnum,
it is intra-arachnoid, there is a fracture of the dens with
associated sequestrum, or the cranial settling is compli-
cated by lateral or rotational dislocation. Traction should be
performed in the intensive care unit with the head up
30 degrees. Cardiac and respiratory monitoring should be
performed and deep venous thrombosis prophylaxis uti-
lized. With reducible lesions, traction should be maintained
at the level at which reduction was obtained. Patients
should be followed with plain radiographs while traction is
administered. Neural decompression is verified by perform-
ing MRIin traction after the patient appears to be radi-
ographicallyreduced.
Rheumatoid patients
with
reducible cranial settling
should be maintained in traction until surgery. The defini-
tive treatment is dorsal occipitocervical fusion. Avariety of
techniques have been used to achieve fusion in these pa-
tients, including bone and wire or cable fixation, which may
also be reinforced with methyl methacrylate. Internal fixa-
tion appears to represent an advance in the treatment of
these individuals. Internal fixation may be achieved with a
bent Luque rectangle or one of a variety of custom-made
loops. Alternatively, the surgeon may choose to bend a
Steinmann pin into the appropriate shape at the time of
surgery.The loops or pins are secured with wire or cable to
the skulland upper cervical spine.
Plate constructs are another means of achieving internal
fixation.The occipital portion of the plate must be secured
to the midline of the skull because the bone is too thin else-
where for adequate purchase.
Posterior transarticular screws may be used to eliminate
rotation across the atlantoaxial joint and thereby increase
fusion rates. Care should always be taken when using such
screws and this is particularly important in the rheumatoid
patient. Careful analysis of the anatomy with CTis neces-
sary before surgery. If the inflammatory process has de-
stroyed a large portion of the lateral masses of C1 then
transarticular screws should not be employed. Inability to
realign the C1-C2 segment represents a relative contraindi-
cation to screw fixation. Preoperative CTis also important
for determining the course of the vertebral artery in refer-
ence to proposed screw trajectories.
Autogenous bone provides a better fusion substrate than
allograft. It is recommended therefore that autograft be
used in these individuals. This may be obtained from the
posterior iliac crest or, alternatively, rib may be harvested
with very little morbidity.
Rheumatoid patients who have been treated with a dor-
sal occipitocervical fusion should be managed postopera-
tively in an orthosis. The type of orthotic employed is cho-
sen on an individual basis depending
on the patient's
overall condition.
Patients with irreducible rheumatoid cranial settling re-
quire decompression (Fig.2-3). The decompression should
be directed toward the region of compromise, which is usu-
ally ventral. Exposure is obtained through the posterior
pharynx. Using the transoral approach, 2 cm of exposure to
either side of the midline can be realized. Patients with
temporal mandibular joint disease may not be able to open
their mouth enough for this approach and, in those cases,a
glossomandibular splitting procedure may be considered.
The specifics of these approaches will be described in sub-
sequent chapters.
Following ventral decompression it is important to per-
form a fusion in these patients. The fusion may be per-
formed immediately following the ventral decompression
or, alternatively, these procedures may be staged. The de-
tails of the dorsal fusion have already been discussed.
Atlantoaxial Subluxation
In 1951,Davisand Markley published the first case report of
AASin association with RA.16MS is now recognized as the
most common type of cervical subluxation, accounting for
65%of all subluxations in patients with RA.Anterior sublux-
ation makes up the majority of these cases whereas lateral
subluxation may occur in -20% and posterior subluxation
in fewer than 10%,17Rotatory dislocation, although previ-
ously reported only infrequently in association with RA,
was found in 10%of patients with AASin a large series re-
ported by Menezes.12
AASis the result of erosive synovitis in the atlantoaxial
and atlanto-occipital joints and in the synovial lined bursa
between the atlas, the odontoid process, and the transverse
Iigament.1OLigamentous laxity is also implicated. The
atlantoaxial complexdepends on the transverse and alarl
ligamentsandto a lesserdegreeon the apicalligamentsfori
stability. Bonychanges to the dens also contribute to insta'i
bility and include loss of volume, osteoporosis, angulationt
of the softened bone, and occasional fracture.s

2
Degenerativeand RheumatologicDiseasesof the OccipitocervicalJunction
17
Figure2-3
SagittalTl-weighted magnetic resonance imagingbefore (left)and after (right)traction revealingirreduciblecervicomedullarycom-
pressionsecondaryto a largerheumatoid pannus. Patientrequiredtransoraldecompressionand posterioroccipitocervicalfusion.
Anterior MS may result
in compression
of the cervical
spinalcord between
the dens and the posterior
arch of the
atlas. Even with
minimal
abnormal
motion,
exuberant
pannusformation around the odontoid may be sufficient to
impingeon the spinal cord. The cervical cord is particularly
vulnerableto compression
when the neck is flexed because
(1slidesforwardon C2.
Theclinical manifestations
of Cl-C2 instability
may arise
fromcompressionof the medulla, the upper cervical spinal
cord,and occasionally the vertebral arteries. Compression
ofthe spinal cord at the C1-C2 level may also produce
is-
chemiain more caudal portions
of the cervical cord, partic-
ularlyinthe anterior horn. The corticospinal tracts, lateral
sensorytracts, second cervical nerve roots, and spinal tract
ofthetrigeminal nerve are among the significant structures
atriskwith MS.
The most frequent
complaint
of patients
with
Cl-C2
subluxationis pain, which is present
in 60% of cases.12 The
painis often greatest
in the upper
neck and frequently
radiatesto the occiput
and/or
vertex. The pain associated
withC1-C2 subluxation
is usually increased with neck
nexionand rotation and is occasionally accompanied by a
'clunking"sensation
or a feeling of the head falling forward
withflexion and rotation
motions.
Paresthesias
in the C2
dermatomeshould also alert the clinician to MS. Neurolog-
icalsymptomsare multiple and may be vague, ranging from
paresthesias in the
hands
to L'hermitte's
phenomenon,
especially with neck flexion. With advancing spinal cord or
medullary compression, these patients may complain of
weakness or incoordination of the arms or legs, vertigo, gait
abnormalities, and, rarely, bowel or bladder problems. Addi-
tional symptoms ofvertebrobasilar
insufficiency, including
drop attacks, may also be experienced, especially when MS
is combined with basilar impression.
Although objective clinical findings often corroborate a
patient's complaints, the examination of the rheumatoid
patient may be difficult, and typical signs of myelopathy are
often masked by severe peripheral rheumatoid
involve-
ment.
Atlantoaxial instability is easily demonstrated
on plain
radiography (Fig,2-4A,B). Lateral cervical radiographs ob-
tained in both flexion and extension are used for initial
evaluation as well as screening purposes. The anterior at-
lantodental interval (AD!)measured from the midposterior
margin of the anterior ring of the atlas to the anterior sur-
face of the dens has been the most commonly cited mea-
surement for quantitating the amount of subluxation. The
upper limit of normal is 3 mm in adults and 4 mm in chil-
dren. AD!of more than 10to 12 mm implies complete dis-
ruption of the entire atlantoaxial ligamentous complex.This
interval is generally accentuated with neck flexion and di-
minished with extension. The difference in AD!between
flexion and extension is thought to carry more clinical rele-
vance than any single measurement alone. It has become

.....
18
Occipitocervical Junction: Pathology of the Occipitocervical Junction
A
~ ~.:
-',
~
B
Figure 2-4
Lateralcervical radiograph(A) before and (B) after traction revealingreducible (1-(2
dislocation. Sagittal Tl-weighted magnetic res-
onance imaging
after traction
also demonstrates
partially
reducible
cranial settling
and cervicomedullary
compression.
Patient presented
with high
cervical myelopathy
and dysfunction
of cranial nerves IX, X, and XII. Symptoms
were ameliorated
with posterior
occipitocervical
fusion.
increasingly evident, however, that the AD! is unreliable at
identifying
which patients have neurological deficits and
which are at risk to incur them. The posterior atJantodental
interval (PAD!) measured from the posterior aspect of the
dens to the anterior margin of the (1 lamina has been
found to be more reliable (Fig. 2-2).17 The AD! and PAD!
were recently compared in a cohort of rheumatoid patients
followed
over 20 years.18In evaluating the presence of
paralysis, use of the PAD!with a cutoff of :5;14 mm yielded
a sensitivity of 97%,specificity of 52%,and negative predic-
tive value of 94%.In other words, the ability of this mea-
surement to detect paralysis was 97%,and if the PAD!was
> 14 mm, there was a 94%chance that the patient was not
paralyzed. These values compared very favorably with those
for the AD!, which, when AD! was 2=8, were 59%,58%,and
56%,respectively. It is important to note, however, that the
PAD!does not represent the spaceavailable for the cord in a
rheumatoid patient who may have a pannus extending be-
hind the dens that is invisible on plain radiography.
MRI can demonstrate cord compression directly as well
as identify other soft tissues such asligaments and pannus.
Computed tomography (CT) provides lessinformation about
soft tissues but displays better bony detail. These studies
are invaluable in patients with neurological deficit and for
preoperative evaluation. MRIobtained in flexion and exten-
sion allows visualization
of dynamic cord compression. A
spinal cord diameter of less than 6 mm leaves the patient
susceptible to myelopathy.19
Although the diagnosis of MS is straightforward, the de-
cision to intervene operatively is complex. The treatment of
AASmust be based on a clear understanding of the patient's
overall health, the severity of the symptoms, and the pres-
ence of neurological findings. Two indications for surgical
management are severe or unremitting
pain and the pres-
ence of neurological
deficits.
In patients
with
deficits,
surgery should be performed as soon as neural dysfunction
is recognized.
No clear guidelines
exist for surgical intervention
in
patients with
asymptomatic
atlantoaxial
instability.
The
mere presence of (1-C2 subluxation is not an indication for
operation. Although many surgeons in the past based the
decision to operate on measurements of the anterior ADI
(AD! ranging from 6 to 10 mm),4 this, as already mentioned,
has not proven reliable. Instead, it is recommended that
these patients undergo thorough baseline clinical evalua-
tion including neurophysiological
testing. If no abnormali-
ties are found and the PAD!is greater than 14 mm on plain
radiography, expectant management may be appropriate.
Regularly scheduled annual checkups with repeat thorough
investigations
are imperative
for
timely
intervention.
Progressive radiographic subluxation with a PAD!lessthan
14 mm, a cervicomedullary angle less than 135degrees,or a
cord diameter
less than 6 mm are all indications
for
arthrodesis because these patients are at risk for myelo-
pathic deterioration.
Of note, patients with asymptomatic
AASand any significant degree of cranial settling may war-
rant a more aggressiveapproach.
The most common
surgical
procedure
employed
for
stabilization
of AAS is posterior arthrodesis, which can be
accomplished by several techniques. Ideally, proper spinal
alignment
is obtained prior to surgery. When that is not
possible and there is a fixed subluxation, a C1 laminectomy

2
Degenerativeand RheumatologicDiseasesof the OccipitocervicalJunction
19
-
Figure2-5
Lateralcervical radiograph demonstrating (1-(2
fusion
withtransarticular screws and posterior
cable and bone construct
in a
patient with neck pain and
progressive
radiographic
atlantoaxial
subluxation.
~-
~I
~-
~,
In
mayberequiredif the canal is stenotic. Traditionally C1-(2
arthrodesishas been achieved
using
wire
and bone
constructs.More recently, the posterior
screw fixation
techniquehasgained popularity
(Fig. 2-5). This technique
essentiallyeliminates
rotatory
motion
across this joint
therebyincreasingthe likelihood of fusion. Careful preoper-
ativeplanning is necessary before performing
this proce-
dure,especiallyin rheumatoid patients, to make sure that
the lateral mass of the atlas will
accept a screw. If a
laminectomyhas not been performed,
then wire should
alsobeemployedto fix the posterior arches of the atlas and
axis.
Ingeneral,atlantoaxial arthrodesis should be employed
cautiouslyin patients with RA because this is a progressive
systemicdisorder. As such, patients are at risk for develop-
ingcranialsettling, and fusion at C1-C2 may theoretically
hastenthis event. If there is any evidence of early settling or
the occipitoatlantal
joint
is radiographically
abnormal
strongconsideration should be given to performing a dorsal
occipitalcervical fusion. The increased
use of internal
fixa-
tionhasimproved the fusion rate with these operations and
extendingthe atlantoaxial
fusion to the occiput only results
in a modest additional loss of flexion/extension motion.
Likewise,patients with atlantoaxial instability must be as-
sessedfor subaxial instability
and, if present,
it should be
addressedappropriately.
A detailed description of the afore-
mentionedprocedures can be found in subsequent chapters
ofthisbook.
PosteriorAtlantoaxialSubluxation
Posterior C1-C2subluxation occurs infrequently. It is gener-
ally a result of erosion or fracture of the odontoid process
and may result in myelopathy secondary to spinal cord
compression. Because of their high degree of instability, all
posterior MSs should be surgicallystabilized.
Atlantoaxial Rotatory Subluxation
Atlantoaxial rotatory subluxation occurs from the same
destructive rheumatoid synovitis at the cervical-occipital
and atlantoaxial joints, allowing rotation at the 0-C1 and
C1-C2 joints. This type of subluxation is progressive and
may result in a fixed torticollis occurring over a period of
1 to 6 months. Ifnot recognized and corrected, this defor-
mity will become permanent
and will be a continued
source of pain.
Cervical and occipital pain in addition to various neuro-
logical signs and symptoms are the usual cIinic~ findings.
The incidence of CI-C2rotatory subluxation may be under-
estimated by many. This may be due to the difficulties in
making the diagnosis. Weissman et al found that C1-C2 ro-
tatory subluxation accounted for 21%of all MSs in their se-
ries,20whereas Menezes reported an incidence of 10%in his
series.12
Thediagnosisis suspectedclinicallyin patients whopre-
sent with posterior cervical or suboccipital pain and a head
tilt. There may be hypesthesia or hypalgesia in the C2der-
matome.
The diagnosis is confirmed radiographically. Atlantoaxial
rotatory subluxation has been defined as more than 2 mm
of subluxation of the C1lateral masses on C2.This is associ-
ated with a rotational deformity and can be best visualized
on CT,both with and without three-dimensional
(3D) re-
construction of the occipitoatlantoaxial complex. Using CT,
Dvorak et al suggested that axial rotation between C1 and
C2greater than 56 degrees is abnormal.21Also,a right-left
differencein rotationbetweenC1and C2greaterthan 8 de-
grees represents excessive motion. Such findings may con-
stitute clinically significant rotatory instability. Asymmetry
of the lateral masses on APplain radiography is also sugges-
tive of rotation.
Treatment consists of low-weight halo ring traction. Over
a period of 3 to 10 days the deformity, if not fixed, corrects
and then a fusion extending from the occiput to C2can be
performed to hold the reduction permanently. All of the
precautions taken in patients with cranial settling should be
exercised. These patients are held in a halo vest for 10 to
12 weeks postoperatively and then placed in a soft collar for
an additional 6 to 8 weeks.
Outcomes
The goal of operative management in patients with RA
involving the CVJis to relieve pain, reduce deformity,
and prevent neurological deterioration. This goal may be
achieved
by posterior
arthrodesis
combined
with
a
decompressive
procedure
when needed. Although lack
of uniform outcome measures in the literature makes

20
Occipitocervical Junction: Pathology of the Occipitocervical Junction
generalizations
about prognosis difficult, several factors
have been shown to correlate with decreased potential for
neurological recovery after surgical stabilization. These
include preoperative PADIof less than 10 mm, subluxation
accompanied by BI,poorer Ranawat class, and postopera-
tive pseudarthrosis.17,18In a meta-analysis of 492 patients,
only 25%of Ranawat class IIIBpatients improved to class
II. This group had a 15%perioperative mortality, which
rose to 60%by the first 15 months. In contrast, when alI
rheumatoid patients
were taken together, the average
mortality was 6%.4Although improved operative tech-
niques and perioperative care are decreasing morbidity
and mortality rates, RAof the (VJ remains a chalIenging
problem for the surgeon. Maximal benefit can be realized
when patients are treated early in the disease process.
.
SpontaneousAtlantoaxial
Rotatory Fixation
Spontaneous atlantoaxial rotatory fixation (MRF) of (1-(2
is seen almost exclusively in children. Most authors have
noted that it is a rare sequela of an infection of the head or
neck, a surgical procedure
on the pharynx, or minor
trauma.22When associated with a nasopharyngeal infection
it is more commonly calIed Grisel's syndrome, although it
was originally described by Bellin 1830,23a century before
Grisel'swork,24was published.
Patients typically present with a characteristic head and
neck posture termed a "cock-robin" deformity in which the
chin is turned toward one side while the neck is lateralIy
flexed to the opposite side. Pain and tenderness may be se-
vere in the acute phase but need not be present. Neck mo-
bility is limited except in the direction that accentuates the
deformity, and attempted "corrective" rotation often elicits
pain. Blockage of the eustachian tube on the affected side
may cause a middle ear effusion and related conductive
hearing loss. Neurological exam is often normal, although
(2 radiculopathy, high cervical myelopathy, and sudden
death have alI been reported.22
Clinicalsuspicionof AARFcan be confirmedwith radi-
ographic imaging. Although plain films can be difficult to
interpret, some findings are suggestive. On a true lateral
cervical radiograph, the lateral masses of C1will not be su-
perimposed and may be visible anterior to the odontoid
process, whereas on APview, the spinous process of (2 will
be deviated toward the side of chin deviation (so-calIed
Sudeck's sign). CThas been most helpful in establishing the
diagnosis
of AARF with
certainty.
Li and Pang have
proposed a dynamic (T protocol in which (T scans are
obtained in three positions,22 In the authors' experience,
best visualization of this abnormality has been obtained
with 3DCT(Fig.2-6). Althoughthe name AARFdenotes
AAS, CT imaging
often demonstrates
occipitocervical
instability in these cases as well. MRImay also reveal the
abnormality as welI as provide information regarding the
patency of vascular structures
and the possible neural
compromise.
-
t~(~
ji''y'''*''-
Figure 2-6
Three-dimensional computed tomography revealing
spontaneous atlantoaxialrotatory subluxationina 7-year-oldboypre-
senting with neckpain and head tilt. Note the anterior subluxationof
the C1 right lateral mass on C2. Occiput-C1 dislocation is also
apparent.

2
Degenerative and Rheumatologic Diseases of the Occipitocervical Junction
21
Mostcases ofAARF,if diagnosed early, require only non-
operativetreatment, including eradication of any infection,
and cervical traction
until an adequate
reduction
is
obtained,followed by orthotic immobilization for up to
3 months. Infrequently, surgical fusion is necessary for
recurrentsubluxation or for irreducible deformity.
. Miscellaneous Inflammatory
Conditions Affecting the
Occipitocervical Junction
Theseronegativespondyloarthropathies
are a group of re-
lateddisorders that cause inflammation and ossification
ofthe entheses or sites of ligamentous/tendinous
inser-
tion into bone. They commonly
affect the spine and
sacroiliacjoints, as well as the peripheral joints. Rheuma-
toidfactoris generally not detected in the serum of pa-
tientswiththese diseases, but there is an association with
the specific genetic
marker,
HLA-B27. Ankylosing
spondylitis(AS),psoriatic arthropathy,
reactive arthritis
(Reiter'ssyndrome), and the enteropathic
arthropathies
(Crohn'sdisease and ulcerative colitis) all fit under this
designation.Whereas these enthesopathies
typically re-
sult in stiffening
or fusion
of the
involved
joints
(spondylitis),the associated arthritis
can cause severe
erosivechangesin the ligaments and associated joints.25.26
Whenthis occurs in the occipitocervical region, signifi-
cantinstabilitycan result.26.27
Althoughthe primary pathological
process in ankylosing
spondylitis usually
involves
the
subaxial
spine,
the
at-
lantoaxialregion can be involved secondarily.
Fusion of the
subaxialspine can lead to excessive dynamic loading of the
CVJ,resulting in subluxation
and promoting
secondary
BA.5
Ina review of 39 patients
with AS, atlantoaxial
instability
wasdemonstrated in nearly one third of those who also had
associated psoriasis,
Reiter's
syndrome,
or inflammatory
boweldiseaseY
Type II odontoid
process
fractures
and
hangman'sfractures
have also been seen in patients
with
ASinwhom spontaneous
occipitoatlantal
fusion had previ-
ously occurred.
Psoriaticarthropathy
affects 7%of patients with psoriasis.
Thespine is eventually involved in 20% of these individuals,
witheVJinvolvement
occurring
in much the same way as
inAS.5
Reiter'ssyndrome (arthritis,
urethritis,
and uveitis) may
beassociated with an acute inflammatory
synovitis and has
beenreported in association with MS.5
Rheumatological complications
have been described
in
upto 30%of patients
with inflammatory
bowel disease.25
Althoughinfrequent, these complications
do include severe
References
1. GarrodAB.On the blood and effused fluids in gout, rheumatism
and
Bright'sdisease.Transactions ofthe Medico-chirurgical
Society of Ed-
inburgh1854;37:49
2. GarrodAE.ATreatiseonRheumatismandRheumatoidArthritis. Lon-
don:1890
Figure 2-7
Tl-weighted sagittal magnetic resonance imaging revealing
cervicomedullary
junction compression
(black arrow) secondary to a
large mass posterior to the dens. Note the hypointense mass both ante-
rior and posterior to the tectorial membrane (white arrow).
erosive arthritis that involves the CVJ.25In 1969, Newman
and Sweetnam28 in describing their technique for occipito-
cervical fusion reported a case of AAS in a 25-year-old
woman with ulcerative colitis. In 1986,Jordan et al reported
a similar case in a patient with Crohn's disease and indi-
cated that, in addition to spondylitis, which is relatively
common in patients with seronegative arthritides, inflam-
matory bowel disease could cause an erosive arthritis simi-
lar to that in RA.They concluded that inflammatory bowel
disease should be added to the differential diagnosis ofpa-
tients who present with isolated atlantoaxial instability.26
Calcium pyrophosphate deposition in the synovialjoints
of the CVJhas also been described. This phenomenon has
been termed "pseudogout" and may present with compres-
sion of the cervicomedullary junction (Fig.2-7).5
Although the etiologies may be different, the same princi-
ples applied to occipitocervical disease in cases of RAap-
pear to be appropriate to guide management decisions in
these unusual cases.
3. KatzjN,LiangMH. Differential
diagnosis and conservative treatment
of rheumatic disorders. In: Frymoyer jW. ed. The Adult Spine: Princi-
ples and Practice. Voll
New York: RavenPress; 1991:699-718
4.
CaseyATH. Crockard HA. Rheumatoid arthritis.
In: Dickman CA. Spet-
zler RF.Sonntag VKH.eds. Surgery of the Craniovertebral
junction.
New York: Thieme; 1998:151-174

22
Occipitocervical Junction: Pathology of the Occipitocervical Junction
5.
Menezes
AH. Rheumatological
disorders.
In: Menezes
AH, Sonntag
VKH, eds. Principles
of Spinal Surgery. Vol 1. New York: McGraw Hill;
1996:705-722
6.
Winfield J, Cooke D, Brook AS. A prospective
study of the radiological
changes in the cervical spine in early rheumatoid
disease. Ann Rheum
Dis 1981 ;40: 109- 114
7.
Pellicci PM, Ranawat
CS, Tsairis P. et al. A prospective
study
of the
progression
of rheumatoid
arthritis
of the cervical
spine. J Bone Joint
Surg Am 1981 ;63:342-350
8.
Mikulowski P. Wollheim
FA, Rotmil P. et al. Sudden death
in rheuma-
toid
arthritis
with
atlanto-axial
dislocation.
Acta
Med
Scand
1975; 198:445-451
9.
Marks JS. Sharp J. Rheumatoid
cervical
myelopathy.
QJ Med 1981;
50:307 -319
10.
Delamarter
RB, Bolesta MJ. Bohlman HH. Rheumatoid
arthritis:
surgi-
cal treatment.
In: Frymoyer
JW, ed. The Adult Spine:
Principles
and
Practice. Voll
New York: Raven Press; 1991 :745-762
11.
Corbett M, Dalton S. Young A. et al. Factors predicting
death,
survival
and functional
outcome
in a prospective
study of early rheumatoid
disease over fifteen years. Br J RheumatoI1993;32:717-723
12.
Menezes AH. Congenital
and acquired
abnormalities
of the craniover-
tebral junction.
In: Youmans JR, ed. Neurological
Surgery.
Vol 2. 4th
ed. Philadelphia:
WB Saunders;
1996:1035-
1089
13.
Menezes
AH, VanGilder JC. Clark CR, et al. Odontoid
upward
migra-
tion in rheumatoid
arthritis:
an analysis
of 45 patients
with cranial
settling.J
Neurosurg
1985;63:500-509
14.
Breedveld FC.Algra PRoVielvoye CJ.et al. Magnetic
resonance
imaging
in the evaluation
of patients
with rheumatoid
arthritis
and subluxa-
tions ofthe
cervical spine. Arthritis
Rheum 1987; 30:624-629
15.
Bundschuh
C, Modic MT. Kearney F, et al. Rheumatoid
arthritis
of the
cervical
spine:
surface
coil
MR imaging.
AJR Am J Roentgenol
1988;151
:181
- 187
16. Davis FW, Markley HE. Rheumatoid
arthritis
with
death
from
medullary compression. Ann Intern Med 1951;35:451-455
17.
Boden SD, Clark CR. Rheumatoid
arthritis
of the cervical
spine. In:
Clark CR, ed. The Cervical
Spine.
3rd ed. Philadelphia:
Lippincott-
Raven; 1998:693-704
18.
Boden SD. Dodge LD,Bohlman
HH, et al. Rheumatoid
arthritis
of the
cervical spine: a twenty-year
analysis with predictors
of paralysis and
recovery. J Bone Joint Surg Am 1993;75:1282-
1297
19.
Crockard
A. Grob D. Rheumatoid
arthritis:
upper
cervical
involve-
ment.
In: Clark CR, ed. The Cervical
Spine.
3rd ed. Philadelphia:
Lippincott-Raven;
1998:705-714
20.
Weissman
BNW, Alliabadi P,Weinfeld
MS. et al. Prognostic
features of
atlanto-axial
subluxation
in rheumatoid
arthritis
patients.
Radiology
1982:144:745-751
21.
Dvorak J. Hayek J. Zehnder
R. CT-functional
diagnostics
of the rotatory
instability
of
the
upper
cervical
spine,
II:
An
evaluation
on
healthy
adults
and
patients
with
suspected
instability.
Spine
1987;12:726-731
22.
Li V.Pang D. Atlanto-axial
rotatory
fixation.
In: Pang D, ed. Disorders
ofthe
Pediatric
Spine.
New York: Raven Press; 1995:531-553
23.
Bell C.The nervous
system ofthe
human
body: embracing
the papers
delivered
to the Royal Society
on the subject
of nerves.
1830;Case
143:403
24.
Grisel P. Enucletron
de I'atlas
et torticolis
naso-pharyngien.
Presse
Med 1930;38:50-53Ix1)
25.
Ryken TC, Menezes
AH. Inflammatory
bowel disease
and the cranio-
cervical junction.
Neurosurg
Focus 1999;6:article
10
26.
Jordan
JM. Obeid LM. Allen NB. Isolated
atlantoaxial
subluxation
as
the presenting
manifestation
of inflammatory
bowel
disease.
Am J
Med 1986;80:517-520
27.
Suarez-Almazor
ME. Russell AS. Anterior
atlantoaxial
subluxation
in
patients
with spondyloarthropathies:
association
with peripheral
dis-
ease.J Rheumatol
1988;15:973-975
28.
Newman
P. Sweetnam
R. Occipito-cervical
fusion: an operative
tech-
nique and its indications.J
BoneJoint
Surg Br 1969;51:423-431
..

3
Tumorsof the Occipitocervical Junction
ChinyereObasi,
J. PatrickJohnson,
MichaelS.Hahn, and
RinaldoF.Canalis
. Anatomy
and Biomechanics
1
. Neurological Evaluation
Symptoms
Signs
. Medical Evaluation
.
Radiological Evaluation
.
Differential Diagnoses
. IndividualTumors
Chordoma
Theoccipitocervicaljunction
is the transition
zone between
thecraniumand the cervical spine. It includes multiple com-
plexjoints and ligaments
that
ensure
necessary
stability
whilestill permitting a wide range of normal physiological
movementsof the head and the neck. Due to this complexity,
masslesionsin this area pose a challenge to the surgeon in
bothdiagnosisand management. The close proximity of vital
neuraland vascular structures
and difficult surgical access
presentunique challenges to treating these occipitocervical
lesions.Earlyexperience for surgical procedures in this region
hadhighrates of morbidity and mortality that have improved
withmodern diagnostic and surgical techniques,
but routine
accessto this area remains
limited. Standard
posterior
ap-
proaches,although
useful, have limitations
for anteriorly
placedlesions.Anterior transoral, transpalatal, transmandibu-
lar,andtranslingual approaches
provide direct access but are
technicallydemanding with some risk of infectious complica-
tions.Other approaches
such as the lateral and transcervical
routeshave limited visualization
of anteriorly
placed struc-
tures.lnviewof these limitations, a multidisciplinary team
approachincluding
neurosurgeons;
maxillofacial
and ear,
nose,and throat (ENT) surgeons; and plastic surgeons is often
utilizedin treating
tumors
of this area. The initial
postopera-
tivemanagement of patients with these tumors involves air-
waycontrol, wound care, and nutritional
support,
and the
long-termmanagement includes rehabilitation
and follow-up
imagingwithpossiblechemotherapy and radiotherapy.
Thischapter focuses on the neurological and medical
evaluations,differential diagnoses. and imaging characteris-
ticsofoccipitocervical region tumors.
.
Benign Tumors
.
Malignant Tumors
Chondrosarcoma
Nasopharyngeal
Carcinoma
Lymphoma
Multiple Myeloma or Solitary Plasmacytoma
Meningioma
Glomus Jugulare Tumor
. SummaryandConclusion
.
Anatomy and Biomechanics 1
Avariety of surgical approaches and novel techniques are
currently available for access to the occipitocervical junc-
tion. Athorough understanding of the anatomy and biome-
chanics is crucial for surgical teams treating neoplastic
lesions in this region (Figs.3-1. 3-2).
The occipital bone forms the posterior portion of the skull
base, and the condyles articulate with the atlas to form the
occipitocervical junction. The inferior surfaces of these
condyles articulate with the superior surfaces of the lateral
masses of the atlas, and the inferior articular surfaces of the
atlas articulate with the lateral masses of the axis. The
odontoid peg arises from the cranial aspect of the axis and
projects superiorly through the anterior aspect of the ring
of the atlas vertebra where it articulates with the atlas. The
foramen magnum is situated within the occipital bone and
the cervicomedullary junction of the spinal cord, and verte-
bral arteries course through.
The primary movement occurring at the (1-(2 junction
is rotation around the vertical axis of the odontoid process,
which allows head turning. Minimal rotation occurs at the
atlanto-occipital joint but flexion, extension, and lateral
bending occurs in sagittal and coronal planes.2
Multiple ligaments function to maintain the stability be-
tween the joints of the occipitocervicaljunction.3 (Fig.3-3).
The most anterior ligament is the anterior atlanto-occipital
membrane extending cephalad from the anterior arch of
the atlas to the anterior margin of the foramen magnum
and caudally
as the anterior atlantoaxial
ligament and
23

24
Occipitocervical Junction: Pathology of the Occipitocervical Junction
C1
C2
C3
C4
C5
Figure 3-1
The occipital bone and rostral five cervical verte-
brae viewed obliquely from the right and caudally. The verte-
brae are illustrated in a sagittal midline plane. (With permission
from VanGilder jC, Menezes AH, Dolan OK.The craniovertebral
junction and its abnormalities.
Mount Kisco, NY:Futura; 1987.j
Figure
3-2
(A) Coronal and (8) parasagittal
sections
through
the
occipitocervical
region
showing
the
articulations
of the
occipital
bone/C1-C2
complex. (With permission from Dickman CA, Crawford NR.
Brantley AGU.Invitro cervical spine biomechanical testing. In:Spetzler RF.
ed. BNIQuarterly 1993;9:4.)
Transverse
Atlas
I.
Atlanto-axial
I.
Anterior
Atlanto-
occipital
Membrane
Apical
Dental
I.
Anterior
Atlanto-axial
A.nterior
Longitudinal
Ligamentum
Flavum
Figure 3-3
Midsagittal section through the craniovertebral junction. (With permission from Vangilder jC, Menezes AH. Dolan OK.The cranioverte-
bral junction and its abnormalities. Mount Kisco. New York:Futura; 1987.)
=-=-
---~

Odontoid process of axis
A
B
ultimately becomes the anterior longitudinal
ligament.
Deepto this is the apical dental ligament. which is a dense
fibrousconnection from the tip of the odontoid process to
theinferiormargin of the divus.
Oneof the most important
ligaments
in the cranioverte-
bral junction
is the
transverse
ligament
of the
atlas
(Fig.3-4). It is oriented horizontally
behind the dens and is
attachedto the medial surfaces of the lateral masses of the
atlas,holdingthe odontoid in the ventral aspect of the atlas.
It dividesthe ring of the atlas into a smaller anterior bony
compartment for the odontoid
process
and its ligaments,
anda larger posterior compartment
for the spinal cord. The
transverse ligament
extends
rostral
to the foramen
mag-
numsuperiorlyand inferiorly to the axis vertebra to com-
pletethecruciateligament of the atlas.
Thetectorial membrane
is closely applied to the posterior
surfaceofthe transverse ligament arising from the poste-
riorsurface of the clivus and extending
caudally to the pos-
teriorsurface of (3 then continuing
as the posterior
longi-
tudinalligament.
Thealar ligaments
are important
in the occipitocervical
articulation because they attach the occipital condyles and
3
Tumorsof the OccipitocericalJunction
25
Figure 3-4
(A) Superior and (8) dorsal views of the liga-
ments at the occipitocervical
junction.
(With
permission
from
Dickman
CA, Crawford
NR, Brantley
AGU. In vitro
cervical
spine biomechanical
testing.
In: Spetzler
RF,ed.
BNI Quarterly
1993:9:4.)
lateralmassesof(1 to the dens(Fig.3-4). Thesestronglig-
aments playa major role by preventing excessive rotation
or lateral bending of the occiput on (1 and (2. The posterior
atlanto-occipital membrane also attaches the occipital bone
to the posterior rim of the atlas and continues inferiorly as
the posterior atlantoaxial membrane.
These multiple and complex ligaments maintain stability
of the occipitocervical and atlantoaxial joints. Compromise
of these ligaments by tumor mass or traumatic injury may
result in instability and neurological deficit.
. Neurological
Evaluation
Careful neurological evaluation is essential to assess mass
lesions involving the craniovertebral junction. The early
symptoms are frequently subtle and inconsistent and may
not be fully appreciated due to the paucity of objective
signs. This often results in lengthy delays between the ini-
tial symptoms and eventual diagnosis.The large diameter of
the spinal canal at the level of the foramen magnum often

26
Occipitocervical Junction: Pathology of the Occipitocervical Junction
allows tumors to reach a large size before becoming symp-
tomatic.4 Some well-recognized clinical features such as
suboccipital pain may provide clues to the abnormalities in
this area. Cranial nerve palsies are comparatively rare ex-
cept for chordomas, which often present with cranial nerve
VIpalsies. Clinicalneurological evaluation is also important
for establishing a baseline to compare with the postopera-
tive outcome. The temporal changes of the clinical neuro-
logical examination provide some insight into the nature of
a neoplasm, with benign tumors developing slowly and ag-
gressive tumors progressing more rapidly.
Preoperative biopsy may be required forlesions where the
diagnosis is unclear and subsequent treatment may be other
than surgery (e.g., lymphoma and plasmacytoma treated
with irradiation). Computed tomography (a)-guided biopsy
can be highly accurate and avoid the need for open biopsy.
Symptoms
Neck pain in the suboccipital region and the second cervical
dermatome is present in nearly all cases of occipitocervical
junction tumors. Patients may hold their head in a fixed
tilted position4 mimicking torticollis and not infrequently
their pain is ascribed to other conditions such as cervical
spondylosis, tension headaches, or muscle strain. Other fre-
quent symptoms are gait disturbance that may be a mild
imbalance, a vertiginous sensation, progressive hand weak-
ness and numbness, or, rarely, a sudden loss of strength in
the lower extremities. These symptoms are often initially
mild and are overlooked by both patient and physician and
only become clearer in hindsight.
Signs
The level of consciousness is rarely altered except as a late
feature of increased intracranial pressure, mass effect in the
posterior fossa, or hydrocephalus from obstruction of cere-
brospinal fluid (CSF) outflow pathways. Speech may
however be altered, with hoarseness occurring from cranial
nerve IXand Xdisturbance.
Other lower cranial nerves may also be affected, with re-
sulting dysphagia, impaired gag reflex,tongue atrophy, and
weakness
of
the
sternocleidomastoid
and
trapezius
muscles. Horner's syndrome occurs occasionally from in-
volvement of the cervical sympathetics.
Spastic weakness
of the extremities
is a prominent
feature of occipitocervical junction tumors. It is classically
described as beginning in the ipsilateral upper limb, then
the ipsilateral lower limb followed by the contralateral
lower and upper limbs in sequence. This distinct progres-
sion of symptoms is an important characteristic, but it
rarely occurs in its pure clinical form.
Tendon reflexes may be increased with or without upgo-
ing plantar responses.
Atrophy of intrinsic hand muscles is seen occasionallybut
may result in false localization of more caudal levels in the
cervical region,4 possibly due to proximal compression of
the anterior spinal artery affecting lower cervical segments.
Sensory examination reveals a contralateral dissociated
sensory loss with preserved tactile sensibility. Vibration
sense may be absent and proprioception decreased. Sphinc-
ter disturbance is usually a late feature.
. Medical Evaluation
Similarto neoplasms in general, those involvingthe occipito-
cervicaljunction occur in older or younger people. Older pa-
tients often have other medical problems requiring workup
as part ofthe preoperative protocol that includes optimizing
cardiovascular and pulmonary function, nutrition, and meta-
bolic disorders that couldjeopardize successful treatment.
.
Radiological Evaluation
Plain x-rays have limited value for lesions involving the
craniovertebral junction except for evaluation of dynamic
instability with flexion-extension views. Nevertheless, plain
radiographic findings can be suggestive of occipitocervical
junction tumors demonstrating erosion, sclerosis, or abnor-
mal expansion of the bony architecture.
a, with or without myelography, allows the detection of
bony lesions and can reveal displacement of neural struc-
tures produced by a tumor that would have a bearing on the
choice of operative management.
Sagittal,coronal, and three-dimensional reconstructions of
a
images with bone windows provide invaluable informa-
tion of the relevant bony anatomy and further clarifythe pres-
ence of instability. a
is less useful for the delineation of soft
tissue masses, and the mastoid process, occipital condyles,
and lateral masses of C1 may introduce significant imaging
artifacts obscuringvisualization ofpathologicallesions.
Magnetic resonance imaging (MRI)is ideal for evaluating
the soft tissues in the occipitocervical region. Multiplanar
views (Le.,sagittal, coronal, and axial) are particularly use-
ful for showing the spinal cord and adjacent structures.
Some sequences may be used to evaluate the integrity of
ligaments such as the transverse ligament. MRI however
does not provide optimal imaging of the bony anatomy.
Magnetic resonance angiography is a useful vascular exami-
nation to evaluate the patency of major vessels but has
limitations of resolution and potential artifacts. Cerebralan-
giography remains useful in demonstrating flow dynamics
and tumor vascularity. Preoperative embolization is useful
to selectively devascularize a neoplastic lesion or safely
occlude major vessels with prior test occlusion.4
.
Differential Diagnoses
Avariety of neoplasms occur in the occipitocervicaljunction
and can arise from bony and ligamentous or neural and vas-
cular structures. The differential diagnoses of these lesions
can also range from developmental to acquired abnormali-
ties that also include some infectious lesions. Neoplasms in
this region may arise either primarily in the craniovertebral
junction, intracranially, or from local extension or metastatic
spread into the craniocervical area. There are no particular
clinical features that are specific to any of these conditions,
and they all present with similar clinical findings.

3
Tumors of the Occipitocervical Junction
27
Intracranialor intraspinal tumors with secondary exten-
sionintothecraniovertebraljunction include:
. Meningiomas(the most common)
. Cranialnerve schwannomas or neurofibromas
. Glomustumors
. Nasopharyngealtumors
Primaryosseous tumors occurring
in the area of the oc-
cipitocervicaljunction include:
. Chordomas
. Chondrosarcomas
. Fibrousdysplasia
. Eosinophilicgranuloma
. Plasmacytomas
. Osteoblastomas
. Giantcell tumors
. Osteoidosteomas
Metastatictumors that have a predilection
for the verte-
bral column arise
from
paired
and
midline
viscera
includings:
. Breast
. Lung
. Kidney
. Prostate
. IndividualTumors
Chordoma
Epidemiology
0.15 to 0.2%of intracranial tumors
Peak age 30 to 60 years
Male:female ratio 2:1
Table3-1
Symptoms of Chordoma Related to Origin of Lesion
Locationof Notochordal Remnants
Type of Chordoma
ClinicalPresentation
Dorsumsellae
Sellar
Parasellar
Spheno-occipital
Ventral
Dorsal
Body of clivus
Basion
Lateral (petrosal)
Inferior dival
Clinical Features
VInerve palsy-60%
VII-XIInerve palsies-SO%
Headaches-SO%
Nasal mass-2S%
Chordomas are one of the most frequently encountered
extradural tumors at the occipitocervicaljunction. These tu-
mors are thought to arise from notochordal elements and
can occur anywhere along the spinal axis. Asshown in the
following text and in Table 3-1, the presenting symptoms
can be correlated with the site of the notochordal remnant,
which has a predilection for the cIival and sacrococcygeal
regions (Fig.3-5).
Although chordomas usually arise from and occur in the
midline. spinal lesions may occur eccentric to the spinal
canal. and skull base lesions may extend into the infratem-
poral fossae. Histologically chordomas are benign but be-
have in a malignant manner due to local invasiveness and
may even breach the dura to invade neural structures in late
stages. Up to 10% have evidence of distant bloodborne
metastases and have been found in various parts of the
body, including the lungs and liver. Radiologically,chordo-
mas have a variable degree of density on CTand are of in-
termediate to low signal on MRI.Multiple punctate calcifi-
cations and bony erosions are often seen in these tumors.
Variable gadolinium contrast enhancement
is seen and
ranges from mild to intense. Angiography shows a poorly
vascularized or avascular mass.
DifferentialDiagnosesof Chordoma
Tumors that by virtue of their location or behavior mimic
cIivalchordomas include:
Primary midline tumors
.
Fibrous dysplasia/Paget's disease
.
Osteoblastoma
Pituitary endocrinopathy,
chiasmal syndrome
Visual loss. cavernous sinus syndrome
Nasopharyngeal mass
Abducens nerve palsy,
multiple cranial nerve palsies, brain stem
syndrome, hydrocephalus
Cerebellopontine angle
syndrome
Hypoglossal
nerve palsy,
foramenmagnum
syndrome

28
Occipitocervical Junction: Pathology of the Occipitocervical Junction
Figure 3-5
Sagittal magnetic resonanceimaging scanof a 12-year-
old female patient with a craniovertebral junction lesion presenting
with nasal congestion. Examination showed a cranial nerve IV palsy
and mild spasticquadriparesis.Pathologicaldiagnosis:chordoma.
.
Osteochondroma
.
Osteoma
Intracranial midline lesions
. Meningioma
.
Pituitaryadenoma
.
Craniopharyngioma
.
Olfactoryneuroblastoma
. Teratogeniccystofthebrainstem
Extracranial midline lesions
. Adenoid cystic carcinoma
.
Angiofibroma
.
Nasal glioma
.
Aciniccell adenocarcinoma
. Primary lateral tumors with clivalextension
. Benign Tumors
.
Cholesteatoma
.
Chondroma
.
Histiocytosis
.
Glomus tympanicum
.
MalignantTumors
.
Chondrosarcoma
.
Sarcoma
. Rhabdomyosarcoma
Chordomas consist of two subgroups-the typical and the
chondroidvarieties.Macroscopicallythey appearsimilaras
asoft,lobulatedmassfrequentlysurrounded bya pseudo-
capsule.6Microscopically,they consist of three cell types;
namely, stellate cells, physaliphorous cells, and intermedi-
ate cells. Chondroid chordomas have additional chondroid
elements. The stellate cells are thought to be more malig-
nant
in behavior
and
are considered
to be mature
physaliphorouscells.Chondroidchordomasappearto have
a better prognosisthan typical chordomas,but some au-
thors maintain there is a poor correlation between histolog-
ical appearance and prognosis. It is the uncontrolled pri-
mary tumor growth or local recurrence after surgery that
results in death.
Thesurvivalrates forchordomasvaryfrom28 monthsin
untreated cases to a mean survival of 3.3 and 6.6 years for
those treated with surgery and those treated with both
surgery and radiation, respectively. The 5-year survival rate
for the classic form of chordoma is30 to 50%.
Surgicalcure for chordomasrequires en bloc removal,
and this has been reported in isolated sacral lesions. Thus
far this has not been achievable in the skull base and cran-
iocervicaljunction. Subtotal surgical resection is frequently
combined with radiotherapy
or heavy particle (proton
beam) radiation despite the fact that chordomas are poorly
radiosensitive.
Chondrosarcoma
Similar to chordomas,
chondrosarcomas
tend to occur at the
base of the skull. They represent up to 6%of all skull tumors
and 75%of these are at the skull base. This is thought to be
related to the fact that the skull base is derived from a carti-
laginous matrix through endochondral
ossification, and
chondrosarcomas
may arise from the primitive
mesenchy-
mal cells within this matrix. They are slow growing and lo-
cally aggressive with a propensity for local recurrence, and
they produce symptoms from intracranial mass effect.
The average age at presentation
is 30 years in the head
and neck region, and they have the same incidence
in both
males and females. Imaging characteristics are similar to
those of chordomas, but chondrosarcomas are more fre-
quently not midline in location.5
Nasopharyngeal Carcinoma
These tumors are more common in southern Chinese (Can-
tonese) people and their high risk continues
despite immi-
gration to other parts of the world. There is an associati~n
with the Epstein-Barr viral infection earlier in life and the de-
velopment
of a tumor later in life. There is also an association
with human
leukocyte
antigens
(HLAs). These lesions may
extend
posteriorly
to involve the occipitocervical
junction
oc-
casionally, but basiocciput and skull base involvement is seen
in 25 to 50%of cases of nasopharyngeal
carcinoma.
lymphoma
Theseusually arise from Waldeyer'sring of lymph nodes
and may similarly extend to the clivus in a manner similar
to the nasopharyngeal tumors.