Neurosurgical operative atlas 2nd ed pediatric neurosurgery

Neurosurgical Operative AtlasSecond Edition Pediatric Neurosurgery James Tait Goodrich, MD, PhD, DSci Honoris Causa Professor of Clinical Neurological Surgery, Pediatrics, Plastic and Re

Neurosurgical Operative Atlas Second Edition

Pediatric Neurosurgery

American Association of Neurosurgeons • Rolling Meadows, Illinois

Neurosurgical Operative Atlas

Second Edition

Pediatric Neurosurgery

James Tait Goodrich, MD, PhD, DSci (Honoris Causa)

Professor of Clinical Neurological Surgery, Pediatrics, Plastic and Reconstructive Surgery Albert Einstein College of Medicine

Director, Division of Pediatric Neurosurgery

Center for Craniofacial Disorders

Children’s Hospital at Montefi ore

Bronx, New York

Thieme

New York • Stuttgart

American Association of Neurosurgeons

Rolling Meadows, Illinois

New York, NY 10001 Rolling Meadows, Illinois 60008-3852

*The acronym AANS refers to both the American Association of Neurological Surgeons and the American Association of Neurosurgeons.

Associate Editor: Birgitta Brandenburg

Assistant Editor: Ivy Ip

Vice President, Production and Electronic Publishing: Anne T Vinnicombe

Production Editor: Print Matters, Inc

Vice President, International Marketing and Sales: Cornelia Schulze

Chief Financial Offi cer: Peter van Woerden

President: Brian D Scanlan

Cover illustration: Anita Impagliazzo

Compositor: Compset, Inc

Printer: Everbest Printing Company

Library of Congress Cataloging-in-Publication Data

Neurosurgical operative atlas Pediatric neurosurgery / [edited by] James Tait Goodrich

p ; cm

Includes bibliographical references and index

ISBN 978-1-58890-510-9 (alk paper)

1 Nervous system—Surgery—Atlases 2 Children—Surgery—Atlases 3 Pediatric neurology—Atlases I Goodrich, James T

[DNLM: 1 Nervous System Diseases—surgery—Atlases 2 Child 3 Infant 4 Neurosurgical Procedures—methods—Atlases

WL 17 P371 2008]

RD593.P3822 2008

618.92’8—dc22

2007048827Copyright © 2008 by Thieme Medical Publishers, Inc., and the American Association of Neurosurgeons (AANS) This book, including all parts thereof, is legally protected by copyright Any use, exploitation, or commercialization outside the narrow limits set by copyright legislation without the publisher’s consent is illegal and liable to prosecution This applies in particular to photostat reproduction, copying, mimeographing or duplication of any kind, translating, preparation of microfi lms, and electronic data processing and storage

Important note: Medical knowledge is ever-changing As new research and clinical experience broaden our knowledge, changes in

treatment and drug therapy may be required The authors and editors of the material herein have consulted sources believed to be reliable in their efforts to provide information that is complete and in accord with the standards accepted at the time of publication However, in view of the possibility of human error by the authors, editors, or publisher of the work herein or changes in medical

knowledge, neither the authors, editors, or publisher, nor any other party who has been involved in the preparation of this work, warrants that the information contained herein is in every respect accurate or complete, and they are not responsible for any errors or omissions or for the results obtained from use of such information Readers are encouraged to confi rm the information contained herein with other sources For example, readers are advised to check the product information sheet included in the package of each drug they plan to administer to be certain that the information contained in this publication is accurate and that changes have not been made in the recommended dose or in the contraindications for administration This recommendation is of particular importance in connection with new or infrequently used drugs

Some of the product names, patents, and registered designs referred to in this book are in fact registered trademarks or proprietary names even though specifi c reference to this fact is not always made in the text Therefore, the appearance of a name without designation

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

Printed in China

5 4 3 2 1

ISBN 978-1-58890-510-9

To Setti S Rengachary, MD, and Robert H Wilkins, MD

When the fi rst edition of this remarkable atlas came out in early 1990s, it was an instant and powerful success in the

neurosurgical literature Drs Rengachary and Wilkins recognized the power of the illustrated text and in this case designed

a work that was clearly visual with the text being secondary As neurosurgeons are visual animals, this was a successful design Drs Rengachary and Wilkins’ contributions to neurosurgery have been enormous It is a true pleasure to help bring this remarkable atlas back in a second edition However, it must be remembered that their original editorship led to this most elegant and infl uential series of operative chapters In acknowledgment of their insights, their educational leadership, and, most importantly, their longstanding contributions to neurosurgery, I dedicate this work to these two scholars and superb neurosurgeons

v

Continuing Medical Education Credit Information and Objectives xi

Continuing Medical Education Disclosure xii

Series Foreword Robert Maciunas xiii

Foreword Richard D Hayward xv

Preface xvii

Contributors xix

Chapter 1 Fibrous Dysplasia Involving the Craniofacial Skeleton 1

James Tait Goodrich Chapter 2 Chiari Malformations and Syringohydromyelia 7

Elizabeth C Tyler-Kabara and W Jerry Oakes Chapter 3 Unilateral and Bicoronal Craniosynostosis 13

Kant Y K Lin, John A Jane Jr., and John A Jane Sr. Chapter 4 Transoral Surgery for Craniovertebral Junction Abnormalities 20

Arnold H Menezes Chapter 5 Malposition of the Orbits 27

John A Persing and Bianca I Knoll Chapter 6 Ventriculoatrial Shunting 34

John Drygas and Stephen J Haines Chapter 7 Repair of “Growing” Skull Fracture 40

Tadanori Tomita Chapter 8 Occipital Encephaloceles 43

William O Bell Chapter 9 Surgical Management of Pansynostosis (Craniosynostosis) 50

James Tait Goodrich and David L Staffenberg Chapter 10 Tethered Spinal Cord, Intramedullary Spinal Lipomas, and Lipomyelomeningoceles 62

Elizabeth C Tyler-Kabara and W Jerry Oakes Chapter 11 Encephaloceles of the Anterior Cranial Base 69

Jonathan P Miller and Alan R Cohen Chapter 12 Exorbitism 76

Constance M Barone, David F Jimenez, and James Tait Goodrich Chapter 13 Depressed Skull Fracture in Infants 83

Marion L Walker Chapter 14 Orbital Hypertelorism and Orbital Dystopia 88

Constance M Barone, David F Jimenez, and James Tait Goodrich

vii

Chapter 15 Closure of the Myelomeningocele 96

David G McLone

Chapter 16 Dandy-Walker Malformation 104

Arthur E Marlin and Sarah J Gaskill

Chapter 17 Surgical Management of Chiari I Malformations and Syringomyelia 111

Elizabeth C Tyler-Kabara, Richard B Morawetz, and W Jerry Oakes

Chapter 18 Split Cord Malformations 116

Dachling Pang

Chapter 19 Tethered Cord Syndrome Secondary to Previous Repair of a Myelomeningocele 129

Timothy A Strait

Chapter 20 Sectioning of the Filum Terminale 136

Frederick B Harris, Naina L Gross, and Frederick A Boop

Chapter 21 Diastematomyelia 142

Frederick B Harris, Naina L Gross, and Frederick A Boop

Chapter 22 Lipomyelomeningoceles 147

Frederick B Harris, Naina L Gross, and Frederick A Boop

Chapter 23 Untethering of the Spinal Cord after a Previous Myelomeningocele Repair 152

Frederick B Harris, Naina L Gross, and Frederick A Boop

Chapter 24 Brain Abscesses 157

Darric E Baty, Eli M Baron, and Christopher M Loftus

Chapter 25 Unilateral Coronal Synostosis (Plagiocephaly) 165

James Tait Goodrich and David L Staffenberg

Chapter 26 Moyamoya Syndrome in Children with Pial Synangiosis 171

R Michael Scott and Edward R Smith

Chapter 27 Selective Dorsal Rhizotomy for Spastic Cerebral Palsy 177

Tae Sung Park and James M Johnston

Chapter 28 Treatment of Lambdoidal Synostosis with Calvarial Reconstructive Techniques 184

David F Jimenez, Constance M Barone, and James Tait Goodrich

Chapter 29 Early Treatment of Lambdoid Synostosis with Endoscopic-Assisted Craniectomy 190

David F Jimenez and Constance M Barone

Chapter 30 Posterior Plagiocephaly 194

Richard G Ellenbogen, Sudesh J Ebenezer, and Richard Hopper

Chapter 31 Sagittal Synostosis 203

Larry A Sargent and Timothy A Strait

Chapter 32 The Separation of Craniopagus Twins 209

Sami Khoshyomn and James T Rutka

Chapter 33 Endoscopic Approaches to the Ventricular System 215

David F Jimenez

Chapter 34 Intraventricular Endoscopy 227

Jonathan P Miller and Alan R Cohen

Chapter 35 Infected Ventriculoperitoneal Shunts 233

Keyne K Thomas, Sohaib A Kureshi, and Timothy M George

Chapter 36 Combined Fronto-Orbital and Occipital Advancement for Total Calvarial Reconstruction 241

Ian F Pollack

Chapter 37 Lumbosacral Meningoceles 251

Ciaran J Powers, Eric M Gabriel, and Timothy M George

Chapter 38 Surgical Correction of Unilateral and Bilateral Coronal Synostoses 256

Jack Chungkai Yu and Ann Marie Flannery

Chapter 39 Myelomeningoceles, Split Cord Malformations, and Filum Terminale Dysgenesis 262

Robert F Keating

Chapter 40 Lipomyelomeningoceles 269

James Tait Goodrich

Chapter 41 Brain Stem Gliomas 275

Darlene A Lobel and Mark R Lee

Chapter 42 Posterior Fossa Decompression without Dural Opening for the Treatment of Chiari I Malformation 281

Jonathan D Sherman, Jeffery J Larson, and Kerry R Crone

Chapter 43 Metopic Synostosis 286

Kant Y K Lin, John A Jane Jr., and John A Jane Sr.

Chapter 44 Total Cranial Vault Repair for Sagittal Craniosynostosis 291

John A Jane Jr., Kant Y K Lin, Tord D Alden, and John A Jane Sr.

Chapter 45 Metopic Craniosynostosis 296

Paul C Francel and Jayesh Panchal

Chapter 46 Unicoronal Synostosis 304

Jayesh Panchal and Paul C Francel

Index 313

Contents ix

Continuing Medical Education Credit

Information and Objectives

◆ Objectives

Upon completion of this activity, the learner should be able to:

1 Describe the treatment and surgical management of pediatric neurosurgical disorders

2 Demonstrate a full understanding of current neurosurgical operative techniques in pediatric neurosurgical disorders

3 Discuss the operative management of complex pediatric neurosurgical disorders

The AANS designates this educational activity for a maximum of 15 AMA PRA Category 1 credits™ Physicians should only

claim credit commensurate with the extent of their participation in the activity

The Home Study Examination is online on the AANS Web site at: www.aans.org/education/books/atlas3.asp

Estimated time to complete this activity varies by learner; activity equaled up to 15 Category 1 credits of CME

◆ Release/Termination Dates

Original Release Date: August 1, 2008

The CME termination date is: August 1, 2011

*The acronym AANS refers to both the American Association of Neurological Surgeons and the American Association of

Neurosurgeons.

xi

Continuing Medical Education Disclosure

The AANS controls the content and production of this CME activity and attempts to ensure the presentation of balanced, objective information In accordance with the Standards for Commercial Support established by the Accreditation Council for Continuing Medical Education, speakers, paper presenters/authors, and staff (and the signifi cant others of those mentioned) are asked to disclose any relationship they or their co-authors have with commercial companies which may be related to the content of their presentation

Speakers, paper presenters/authors, and staff (and the signifi cant others of those mentioned) who have disclosed a ship* with commercial companies whose products may have a relevance to their presentation are listed below

relation-Author Name Disclosure Type of Relationship

Speakers, paper presenters/authors, and staff (and the signifi cant others of those mentioned) who have reported they do not have any relationships with commercial companies:

John A Jane Sr

David F JimenezJames M JohnstonRobert F KeatingSami KhoshyomnBianca KnollSohaib A Kureshi

Jeffery J Larson Mark R LeeKant Y K LinDarlene A LobelChristopher M LoftusDavid G McLoneArnold H MenezesJonathan P MillerRichard B Morawetz

W Jerry OakesJayesh PanchalDachling PangTae Sung Park

Ian F PollackCiaran J PowersJames T RutkaLarry A Sargent

R Michael ScottEdward R SmithDavid L StaffenbergTimothy A StraitKeyne K ThomasTadanori TomitaElizabeth C Tyler-KabaraMarion L WalkerJack C Yu

*Relationship refers to receipt of royalties, consultantship, funding by research grant, receiving honoraria for educational services elsewhere, or any other relationship to a commercial company that provides suffi cient reason for disclosure

xii

Series Foreword

The Publications Committee of the American Association

of Neurological Surgeons began publishing the fi rst edition

of the Neurosurgical Operative Atlas in 1991 To allow for

timely publication, coverage of six operations was published

at bimonthly intervals in looseleaf format in the order fi

n-ished manuscripts were received The completed series had

nine volumes and covered the entire spectrum of

neuro-surgery

The goal was to publish a comprehensive reference that

included well-established neurosurgical procedures as

practiced in the United States and Canada by authors who

are respected in the fi eld

Working together, the AANS Publications Committee and

Thieme New York have organized the second edition of this

atlas series The atlas’s main purpose remains the same, to

be a ready reference for well-established neurosurgical

pro-cedures for trainees and practitioners of neurosurgery

world-wide The new edition contains fi ve volumes, covering

neuro-oncology; spine and peripheral nerves; functional; pediatric;

and vascular neurosurgery For each volume, one or more

lead editors with known expertise in the subject area were selected Each volume editor had complete freedom to add, revise, or delete chapters The number of chapters per volume

is approximately the same as the number of chapters in that particular subject area found in the fi rst edition

Each chapter is designed to teach a specifi c surgical nique or approach The illustrations of the techniques are a vital part of the work, and the authors commissioned most

tech-of the drawings in color The text in each chapter covers the case selection, the operative indications and contraindica-tions, special points in the anesthetic technique, a step-by-step detailed description of the operation, and postoperative complications Detailed discussion of diagnostic techniques, pathology, mechanisms of disease, histology, and medical management are not included since they are logically out-side the scope of a surgical atlas Detailed tables, reference lists, and statistical analysis of results are also not included because they are readily available in standard texts

We hope you fi nd this reference of value in your practice

I came to pediatric neurosurgery after a nearly exclusively

adult neurosurgical training, and I confess to being a late

convert to pediatric neurosurgery as an almost autonomous

specialty The surgical skills required to remove a

medullob-lastoma were no different, I thought, to those needed to

ex-cise a cerebellar metastasis (a far more frequently occurring

pathology), and as for all those shunts !

And the conditions whose management fell within the

province of the pediatric neurosurgeon were all so rare

I was wrong for several reasons, not least of which was to

regard pediatric neurosurgery too narrowly—as no more than

the deployment of particular operations But I was right about

how uncommon (fortunately) in terms of their overall incidence

the conditions we deal with are Pediatric neurosurgery is a

spe-cialty greedy for the resources it devours to treat comparatively

few patients, hydrocephalus aside How should the expense of

managing a newborn with, say, Apert syndrome through

in-fancy, childhood, and adolescence be balanced against returning

so many more adults to their former lifestyle after the

replace-ment of a painful hip or knee? Or screening for such occult

har-bingers of morbidity as hypertension or glaucoma?

It does not take long for the fascination, indeed the privilege,

of working with children and their families to suppress such

thoughts, but nevertheless these remain questions to which

every pediatric neurosurgeon must have their own answer

It has been said, and rightly so, that a society should be

judged by the way it treats its young and its old—those on

the vulnerable edges of life James Goodrich, in assembling

the impressive list of internationally renowned experts who

make up the list of his contributors, has demonstrated only

too clearly the commitment of the North American pediatric

neurosurgical community to the care of its sick children

Since the fi rst edition of this book there has been further

acceptance and consolidation of pediatric neurosurgery as a

discipline that requires its own specialty training

The conditions that are encountered in a pediatric

neuro-surgical practice vary markedly from those encountered in

an adult practice, as a glance at the titles of these chapters

with their emphasis upon a variety of congenital disorders

immediately reveals

The days are long past, I hope, when a surgeon, as ambitious

as foolish, would wish to embark upon his or her fi rst transoral procedure with no more technical experience than having read Arnold Menezes’s excellent chapter on this subject

Then who—and what—is an Operative Atlas such as this for? It is fi rst and foremost a most valuable educational tool, one that I would submit should be an essential companion for pediatric neurosurgeons at all stages of their career

Neurosurgical residents can read up on the procedures on which they are about to assist; the increased understanding

of how and why these procedures are done will make them not only more knowledgeable but all the more useful Fur-thermore, when the surgery is over they can come back to the atlas to fi nd out exactly why and how some maneuver, whose signifi cance may have escaped them at the time, was accomplished

And not only the residents Just as there exists no tion that cannot be improved (the fi nal improvement being

opera-to do away with the need for surgery alopera-together) so there is

no neurosurgeon whose training is fi nished; indeed, anyone who makes such a claim about themselves has, whether they recognize it or not, already retired

What pediatric neurosurgeon, however long ago their idency ended, would not wish to discover how the experts who have contributed to this volume deal with conditions as frustrating as a lipomyelomeningocele or a brainstem glioma?

res-Or the management of a common nuisance such as a shunt infection? Or something more critical, such as a total calvarial remodelling for the older child with sagittal synostosis—surely the limit to which “cosmetic” neurosurgery can be stretched?

I cannot imagine a pediatric neurosurgeon (in or residency) who will not be stimulated, intrigued, and (hope-fully) sometimes provoked by what has been contributed

post-by the heady selection of experts James Goodrich has sembled here

as-He is to be congratulated not only for bringing them gether to produce this book but also for demonstrating so clearly the commitment of the pediatric neurosurgical com-munity of North America to its own continuing education for the benefi t of sick and disabled children worldwide

to-Richard D Hayward, FRCS

Professor, Pediatric NeurosurgeryGreat Ormond Street Hospital for ChildrenLondon, United Kingdom

xv

O! Author, with what words will describe

with such perfection the whole confi guration,

such as the sketch does here?

Leonardo da Vinci Quaderni d’Anatomia

Volume II, fol 2r

Christiania: Dybwad, 1911–1916

O! reader, the same feeling that inspired Leonardo to

re-state the Vitruvian man and provide the perfect proportion

inspired the authors to provide this palimpsest atlas, now

in the second edition with pages now etched and

re-done Surgical techniques have continued to evolve with

both new technologies and also newly designed

surgi-cal approaches In the early part of the 16th century,

Le-onardo da Vinci planned a 120-volume text on anatomy

with mostly anatomic illustrations Early on, Leonardo

recognized that the visual images were more important

in educating the individual; he has clearly remained the

master at that concept In producing a second edition of

this work, we clearly wanted to keep the original design

with the illustrations being paramount and with text being

added clarification In an effort to disseminate these

surgi-cal techniques, this atlas was formulated on the principle

that the visual image is most important; it must be clear,

precise, and bring forth the surgical design with precision

In addition, the text design and presentation needs to be

straightforward and practical The atlas-style format using

an operative narrative was selected in the belief that, like

Leonardo da Vinci, surgeons are more comfortable with

the “visual” image than the written word—though both

are provided! Starting with the first edition of this work,

we selected the chapters that dealt with pediatric subjects

The original authors were asked to update and revise their

presentations as they felt necessary In some cases

exten-sive changes were made, and in others only some editing

was done A number of the chapters are edited by several

surgical subspecialists, a common trend these days Many

surgical procedures have clearly benefited from the skills

of several surgical subspecialties

In recent years new materials, techniques, and equipment

have been offered to neurosurgeons for their operations When

relevant, those contributions have been added We specifi cally

asked the authors to avoid lengthy bibliographies and to be

practical in their presentations; we think the readership will see that this is clearly evident throughout the volume Where appropriate, the authors have been asked to include imaging, whether computed tomography, magnetic resonance imag-ing, or other radiologic studies The format of the chapters has been kept the same throughout in order that the presentation remains clear and follows a consistent structure

For our surgical colleagues outside of neurosurgery, a careful review of this book will reveal useful surgical ideas and techniques The format is designed so that not only is the concept provided and discussed, but the surgical tech-nique is discussed step by step in an atlas format, detailing each member of the surgical teams’ contributions Stand-ards, techniques, and styles are continuing to change so that hopefully a third edition of this book will be necessary in the not so distant future Our founding neurosurgical father Harvey Cushing put it best when he stated:

The knowledge which a man can use is the only real knowledge, the only knowledge which has life and growth in it

and converts itself into practical power.

The rest hangs like dust about the brain and dries like raindrops off the stones.

is clearly through their efforts that the published result is

so outstanding At the top of the list of people are Brian Scanlan, Tim Hiscock, Birgitta Brandenburg, Richard Roth-schild, Dominik Pucek, and Ivy Ip A special thanks to you all for your individual contributions, which included skilled editing, production, and design

To Helen Lopez and Daniel Jimenez, a sincere thanks for handling all the calls, mailing the bulky manuscripts, and reminding us to be nice and to be on time

xvii

This book is about neurosurgery, and a fundamental part of

that team is our neurosurgical operating room nurses and

tech-nicians To my operating room nurses and technicians, such an

essential part of my surgical team, special thanks for watchful

vigilance and your helpful advice and insight offered in the care

of patients Hopefully this volume will be helpful to operating

room teams around in the world Thanks to Mary Speranza,

Esther Ko-Uy, Katie Thompson, Charles Price, Loretta Caldwell, Sylvan Fowles, Gabriel Ofurhie, Noel Greene, Danielle Dunne, Cecille Edwards, Bindu Peter, and, fi nally, Charisse Terry—a most remarkable and skilled team with which to work!

Finally, to all the authors who contributed to this book, thanks for doing such a wonderful job in presenting some very complex subjects

Tord D Alden, MD

Assistant Professor

Department of Pediatric Neurosurgery

Feinberg School of Medicine

Cedars-Sinai Institute for Spinal Disorders

Los Angeles, California

Constance M Barone, MD, FACS

Division Head and Professor

University of Texas Health Science Center at San Antonio

Division of Plastic and Reconstructive Surgery

San Antonio, Texas

Darric E Baty, MD

Resident

Department of Neurosurgery

Temple University School of Medicine

Temple University Hospital

Philadelphia, Pennsylvania

William O Bell, MD, FACS

Neurosurgical Associates of the Carolinas

Winston-Salem, North Carolina

Frederick A Boop, MD

Associate Professor of Neurosurgery

Chief, Pediatric Neurosurgery

Semmes-Murphey Clinic

LeBonheur Children’s Hospital

Memphis, Tennessee

Alan R Cohen, MDDivision of Pediatric NeurosurgeryRainbow Babies and Children HospitalCleveland, Ohio

Kerry R Crone, MDProfessor of Neurosurgery and PediatricsDirector, Pediatric Neurosurgery

Cincinnati Children’s Hospital Medical CenterCincinnati, Ohio

John Drygas, MD, MSNeuroscience and Spine AssociatesNaples, Florida

Sudesh J Ebenezer, MD, EdMDepartment of Neurological SurgeryThe University of WashingtonChildren’s Hospital and Regional Medical CenterSeattle, Washington

Richard G Ellenbogen, MD, FACSProfessor and Chairman

Department of Neurological SurgeryUniversity of Washington School of MedicineNeurological Surgeon

Children’s Hospital and Regional Medical CenterSeattle, Washington

Ann Marie Flannery, MD, FACS, FAAPReinert Chair in Pediatric NeurosurgeryDepartment of Surgery

Saint Louis University School of MedicineCardinal Glennon Children’s Hospital

St Louis, MissouriPaul C Francel, MD, PhDOklahoma Sports Science and OrthopedicsOklahoma City, Oklahoma

xix

Professor of Clinical Neurological Surgery,

Pediatrics, Plastic and Reconstructive Surgery

Albert Einstein College of Medicine

Director, Division of Pediatric Neurosurgery

Center for Craniofacial Disorders

Children’s Hospital at Montefi ore

Bronx, New York

Department of NeurosurgeryUniversity of Virginia Health SystemCharlottesville, Virginia

John A Jane Sr., MD, PhDProfessor and ChairmanDepartment of NeurosurgeryUniversity of VirginiaCharlottesville, VirginiaDavid F Jimenez, MDProfessor and ChairmanDepartment of NeurosurgeryUniversity of Texas Health Science Center at San AntonioSan Antonio, Texas

James M Johnston, MDDepartment of NeurosurgeryWashington University School of Medicine

St Louis Children’s Hospital

St Louis, MissouriRobert F Keating, MDAssociate Professor of Neurological Department of Surgery and Pediatrics

George Washington University School of MedicineDivision of Pediatric Neurosurgery

Children’s National Medical CenterWashington, DC

Sami Khoshyomn, MDPediatric Neurosurgery FellowHospital for Sick ChildrenToronto, Ontario

CanadaBianca I KnollChief ResidentDepartment of Plastic SurgeryYale University School of MedicineDivision of Plastic Surgery

Yale-New Haven HospitalNew Haven, ConnecticutSohaib A Kureshi, MDNeurosurgical Medical ClinicChula Vista, CaliforniaJeffrey J Larson, MDNeurosurgeonCoeur d’ Alene Spine and Brain, PLLCCoeur d’Alene, Idaho

Mark R Lee, MD

Chairman, Department of Neurosurgery

Medical College of Georgia

Augusta, Georgia

Kant Y K Lin, MD

Professor

Department of Plastic Surgery

University of Virginia School of Medicine

Christopher M Loftus, MD, DHC (Hon.), FACS

Professor and Chairman

Department of Neurosurgery

Assistant Dean for International Affi liations

Temple University School of Medicine

Philadelphia, Pennsylvania

Arthur E Marlin, MD, MHA

Professor

Department of Neurosurgery

University of South Florida

Division of Pediatric Neurosurgery

All Children’s Hospital

Tampa, Florida

David G McLone, MD

Professor

Department of Pediatric Neurosurgery

Feinberg School of Medicine

Northwestern University

Children’s Memorial Hospital

Chicago, Illinois

Arnold H Menezes, MD, FACS, FAAP

Professor and Vice Chairman

Department of Neurosurgery

University of Iowa Carver College of Medicine Department

of Neurosurgery

University of Iowa Hospitals and Clinics

Iowa City, Iowa

Children’s HospitalBirmingham, AlabamaJayesh Panchal, MD, MBA, FRCSGenesis Plastic Surgery and Medical SpaEdmond, Oklahoma

Dachling Pang, MD, FRCS(C), FACSProfessor of Pediatric NeurosurgeryUniversity of California

Davis Chief, Regional Centre of Pediatric NeurosurgeryKaiser Permanente Hospital, Northern CaliforniaOakland, California

Tae Sung Park, MDShi H Huang Professor of NeurosurgeryDepartment of Neurosurgery

Washington University in St Louis–School of MedicineDivision of Neurosurgery

St Louis Children’s Hospital

St Louis, MissouriJohn A Persing, MDProfessor and ChiefDepartment of Plastic SurgeryYale University School of MedicineDivision of Plastic Surgery

Yale–New Haven HospitalNew Haven, ConnecticutIan F Pollack, MD, FACS, FAAPProfessor

Department of NeurosurgeryUniversity of Pittsburgh School of MedicineChief of Pediatric Neurosurgery

Children’s Hospital of PittsburghPittsburgh, PennsylvaniaCiaran J Powers, MD, PhDDepartment of Surgery, Division of Neurosurgery

Duke UniversityDivision of NeurosurgeryDurham, North CarolinaJames T Rutka, MD, PhD, FRCS(C), FACS, FAAPProfessor and Chairman

Department of NeurosurgeryUniversity of TorontoDivision of NeurosurgeryThe Hospital for Sick ChildrenToronto, Ontario

Canada

Contributors xxi

Larry A Sargent, MD

Professor and Chair

Department of Plastic Surgery

UT College of Medicine–Chattanooga Unit

Mountain Neurosurgical and Spine Center, PA

Asheville, North Carolina

Department of Clinical Plastic Surgery, Neurological

Surgery, and Pediatrics

Albert Einstein College of Medicine, Yeshiva University

Montefi ore Medical Center, Children’s Hospital at

Feinberg School of MedicineNorthwestern UniversityChairman, Division of Pediatric NeurosurgeryChildren’s Memorial Hospital

Chicago, IllinoisElizabeth C Tyler-Kabara, MD, PhDAssistant Professor

Department of Neurological SurgeryUniversity of Pittsburgh School of MedicineDivision of Pediatric Neurosurgery

Children’s Hospital of PittsburghPittsburgh, PennsylvaniaMarion L Walker, MDProfessor

Department of NeurosurgeryUniversity of Utah School of MedicineDivision of Pediatric NeurosurgeryPrimary Children’s Medical CenterSalt Lake City, Utah

Jack Chungkai Yu, MD, DMD, MS EdDepartment of Surgery

Section of Plastic and Reconstructive SurgeryMedical College of Georgia

Augusta, Georgia

1

Fibrous Dysplasia Involving the Craniofacial

Skeleton

James Tait Goodrich

This chapter will deal with fi brous dysplasia of the

cranio-facial complex, in particular those regions involving the

forehead, orbital rim, lateral and medial orbital walls, the

orbital roof, and the optic foramen The discussion will

in-volve the “worst case scenario,” assuming that, if the

sur-geon can handle this type of case, the simpler cases will be

easier to treat

Fibrous dysplasia can involve the calvaria and any of the

upper facial bones Its etiology is unknown, but the

pathol-ogy involves a replacement of normal bone with a fi

bro-osseous matrix The surgical principle involves removing

all of the dysplastic bone (or as much as possible) and

re-placing it with normal calvarial bone harvested from other

parts of the head Fibrous dysplasia can be of a simple type

called monostotic, where only one bone unit is involved,

or polyostotic, where two or more bones are involved In

this chapter we will deal with the more complicated

poly-ostotic type

The most common presenting complaints in fi brous

dys-plasia of the craniofacial complex are proptosis ( Fig 1–1 ),

diplopia and headaches, and in severe cases, progressive

blindness due to optic nerve compression; fortunately, blindness is an extremely rare outcome

An x-ray fi lm of the skull will show a sclerotic mass panding the calvarial and orbital bones The radiologist typi-cally describes a “ground glass” appearance There will also be sclerosis or even a cystic appearance to the bone It is not un-common to see complete obliteration of the frontal and nasal sinuses The proptosis is secondary to the orbital fi brous dys-plasia compressing the globe and forcing the eye forward As a result of this, an early presenting complaint can be diplopia

The principle behind the surgical treatment of fi brous dysplasia of the craniofacial complex is threefold: (1) relief

of optic nerve compression (decompression of the nerve should be considered though is not always essential); (2) removal of all dysplastic bone if possible, as any residual can form a new dysplastic center; and (3) use of the patient’s own bone for grafts to achieve a satisfactory cosmetic result

is preferred We now avoid the use of any foreign able materials such as methylmethacrylate, wire mesh, or metal fi xation plates, particularly in children, due to high risk of migration and infection

10.1055/978-1-60406-039-3c001_

Figure 1–1 (A) Frontal view and (B) superior view of a patient with

orbital proptosis secondary to fi brous dysplasia Typical proptosis is

evident and fi brous dysplasia involving the right orbital unit including

rim, lateral, and medial walls As a result, the eye is pushed forward and downward Interestingly, the only visual symptom was double vi-sion: The visual acuity was normal

At the Craniofacial Center of the Children’s Hospital at

Montefi ore we now do as much as possible of the

recon-struction with “normal” calvarial bone, that is, bone not

in-volved with fi brous dysplasia We have found this

consider-ably lessens the risk of resorption, which occasionally occurs

with rib grafts placed in the craniofacial region The use of

ribs, particularly in the forehead region, can sometimes lead

to an unacceptable “washboard” appearance Another

ad-vantage of using calvarial bone is the reduction in operative

exposure This technique also avoids the complications that

can occur with rib harvesting, such as pneumothorax and

chest wall pain

Preoperative Preparation

Evaluation

All patients should have radiographic studies of the skull

in the routine views to document the extent of dysplastic

involvement of the skull and surrounding orbital and

na-sal structures Computed tomography scanning with bone

windows in the axial and coronal views along with

three-dimensional reformatting are obtained for the operative

planning We have not found magnetic resonance imaging

to be helpful, so we do not use it routinely

If the optic nerve is compressed, we routinely do visual

acuity and visual fi eld testing to have baseline values

Dam-age to the optic apparatus and to the nerves supplying the

extraocular muscles are the most signifi cant complications

to be avoided Subtle damage may already have occurred

preoperatively, and it is essential to document this prior to

any surgical intervention In recent years our

ophthalmo-logic colleagues now feel it is no longer always necessary to

decompress the optic nerve, even in cases of severe

radio-logical compression Some surgical teams now feel the risk

of removing the dysplastic bone is too great in causing direct

injury to the nerve As a result of these recent discussions

we no longer just routinely decompress the optic nerve The

exception is a rapid and clear progression of visual loss due

to an overgrowth of dysplastic bone

We routinely start an anti-staphylococcal antibiotic at the

time of anesthetic induction in the operating room Because

the surgical manipulations are extradural, we do not

rou-tinely use anticonvulsant medications

Preparation

Fibrous dysplastic bone can be, and usually is, highly

vas-cular As a result, the blood loss in these procedures can be

signifi cant We routinely plan for a blood loss of 2 to 3 units

If the family wishes, we arrange for pedigree blood

dona-tions from family members 1 week in advance The patient

can also donate his/her own blood prior to surgery If

avail-able, a “cell saver” unit can rescue up to 50% of the patient’s

lost blood volume Because of the risk of extensive blood

loss, all patients require at least two large-bore intravenous

lines of 16 gauge or larger If there is any history of cardiac or

pulmonary problems, we routinely put in a central venous

pressure line An arterial line is highly recommended for monitoring blood gases, hematocrit, electrolytes, etc., dur-ing the procedures We request an osmotic diuresis, usually with mannitol (0.5 mg/kg) at the time of anesthetic induc-tion A spinal drainage system for cerebrospinal fl uid (CSF) removal can sometimes also be helpful for brain relaxation

These relaxation measures can be key in getting a relaxed frontal lobe for retraction when working back toward the optic foramens

We do not routinely use steroids in these types of cases;

the exception is if there is evidence of brain or optic nerve edema during the case

Operative Procedure Positioning

The patient is placed in the supine position with the head

resting on a cerebellar (horseshoe) headrest ( Fig 1–2 ) The

head is placed in a slightly extended, brow-up position

Rigid fi xation devices such as a Mayfi eld clamp are cifi cally avoided, as the surgical team will need to move

Figure 1–2 Schematic showing the location of the surgical and

an-esthesia teams

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1 Fibrous Dysplasia Involving the Craniofacial Skeleton 3

the head (usually never more than 10 to 15 degrees): This

fl exibility can prove to be very useful

We also like to reverse the operating room table so the

head of the patient is at the foot end of the operating room

table This positioning allows the surgeon and assistant to

sit with their knees comfortably under the table and not

obstructed by the table pedestal or foot unit

Anesthesia equipment is placed on the side opposite the

lesion and parallel to the table Routine orotracheal

intuba-tion is performed All lines are run off to the side of the

anesthesia unit The operating surgeon is placed at the head

of the patient with the assistant to the side The scrub nurse

comes in over the patient’s abdomen but is positioned no

higher than the mid-thoracic region This allows the surgeon

to be able to move around to see the patient’s face fully for

cosmetic evaluation For this reason we also avoid the use of

bulky overhead tables, such as the Fallon table

If the patient has signifi cant proptosis or the threat of

in-jury to the globe is signifi cant, then we place tarsorrhaphies

just prior to formal surgical draping This maneuver can be

quite helpful in preventing any unintentional injury to the

globe and cornea

Surgical Draping

The head is draped for a bicoronal incision The hair is not

shaved but is either parted for the incision or a small 1.5

cm width of hair is taken for the incision line We also fi nd

it helpful to braid the hair if it is long to keep it out of the

fi eld In children a zig-zag type of incision is made We have

found these incisions reduce the keloid formation over the

temporalis muscle and also prevent the hair from parting

directly over the incision when it is wet The draping is done

in such a fashion that both eyes are visible The facial drape

is placed over the nose and nares but well below the lower

orbital rim This allows the eyes to be visualized during the

reconstruction The rest of the draping can be done

accord-ing to the surgeon’s preference An important additional

point is to keep the drapes reasonably loose, so that the

head can be moved

We routinely run all our suction lines, cautery cords, etc.,

past the foot of the patient As both surgeons are sitting, this

allows easy mobility of the chair; that is, they are not rolling

over the cords and tubes

Because the operative site is usually copiously irrigated

during the procedure, it is important to have waterproof

outer drapes Some of the recent drape designs provide a

large plastic bag for fl uid collection: We have found these

to be quite useful

Skin Incision

Over the years we have used several different incisions but

now almost always routinely use a bicoronal incision

car-ried from ear to ear The incision is started behind the ear

helix, not in front (as is typically the case with most

surger-ies), to reduce scarring The incision, particularly in

chil-dren, is done in a zig-zag fashion until reaching the vertex,

where it is straightened The incision is made well behind

the patient’s hairline, not at the hair edge, a common ror in placement This incision type allows for an extensive exposure of the calvaria for tumor removal and additional bone harvesting as necessary In addition a large sheet of pericranium is available for any repairs of dura or frontal sinuses

Flap Elevation

A full-thickness fl ap is turned following the standard galeal plane It is important to leave the pericranium intact

sub-The pericranium is then elevated as a second separate layer

The fl aps are carried down to the orbital rim to the level of the supraorbital nerve and artery These structures are fre-quently encased in a small notch of bone This notch can be opened with a small Kerrison rongeur or osteotome It is eas-ier to elevate the artery and nerve with the pericranial layer

It is important to preserve these structures or there will be anesthesia, or even worse dysesthesia, in the forehead post-operatively The fl ap must also expose the entire belly of the temporalis muscle and the zygomatic arch In the midpor-tion of the face the nasion suture should be fully exposed

Using the small periosteal dissector or a Penfi eld dissector it

is possible to come under the orbital rim and dissect it safely back ~1 to 2 cm The temporalis muscle has to be elevated as

a unit Starting at its squamosal insertion, it is elevated using

a Bovie electrocautery with a fi ne needle tip The dissection

is performed in such a fashion that the temporalis muscle will be elevated from the frontozygomatic suture back to the ear, fully exposing the pterional “keyhole.”

Craniotomy

The craniotomy is performed to incorporate all of the dysplastic bone in the removal It is easiest to do the frontal craniotomy

by fi rst taking out a forehead bone fl ap that encompasses

as much of the forehead dysplasia as possible (labeled A in

Fig 1–3 ) This provides the window that will allow exposure

to the orbital roof and walls We prefer to use a high-speed drill system with a craniotome (e.g., Midas Rex with a B-1;

Medtronic Inc footplate [Fort Worth, Texas]) as this gives

a speedy bone removal, thereby decreasing blood loss In some cases the dysplastic bone can be extremely thick and

we will use an S-1 attachment We next elevate the frontal lobe with gentle retraction to see how far into the orbital roof the dysplastic bone extends Then, by further dissect-ing under the orbital roof, the dysplastic portion can be

completely visualized ( Fig 1–4 ) There is usually extensive

blood supply crossing these planes, so the bleeding can be quite copious Keep plenty of Avitine and Gelfoam available for packing in these spaces to control the oozing Once the limits of the dysplastic bone have been determined and the brain is adequately relaxed and retracted, we proceed with the bone resection Using a combination of osteotomes and

a small cutting bur, such as the Midas Rex C-1 attachment,

the roof is removed as a unit ( Fig 1–4 ) It is helpful to have

the assistant place a malleable retractor under the orbital roof This will prevent the drill or osteotome from damaging the perioribita On occasion, the dysplasia can go back to the

clinoids and orbital foramen In these cases, an operative

de-cision has to be made in regards to the orbital nerve—leave

the foramen alone or unroof it ( Fig 1–4 ) A small diamond

bur on a high-speed drill unit is the best method for

remov-ing this part of the bone Copious irrigation is applied to

prevent any unnecessary thermal injury to the bone and

nerve Once this is completed, attention is turned to the

lateral orbital wall and zygoma (labeled B in Fig 1–3 ) This

portion of the procedure can be done quite easily The only

important points are to have adequate exposure of the

zy-gomatic arch and a good dissection of the orbit The lateral

canthal ligament must be sectioned and then reattached at

the end of the procedure We often place a suture through

the canthal ligament for later identifi cation Doing this prior

to the medial part will allow easy mobilization of the eye

and surrounding structures with minimal trauma

Next, attention is turned to the most diffi cult phase—

resecting the medial nasal structures (labeled C in Fig 1–3 )

By removing the orbital roof and lateral orbital wall, the

sur-geon now has some mobility and freedom in the moving the

globe If the dysplastic bone involves the nasal bone and

me-dial orbital wall, the meme-dial canthal ligament is identifi ed

with a ligature and then cut The assistant then retracts the

eye laterally, and the bone is removed with an osteotome and

fi ne cutting bur The frontal sinuses are often obliterated with dysplastic bone, which can complicate matters If the sinuses are not occluded, the frontal sinus can be entered and used as

an operating space within which to work Once all the plastic bone is removed, the reconstruction is started

Some Helpful Hints

On occasion, the dysplastic bone can be extremely thick, in one case more than 8 cm in thickness, which exceeds the cutting width of any known craniotome In these cases one can just shave the bone down with a large bur The other option is to put a long, fi ne cutting tip on a short attach-ment and then gently cut the bone The disadvantage is one cannot see deep into the craniotomy so the craniotomy is all done by feedback to the fi ngers Careful attention has

to be focused on the midline structures such as the sagittal sinus We have also found on occasion the dura can also be very dysplastic and densely adherent to the overlying bone

It can be extremely tedious to remove the dura from the dysplastic bone and care must be taken to avoid disrupt-ing large veins that commonly run through the dura On a couple of occasions serious air embolisms have occurred, and the anesthesia and surgical teams need to prepare to ag-

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Figure 1–4 Schematic drawing showing the frontal fossa after

re-moval of the dysplastic orbital roof and decompression of the optic nerve at the foramen

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Figure 1–3 Frontal view showing four-piece bone removal ( A) Frontal

bone maximally involved with fi brous dysplasia; ( B) lateral orbital wall;

( C) medial orbital wall The orbital wall roof, which is also removed, is

not shown in this drawing ( D) Graft site from the opposite calvaria

1 Fibrous Dysplasia Involving the Craniofacial Skeleton 5

gressively deal with an air embolism as these are potentially

life-threatening situations if not treated rapidly

Calvarial Bone Harvesting

By using a bicoronal skin fl ap, typically a large amount of

nor-mal calvarial bone can be exposed Once the surgeon has

re-sected the dysplastic bone and determined how much bone is

needed to reconstruct the defect, a craniotomy is performed

on the opposite calvaria (labeled D in Fig 1–3 ) Remember

that the most useful bone is over the convexity, where the

diploë is well formed In the squamosal area, the bone thins

out and is harder to split The bone is taken to a sterile table

set up next to the operating fi eld Using a combination of

small osteotomes, a fi ne cutting tip such as a Midas Rex C-1,

and a reciprocating saw, the bone is split along the diploic

space Copious irrigation is essential to prevent thermal

in-jury to the bone; dead or necrotic bone does not heal well

Once the bone has been split, the inner table of the calvaria is

placed back in the harvest site The outer table, because of its

smooth contours, is used as the reconstructing bone

Craniofacial Reconstruction

The reconstruction is done in the reverse order from the

resection The medial orbital wall is constructed fi rst and

plated into position (labeled C in Fig 1–5 ) The nasal bone

and cribriform plate are usually the most solid structures to

work with The medial canthal ligament also has to be

reat-tached, which can be done easily through a small drill hole

Next, a piece of bone is fashioned to form the orbital roof

This is an important structure that must be solidly placed

( Fig 1–6 ) If it is not, subsequent proptosis (sometimes

en-ophthalmos, too) of the eye can occur due to downward

pressure of the frontal lobe The bone used to reconstruct

the lateral orbital wall is attached to the roof with either

wires or miniplates (labeled A in Fig 1–5 ) The squamosal

portion of the temporal bone can also act as an excellent

place to anchor this bone The orbital rim is then fashioned

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Figure 1–5 Schematic drawing showing the harvested bone grafts in

position

10.1055/978-1-60406-039-3c001_f006

Figure 1–6 Schematic drawing showing the split-thickness calvarial

bone graft in position in the orbital roof region This bone unit is key

to preventing an unacceptable eye migration

and attached medially to the nasal unit and opposite orbital

rim (labeled B in Fig 1–5 ) This is the key cosmetic unit and

must be perfectly placed to avoid facial asymmetry The rest

of the craniotomy is then closed in a mosaic fashion using the remaining pieces of bone Miniplates have proved to be extremely useful in stabilizing these various bone units In children and adolescents we now routinely use the absorb-

able plating systems ( Figs 1–7 and 1–8 )

Repair of Frontal Sinus

One of the most devastating postoperative complications

is infection arising from the sinus If the frontal sinus is not obliterated by dysplastic bone, it must be cleaned and exenterated of mucosal lining We routinely cover the sinus with the pericranial fl ap to isolate it from the epidural space

The same principle applies to the other paranasal sinuses if they are violated

Pericranial Tissue

The pericranial tissue is a most useful repair structure It not only provides additional vascularity to the bone, but it also helps smooth out the rough contours of the bone that

has been harvested and used as grafts Therefore, we make

every effort to use this structure and place it back into its

natural anatomical position

Temporalis Muscle

To prevent a postoperative depressed concavity over the

temporal unit, the temporalis muscle is laid back into

posi-tion Sometimes a relaxing incision must be made

posteri-orly to allow the muscle to be advanced forward to cover the

keyhole and to be reattached to the zygoma This is critical

or there will be a signifi cant “hourglass” deformity over this

region postoperatively

Use of Dysplastic Bone in Repair

In some cases, if there is a shortage of bone for the repair, the dysplastic bone can be reused The dysplastic bone must

be fi rm, if not hard, with no soft or mushy spots present In some cases we have found the dysplastic bone to be nearly

as fi rm as normal bone and have reused it in the struction In some cases, where there is extensive fi brous dysplasia, one has no choice but to reuse the original dis-eased bone However, the caveat remains: If normal bone is available, this is the better option to use

Closure

The closure is done in a routine fashion Hemostasis must

be meticulous because of the amount of dead space that can form In some, but not all, cases a subgaleal drain to light suction is placed for 24 to 48 hours A fl uid collection next to sinus spaces can lead to a devastating postoperative infection Scalp closure is done in a routine fashion closing both the subgaleal and skin layers

Postoperative Management Including Possible Complications

We routinely place the patient on antibiotics to cover skin organisms and possible nasal contaminants for at least 72 hours The risk of osteomyelitis is high and can be quite devastating to the patient, so every attempt must be made

to avoid it There may be signifi cant periorbital swelling postoperatively; ice packs are applied to the eye and peri-orbital region for symptomatic relief If there is signifi cant swelling at the end of the operation, we ordinarily leave the tarsorrhaphy in place for about 2 days Intensive care for at least 48 hours is mandatory with close monitoring for he-modynamic changes from excessive blood loss and for the development of an epidural hematoma

The neurosurgeon must always be attentive to tive CSF leaks If dural tears have occurred, they must be re-paired meticulously Should a postoperative CSF leak occur, then placement of a lumbar CSF drain may be necessary to divert the fl uid These drains usually need to be left in place for 5 to 7 days However, close attention to dural tears and verifying dural integrity by asking the anesthesiologist to perform a sustained Valsalva maneuver at the end of the case should prevent this problem from occurring

Acknowledgment This chapter is a revision of the chapter, “Fibrous Dysplasia Involving the Craniofacial Skeleton” by James T Goodrich, M.D and Craig D Hall, M.D The chapter appeared in the

Neurosurgical Operative Atlas, Volume # 1, edited by Setti S

Rengachary and Robert H Wilkins The Neurosurgical

Op-erative Atlas was published by the American Association of Neurological Surgeons (AANS) from 1991 to 2000

We would like to acknowledge and thank Craig Hall, M.D., for his help and efforts on the original chapter published in the fi rst edition of this work

10.1055/978-1-60406-039-3c001_f008

Figure 1–8 Postoperative photograph taken 6 weeks after surgery

showing aesthetic reconstruction obtained

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Figure 1–7 Intraoperative view showing the harvested bone grafts in

position

Chiari malformations, or hindbrain hernias, are being

diag-nosed and operated upon with increasing frequency For the

purposes of this chapter, two separate entities will be

dis-cussed The Chiari I malformation is characterized by caudal

descent of the cerebellar tonsils The brain stem and neocortex

are typically not involved and the patient does not suffer from

a myelomeningocele Syringomyelia is commonly but not

in-variably present The Chiari II malformation is almost always

seen in conjunction with spina bifi da and is a more severe

form of hindbrain herniation The neocortex and brain stem

are dysmorphic and the cerebellar vermis (not the tonsils) is

displaced into the cervical spine Accompanying the vermis are

dysmorphic and elongated aspects of the medulla and lower

pons as well as the lower aspect of the fourth ventricle Again,

syringomyelia is commonly associated with this lesion Not

discussed in this chapter is the rare Chiari III malformation

Chiari I Malformations

Patient Selection

With the advent of magnetic resonance imaging (MRI) the

detection of caudal displacement of the cerebellar tonsils

and the presence of an associated syrinx has become safe

and accurate Typically the tonsils are at least 3 mm below

the plane of the foramen magnum They lose the rounded

appearance of their caudal pole and become pointed or

“peg-like.” This is associated with obliteration of the

sub-arachnoid space at the craniocervical junction with the

im-paction of tissues into this confi ned region When all of the

above criteria are not met, the situation should be judged

in conjunction with the clinical symptomatology of the

pa-tient The presence of syringomyelia or other developmental

anomalies will further assist in the interpretation of the

intradural fi ndings at the craniocervical junction

Patients with a symptomatic Chiari I malformation are

generally offered operative intervention The more severe

the neurological defi cit, the stronger the case for

interven-tion When occipital pain is the only symptom and no

neu-rological signs are present, the degree of disability from the

discomfort should be carefully weighed against the risks

of the procedure, prior to the implementation of surgical

intervention With advances in cine MRI, some patients with

occipital headaches and mild hindbrain hernias have been

found to have abnormal cerebrospinal fl uid (CSF ) fl ow at the craniocervical junction When syringomyelia is present,

we generally favor intervention even with minimal toms The absence of caudal displacement of the cerebellar tonsils but with a “compressed look” to the tissues at the foramen magnum associated with a signifi cant syrinx has been termed a Chiari 0 When the syrinx is signifi cant, the Chiari 0 patient should be considered for decompression In-tracranial pressure should be normalized prior to considera-tion of craniocervical decompression Approximately 10% of patients with Chiari I malformation will have hypertensive hydrocephalus, and ventriculoperitoneal shunt insertion should precede other considerations Flexion and extension views of the cervical spine are also important to resolve questions of spinal stability and other bony anomalies If signifi cant basilar invagination or retrofl exion of the dens

symp-is present, the need for an anterior decompression should

be discussed prior to proceeding with a posterior procedure

If the posterior procedure is performed fi rst, it should be recognized that acute neurological decompensation postop-eratively warrants emergent anterior decompression

Preoperative Preparation

Once a candidate for surgery has been appropriately chosen, the patient is prepared with preoperative antibiotics The

patient is positioned prone ( Fig 2–1 ) in a pin-type head

holder with the neck fl exed The head of the table is elevated somewhat, but no central venous access is mandatory be-cause lowering the head will eliminate the gradient for air embolization A chest Doppler monitor may be used for the detection of air embolization and to monitor slight changes

in the patient’s pulse Patients are paralyzed and are not allowed to breathe spontaneously This signifi cantly lowers the likelihood of serious pulmonary complications post-operatively Muscle relaxants are allowed to become fully effective during the induction of anesthesia to avoid the Valsalva maneuver during placement of the endotracheal tube A severe Valsalva maneuver has been associated with progression of symptoms in some patients

Operative Procedure

The skin incision is made from a point 2 cm below the external occipital protuberance to the midportion of the

spinous process of C-2 ( Fig 2–2A ) It is quite unusual for

the tonsilar tissue to descend below the level of the

up-per portion of C-2 ( Fig 2–2B ), and by preserving the

im-portant muscular attachments at C-2 postoperative pain

is signifi cantly decreased The likelihood of postoperative

spinal deformity seen in conjunction with syringomyelia

is also substantially lessened The avascular midline plane

of the occipital musculature is divided with monopolar

current No incision transecting muscle is necessary in this

procedure because the plane dividing the left and right

muscular bundles completely separates these two groups

A small amount of fat will mark this natural cleavage plane

Again using the monopolar current, the muscle insertion

immediately above the foramen magnum is separated

from the occipital bone and the posterior arch of C-1 First

the occipital bone is removed followed by the arch of C-1

( Fig 2–2C ) There is no need for lateral exposure, and bone

laterally situated is left intact This minimizes the risk of

injury to the vertebral veins and arteries The bone edges

are waxed, and the dura is opened in the midline Initially,

the dura over C-1 is opened Care is taken as the incision is

extended across the circular sinus near the foramen

mag-num This sinus can be formidable and should not be

ap-proached nonchalantly With the dura retracted laterally, the arachnoid is opened in the midline The subarachnoid adhesions are lysed with a sharp instrument and are not simply torn The arachnoid edge is then clipped to the dural edge with metal clips

The tonsils, which can be recognized by their vertical lia, are separated in the midline to expose the fl oor of the

fo-fourth ventricle ( Fig 2–2C ) Care is taken to free the caudal

loop of the posterior inferior cerebellar artery and to avoid damage to this vessel or its branches Again adhesions are cut rather than torn On separating the cerebellar tonsils, a veil of arachnoid is sometimes encountered This veil should

be opened widely Obstruction to CSF fl ow can also occur from the posterior inferior cerebellar arteries These vessels may approximate in the midline and be adherent to one another They should be separated and mobilized laterally with great care Closure is then accomplished with a gener-ous dural graft We prefer to use the patient’s own pericra-nium, but either cadaveric or artifi cial dural substitutes may

be used The dural closure is with absorbable suture, which

is known to react minimally in the subarachnoid space A Valsalva maneuver is performed to check for CSF leaks prior

to closing the wound in multiple layers

Figure 2–1 Optimal positioning of a patient for exposing a Chiari malformation.

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2 Chiari Malformations and Syringohydromyelia 9

Postoperative Management Including Possible

Complications

Following the operation, patients may experience some

nausea and vomiting as well as hiccups These are almost

always self-limited Neurological defi cits that are

well-established prior to the operation are unlikely to reverse

following manipulation Long-standing pain and

tempera-ture loss is very unlikely to return Hand and arm weakness

with fasciculations and loss of muscle bulk may improve

functionally but may not normalize A particular problem

exists when pain is a major component of the presentation

Children and adolescents infrequently have a major problem

with pain Adults, however, may be quite discouraged by

the persistence of discomfort in the neck, shoulders, and/or

arms Pain may very well persist despite a physiologically

successful operation with obliteration of the syrinx cavity

This limitation of surgical intervention should be carefully explained to the patient prior to surgery Mild scoliosis (less than 35 degrees) may improve or simply stabilize, whereas more severe spinal deformity may well progress despite adequate treatment With the advent of MRI scanning the status of syringohydromyelia can be assessed easily If a sizable syrinx persists months to years after craniocervical decompression, a second decompression should be consid-ered It is our experience that >85% of children will have resolution of their syringes following a simple craniocervi-cal decompression If the syrinx persists for 9 to 12 months following the initial decompression or if there is a return

of symptoms and a syrinx that had once shown evidence

of decompression, then consideration should be given to a secondary decompression During this secondary procedure

10.1055/978-1-60406-039-3c002_f002

Figure 2–2 (A) Schematic of incision placement and bone work for

operative exposure of a Chiari I malformation (B) Chiari I tion associated with syringomyelia, midline sagitttal section (C) Op-

malforma-erative exposure of a Chiari I malformation with the fl oor of the fourth ventricle exposed

C

one or both cerebellar tonsillar tips are resected to allow an

unimpeded expansion of the foramen of Magendie With

this second intervention the vast majority of the recurrent

and persistent syringes will resolve If after two

decompres-sions a larger syrinx is persistent and symptoms attributable

to this lesion are serious or progressive, consideration can

be given to a laminectomy over the lower aspect of the

sy-rinx and the placement of a sysy-rinx to subarachnoid shunt

or a syrinx to peritoneal shunt If a syrinx to subarachnoid

shunt is chosen, placement of the distal catheter in the free

subarachnoid space is an important technical maneuver

Catheters can easily be mistakenly placed in the subdural

space without benefi t to the patient

Chiari II Malformations

Patient Selection

Children with myelomeningocele may develop symptoms

referable to their hindbrain hernias Symptoms and signs are

generally age-specifi c, with infants developing lower

cra-nial nerve disturbances (diffi culty with swallowing, weak

cry, inspiratory wheeze, aspiration pneumonia, absent gag,

and opisthotonos) and older children more commonly

de-veloping progressive upper extremity spasticity Ataxia of

the trunk or appendages is recognized much less often

Be-cause some degree of hindbrain herniation is present in

the vast majority of spina bifi da patients, MRI evidence of

hindbrain herniation must be accompanied by progressive

or signifi cant symptomatology to warrant operative

inter-vention Many patients will remain clinically stable for long

periods despite signifi cant anatomical deformity As many

as one-third of patients will develop diffi culty with

phona-tion, swallowing, or apnea by age 3 years If the

“asymp-tomatic” remainder were followed for a longer period or

if less serious symptoms were considered signifi cant, this

one in three fi gure would undoubtedly be higher Because

the symptoms of the Chiari II malformation are frequently

life-threatening, symptomatic Chiari II malformation is the

leading cause of death in the treated myelomeningocele

population today When treated conservatively, as many as

5 to 10% of all patients will die from the malformation by

the age of 3 years

The decision for surgical intervention is controversial

Because there is a signifi cant likelihood of stabilization or

actual improvement with conservative care, some would

argue against operative intervention This is supported to

some degree by autopsy material that demonstrates

hypo-plasia or ahypo-plasia of vital lower cranial nerve nuclei Against

this, however, is the experience of numerous surgeons who

have seen dramatic improvement in many patients

follow-ing decompression In addition, objective evidence of

physi-ological functioning has been reported to improve with both

brain stem evoked responses and CO 2 curve following

op-eration With these confl icting pieces of evidence one can

quickly appreciate the surgeon’s dilemma

With increasing experience, the senior author’s

willing-ness to operatively intervene is increasing This is due to the

relatively low incidence of operative complications and the clear improvement demonstrated by some patients Poor results are more commonly due to a delay in offering op-erative intervention Once serious diffi culties are clinically evident with breathing, swallowing, or phonation, the situ-ation may very well be irreversible In that case, the best outcome that surgery can be expected to yield is mainte-nance of the poor level of lower cranial nerve function seen immediately prior to operation Problems with aspiration pneumonia, apnea, and other life-threatening diffi culties may very well persist

The solution to this problem does not seem to be a tinuation of a conservative approach, accepting 10 to 15%

con-mortality Rather, an earlier identifi cation of patients at high risk for serious problems, and offering this group interven-tion, seems to be a more logical option Being able to detect this high-risk group prior to the development of irreversible life-threatening problems is a key provision

If serious problems with phonation, swallowing, or ing are detected and normal intracranial pressure is present, urgent intervention is appropriate when full support of the child is proposed It is also important to emphasize that normalization of intracranial pressure is a prerequisite to consideration of craniocervical decompression Patients with questionable shunt function are well served to fi rst have their shunts revised If progressive or serious symp-toms persist after adequate shunt revision, decompression

breath-of the craniocervical junction can be contemplated Again, the MRI has made the diagnostic evaluation of this group of patients almost risk-free and quite precise

Preoperative Preparation

As with the Chiari I patients, preoperative antibiotics are given The anesthetic management and positioning of the patient are similar to those for the Chiari I patient Of some difference, however, is the fact that decompression should extend to the level of the caudally displaced posterior fossa tissue This is frequently below the level of C-4 By remov-ing this additional bone and displacing the musculature, the risks of cervical deformity are substantially increased even if the laminectomy is kept quite medial, preserving the facets Because the lower portion of the fourth ven-tricle is usually not within the posterior fossa, the occiput

may need to be removed minimally if at all ( Figs 2–3A and

2–3B ) If it is elected to open the dura over the posterior

fossa, great care is necessary The transverse sinus in the patient with spina bifi da is frequently placed near if not at

the level of the foramen magnum ( Fig 2–3B ) An

unknow-ing openunknow-ing of the dura and sinus in this area may well lead

to an operative disaster The elasticity of the tissues of the cervical spine is pronounced In removing the laminal arch

of small infants, each bite with the rongeur needs to be crisp and clean Undue distortion of the spinal cord may occur if this principle is not followed It is important to study the preoperative MRI for the position of the fourth ventricle, the cerebellar vermis, and the possibility of a medullary kink The position of all these structures is critical to the intradural exploration

2 Chiari Malformations and Syringohydromyelia 11

Operative Procedure

Once the dura is opened, fi nding the caudal extent of the

fourth ventricle can be diffi cult ( Fig 2–3C ) Intraoperative

ultrasound may be of help in localizing this structure The

choroid plexus usually maintains its embryonic tricular position, marking the caudal end of the fourth ven-tricle When present, this is a reliable intraoperative marker

extraven-Unfortunately, dense adhesions and neovascularity at points

of compression or traction may be found, especially near

610.1055/978-1-60406-039-3c002_f003

Figure 2–3 (A) Schematic of incision placement and bone work for operative exposure of a Chiari II malformation (B) Chiari II malformation,

midline sagittal section (C) Operative exposure of a Chiari II malformation before and after the fl oor of the fourth ventricle is exposed.

C

C-1, and this may make dissection treacherous The fourth

ventricle may be covered by vermis with its horizontal folia,

or the choroid plexus may simply lie within the displaced

ventricle

The purpose of the intradural manipulation is to open

the fourth ventricle and provide free egress of CSF from the

fourth ventricle It is necessary to fi nd and open the tissue

widely over the caudal aspect of the fourth ventricle It may

happen that several planes of dissection are developed

be-fore the fl oor of the fourth can be adequately appreciated

It is important during the exploration of each of these

av-enues that vascular and neural tissues be preserved and that

natural planes are developed so that no irreparable damage

to the delicate tissues of the lower brain stem occurs The

caudal aspect of a medullary kink can easily be mistaken

for the appropriate target This dissection is one of the most

diffi cult in pediatric neurosurgery Errors or simple tissue

manipulation may convert a tenuous portion of the medulla

or lower pons to permanently damaged tissue The surgeon

should always bear in mind the risk-benefi t ratio for each

of his or her actions, as this particular area is unforgiving of

even small excesses of manipulation Grafting of the dura

and closure are similar to the previous description

Postoperative Management Including Possible

Complications

Following the operation, patients may experience some

nausea and vomiting as well as hiccups These are almost

always self-limited Neurological defi cits that are

well-established prior to the operation are unlikely to reverse following manipulation With the advent of MRI scanning the status of syringohydromyelia can be assessed easily If a sizable syrinx persists months to years after craniocervical decompression, a second decompression should be consid-ered If after two decompression a larger syrinx is persist-

ent and symptoms attributable to this lesion are serious or

progressive, consideration can be given to a laminectomy over the lower aspect of the syrinx and the placement of

a syrinx to subarachnoid shunt or a syrinx to peritoneal shunt If a syrinx to subarachnoid shunt is chosen, place-ment of the distal catheter in the free subarachnoid space

is an important technical maneuver Catheters can easily be mistakenly placed in the subdural space without benefi t to the patient

Conclusion

In addition to the avoidance of problems with infection, hemorrhage, and increased neurological defi cit, patient se-lection and the timing of intervention are critical to the suc-cessful outcome of decompressing a patient with a Chiari malformation Despite what was thought to be appropri-ate and timely intervention, an alarmingly high percentage

of patients with lower cranial nerve abnormalities treated surgically eventually progress This raises the question of whether the current strict selection criteria are too restric-tive and whether less symptomatic infants should be con-sidered for decompression This area of speculation remains

in dispute

3

Unilateral and Bicoronal Craniosynostosis

Kant Y K Lin , John A Jane Jr., and John A Jane Sr

Coronal craniosynostosis is defi ned as the premature fusion

of the coronal suture(s) of the skull; sutural involvement

may be either unilateral or bilateral Because of the position

of the coronal suture, the consequences of premature fusion

are manifested in the calvaria as well as in the face As with

all forms of craniosynostosis, compensatory growth occurs

at the adjacent nonaffected suture sites This is evident in

cases of unilateral involvement at the contralateral coronal

suture, where the contralateral side of the metopic and

sag-ittal sutures, and at the ipsilateral squamosal suture growth

leading to a unilateral anterior plagiocephaly ( Fig 3–1 ) In

bilateral involvement, compensation is noted at both

squa-mosal sutures, as well as at the sagittal suture leading to an

overall turribrachycephalic or “tower-shaped” appearance

( Fig 3–2 ) With the resulting skull shapes being so

dispa-rate, operative treatments must be geared toward different

issues, and the two types will be discussed separately

Coronal craniosynostosis may be associated with elevated

generalized intracranial pressure The likelihood of this

oc-currence increases when more than one suture is involved

Bilateral coronal craniosynostosis in often associated with

craniosynostosis syndromes, such as Crouzon’s or Apert’s

syndrome A distinction must be made between the

syn-dromic and nonsynsyn-dromic varieties as management and

expectations of outcome differ between the two

Patient Selection

Diagnosis is based on the characteristic medical history and

physical examination Confi rmation and more precise

delin-eation of the dysmorphology are obtained from computed

tomography of the skull In particular, three-dimensional

reconstruction of the images is useful for presurgical

plan-ning A thorough ophthalmologic examination is indicated

both for purposes of detecting intracranial hypertension, as

well as to document any orbital axis issues related to the

changes in the bony orbit secondary to the stenotic adjacent

coronal suture Often an eyelid ptosis or extraocular muscle

imbalance is seen and must be addressed, usually after the

bone deformities are corrected Increasingly sophisticated

DNA mapping techniques have resulted in an additional

method of diagnosis that is especially useful with inherited

forms of coronal craniosynostosis, or when a

craniosynoso-tosis syndrome is involved

Indications and Timing of Surgery

Indications for surgical correction of a unilateral deformity are improvement of overall skull shape with advancement

of a recessed forehead and correction of the bossed lateral forehead, correction of the orbital dysmorphology, which can subsequently allow for correction of the orbital adnexal structures, and possible relief of either generalized

contra-or localized intracranial hypertension Indications fcontra-or cal correction of the bilateral deformity are similar but also include the need to correct the overly high or tower-shaped skull and the overall brachycephaly

Diagnosis of intracranial hypertension can be diffi cult and is based on “soft” fi ndings such as cerebral markings seen on the inner calvarial table (“copper-beaten” appear-ance) on plain x-rays, or by late fundoscopic changes seen

by slit lamp evaluation Earlier signs suggestive of increased pressure may be seen with subtle behavioral changes in the child, or with a bulging anterior fontanelle In the fi nal analysis, a monitoring bolt is needed to accurately record pressures intracranially Any evidence of elevated pressures

is an indication for a more urgent need for surgery

Although controversial, most surgeons would agree that surgery is best performed before the child has reached the age of 1 year Our tendency is to perform surgery closer to 6 months of age Because the volume of the brain almost tri-ples in the fi rst year of life, it would seem prudent to allow the intracranial cavity to accommodate this rapid growth through earlier surgery The correction should certainly be performed before brain damage has occurred; often, sub-sequent brain growth can be utilized to help direct future growth and maintain the newly corrected skull and orbit shape following suture release and bony recontouring Ear-lier correction also spares the child emotional or psycho-logical trauma over his/her appearance, before the age of self-awareness (5 years or younger)

Preoperative Preparation

Once the decision has been made to proceed with surgery,

a preoperative workup consisting of routine blood tests, cluding a complete blood cell count, electrolyte panel, and

in-a pro-time in-and prothrombin time, in-are performed Becin-ause

of the potential for signifi cant blood loss, a type and screen

are obtained and compatible donors among relatives are encouraged to donate for donor-directed intra- and periop-erative transfusions

The child is brought to the hospital on the day of surgery having been kept NPO for 4 hours prior to the anticipated start time for surgery At least two large-bore (≥20 gauge) intravenous lines are required for access due to the poten-tial for signifi cant blood loss or fl uid shifts during surgery

An arterial line is placed and a central line is also helpful to monitor the total body intravascular volume for both opera-tive and postoperative fl uid management A Foley catheter is useful to record urinary output, and a thermistor is used to record core body temperature A Doppler monitor is placed over the heart to monitor blood fl ow and is used to detect the possibility of unanticipated intraoperative air embolism

Steroids and anticonvulsants are not routinely used lactic antibiotics are given just prior to the incision

In young children, the hair is clipped to allow the surgeon full visualization of the degree of the skull deformity, so that the surgical correction can be tailored accordingly This also helps facilitate the scalp closure and postoperative wound care by the nursing staff and the parents

Once the intraoral endotracheal intubation has been formed, we have found it helpful to secure the tube with either a circummandibular or a circumdental wire, thus ob-viating the need for taping and allowing full access to the face during surgery Temporary tarsorrhaphy sutures are also placed for intraoperative corneal protection

Operative Procedure Positioning

The patient with unilateral coronal synostosis is placed in a supine position on the operating table with the head resting in slight extension in a Mayfi eld headrest The patient with bilat-eral coronal synostosis is positioned differently, the details of which will be discussed separately from the unilateral deform-ity The headring is reinforced with additional soft padding

to prevent excessive pressure over bony prominences during the lengthy procedure The scalp and face are prepped with Betadine (providone-iodine ) solution, with emphasis placed

on scrubbing the external auditory canals, which tend to nize with bacteria The head, face, and neck are then draped to the clavicles, and staples are used to secure the drapes A 180 degree access to the head and facial region is required, and the surgical table is rotated so that the anesthesiologist is po-sitioned at the patient’s side at the foot level The nursing staff and all instrumentation, which has been placed on a single large table, is positioned opposite the anesthesiologist, who is also at the foot of the bed A smaller Mayo stand is positioned over the patient’s abdomen, and only those instruments most currently in use are kept for ready access

Skin Incision and Flap Elevation

A standard wavy bicoronal incision is performed extending from just behind one ear across to the opposite side Care is

A

B

10.1055/978-1-60406-039-3c003_f001

Figure 3–1 Skull deformity in unilateral coronal synostosis The

ipsilat-eral forehead is fl attened and the superior and latipsilat-eral orbital rims are

recessed (A) Compensatory growth (depicted by arrows) occurs at

ad-jacent sutures Compensatory growth at the metopic and contralateral

open coronal sutures causes unilateral frontal bossing Growth at the

sagittal and open coronal sutures leads to a contralateral parietal bulge

(B) Skull-base deformity along the anterior cranial fossa also occurs.

3 Unilateral and Bicoronal Craniosynostosis 15

taken to make the incision posterior to the anterior hairline,

yet forward enough to allow for access to the orbital region

once the scalp fl ap is dissected The scalp fl ap is elevated

anteriorly down to the level of the supraorbital rim The

supraorbital neurovascular bundle is preserved and may

occasionally need to be freed from its foramen with a thin

osteotome Dissection is then extended laterally down each

lateral orbital rim detaching the lateral canthi to the

junc-tion with the inferior orbital rim, and medially up to, but

not detaching, the insertion of the medial canthal tendons

The nasolacrimal apparati are also carefully preserved The

nasion is exposed during this part of the dissection as well

Inferolaterally, the anterior aspect of the maxilla, the malar

eminence, and the anterior aspect of the zygomatic arch are

also exposed The temporalis muscles are elevated off their

insertions and left attached to the undersurface of the scalp

fl ap, thus allowing access to the infratemporal hollow The

temporal and sphenoid bones are exposed from the lateral

orbital rim close to the junction where the zygomatic arch

meets the posterior temporal bone This area will allow the

formation of a tenon extension, once the orbital

osteoto-mies are performed, of the supraorbital bone unit that will

be advanced and reshaped to compensate for the temporal

narrowing seen in this condition

Craniotomy and Craniofacial Reconstruction

Unilateral Coronal Craniosynostosis

Emphasis has been placed on the concept that despite lateral sutural involvement, the deformity is, in almost all cases and occasionally signifi cantly, bilateral Whereas the ipsilateral side refl ects growth restriction, the contralateral side exhibits the effects of compensatory changes driven by the growth of the brain

A bifrontal craniotomy is performed with the posterior extent of the cuts being posterior to both the fused and non-fused coronal sutures and the anterior cut ~1 cm above the level of the supraorbital rims Retraction of the frontal and temporal lobes of the brain is then performed, taking care to remain anterior to each olfactory bulb Three-quarter orbital osteotomies are completed across the orbital roof, superior aspect of the medial orbital wall, lateral orbital wall, and the lateral aspect of the orbital fl oor into the inferior orbital

fi ssure Tenon extensions are made extending laterally into the sphenoid and temporal bones The fi nal remaining cut

is made across the nasion just above the nasofrontal suture

( Fig 3–3 ) This forms a single orbital unit that is removed

in its entirety to be reshaped The remaining portion of the

Figure 3–2 Skull deformity in bilateral coronal synostosis Bilateral

coronal synostosis leads to signifi cant bilateral forehead fl attening (with

a decrease in the overall anteroposterior dimension of the skull) and

re-cession of the orbital rims Compensatory growth (depicted by arrows)

at the squamosal suture causes vertical elongation of the skull Growth

at the sagittal suture causes the skull to widen

10.1055/978-1-60406-039-3c003_

abnormally shaped and positioned greater wing of the

sphe-noid bone is then carefully rongeured medially up to the

fused frontosphenoid suture, and into the superior orbital

fi ssure This will allow for subsequent brain expansion

be-hind the newly confi gured orbital unit

The goals for reshaping the orbital unit include: (1)

ad-vancement of the ipsilateral lateral orbital rim; (2)

advance-ment of the retruded supraorbital rim in relationship to the

inferior orbital rim in the anteroposterior (AP) plane; (3)

recreation of the overall shape of the orbit to match the

op-posite orbit; and (4) recessment of the contralateral lateral

orbital rim to take out any compensatory changes These

changes are effected by a combination of burring down the

inner cortex of the orbital rims, thus softening them enough

to use the Tessier bone benders to reshape the bone in the

proper confi guration The recessed portion is given

addi-tional projection via advancement of the tenon extension

along the lateral temporal bone A portion of the distal end

of the tenon extension on the contralateral side is removed

to allow for recessing, again at the temporal bone region

( Fig 3–4 ) Finally, the retruded supraorbital rim and the

reshaping of the orbital box are addressed simultaneously

by placing an onlay bone graft, harvested from the bifrontal

bone piece and fi xed with an absorbable lag screw, over the

defi cient area and burred to the matching confi guration of

the opposite side ( Fig 3–5 )

10.1055/978-1-60406-039-3c003_f003

Figure 3–3 Craniotomy and orbital rim osteotomies for unilateral

coronal synostosis The surgery begins with a bifrontal craniotomy

that includes both coronal sutures Radial osteotomies are performed,

and the frontal bone is recontoured Bilateral three-quarter orbital

os-teotomies are then performed, elevating the visor as a single unit

Dotted lines depict areas of osteotomies

10.1055/978-1-60406-039-3c003_f004

Figure 3–4 Orbital rim reconstruction in unilateral coronal synostosis

During the reconstruction, the ipsilateral superior and lateral orbital rims are advanced and reshaped to match the contralateral side The contralateral orbital rim often needs to be recessed by removing a por-tion of the contralateral tenon A template of bicortical graft is then placed over the contralteral orbital rim and is used as an onlay graft for the ipsilateral orbital rim Further reshaping of the ipsilateral rim often requires a combination of burring down the inner cortex of the orbital rims, thus softening them enough to use the Tessier bone benders

10.1055/978-1-60406-039-3c003_f005

Figure 3–5 Orbital rim reconstruction and advancement in unilateral

coronal synostosis The recessed portion is given additional projection via advancement of the tenon extension along the lateral temporal bone A portion of the distal end of the tenon extension on the con-tralateral side is removed to allow for recessing, again at the temporal bone region The onlay graft is fi xed to the ipsilateral orbital rim with lag screws In addition, a portion of the greater wing of the sphenoid

is also removed up to the frontosphenoid suture and into the superior orbital fi ssure to allow for subsequent brain expansion into the previ-ously constricted space

3 Unilateral and Bicoronal Craniosynostosis 17

The newly confi gured orbital unit is then returned to its

original position, albeit advanced on the affected side and

recessed on the opposite side, and secured with 2 mm thick

resorbing plates and screws bridging the tenon extensions

to the adjacent temporal skull The segment of frontal bone

is also reshaped through a combination of Tessier bone

benders, inner and outer cortex burring, and

barrel-staven-like osteotomies to match the new curve of the

supraor-bital unit and to recreate a smooth and symmetric forehead

The segment can be rotated 180 degrees to use the more

properly shaped curve of the posterior edge to match the

curve of the supraorbital unit if needed This segment can

be secured with either resorbable plates and screws or even

absorbing sutures to avoid any possibility of future growth

restriction or transcranial migration of any fi xation

hard-ware ( Fig 3–6 )

To prevent early relapse of the deformity, we believe that

fi rmer rigid fi xation via plate-and-screw use should be

em-ployed but judiciously and only in those areas where

sig-nifi cant postoperative pressure can be expected Prior to

closure, lateral canthopexies are performed by attaching

the lateral canthi to the orbital rim with permanent sutures

anchored through drill holes in the bone

Bilateral Coronal Craniosynostosis

The problem with the bilateral deformity is twofold: fi rst, the height of the skull and the recession of both supraorbital rims and lateral orbital rims and second, the brachycephaly that presents a signifi cant problem because it is diffi cult to correct and failure to correct it will compromise the over-

all result ( Fig 3–2 ) The issue is whether its correction is

warranted in every instance This can be addressed in two ways: (1) osteotomy and advancement of the single orbital unit consisting of both orbits and the supraorbital bar, as previously described; and (2) expansion of the entire cranial base region that allows for a downward settling of the top portion of the skull along the vertex, thus reducing overall skull height It is this second goal that necessitates a change

in the operative positioning from that used in the eral deformity The patient is placed in a modifi ed prone position, the so-called sphinx position, to correct both the frontal and height abnormalities Before placing the patient

unilat-in this position, however, it is important to assess the ity of the cervical spine and the craniovertebral junction by preoperative lateral cervical spine roentgenograms in fl ex-ion and extension Positioning the patient on the operating table is greatly aided by a vacuum-stiffened bean bag to mold the upper body and neck The face and arms are pad-ded with thick, cushioning foam to prevent pressure sores

stabil-and compression nerve palsies ( Fig 3–7 )

Bur holes are placed in the pterion regions bilaterally, and parasagittally in the anterior parietal bone, just posterior

to the coronal suture Similarly, a biparieto-occipital bone graft is outlined with multiple bur holes adjacent to the sagittal and transverse sinuses Once the bone is elevated both frontally and parieto-occipitally, further dissection epi-

10.1055/978-1-60406-039-3c003_f006

Figure 3–6 Final reconstruction in unilateral coronal synostosis The

orbital rims have been reconstructed using an onlay graft and by

ad-vancing the recessed rim and recessing the advanced rim The orbital

rims are attached to the parietal bone using absorbable plates The

segment of frontal bone is also reshaped through a combination of

Tessier bone benders, inner and outer cortex burring, and

barrel-staven-like osteotomies to match the new curve of the supraorbital

unit and to recreate a smooth and symmetric forehead The segment

can be rotated 180 degrees to use the more properly shaped curve

of the posterior edge to match the curve of the supraorbital unit if

needed This segment can be secured with either resorbable plates

and screws or even absorbing sutures to avoid any possibility of future

growth restriction or transcranial migration of any fi xation hardware

10.1055/978-1-60406-039-3c003_f007

Figure 3–7 Operative positioning for bilateral coronal synostosis The

patient is placed in a modifi ed prone position, the so-called sphinx position, to correct both the frontal and height abnormalities Before placing the patient in this position, however, it is important to assess the stability of the cervical spine and the craniovertebral junction by preoperative lateral cervical spine roentgenograms in fl exion and ex-tension Positioning the patient on the operating table is greatly aided

by a vacuum-stiffened bean bag to mold the upper body and neck