Video Atlas of Neurosurgery: Contemporary Tumor and Skull Base Surgery [1st Edition] 9780323319720, 9780323277358

Table of contents :
Praise for Video Atlas of Neurosurgery: Contemporary Tumor and Skull Base Surgery......Page 2
Video Atlas of Neurosurgery......Page 8
Copyright Page......Page 9
Video page......Page 10
Foreword......Page 11
Preface......Page 13
List of Contributors......Page 15
Dedication......Page 18
Microscope Setup......Page 19
Patient Positioning......Page 21
Head Fixation......Page 22
Operative Modifications for Specialized Cases......Page 23
Suggested Reading......Page 24
Acknowledgments......Page 25
Preoperative Considerations......Page 27
Neurophysiological Monitoring......Page 30
Intraoperative Mapping......Page 31
Closure......Page 32
Suggested Reading......Page 33
Preoperative Considerations......Page 34
Anesthetic Considerations......Page 35
Patient Positioning......Page 36
Craniotomy......Page 37
Identification of the Central Sulcus (Figure 2.3)......Page 38
Direct Cortical Mapping (Figure 2.5)......Page 39
Complications......Page 40
Suggested Reading......Page 41
Indications of the Trans-Sulcal Approach......Page 42
Procedure......Page 43
Trans-Sulcal Approach......Page 44
Pitfalls and Limitations......Page 45
Suggested Reading......Page 46
Dural Opening and Intradural Dissection......Page 47
Closure......Page 48
Suggested Reading......Page 49
Preoperative Considerations......Page 50
Frame Biopsy for Transfrontal Extraventricular Approach......Page 51
Open Biopsy......Page 52
Brain Mapping......Page 53
Complications......Page 55
Suggested Reading......Page 56
Patient Positioning......Page 57
Craniotomy......Page 58
Intradural Dissection......Page 59
Suggested Reading......Page 60
Craniotomy......Page 61
Intradural Dissection......Page 62
Suggested Reading......Page 64
Patient Positioning......Page 65
Intradural Dissection......Page 66
Procedure......Page 67
Complications......Page 68
Suggested Reading......Page 69
fMRI/DTI (Figure 9.1)......Page 70
Intraoperative Techniques to Improve Extent of Resection......Page 71
iUS (Figure 9.3)......Page 72
5-ALA (Figure 9.4)......Page 74
ICG (Figure 9.5)......Page 76
Suggested Reading......Page 78
Indications and Preoperative Considerations......Page 79
Craniotomy......Page 80
Dural Opening......Page 81
Closure......Page 82
Complications Avoidance......Page 83
Suggested Reading......Page 84
Patient Positioning......Page 85
Dural Opening......Page 86
Complications Avoidance......Page 87
Suggested Reading......Page 88
Patient Positioning......Page 89
Craniotomy......Page 90
Dural Opening and Tumor Resection......Page 91
Complications Avoidance......Page 92
Suggested Reading......Page 93
Contraindications......Page 94
Patient Positioning......Page 95
Posterior Transcortical Approach......Page 96
Craniotomy......Page 97
Intradural Dissection of the Tumor......Page 98
Suggested Reading......Page 99
Craniotomy......Page 100
Intraventricular Dissection and Tumor Resection......Page 102
Transforaminal Approach (Figure 14.6)......Page 103
Transchoroidal Approach (Suprachoroidal or Subchoroidal) (Figure 14.7)......Page 106
Complications Avoidance......Page 107
Suggested Reading......Page 108
Skin Incision, Soft Tissue Dissection and Craniotomy......Page 109
Neuromonitoring and Brainstem Mapping......Page 110
Closure......Page 112
Suggested Reading......Page 114
Contraindications – Alternatives......Page 115
Skin Incision......Page 116
Neuroendoscope......Page 117
Colloid Cysts......Page 119
Endoscopic Septal Fenestration......Page 120
Closure......Page 121
Suggested Reading......Page 122
Skin Incision......Page 123
Craniotomy......Page 125
Closure......Page 127
Suggested Reading......Page 128
Indications and Contraindications......Page 129
Skin Incision......Page 130
Intradural Dissection......Page 131
Closure......Page 132
Suggested Reading......Page 133
Indications......Page 134
Eyelid Incision......Page 135
Craniotomy (Figures 19.5 and 19.6)......Page 136
Fronto-Temporal Bone Flap with Orbital Rim Removal......Page 137
Microsurgical Dissection (Figure 19.8D)......Page 138
Complications Avoidance......Page 139
Suggested Reading......Page 141
Potential Contraindications......Page 142
Deep Tissue Dissection......Page 143
Subfrontal Craniotomy (Figure 20.6)......Page 144
Extended Subfrontal Craniotomy (Figure 20.7)......Page 145
Microscopic Dissection......Page 147
Dural Closure and Reconstruction (Figure 20.10)......Page 148
Suggested Reading......Page 149
Indications......Page 150
Patient Positioning......Page 151
Landmarks......Page 152
Dural Opening......Page 153
Complications Avoidance......Page 156
Suggested Reading......Page 157
Bone Anatomy (Figure 22.1)......Page 158
Skin Incision (Figure 22.2)......Page 159
Muscular Layer......Page 160
Craniotomy......Page 161
Variations and Drilling of the Occipital Condyle......Page 163
Intradural Dissection (Figures 22.4B and 22.5)......Page 164
Suggested Reading......Page 167
Operating Room Setup for the EEA......Page 168
Bone Anatomy of the Endonasal Corridor......Page 169
Surgical Anatomy of the Endonasal Corridor......Page 171
Suprasellar Region (Figure 23.10A)......Page 172
Suggested Reading......Page 175
Indications......Page 176
Sellar Phase......Page 177
Complications Avoidance......Page 179
Suggested Reading......Page 180
Indications......Page 181
Endonasal Phase......Page 182
Intradural Dissection and Tumor Resection......Page 183
Intradural Tumor Removal......Page 185
Complications Avoidance......Page 187
Suggested Reading......Page 188
Indications......Page 189
1. Nasal Phase (Figure 26.3)......Page 191
2. Opening of Sphenoid and Clivus......Page 192
Tumors in the Midline of the Upper Clivus......Page 193
4. Reconstruction......Page 194
Complications Avoidance......Page 196
Suggested Reading......Page 198
Surgical Procedure......Page 199
Complications Avoidance......Page 203
Suggested Reading......Page 204
Skin Incision......Page 205
Craniotomy Cuts (Figure 28.2)......Page 206
Closure......Page 208
Complications Avoidance......Page 209
Suggested Reading......Page 210
Preoperative Considerations......Page 211
Transconjunctival Approach......Page 212
Endonasal Endoscopic Approach......Page 213
Suggested Reading......Page 214
Preoperative Considerations......Page 215
Patient Positioning (Figure 30.3)......Page 216
Subfrontal......Page 217
Transmaxillary......Page 218
Dural Opening and Tumor Resection......Page 220
Subcutaneous Tissue Reconstruction and Skin Closure......Page 221
Suggested Reading......Page 223
Indications and Preoperative Considerations......Page 224
Pterional/Orbitozygomatic Approach (Figure 31.4)......Page 226
Intradural Dissection and Tumor Resection......Page 227
Intradural Dissection and Tumor Resection......Page 228
Transpalpebral Eyelid Approach (Figures 31.9 and 31.10)......Page 231
Suggested Reading......Page 232
Indications and Preoperative Considerations......Page 233
Skin Incision......Page 234
Dural Opening and Intradural Dissection......Page 235
Optic Nerve Dysfunction and Predictor Factors of Postoperative Impaired Visual Acuity......Page 236
Meningiomas Invading the Orbit......Page 237
Suggested Reading......Page 238
Imaging Modalities......Page 239
Tumor-Specific Considerations......Page 240
Surgical Approaches......Page 241
Tumor Removal......Page 242
Skin Incision......Page 243
Dural Opening......Page 244
Closure......Page 245
Suggested Reading......Page 246
Indications......Page 247
Skin Incision......Page 248
Craniotomy......Page 249
Intradural Dissection and Tumor Resection (Figure 34.3)......Page 251
Complications Avoidance......Page 252
Suggested Reading......Page 253
Patient Position (Figure 35.1)......Page 254
Dural Opening......Page 255
Contraindications......Page 256
Relevant Surgical Anatomy......Page 257
Mastoid Part......Page 258
Labyrinthectomy......Page 259
Procedure......Page 260
Suggested Reading......Page 261
Surgical Procedure......Page 262
Indications......Page 264
Dissection (Figure 36.6)......Page 265
Preoperative Considerations......Page 266
Endoscopic Endonasal Transellar Approach (Figure 36. 9)......Page 268
Transantral Endoscopic Approach......Page 269
Evisceration and Enucleation......Page 270
Suggested Reading......Page 271
Preoperative Considerations......Page 272
Important Anatomy......Page 273
Relevant Surgical Anatomy......Page 275
Tumor Removal......Page 276
Dural Opening and Tumor Resection......Page 278
Dural Opening and Tumor Resection (Figure 37.11)......Page 280
Suggested Reading......Page 283
Preoperative Considerations......Page 285
Muscular Stage......Page 287
Suboccipital Craniectomy and Hemilaminectomy......Page 288
Condylar Stage......Page 289
Closure......Page 291
Complications Avoidance......Page 292
Suggested Reading......Page 293

Citation preview

Praise for Video Atlas of Neurosurgery: Contemporary Tumor and Skull Base Surgery “The Video Atlas of Neurosurgery couples outstanding graphics and animation with intraoperative video to bring to life operative neurosurgical procedures in a way that dramatically enhances understanding. I anticipate that this will substantially improve replicability of best intraoperative neurosurgical technique. I particularly enjoyed the pearls embedded throughout the learning materials. I can easily recommend this as a tool for those seeking to improve their surgical repertoire.” Bob S. Carter, MD, PhD Chair, Department of Neurosurgery Professor of Surgery and Neuroscience UC San Diego Health System UC San Diego School of Medicine San Diego, CA, USA

“The text and videos I was able to observe provide up-to-date, concise, and highly helpful information about operative techniques and indications. The step-by-step instructions should provide trainees and practitioners with highly useful information that they can apply to their practice. The ability to read text but also to correlate this with narrated videos is very instructive and educational and can only lead the reader to useful learning.” E. Antonio Chiocca, MD, PhD Harvey W. Cushing Professor of Neurosurgery, Neurosurgery, Harvard Medical School Chairman, Neurosurgery, Brigham & Women’s Hospital Co-Director, Institute for the Neurosciences, Brigham & Women’s Hospital Surgical Director, Center for Neuro-Oncology, Dana-Farber Cancer Institute Boston, MA, USA

“The Video Atlas of Neurosurgery is an exciting new publishing and educational venture. This monumental effort has used a systematic, case-oriented approach to describe a large number of neurosurgical procedures. They include both relatively common operations, and some that are infrequent, but offer important nuances and “pearls” that are generally applicable to many of our operative procedures. The cases are well described, the instructive illustrations, often animated, are clear and explicit. They show not only the normal anatomy, but the deformation and displacement of normal structures. Approaches are clearly defined, and avoidance of complications is emphasized, as is the use of a variety of intraoperative adjuncts.” “The narrated videos are clear and satisfying, even though they are two dimensional. They offer stepby-step lessons in elegant techniques that produce successful surgical outcomes.” “One can only imagine the prodigious amount of work involved in producing this educational treasure chest. Credit is due to the authors and to the publishers for creating this appealing and useful Atlas.” Edward R. Laws, Jr., MD, FACS Professor of Neurosurgery, Harvard Medical School Brigham & Women’s Hospital Boston, MA, USA

“Thank you for sharing these videos and chapters. I think this will be an invaluable resource for neurosurgeons of all stages of training and practice. The surgical procedures are illustrated with exquisite artwork that beautifully depicts the anatomy and techniques. The concise text makes the chapters easy to read and to the point. The pearls are an excellent summary of Dr Quiñones’s years of experience and wisdom. I am proud to have played a role in the training of this extraordinary neurosurgeon and happy that he has devoted so much of his time and energy to produce such an insightful and exciting collection.” Michael T. Lawton, MD Professor and Vice-Chairman, Neurological Surgery Professor, Anesthesia and Perioperative Care Chief of Vascular Neurosurgery Tong-Po Kan Endowed Chair Director, Center for Cerebrovascular Research University of California – San Francisco San Francisco, CA, USA

“I just previewed this video atlas, and I think it is excellent. The print chapters are very wellorganized, and the videos are clear and easy to understand. This will undoubtedly be a very useful neurosurgical atlas for future neurosurgical trainees. Congratulations on this tour de force!” Linda Liau, MD Professor, Department of Neurosurgery Director, Brain Tumor Program UCLA School of Medicine Los Angeles, CA, USA

“The Video Atlas of Neurosurgery is a masterwork companion for the general neurosurgeon and neurosurgical oncologist. The meticulous attention to operative detail and insightful surgical pearls will certainly not disappoint the audience, from junior resident to senior attending.” Nader Sanai, MD Director, Division of Neurosurgical Oncology Director, Barrow Brain Tumor Research Center Barrow Neurological Institute Phoenix, AZ, USA

“In this video textbook, Dr. Q does a spectacular job presenting complex neurosurgical procedures in a simple and easily understood format. The operative videos, images and narration are superb and filled with valuable and hard won priceless pearls borne of Dr. Q’s immense clinical experience and wise judgement. This masterpiece will no doubt become an instant classic and required reading and watching not only for neurosurgical trainees but also well-established surgeons who wish to pick up a few tricks from a master technician.” Theodore H. Schwartz, MD, FACS Professor of Neurosurgery, Otolaryngology and Neuroscience David and Ursel Barnes Professor of Minimally Invasive Neurosurgery Director, Anterior Skull Base and Pituitary Surgery, Epilepsy Research Laboratory Weill Cornell Medical College New York Presbyterian Hospital New York, NY, USA

“In this video atlas, Dr. Quiñones has developed an extraordinary work showing the most up-todate techniques to treat brain and skull base tumors. In a condensed and easy-to-read, he indicates the many steps and surgical strategies as well as clinical pearls and tips for each procedure. Videos are pristine and without any doubt will become a source of consultation for neurosurgeons in-training as well as experienced ones wishing to be brought up to date. We again want to thank Dr. Q for his unremitting effort to spread his knowledge and to provide us with this tool that will help reach our professional goal: to better help our patients.” Claudio G. Yampolsky, MD Chairman, Department of Neurosurgery Chairman, Neurooncology Hospital Italiano Buenos Aires, Argentina

“Dr. Quiñones and his team have put together an amazing collection of didactic videos. Especially designed for young neurosurgeons, this is a mustread for all of those treating intracranial tumors.” Feres Chaddad, MD, PhD Professor of Cerebrovascular Surgery Federal University of São Paulo – UNIFESP São Paulo, Brazil

“The Video Atlas of Neurosurgery: Contemporary Tumor and Skull Base Surgery is a cutting-edge masterpiece. This innovative product which was created by Dr. Alfredo Quiñones-Hinojosa will make a tremendous contribution to the development of neurosurgery. It will make it much easier for residents and fellows to learn the key points of a procedure. Moreover, it could play an important role to neurosurgeons-in-training around the world.” Lei Ting, MD, PhD Professor and Chairman Department of Neurosurgery Tongji Hospital Tongji Medical College Huazhong University of Science & Technology Wuhan, P. R. China

“I am amazed that complex neurosurgical procedures have been illustrated in a very simple and clean manner. It shows the surgeon’s expertise and experience and how wonderful a teacher he is.” Anupam Jindal, MCh, MBBS Consultant Neurosurgeon Mayo Healthcare Mohali, Punjab, India

“In the Video Atlas of Neurosurgery, the authors have compiled a beautiful potpourri of neurosurgical operative videos encompassing the broad spectrum of the neurosurgical approaches. The approaches are sagaciously chosen to cover the most important surgical nuances in operative neurosurgery from the traditional pterional approach to the recently developed and enhanced endoscopic endonasal approaches to the skull base. The videos are supplied by succinct text descriptions that provide the reader with pearls for patient selection, technique, complication avoidance and practical anatomical knowledge. Virtually, all the information provided falls into the category of ‘must know’ for the contemporary neurosurgeon who specializes in the field of skull base, tumor, and cerebrovascular surgery. One can hardly find any important neurosurgical nuance missed. This book excellently bridges the basics of neurosurgical planning and the most delicate technical points and is a valuable asset to every neurosurgeon’s library.” Ali Tayebi Meybodi, MD University of California San Francisco San Francisco, California, USA

“I am certain that this will be a major contribution for neurosurgeons-in-training who would like to optimize their knowledge in the field of surgical neuro-oncology. I congratulate the authors for this fantastic and unique Video Atlas!” Hugues Duffau, MD, PhD Professor and Chairman, Department of Neurosurgery Gui de Chauliac Hospital, Montpellier University Medical Center Director of the Team “Brain plasticity, Human stem cells and Glial tumors” National Institute for Health and Medical Research (INSERM) Institute for Neurosciences of Montpellier Montpellier, France

“This dynamic and innovative video atlas will surely be a benchmark for neurosurgical education from a translational perspective of knowledge. It applies state-of-the-art operating strategies with support in the scientific literature and at an appropriate level of evidence, which makes this atlas a core publication for the formation of the neurosurgeon.” Rodrigo Ramos-Zúñiga, MD, PhD Chairman of Neurosciences Department University of Guadalajara Guadalajara, México

“This is the most concise, graphical and comprehensible resource about procedures such as awake craniotomy I have ever seen. This is the best stepby-step surgical approach guide for both novel and experienced neurosurgeons.” Josep Gonzalez, MD, PhD Director of the Residency Program Hospital Clinic Barcelona Neurosurgical Oncology and Spine Unit Hospital Clinic i Provincial Barcelona Barcelona, Spain

“All at once, the reader knows about key aspects of this topic: when to indicate this procedure, which patients are the most eligible to get better results, which are the contraindications to carry it out, what is the required infrastructure to perform it and, perhaps most importantly, the necessity of having a multidisciplinary team. The clinical examples are very demonstrative by showing how experts handle such cases. The video linked to the written information is a very useful complement. Surgeries are masterfully undertaken and neatly and didactically presented, in a way that provides a great deal of information in a very short time. The clarity, with which the theme is shown, eases the comprehension for both the resident in training and the young neurosurgeon, but it also provides tips and tricks of high value, even for the expert.” “Information obtained by this means may be used as a fast and practical reference. The sole fact of reading the Pearls Summary that appears at the end of the chapter, and carefully watching the video, will be enough to obtain compact, but detailed information, which will serve as a very good help when facing similar cases.”

“Nevertheless, it must be clarified that the ease with which the handling of gliomas in eloquent areas and the excellent results achieved with awake craniotomy by Dr. Quiñones-Hinojosa’s group, is the result of many years of hard and dedicated labor. Even though the clearness and deftness with which the theme is exposed in this work may stimulate in the reader the desire to carry out these procedures immediately, the truth is that they are of great complexity, requiring a long time of training, a complex technological environment and highly specialized human resources. In order to be able to begin undertaking these surgeries with safety, it is mandatory to search for assessment coming from centers dedicated to these topics, such as the one shown in this chapter.” Gerardo Guinto Balanzar, MD Department of Neurological Surgery Hospital de Especialidades Centro Medico Nacional Siglo XXI Mexico City, Mexico

“The structure of the Video Atlas, combining the reading of the theoretical part with the corresponding visualization of surgical videos, allows for knowledge acquisition and consolidation in a pleasant and systemic way, making it a high-value pedagogical tool.” “Moreover, their detailed and didactic description of the essential steps related to this kind of surgery, in my opinion, highly contributes to the training of countless young neurosurgeons all around the world.” Armando Manuel Tavares de Rocha, MD Department of Neurosurgery Hospital Center and University of Coimbra Coimbra, Portugal

“Excellent literary work with an iconography and superlative videography. I highly recommend it for all the scientific world of neuroscience and medicine” Ariel Chari, MD Head and Neck Surgeon Hospital General de Agudos Ignacio Pirovano Buenos Aires, Argentina

“Definitely, this kind of video/text chapter is the future of surgical neuro-oncology. The authors turn a complex issue into content that is easily understood, making it clear using step-by-step descriptions, well-described techniques, and good case selections.”

“Neurosurgeons-in-training as well as those who need to brush up on these techniques will find this an important and extremely useful contribution.” Andres M. Lozano, MD, PhD, FRCSC, FRSC, FCAHS Professor and Chairman, Dan Family Chair in Neurosurgery RR Tasker Chair in Functional Neurosurgery Canadian Research Chair in Neuroscience (Tier 1) University of Toronto Senior Scientist, Toronto Western Research Institute Past-President, World Society for Stereotactic and Functional Neurosurgery Toronto Western Hospital Toronto, Ontario, Canada

“It really is a milestone in the field tumor and skull base surgery.” Xuequan Feng, MD, PhD Attending neurosurgeon Associate Professor First Center Hospital Tianjin, China

Marcos V. C. Maldaun, MD, PhD Co-Coordinator of Neurology and Neurosurgery Center Hospital Sírio Libanês Co-Coordinator of Neuroncology Pos Graduation Course Hospital Sírio Libanês São Paulo, Brazil Emeritus President of the Tumor Chapter of FLANC Foundation President of the Society for Neuro-Oncology Latin America

“This is a very interesting and well-designed new educational tool for residents and young neurosurgeons. Dr. Quiñones and his team were able to organize the nuances of different neurosurgical techniques in a very effective format, designing a useful book for review of cases and techniques prior to surgery. Congratulations!” Evandro de Oliveira, MD Professor of Neurosurgery State University of Campinas – UNICAMP Director, Institute of Neurological Sciences São Paulo, Brazil

“The videos are great examples for all training neurosurgeons in the world to learn how to perform the similar surgical procedures, especially for neurosurgeons who have had no opportunities to observe the operations in the OR. Even neurosurgeons who have performed the same procedures can compare their own experience to those in the videos.” Yan Qu, MD, PhD Professor and Chair Department of Neurological Surgery Tangdu Hospital Forth Military Medical University Xi’an, Shaanxi P. R. China

“Es un trabajo extraordinario para mejorar el aprendizaje de la neurocirugia. Felicitaciones al Dr. Q y a su grupo de colaboradores, lo que se hace en equipo siempre se hace mejor.” Alfredo Borrero, MD, FAANS General Dean of Health Sciences University Las Americas (UDLA) Quito, Ecuador

“The videos and chapters are professional, concise and clear. An excellent tool for young or experienced neurosurgeons to review the relevant anatomy and techniques prior to performing these surgical cases. I use this resource routinely in my practice. Dr. Quiñones and his team should be applauded for excellent teaching videos that will serve the neurosurgery community for years to come.” Maryam Rahman, MD, MS Assistant Professor Department of Neurosurgery Preston A. Wells Jr Center for Brain Tumor Therapy University of Florida Gainesville, FL, USA

“There are few neurosurgeons as qualified as Alfredo Quiñones to edit this reference work in surgical neuro-oncology. Moreover both from the point of view of text and video: a masterpiece. The “pearls summaries” at the close of each chapter are especially valuable. The images provide practical counterpoint and usefully complement the procedure. What he has demonstrated is that these procedures can be performed safely many times with low morbidity. Quiñones’s atlas conveys both the science and the art of the neurosurgery to guide us forward in this challenging and most important discipline of helping neuro-oncology patients.” J. L. Gil-Salú, MD Chief of Neurosurgical Department Hospital U. Puerta del Mar Cádiz, Spain

“The written content is focused and concentrates on the important points and becoming a true guide to surgery. Similarly the video is fantastic. I cannot think of a better guide for a trainee or even for a young consultant than have this book with its videos as part of his library. This should also be important reading for neurosurgical units around the world and should be supported by both the EANS and the WFNS.” Jesus LaFuente Baraza, MD President of the European Association of Neurosurgical Societies (EANS)

“Dr. Quiñones-Hinojosa’s Video Atlas of Neurosurgery: Contemporary Tumor and Skull Base Surgery is very exciting. The innovative combination of written text, anatomic diagrams, and video content offered in this work is a unique and effective tool for teaching indications and surgical techniques for both straightforward and complex procedures in surgical neuro-oncology. This exciting, comprehensive volume will undoubtedly be a valuable resource for trainees and practicing neurosurgeons alike.” Amanda M. Saratsis, MD Attending Physician Division of Pediatric Neurosurgery Ann & Robert H. Lurie Hospital of Chicago Assistant Professor Department of Neurological Surgery Northwestern University Feinberg School of Medicine Chicago, Illinois, USA

“This is an innovative approach to educating neurosurgeons, and the ease of access to the material makes this a unique and powerful tool.” “With Dr. Quiñones-Hinojosa’s pioneering work, the way of the future for educating neurosurgeons is finally here. Masterfully done and meticulous attention to detail.” Philip V. Theodosopoulos, MD Professor & Vice-Chair Chief & Director, Skull Base Tumor Program Co-Director, Clinical Programs Neurological Surgery University of California San Francisco San Francisco, CA, USA

Video Atlas of

NEUR SURGERY

Contemporary Tumor and Skull Base Surgery Edited by

Alfredo Quiñones-Hinojosa MD FAANS FACS Member, Miller-Coulson Academy of Clinical Excellence William J. and Charles H. Mayo Professor and Chair of Neurologic Surgery Mayo Clinic, FL, USA; Formerly Professor of Neurological Surgery and Oncology Neuroscience and Cellular and Molecular Medicine Director, Brain Tumor Surgery Program Director, Pituitary Surgery Program Department of Neurosurgery Johns Hopkins Medicine and University Baltimore, MD, USA

Video Editor

Jordina Rincon-Torroella MD Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA For additional online videos visit Expertconsult.com

Edinburgh  London  New York  Oxford  Philadelphia  St Louis  Sydney  Toronto  2017

© 2017 Elsevier Inc. All rights reserved. First edition 2017 Alfredo Quiñones-Hinojosa and Arnau Benet retain copyright for their images and video. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications. It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. ISBN: 978-0-323-26149-4 eISBN: 978-0-323-27735-8

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Printed in China Last digit is the print number:  9  8  7  6  5  4  3  2  1

Videos on ExpertConsult.com

The primary content in this Video Atlas consists of step-by-step videos for each chapter – available on www.expertconsult.com. These can be used in conjunction with written chapters in this volume or as stand-alone videos. Instructions on how to access the videos are available on the inside front cover.

The QR code below will direct you straight to the expertconsult site.

Foreword

The Video Atlas of Neurosurgery is a contemporary and detailed account of tumor and skull base surgery authored and edited by Dr Alfredo Quiñones-Hinojosa. Although he enlisted the help of a number of his colleagues, he is the senior author on all of the chapters in this textbook. This will likely become the authoritative text regarding the management of various intra- and extra-axial tumors of the central nervous system. What I most enjoyed about this comprehensive atlas is the detailed nature of the description of the various procedures and methods to gain access to and remove lesions in these complicated locations. This is an absolute masterpiece in terms of how the information is portrayed to the reader in a very sensible and logical fashion. Even the most complex of procedures is very easily understood and conveyed to neurosurgeons, residents and healthcare providers at all levels. The atlas is divided into a number of different sections, encompassing intra- and extra-axial tumors in addition to lesions within the ventricular system. In Section 4 there are very detailed descriptions and illustrations of the commonly used skull base approaches, followed in Section 5 by endoscopic approaches to these same skull base tumors. This is particularly insightful in light of the fact that it presents the reader the various options available in terms of open versus minimally invasive procedures which, of course, is extremely timely. The final two sections deal with combined approaches to the skull base as well as surgical procedures involving various types of

tumors located from the anterior cranial fossa to the foramen magnum. Therefore, this is a comprehensive text that covers all aspects of tumor surgery involving both intra- and extra-axial locations and leaves absolutely nothing uncovered. When you look at the detail of the chapters, it is evident that this is being presented by an extraordinarily experienced surgeon along with his team since he covers the very detailed aspects of each procedure. For example, each chapter is logically arranged in a bullet-point fashion covering aspects of the procedures such as indications and contraindications, as well as the various preoperative considerations and the anesthesia requirements. In addition, the surgical aspects are covered from considerations of positioning, through the incision, dural opening and detailed analysis of the exact surgical procedure, as well as closing. I really appreciated the fact that each chapter is well delineated and demarcated and includes beautiful pictures of excellent quality that are clearly described and labeled. The illustrations are magnificent and very detailed, yet not too complex as to be confusing. Each chapter ends with a summary and also gives a number of learning pearls. Thus the author and his team leave nothing to the imagination in terms of understanding everything from the very beginning of the planning stages, to the understanding of images and how this relates to the surgical procedures, followed by the actual details of the surgical approach. In addition, there are 38 procedural videos that can be used to augment the written chapters in the atlas, with supplementary

xiv

Foreword cases also presented. The videos are narrated by Dr Quiñones-Hinojosa, and have been greatly enhanced through various intraoperative photos, anatomical dissections, drawings and animations. This provides the reader the experience of not only reading a detailed account of the procedure in all of its various aspects, but also having the experience of viewing the surgery in real time. What more could the reader ask for! This extraordinary atlas, along with the accompanying visual presentations, is unlike anything I have seen before in the field of surgical neurooncology. It is an extremely detailed account of every surgical approach for every tumor from the tip of the anterior cranial fossa to the bottom of the posterior fossa. The extraordinary detail provided along with the superb images and intraoperative photos clearly reflect the outstanding knowledge of all of these procedures by the senior author, and the reader is able to actually imagine how Dr Quiñones-Hinojosa is thinking and planning the approach and conducting the operation in each of these areas.

I certainly recommend this textbook to every resident that trains in neurosurgery as well as to every neurosurgeon that operates on any type of tumor within the central nervous system. Because of the tremendously important visual presentation of each chapter, I think this book should be provided to all nurses and allied health personnel as well as other professionals who deal with patients in the realm of neuro-oncology, that is neuro-oncologists, neuro-radiologists and radiation oncologists. In essence, this book is indispensable and will go down in neurosurgical history as one of the very few masterpieces that may never be duplicated. I urge you to buy this book and read it as if it were the neurosurgical bible of surgical neuro-oncology. Mitchel S. Berger, MD, FACS, FAANS Berthold and Belle N. Guggenheim Professor Chairman, Department of Neurological Surgery Director, Brain Tumor Research Center University of California, San Francisco 2016

Preface

As a junior resident in the fall of 2001 I was watching through the observer microscope lens and assisting Dr Michael Lawton with a dissection of an aneurysm in the anterior circulation. That same day I assisted Dr Mitchel Berger with an awake craniotomy, and later that day I helped Dr Michael McDermott with a giant meningioma in the anterior skull base where we removed the orbital rims and devascularized the tumor. Drs Lawton, Berger, and McDermott were already giants in the field and watching them perform surgery was not only a pleasure but also an incredible opportunity to learn surgical techniques. I felt privileged, and at the same time I asked myself “how can you teach others the art of surgery and how do you pass to many others the lessons learned in the operating room?” Right there the idea was born to one day produce a volume of video chapters that would be of use to those who want to learn with visual and auditory stimulation, just the way I was learning from my mentors. This book is not only about surgical techniques and nuances, and lessons I have learned over the years from watching my colleagues operate, but it has a deeper meaning; it is also about our patients and how they put their lives in our hands. Our responsibility to them is to make sure that we pass on to others the small but meaningful tricks we have learned through the years as we develop our own craft. This book and its video content brings the viewer into the intimate setting of the operating room to see how patients can benefit from what we can learn together.

This book took more than 4 years from inception to completion, with a great deal of support, and many people working together to produce these high-quality videos. We had to acquire special equipment not only to make the recordings of the surgeries in high definition but also to ensure that the narrations were accurate and informative. We had to find places to make our recordings, as we do not have a sound-proof studio. I learned a great deal by repeatedly watching myself operate as we were editing the videos. I observed techniques that I didn’t realize I was doing, and it allowed me to become a better technician and try to improve the surgeries and make them more efficient and minimize morbidity. Many of us are extraordinarily lucky that our patients allow us not only to touch their brains but to teach others as we navigate their minds. I changed as an author and a surgeon but, most importantly, I evolved as a friend and partner to all my patients. The best way to use this book is to watch and listen to the videos and ask yourself how you might perform the surgeries differently. I do not want to tell you how to do it, but rather I would like to share with you my experiences and the things I have learned from others through the years. You will be able to develop your own style, and over the years you will find yourself doing it differently. My hope is that you can use some of the things I have learned as an opportunity to learn more about yourself and how to make surgery better and safer for our patients.

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Preface More than 15 years have passed since I was assisting Drs Lawton, Berger and McDermott at UCSF. I was able to record some of those cases, and I now see those videos along with videos of surgeries I am doing today as part of this video atlas. I have the same admiration, respect and love for the brain and our patients as I did back then. I continue to learn every day and I continue to be

thankful to my patients for allowing me to be part of their lives. Alfredo Quiñones-Hinojosa, MD, FAANS, FACS William J. and Charles H. Mayo Professor Neurologic Surgery Chair Mayo Clinic College of Medicine, Florida August 2016

List of Contributors

Shami Yesha Acharya, BSc (Hons), MBBS, MRCSEng Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA; Neurosurgical Trainee St George’s Hospital London, UK João Paulo Almeida, MD Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA; Neurosurgeon State University of Campinas (UNICAMP) São Paulo, Brazil Norma Arechiga, MD Post-Doctoral Fellow Department of Neuro-Oncology The Johns Hopkins University Baltimore, MD, USA; Chief of Neurology at ABC Hospital, Mexico; Professor of Neurology at Universidad Anahuac Mexico Professor of Neurology at Technologico de Monterrey; Adults Neurology, Centro Médico Nacional SXXI; Hospital de Especialidades, IMSS, Mexico City

Arnau Benet, MD Associate Collaborator Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA; Assistant Professor, Departments of Neurosurgery and OHNS Director, Skull Base and Cerebrovascular Laboratory University of California San Francisco San Francisco, CA, USA Eibar Ernesto Cabrera-Aldana, MD Research Fellow in Neuro-Oncological Surgery The Johns Hopkins University Baltimore, MD, USA; Neurosurgeon National Institute of Neurology and Neurosurgery Mexico City Martín A. Chacón Portillo, MD Research Fellow Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA

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List of Contributors Kaisorn L. Chaichana, MD Neurosurgery Resident Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA Chikezie I. Eseonu, MD Neurosurgery Resident Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA Brian Hwang, MD Neurosurgery Resident Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA Christina Jackson, MD Neurosurgery Resident Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA Ignacio Jusué-Torres, MD Salisbury Fellow Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA Alexandra Larsen, BS Research Volunteer Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA; MD Candidate Harvard Medical School Boston, MA,USA Salvador Manrique-Guzman, MD, MSc Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA; Junior Associate Department of Neurosurgery ABC Medical Center Mexico City Roberto Andrés Medina-Molina, MD Research Fellow Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA; Medical Student Escuela Nacional de Medicina Monterrey, NL, Mexico City

Elizabeth Ogando-Rivas, MD Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA; Neurosurgery Resident General Hospital of Mexico Mexico City Eva F. Pamias-Portalatín, MD Neuro-Oncology Research Fellow Department of Neurosurgery The Johns Hopkins University; Neurosurgery Resident University of Puerto Rico Medical Science Campus Puerto Rico Omar Antonio Pérez-Morales, MD Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA Alfredo Quiñones-Hinojosa, MD, FAANS, FACS Member, Miller-Coulson Academy of Clinical Excellence William J. and Charles H. Mayo Professor and Chair of Neurologic Surgery Mayo Clinic, FL, USA; Formerly Professor of Neurological Surgery and Oncology Neuroscience and Cellular and Molecular Medicine Director, Brain Tumor Surgery Program Director, Pituitary Surgery Program Department of Neurosurgery Johns Hopkins Medicine and University Baltimore, MD​, USA Karim Refaey, MD Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA Jordina Rincon-Torroella, MD Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA Alejandro Ruiz-Valls, MD Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA

List of Contributors Danilo Tueme, MD Research Fellow Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA; Telehealth Intern Escuela Nacional de Medicina Tecnologico de Monterrey Monterrey, NL, Mexico City Gabriel Vargas-Rosales, MD Research Fellow Department of Neurosurgery The Johns Hopkins Hospital Baltimore, MD, USA

Tito Vivas-Buitrago, MD Post-Doctoral Fellow Department of Neurosurgery The Johns Hopkins University Baltimore, MD, USA; Universidad de Santander (UDES) Bucaramanga, Colombia

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Dedication

To my dear wife, Anna, and our children, Gabriella, David and Olivia, for their extraordinary patience, love and dedication to our patients, who are also part of our family. Our children are an integral part of what I do since they constantly keep me grounded and humble by asking me questions to which I do not know the answer. To my former and current mentors and to our extraordinary team of nurses, administrators, anesthesiologists, neurologists, neurosurgeons, otolaryngologists, radiologists, endocrinologists, residents, fellows and medical students who have dedicated their lives to the pursuit of perfection and patient care and who are an integral part of these advances in surgery, and who have taught me so much not only about surgery but about being a compassionate physician. All of them have mentored me and guided me through the years and have provided me with the light I needed at times when the room was dark and the

visibility was dimmed by moments of doubt and fear. To my wonderful patients and their families, for putting their lives in our hands, for asking questions, and for pushing us to become better physicians, surgeons and human beings. Much gratitude and thanks also to Elsevier, Jordina Rincon-Torroella, Devon Stuart and the extraordinary team who made this book possible. It has taken many years of work collecting cases and videos, many years’ experience and knowledge to produce this book and video collection — it would not have been possible without all of you. Alfredo Quiñones-Hinojosa, MD, FAANS, FACS William J. and Charles H. Mayo Professor Neurologic Surgery Chair Mayo Clinic College of Medicine, Florida August 2016

Introduction

 

Operating Room Requirements for Brain Tumor Surgery Chikezie I. Eseonu, Jordina Rincon-Torroella, Karim Refaey and Alfredo Quiñones-Hinojosa To see Video Introduction, please go to ExpertConsult.com

Introduction • Achieving an optimal surgical result depends not only on surgical skills but also on proper operative planning. The operating room (OR) setup must be designed to accommodate a variety of cranial cases that may require additional equipment, personnel and supplies. • The setup of the OR provides for safe and efficient operating conditions that allow for appropriate, rapid responses for operative or anesthetic emergencies. • The goal of this chapter is to review the basic OR setup for neurosurgical brain tumor cases.

General Operating Room Setup • Proper positioning of operative equipment and personnel allows for improved OR efficiency. The standard OR arrangement has the operating table in the central area of the operating room. Electric or manual operating tables are used to position patients as needed. • The Mayo stand and back table are located in a sterile area of the OR, preferably opposite entrance to the OR. Instruments should be placed on the Mayo stand to allow for easier accessibility and mobility of the instruments, and can be adjusted as needed during surgery as the patient’s position changes. • The control consoles for the monopolar and bipolar coagulation units, the suction cannisters, drills and electrophysiological monitoring machines are located at the foot of the operating

table. The OR microscope and chair are positioned at the head of the operating table. • Multiple television monitors are placed throughout the OR that can be viewed by the surgeons, OR personnel and anesthesiologist. This allows the ancillary staff to follow the operative procedure, anticipate the surgeon’s needs and estimate blood loss. Radiographic imaging can also be put on these monitors. • Each neurosurgical case is always staffed with a neurosurgeon attending; a scrub technician, a circulating nurse, an anesthesiologist and, at academic centers, each case is often also staffed with a neurosurgery resident and an anesthesia resident or certified registered nurse anesthetist (CRNA). An electrophysiological technician is involved when neurophysiological monitoring is indicated. • The primary surgeon is positioned at the head of the OR table and the scrub technician is positioned at the side of the patient near the surgeon. The anesthesiologist can be placed near the head and chest of the patient on the contralateral side from the site of surgery allowing for access to the endotracheal tube and intravenous/ intra-arterial lines. The ventilator and anesthesia machine are positioned toward the head to the OR table (Figure 0.1).

Microscope Setup • The operating microscope provides intense illumination and stereoscopic visualization that can be used for the intradural portion of most

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Introduction  •  Operating Room Requirements for Brain Tumor Surgery

Surgical chair

Microscope

Neurosurgeon Assistant surgeon Anesthesia machine

Scrub tech

Anesthesiologist Mayo stand

Scrub table

g rin to i on m ion ro tat u s e

N

Suction canisters

Neuromonitoring tech

Control consoles

Monitor 1

Monitor 2

Figure 0.1 Basic operating room setup. Modified with permission from Jandial, R., McCormick, P., Black, P. (Eds.), 2011. Core Techniques in Operative Neurosurgery. Saunders, Elsevier Inc., Philadelphia.

cranial cases. It has improved the technical performance of many neurosurgical brain tumor procedures by allowing better visualization of neural and vascular structures, access to deeper cortical spaces with less retraction of the brain, and better coagulation of bleeding sites with preservation of nearby neural structures. • The microscope should be balanced prior to the operation, and appropriate optic attachments, eyepieces, mouthpiece and video-recording equipment should be checked and adjusted as needed. The light intensity and zoom speed level should also be adjusted to the surgeon’s preference. • The placement of the observer’s (assistant’s) eyepiece varies with the procedure and the surgeon’s preference. For intracranial cases, some surgeons prefer the observer eyepiece to the right of the surgeon, except for trans­ sphenoidal cases (where the surgeon is standing on the right side of the patient), or craniotomies with the patient positioned in the park bench position for access to the right

posterior fossa. Other surgeons prefer the observer eyepiece on the contralateral side of the surgical site. The idea is to position the assistant taking into consideration the position of the surgical tech assistant during the particular procedure in such a way that the surgeon has a 360o control/assistance from the surgical nurse and the resident/ assistant and the flow of hands and passing of instruments is natural. • The microscope can also be synced with stereotactic neuronavigation that allows the surgeon to view reconstructed MRI or CT images that correlate with the focal point of the surgeon’s microscopic view. • Microscope chair: Proper position of the operative chair allows for less physical fatigue during long operations. Mechanical operating chairs allow for horizontal and vertical movement of the chair. The floor stand provides space to place the microscope foot pedal controller (at the surgeon’s left foot), and the bipolar coagulation pedal (at the surgeon’s right foot).

Introduction  •  Operating Room Requirements for Brain Tumor Surgery • Microscope mouthpiece: A mouthpiece (or mouth switch) attachment to the microscope allows a surgeon hands-free repositioning of the microscope using his or her mouth. This limits the amount of time the surgeon looks away from the microscope, thus reducing the amount of distractions and operative time. • The mouthpiece should be adjusted preoperatively, after balancing the microscope, based on the surgeon’s physiognomy, by allowing the surgeon’s top teeth to rest on the adjustment mouth plate. Care should be taken to ensure that when biting down on the mouthpiece the surgeon does not lose his line of vision in the microscope. • The microscope foot control panel pedal is often used with the mouthpiece and allows for remote control of the angulations, focus and zoom power of the scope using the surgeon’s foot. • A large sterile loosely fitting drape can be placed over the microscope for surgery. Tightly fitted drapes should be avoided since that would prevent the full range of microscope movement and prevent utilization of the mouthpiece. • Once the scope is moved into position, the surgeon can move it with his teeth, by biting on the mouthpiece through the mask to move the scope in the horizontal and vertical plane without taking his hands away from the surgical field.

Figure 0.2 Supine patient position. © A. Quiñones-Hinojosa.

Patient Positioning • The main patient positions for intracranial procedures include supine, three-quarter prone (also known as park bench or lateral oblique), prone, or sitting position. • Supine positioning is often used for frontal, anterior parietal, temporal and cranial base region masses. The patient’s head can be appropriately turned to expose the surgical site and elevation of the ipsilateral shoulder and upper torso can be used to prevent venous obstruction caused by extreme head turning (Figure 0.2). • Benefits: This is the simplest position that requires little manipulation of tubes or invasive monitors. Risks: May require excessive rotation or flexion that may impede venous flow or the tracheal tube airway. • Three-quarter-prone positioning is reserved for posterior parietal, occipital and suboccipital masses. In this position, the table should be raised to elevate the head in order to reduce the amount of venous engorgement. Additional material to assist with this positioning include egg-crate foam pads, pillows, a sandbag, gel axillary pad and adhesive tape (Figure 0.3). • Benefits: Allows access to posterior cranial regions without jeopardizing venous outflow. Risks: Concern for brachial plexus injury, palsies from excess pressure, and stretch injury. • Prone positioning is used for occipital and suboccipital masses and requires chest-rolls for

Figure 0.3 Three-quarter prone position. © A. Quiñones-Hinojosa.

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Introduction  •  Operating Room Requirements for Brain Tumor Surgery

Figure 0.4 Prone patient position. © A. Quiñones-Hinojosa.

positional padding. Areas on the patient’s body that have excess pressure or traction should be protected using a thick foam pad in order to prevent complications that result from prolonged immobilization during extensive cases (Figure 0.4). • Benefits: Easy access for posterior approaches and less risk for venous air embolisms. Risks: Difficulty providing appropriate oxygenation and ventilation, poor access to the patient’s airway, excessive manipulation of invasive monitoring wires and lines, decreased venous outflow and pressure sores. • The semi-sitting position is rarely used for operations that involve the posterior fossa (Figure 0.5). • Benefits: Good exposure of the posterior fossa due to tissue retraction, and improved venous drainage. Risks: Increased likelihood of venous air emboli, pneumocephalus and bradycardia. Preoperative cardiology evaluation, cardiac doppler ultrasound and bubble study are part of the preoperative clearance since the presence of a patent foramen ovale is a contraindication of this position. Intraoperative transesophageal echo or precordial doppler monitoring can be used to monitor for an air embolism, while a right atrial central venous pressure line can be placed to aspirate the air embolism.

Figure 0.5 Patient in sitting position for surgery. Reproduced with permission from Jandial, R., McCormick, P., Black, P. (Eds.), 2011. Core Techniques in Operative Neurosurgery. Saunders, Elsevier Inc., Philadelphia.

• Sequential compression devices can also be used for selected patients who need protection from venous thrombosis or stasis.

Head Fixation • Proper head position allows for optimal exposure for surgical access. The use of a three-pin

Introduction  •  Operating Room Requirements for Brain Tumor Surgery skull clamp can firmly fixate the head in the desired position. Pins should be placed in a band-like distribution on the head, like a headband worn above the eyes and ear. The pins can be coated with antibiotic ointment prior to pinning the head. • Care should be taken to avoid pinning thin bone (squamous portion of temporal bone), frontal sinus, mastoid sinus, prior shunt, cranial defects and thick temporalis muscle, which may cause unstable fixation. Pin placement should not obstruct incisions and should be placed away from the orbits. • A horseshoe headholder, or foam/gel doughnut is often used alternatively for cranial remodeling operations, or cranial cases that do not require stereotactic precision. • Patients 1 cm), the trans-sulcal approach may allow easiest access for resection while minimizing

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Section 1  •  Intra-Axial Tumors

A

B

cranial tumor location is projected onto the scalp. • In most cases the patient is placed in the supine or in the lateral position. The tumor region is placed at the top of the operative field, as perpendicular to the horizontal plane as possible. • The head is stabilized using Mayfield skull clamps. • In the case of multiple intracranial metastases it is often possible to resect all accessible lesions without redraping the patient, using single or multiple craniotomies. Some authors advocate the use of an “in-between” position, so the patient may be maneuvered intraoperatively to place each targeted lesion at the top of the operative field in turn. Skin Incision

Figure 3.1 Surgical corridors that can be used to approach supraten-

torial subcortical lesions. (A) Lesions located in contact with the cortical surface are typically approached with the transcortical route. (B) Subsulcal locations are best approached by a trans-sulcal approach splitting the sulcus leading to the lesion. If the overlying cortex is non-eloquent, the lesion can be approached transcortically to avoid damaging the vessels running within the sulci. The transcallosal and the sylvian fissure-splitting route are good options for deeper-seated lesions. Modified from Lang, F.F., Chang, E.L., Suki, D., et al., 2004. Metastatic brain tumours. In Winn, H.R. (Ed.), Youmans Neurological Surgery, fifth ed. WB Saunders, Philadelphia.

disruption of the overlying cortical tissue, which is especially critical in eloquent areas. Contraindications of the Trans-Sulcal Approach • Deep intra-axial lesions that require wider exposure to localize and resect the lesion. Indications of the Transcortical Approach • Subcortical tumors that do not underlie an obvious sulcus and do not involve eloquent cortical regions. • This may provide a more direct access for operative resection than the trans-sulcal approach. Contraindications of the Transcortical Approach • Tumors involving eloquent regions. • Tumors that underlie an evident sulcus that may be better resected with a trans-sulcal approach.

Surgical Procedure Patient Positioning • Using a combination of anatomic landmarks and intraoperative neuronavigation, the intra-

• An incision centered on the tumor is performed. This incision can be linear, curvilinear or trapdoor depending on the location and size. • The planned incision should be large enough for a generous craniotomy to allow ample visualization of the gyrus and sulcal anatomy, as well as provide flexibility during tumor resection. Craniotomy • A large craniotomy allows ample visualization of the relevant sulci and gyri, potential other sulci and the cortical vasculature, namely the veins. • We generally only require one or two burr holes depending on the location and quality of the dura mater. Dural Opening • The dura mater is opened in either a cruciate or C-shaped/trapdoor fashion. A cottonoid can be used in between the arachnoid and the dura mater to protect the cortical surface. Following each subsequent cut the cottonoid can be advanced forwards. Procedure • At this point the surgical corridor can be assessed with direct visualization of the sulci and surrounding gyri, intraoperative neuronavigation and/or intraoperative ultrasonography. • Intraoperative brain stimulation, motor evoked potentials and somatosensory evoked potentials can be used to identify eloquent areas.

Chapter 3  •  Trans-Sulcal Versus Transcortical Resection of Subcortical Metastases Trans-Sulcal Approach (Tumors in the subcortical space underlying a seen sulcus and/or underlying eloquent cortex — Figure 3.2.) • The sulcus or sulci to be entered are identified. • The arachnoid overlying the sulcus is incised sharply with either an 11-blade or 18-gauge needle, with care taken to avoid injuring the underlying vasculature. The sulcus is typically opened where the subarachnoid space is the largest. In general, the subarachnoid space over the arteries is typically more robust than over the veins. • The sulcus is opened as widely as possible, using a combination of sharp and blunt dissection. In order to preserve the anatomy, bipolar cautery is not used unless bleeding occurs. Venous bleeding can typically be stopped with gentle pressure with cotton and/or placement of Gelfoam. It is critical to spare the arteries and veins running within the sulci that supply and provide venous drainage of surrounding gyri, respectively. • We try to avoid the use of retractors to prevent pressure-related iatrogenic injury to the surrounding cortical tissue. Larger and/or deeper tumors may require the need for a fixed

retractor system and/or the use of a tubular retractor (Vycor). • Once the tumor is identified, the tumor can be removed either en bloc or piecemeal. We prefer an en bloc approach (see Figure 3.3). With the en bloc approach the tumor is dissected free from the surrounding parenchyma. Typically, the tumor is surrounded by a rim of gliotic parenchyma that separates the lesion from the edematous parenchyma, forming a pseudocapsule. The tumor is resected circumferentially by dissecting the pseudocapsule from the surrounding parenchyma. The borders are identified and held with the use of cottonoids. In order to reduce bleeding during the tumor resection, the small vessels supplying the metastasis are identified and individually coagulated and cut. Once the complete lesion is dissected away from the parenchyma, the tumor can be extracted en bloc. • In cases where the tumor capsule is not robust and/or involves eloquent cortex, a piecemeal

1

1

2

6

3

2

5

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Figure 3.3 En bloc technique for resection of subcortical metastases.

Figure 3.2 Trans-sulcal approach. First, the tumor is localized by

direct observation, neuronavigation or intraoperative ultrasonography. Cortical eloquence can be tested by direct cortical stimulation. Finally, the best sulcus to approach the lesion is determined. The steps of the procedure are: 1 Arachnoid incision. 2 Splitting of the sulci, vessel dissection and hemostasis. 3 Cortical–subcortical frontier — transection of the subcortical white matter. 4 Tumor visualization. 5 Central debulking. 6 Dissection of the tumor margins.

The steps of the procedure are: 1 Subpial dissection — retraction and dissection of the metastasis away from the healthy parenchyma. 2 Disconnecting the blood supply with the bipolar while advancing. 3 Advancement of the cottonoid from superficial to deep. 4 Repeat steps 1, 2 and 3 until the complete lesion is surrounded by cottonoids. 5 Disconnection of the remaining vascular supply. 6 En bloc extraction of the metastasis. 7 Cavity inspection for tumor remnants and hemostasis. In large tumors, the central core of the lesion is debulked before proceeding with step 1. This allows manipulating the tumor pseudocapsule inwards (from the periphery to the center) and away from the parenchyma instead of pulling the parenchyma away from the lesion. Modified from Hentschel, S.H., Lang, F.F. 2003. Current surgical management of glioblastoma. Cancer J. 9,113–126.

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Section 1  •  Intra-Axial Tumors approach is often preferred. In this case, the tumor is entered and debulked from the center. After the tumor is debulked, the edges of the tumor are moved inwards and removed. In either case, in order to provide sufficient working space, the sulci are usually opened widely. Transcortical Approach (Tumors in the subcortical space that do not underlie an obvious sulcus and do not involve eloquent cortical regions — Figure 3.4.) • Eloquence can be established with preoperative functional imaging and/or intraoperative mapping. • Using navigation, the tumor is located and the site of corticectomy is chosen based on tumor location and avoidance of eloquent regions. • The corticectomy can be done in a linear fashion for small tumors. For larger tumors, either a larger linear corticectomy is made or a circumferential corticectomy is performed.

• The arachnoid overlying the cortex is coagulated with bipolar cauterization and then incised with microscissors. • The underlying white matter is entered until the tumor is encountered. • The tumor is debulked as previously described (see Figure 3.3), either in an en bloc or piecemeal fashion. Closure • Because the parenchyma is violated, there is an inherent increased risk of bleeding. As a result, hemostasis must be ensured prior to closure. • Standard dural, bone and skin closure are performed.

Pitfalls and Limitations • Patients with intracranial metastases often require radiation and chemotherapy. It is imperative to not delay critical adjuvant therapy with iatrogenic complications, including neurologic deficits and wound infections.

1 2 3 4

5

6

A

B

Figure 3.4 Transcortical approach. First, the tumor is localized by direct observation, neuronavigation or intraoperative ultrasonography. Cortical eloquence can be tested by direct cortical stimulation. Finally, the best non-eloquent cortical surgical window to approach the lesion is determined. (A,B) The steps of the procedure are: 1 Cauterizing the margins of the cortical surgical windows. 2 Cutting the margins of the cortical surgical windows. 3 Corticectomy. 4 Tumor visualization. 5 Central debulking. 6 Dissection of the tumor margins.

Chapter 3  •  Trans-Sulcal Versus Transcortical Resection of Subcortical Metastases • The trans-sulcal approach spares overlying cortical tissue at the expense of manipulating vessels within the sulci, which can lead to ischemic deficits. Before conducting this approach one must carefully study the preoperative imaging, especially T2-weighted MRI which better elucidates relevant sucli. The trans-sulcal approach provides a limited operative corridor and may not allow sufficient exposure for resection of large, subcortical lesions. • The transcortical approach is preferred for tumors that come to the cortical surface. Subcortical metastases that do not come to the surface may require a corticectomy. While this approach is advantageous for larger lesions, this comes at the expense of damaging more cortex and underlying white matter than the trans-sulcal approach. Pearls • Select the approach based on tumor location and overlying cortical function. The use of preoperative imaging, intraoperative neuromonitoring, neuronavigation and mapping can minimize the likelihood of causing neurologic deficits. • Minimize manipulation of the sulcal and cortical vasculature, especially in eloquent cortex. • Minimize retraction of surrounding parenchyma with either approach.

Suggested Reading Aoyama, H., Shirato, H., Tago, M., et al. 2006. Stereotactic radiosurgery plus whole-brain radiation therapy vs stereotactic radiosurgery alone for treatment of brain metastases: a randomized controlled trial. JAMA J. Am. Med. Assoc. 295(21), 2483–2491. Chaichana, K.L., Acharya, S., Flores, M., et al. 2014. Identifying better surgical candidates among recursive partitioning analysis class 2 patients who underwent surgery for intracranial metastases. World Neurosurg. 82(1–2), e267–e275. Chaichana, K.L., Gadkaree, S., Rao, K., et al. 2013. Patients undergoing surgery of intracranial metastases have different outcomes based on their primary pathology. Neurol. Res. 35(10), 1059–1069. Chaichana, K.L., Rao, K., Gadkaree, S., et al. 2014. Factors associated with survival and recurrence for patients undergoing surgery of cerebellar metastases. Neurol. Res. 36(1), 13–25. Chang, E.L., Wefel, J.S., Hess, K.R., et al. 2009. Neurocognition in patients with brain metastases treated with radiosurgery or radiosurgery plus whole-brain irradiation: a randomised controlled trial. Lancet Oncol. 10(11), 1037–1044. Patchell, R.A., Tibbs, P.A., Regine, W.F., et al. 1998. Postoperative radiotherapy in the treatment of single metastases to the brain: a randomized trial. JAMA J. Am. Med. Assoc. 280(17), 1485–1489.

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4

 

Deep Intra-Axial Tumors Jordina Rincon-Torroella, Kaisorn L. Chaichana, Salvador Manrique-Guzman and Alfredo Quiñones-Hinojosa To see Video 4, please go to ExpertConsult.com

Indications and Preoperative Considerations

Skin Incision

• Selective deep-seated intra-axial tumors can be surgically resected with the use of a tubular retractor system that creates a controlled surgical corridor with minimal brain retraction and damage to surrounding brain tissue. • This controlled surgical corridor can be used for most intra-axial lesions, including lesions involving: • Basal ganglia. • Insular cortex. • Lateral and/or third ventricle. • Pineal region. • Pulvinar/posterior thalamus.

Contraindications • Infiltrative resection.

lesions

that

preclude

a

safe

Surgical Procedure Patient Positioning • Preoperative MRI is obtained with fiducial markers (stereotactic navigation) and preoperative trajectory planning with special attention not to injure the corticospinal tracts and/or other eloquent tracts in the brain (Figure 4.1). • A Mayfield headholder is applied and registration with the navigation system is performed. • The head is rotated so the tumor plane is perpendicular to the floor. • The head is kept above the level of the heart.

• The incision and craniotomy are planned based on the location of the lesion using preoperative MRI and/or frameless stereotactic navigation. • Patients with anterior lesions in the basal ganglia can also be approached through an eyebrow or eyelid incision with a supraorbital craniotomy. • Soft tissue dissection should be carefully made with good hemostatic control. • The musculocutaneous flap can be retracted with retractors or elastic bands depending on the shape of the flap. Craniotomy • An entry point is selected based on tumor location and image guidance. • One burr hole is often sufficient for small craniotomies. Extended craniotomies may require more burr holes. • Gentle detachment of the dura mater from the bone is done with a Penfield No. 3 dissector. • A tailored craniotomy is performed with a highspeed drill. The craniotomy must be large enough to fit the tubular retractor. Dural Opening and Intradural Dissection • Dural opening is done according to the need of resection and localization of the lesion. Generally a cruciate dural opening is performed. A C-shaped opening is also a feasible option. • For subcortical tumors, a cylindrical retractor may be inserted through the planned surgical

Chapter 4  •  Deep Intra-Axial Tumors

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B

Figure 4.1 Pre- and postoperative imaging. (A) Preoperative T2-weighted FLAIR image. A non-enhancing lesion is seen arising in the posterior third ventricle. This lesion was compatible with an epidermoid tumor. (B) Postoperative T2-weighted FLAIR image after a resection via the transsulcal approach with a tubular retractor. The lesion has been resected and the trajectory of the tubular retractor can be visualized. These images demonstrate the minimal invasive access with minimal impact to the surrounding parenchyma. © A. Quiñones-Hinojosa.

corridor to access the deep-seated pathology and to protect the healthy parenchyma and surrounding white matter during the resection. • The initial approach can be transcortical or trans-sulcal. • Corticectomy or sulcus splitting is planned such that any major veins and arteries will not be sacrificed. Non-eloquent gyrus can be entered so that eloquent gyri may be preserved. Cortical stimulation with cortical mapping can also be useful when eloquent cortex is involved and/or where the question arises. • Some procedures can be performed while the patient is awake. • Major white fiber tracts must be avoided at the depth of the trajectory. • The corticectomy is done via a pial incision for the transcortical trajectory, while an arachnoid dissection is made for a trans-sulcal trajectory. The opening must be large enough to place the retractor tube. • A 14-French peel-away sheath cannula can be advanced into the parenchyma with the navigation probe along the desired trajectory. • The elliptical-shaped tubular retractor gently splits the cortex as it is advanced into white matter without further damage or transection (Figure 4.2). • The selected length of the tubular retractor is several millimeters longer than the planned

trajectory from the cortical surface to the target lesion. • The retractor is opened in order to create a surgical corridor to access the lesion. The tubular retractor is a self-retracting system which that is held in place by a retractor system. We typically use the Greenberg system. • The tumor is visualized at the end of the tubular retractor. Further subsequent white matter dissection may be needed in order to localize the lesion and affected parenchyma. In those cases, the tubular retractor can be mobilized without a need for repositioning. • After the retractor is inserted, the microscope is subsequently brought into the field for microscopic tumor debulking/resection. Either an en bloc or piecemeal resection can be conducted depending on the tumor infiltrative nature and consistency (Figure 4.3). • After obtaining hemostasis at the tumor bed, the retractor is loosened and slowly removed in millimeter increments. Closure • The dura mater is primarily closed. • Dural substitute or a sealant can be placed over the dura mater and can be used in order to facilitate closure. This is especially critical when the ventricle is entered.

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24

Section 1  •  Intra-Axial Tumors

A

B

Figure 4.2 (A) Visual field with the tubular retractor. The white matter can be visualized. (B) Visual field after removing the tubular retractor. The cortical transection is minimal. The surrounding parenchyma has not been affected; there were no signs of ischemia or brain edema on postoperative imaging. © A. Quiñones-Hinojosa.

• Advancing the tubular retractor some additional millimeters in the desired trajectory to the target avoids inadvertent cortical laceration and provides additional room for retractor manipulation. • Bayoneted instruments are very useful for this approach given the relatively small working space/ visualization allowed by the retractor (see Figure 4.3).

Suggested Reading

Figure 4.3 Macroscopic picture of the surgical field. The tubular

retractor provides a safe working channel to access deep-seated pathology. Bayoneted instruments are optimal to work through the narrow space while allowing maximal visualization of the surgical target. © A. Quiñones-Hinojosa.

• The bone flap is then reattached and secured with titanium plates. Pearls • Tubular retractors minimize pressure on surrounding tissue in comparison to traditional spatula retractors.

• Instrument access into the affected area is facilitated by the retractor, thus minimizing injury to the surrounding tissue.

Greenfield, J.P., Cobb, W.S., Tsouris, A.J., Schwartz, T.H., 2008. Stereotactic minimally invasive tubular retractor system for deep brain lesions. Neurosurgery 63, 334–339; discussion, 339–340. McLaughlin, N., Prevedello, D.M., Engh, J., et al. 2013. Endoneurosurgical resection of intraventricular and intraparenchymal lesions using the port technique. World Neurosurg. 79 (2 Suppl), S18.e1–e8. Raza, S.M., Garzon-Muvdi, T., Boaehene, K., Olivi, A., Gallia, G., Lim, M., et al. 2010. The supraorbital craniotomy for access to the skull base and intraaxial lesions: a technique in evolution. Minim. Invas. Neurosurg. 53, 1–8. Raza, S.M., Recinos, P.F., Avendano, J., Adams, H., Jallo, G.I., Quiñones-Hinojosa, A., 2011. Minimally invasive trans-portal resection of deep intracranial lesions. Minim. Invas. Neurosurg. 54, 5–11. Zhong, J., Dujovny, M., Perlin, A.R., Perez-Arjona, E., Park, H.K., Diaz, F.G., 2003. Brain retraction injury. Neurol. Res. 25, 831–838.

5

 

Brainstem Tumors Jordina Rincon-Torroella, Kaisorn L. Chaichana and Alfredo Quiñones-Hinojosa To see Video 5, please go to ExpertConsult.com

Indications • In general, surgical resection is preferred for accessible, symptomatic lesions with a focal growth pattern, while stereotactic biopsy is typically reserved for tumors with a diffuse growth pattern. • If obstructive hydrocephalus is present, it is treated with a CSF diversion technique. In pediatric cases, and selective adult cases, an endoscopic third ventriculostomy (ETV) is preferred over ventriculoperitoneal shunt (VPS) placement.

Contraindications • Diffuse pontine glioma (brain biopsy is also controversial). • Lesions that are clinical and radiologically stable may be initially managed in a non-operative manner with serial imaging. Surgery is performed in cases of tumor progression/new contrast enhancement on MRI or development of obstructive hydrocephalus (third ventriculostomy and/or decompression). • Because most midbrain lesions have an indolent course, some surgeons discourage open resections for these lesions.

Preoperative Considerations • Brainstem tumors account for 10–20% of pediatric and 1.5–2.5% of adult intracranial tumors. • Brainstem gliomas are the most common pathologic entity.

• Pathologies include gliomas, metastatic tumors, cavernous malformations, hemangioblastomas, demyelinating processes, infectious processes, granulomas, infarction or hematomas. • Classification of brainstem lesions is based on CT and MRI (Choux et al., 2000) (Figure 5.1): • Type I: diffuse. • Type II: focal intrinsic. • Type III: focal exophytic. • Type IV: cervicomedullary. • Growth pattern, location and the presence of hydrocephalus or hematoma modifies the surgical management of the lesion. • Preoperative imaging studies: • MRI: Non-contrast enhancement, focal and well-circumscribed exophytic lesions are lowgrade features. Contrast enhancement may be indicative of a higher-grade lesion for both focal or diffuse lesions. • PET (positron emission tomography): Used in the attempt to differentiate low-grade from high-grade gliomas. • DTI (diffusion tensor imaging): Can elucidate the relationship of motor and sensory tracts to the brainstem lesion. Current uses are limited. • Preoperative planning: Careful study of the preoperative imaging is required to select the most suitable approach in order to avoid major neurovascular structures, white matter tracts and brainstem nuclei. • Location: Brainstem gliomas located in the midbrain and medulla are usually focal and low grade. Gliomas located in the pons usually have an infiltrative and more aggressive nature.

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Section 1  •  Intra-Axial Tumors

Focal intrinsic tectal plate (Type II) Focal intrinsic midbrain (Type II) Dorsal exophytic pontine (Type III) Focal intrinsic pontine (Type II) Diffuse pontine (Type I) Dorsal exophytic medullary (Type III) Focal intrinsic medullary (Type II) Cervicomedullary (Type IV)

Figure 5.1 The various locations of brainstem tumors: focal intrinsic tectal plate; focal intrinsic midbrain; focal intrinsic pontine; dorsal exophytic pontine; diffuse pontine; focal intrinsic medullary; dorsal exophytic medullary.

Obstructive hydrocephalus is common in midbrain and dorsally exophytic tumors. • The management of diffuse tumors is controversial. At present, it is still acceptable to initiate standard, non-surgical therapy without pathological confirmation. Brainstem biopsy is not that common because of the risk of permanent damage to eloquent structures. However, with the improvement of surgical techniques and preoperative planning, the management is trending towards performing a biopsy for diagnosis and molecular characterization followed by adjuvant therapies if required.

Surgical Procedure Image-Guided Stereotactic Biopsy

• Transfrontal, extraventricular: lateral pons and middle cerebellar peduncle. Requires the use of a Leksell stereotactic frame. This route avoids the lateral ventricle and the tentorium does not block the access to more lateral lesions. Patient Positioning • Transfrontal: Patients can be positioned supine, in the lateral position or sitting. The head is turned contralaterally and the neck is flexed. • The suboccipital, transcerebellar approach is preferred for pontine lesions. For the suboccipital transcerebellar approach the Leksell frame is secured as inferiorly as possible. The patient is placed in the prone position with the neck flexed. The sitting position is also used by some surgeons.

Approaches

Frame Biopsy for Transfrontal   Extraventricular Approach

• Suboccipital transcerebellar: lower midbrain, pons, middle cerebellar peduncle and medulla. The cerebellar peduncle is a very good target for tumors located in the pons. • Transfrontal, transventricular: midline pons and medulla. Requires crossing the lateral ventricle, and the tentorial incisura set the lateral limits of the access.

• A Leksell stereotactic frame system is used. An MRI is performed following frame placement. • Reconstruction images are used to plan the point of entry, avoiding sulci and large cortical vessels and to set the target coordinates and trajectory. • After that, the frame needs to be assembled, the X and Y coordinates are set and the instrument guide and stopholders are fitted in the arch.

Chapter 5  •  Brainstem Tumors • In the operating room the patient is placed in the sitting position and light intravenous sedation is administered. The skin entry point is shaved, prepped and draped. The coordinates are set and checked. • For the contralateral, transfrontal, extraventricular approach the entry point is placed approximately 4 cm off midline in the coronal plane. • After the skin incision, a small craniotomy is made. • After warning the patient of potential mild discomfort, a spinal needle is used to puncture the dura mater. The biopsy needle is slowly passed down the preplanned trajectory. At the same time the patient is examined for any neurologic changes. Biopsy samples are taken using a sidecutting aspiration needle. • In both cases if the pathologic reading is nondiagnostic, additional samples can be obtained without a second needle pass from another enhancing region of the lesion. • Once the biopsy sample is obtained, a small volume of air can be injected to confirm the site of the biopsy on a postoperative MRI. Frameless Biopsy • Requires the use of preoperative imaging (or intraoperative MRI) and intraoperative neuronavigation. • Areas corresponding to contrast enhancement are targeted for biopsy in both superficial and deep portions of the lesion. The target region is usually selected to minimize the trajectory through the brainstem. • A straight trajectory is planned with the navigation system preoperatively. The trajectory is selected to pass through the largest dimension of the lesion when possible to allow for multiple biopsy sites via one needle pass. • The distance to the site is measured and marked on a 1.7-mm Nashold biopsy needle • A 0.5-cm linear incision and a burr hole are made at the entry point. The dura mater is opened using a sharp needle. • A beveled biopsy needle with a blunt stylet connected to the neuronavigation system is used to penetrate the brainstem. The needle is advanced slowly to the target following the planned trajectory and assisted by the neuronavigation system. A side-cutting biopsy needle is inserted through the passage and several samples are obtained. • Tissue specimens approximately 8 mm long and 1 mm thick are obtained and sent for frozen sectioning.

Open Biopsy The location and size of the tumor within the brainstem dictates the surgeon’s operative approach for resection (see Table 5.1 and Figure 5.2).

Table 5.1  Operative approach for resection is tailored to location and size within the brainstem Mesencephalon Ventral and interpeduncular cistern

Pterional or Orbitozygomatic approach

Lateral

Subtemporal approach

Dorsal

Supracerebellar– infratentorial approach

Pons Ventral

Pterional or Orbitozygomatic approach ± anterior petrosectomy

Lateral (middle cerebellar peduncle)

Retrosigmoid approach

Dorsal

Suboccipital approach

Fourth ventricular floor

Suboccipital approach (Telovelar approach)

Cerebellopontine angle

Retrosigmoid approach

Pontomedullary region Lateral

Far lateral approach

Posterolateral

Retrosigmoid approach

Medulla Ventral

Poor surgical access, high eloquence

Lateral

Far-lateral approach

Dorsal

Suboccipital approach ± cervical laminectomy

Cervicomedullary junction Ventral

Poor surgical access, high eloquence

Lateral

Far lateral approach

Dorsal

Suboccipital approach and/or cervical laminectomy

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Section 1  •  Intra-Axial Tumors b) Solid

Orbitozygomatic

Subtemporal

Petrosal

Retrosigmoid

Far lateral Suboccipital

Supracerebellar infratentorial

Figure 5.2 Approaches to the brainstem. Reproduced with permission from Gilberto, G., Lanzino, G., 2011. Cavernous malformations. In Jandial, R., McCormick, P., Black, P. (Eds.), Core Techniques in Operative Neurosurgery. Saunders, Elsevier Inc., Philadelphia.

tumors resection technique: Debulking with ultrasonic aspiration with low intensity and low suction rate. Use of sharp instruments to dissect and disconnect blocks of tumor at the borders (microbiopsy forceps with microscissors) (Figure 5.3F). c) Highly vascular lesions: the vessels must be coagulated during tumor debulking which may cause ischemic damage to surrounding normal brain. Hemostasis can be challenging and may require the use of abundant irrigation and hemostatic agents. 6. Delineate the tumor borders: When delineation between tumor and normal brain is identified, gross-total resection is feasible in most cases. If that limit cannot be identified, tumor resection should be stopped. The resection also needs to be stopped if firing of the nerves is recorded by neuromonitoring. Mapping the walls of the tumor cavity is also a valid option to detect nearby eloquence. Cauterization should also be avoided at the margins of the lesion as this may cause damage at the surrounding parenchyma. Selection of the Incision Site at the Brainstem

Stepwise Intradural Dissection of Intrinsic Brainstem Tumors (Figure 5.3) 1. Selection

of the safe entry zone at the brainstem (Figure 5.3A). 2. Incision at the brainstem surface: a less than 1-cm incision is performed at the surface of the brainstem (Figure 5.3B). 3. For cystic lesions, aspirate the cystic contents to gain space for manipulation. 4. Send biopsy for perioperative histopathological analysis (if the lesion is not low grade, there is controversy regarding the benefit of debulking). 5. Piecemeal dissection: The brainstem has no redundancy and is very susceptible to manipulation. A technique to avoid temporary or permanent damage is to always manipulate the lesion instead of manipulating the parenchyma. Tumor debulking is achieved in a central to marginal direction. Cotton balls can be placed at the center of the lesion to safely aspirate and also to mobilize the walls of the resection cavity. Microretractors may be used to separate the resection cavity borders (Figure 5.3C). a) Soft tumors resection technique: Coagulation with a microbipolar or N-Yag laser with suction of the cauterized tissue (Figure 5.3D).

• The parenchymal incision is usually placed at the region where the tumor is closest to the surface. Anatomical knowledge, especially of brainstem nuclei and tracts, vascular supply and anatomy, preoperative planning and often brainstem mapping are essential to select the optimal incision site with minimal morbidity. Neuronavigation is used as guidance. Color changes, loss of surface landmarks and bulging may be used as a guide in mapping the floor of the fourth ventricle and brainstem when searching for safe entry zones. Brain Mapping • For tumors approached through the fourth ventricular floor (e.g. telovelar approach), mapping of the floor is extremely important for placement of the incision to avoid cranial nerve nuclei, such as VII, IX, X and XII (see Chapter 15, Telovelar Approach). • Although safe entry zones have been described, intrinsic tumors of the brainstem often distort the normal anatomy and displace the normal landmarks. Neurophysiological mapping helps overcome this limitation and identifies eloquent and non-eloquent regions in order to select the best entry point and avoid brainstem injury.

A

B

C

D

E

F

Figure 5.3 (A–F) Stepwise resection of focal intrinsic brainstem tumors.

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Section 1  •  Intra-Axial Tumors damage in that area while attempting a more aggressive resection (especially cranial nerves VI and VII). Subtotal resection may increase the risk of obstructive hydrocephalus but prevents major deficits.

Intradural Dissection of Exophytic   Brainstem Tumors • No parenchymal incision is required. • Resection starts with the exophytic component. • Dissection is cautiously continued following the corridor provided by the same lesion. • Do not follow the tumor into the brainstem in dorsally exophytic brainstem gliomas. They arise from the floor of the fourth ventricle (high eloquence, risk of major deficits). • The exophytic component can encase critical neurovascular structures. Careful study of the preoperative imaging includes the identification of these structures and connections. Exophytic lesions at the ventral brainstem have to be dissected with extreme caution because they can encase the basilar, vertebral arteries, and/or perforators. Exophytic lesions that protrude towards the fourth ventricle can be successfully reached trough the telovelar approach. • Dorsally exophytic brainstem gliomas arise from the floor of the fourth ventricle. The goal of surgery for the intrinsic component is de­ bulking rather than a complete excision, due to the high likelihood of devastating cranial nerve

Complications • During surgery to the brainstem, the anesthesia team must watch carefully for intraoperative bradycardia or hemodynamic instability. • Retraction on the cerebellar hemispheres should be minimized to diminish the risk of postoperative cerebellar mutism and pseudobulbar symptoms. • Transient or permanent worsening of the neurologic condition is not unusual in brainstem surgery (ataxia, diplopia, nystagmus, facial palsy). • Patients require very close observation postoperatively. In pontine lesions, the patient may experience transient or permanent dysphagia and vocal cord palsy. There is increased risk of aspiration and the patient must be closely monitored. Respiratory difficulties are also common. The patient remains intubated at least overnight and is extubated when full consciousness is

Brainstem glioma MRI of brain and spine

Mesencephalon likely low grade

Cervicomedullary likely low grade

Pons or Medulla high or low grade

Focal/exophytic likely low grade

No

Diffuse likely high grade (exclude NF-1)

Hydrocephalus

Tectal

Tegmental

Observation

Craniotomy for surgical removal

Yes

Endoscopy or shunt

Radiotherapy +/– chemotherapy

Figure 5.4 Surgical management for brainstem tumors depends on location. Mesencephalon: Usually benign, careful watching, ETV if obstructive hydrocephalus is present, no biopsy/resection except in contrast-enhancing lesions or/and progressing symptoms. Pons and medulla: (1) Diffuse intrinsic pontine tumors: MRI has been gold standard for diagnosis with adjuvant treatment. The low specificity of this method is questioning whether biopsy needs to be reintroduced into common practice. (2) Dorsally exophytic brainstem tumors: Surgical removal to prevent obstructive hydrocephalus. ETV if removal is unsuccessful. After Jallo, G.I., Freed, M.S., Roonprapunt, C., Epstein, F. 2003. Current management of brainstem gliomas. Ann. Neurosurg. 3(1), 1–17 (Figure 5).

Chapter 5  •  Brainstem Tumors regained and the ventilator parameters are normalized. If the function is not completely regained the patient may need a thyroplasty or tracheotomy and a feeding gastrostomy. • Watch the patient for obstructive hydrocephalus and hemorrhage. In midbrain tumors, the patient may experience a semi-comatose state and require several days in the neurology intensive care unit to recover. • Highly vascularized lesions may require generous coagulation, which may cause ische­ mic damage to the surrounding healthy parenchyma. • In stereotactic biopsy, a CT scan is performed postoperatively to rule out the existence of hematoma and to confirm the biopsy site. • If an external ventricular drain (EVD) has been placed, the drainage is kept for a few days until deciding whether to remove the drain or place a permanent shunt. Pearls • Select the appropriate brainstem incision site in intrinsic tumors. Keep in mind the anatomy of the white matter tracts. In some instances the region where the tumor is closest to the surface is not the best site to place the incision. • Brainstem tumors are removed in a piecemeal fashion. Maneuvers to remove them en bloc may cause damage to the surrounding parenchyma and marked postoperative deficits. • Surgical management for brainstem tumors will vary depending on tumor location (Figure 5.4).

Suggested Reading Amundson, E.W., McGirt, M.J., Alessandro Olivi, A., 2005. A contralateral, transfrontal, extraventricular approach to stereotactic brainstem biopsy procedures. J. Neurosurg. 102, 565–570. Bowers, D., Georgiades, C., Aronson, L., et al. 2000. Tectal gliomas: natural history of an indolent lesion in pediatric patients. Pediatr. Neurosurg. 32, 24–29. Cage, T.A., Samagh, S.P., Mueller, S., et al. 2013. Feasibility, safety, and indications for surgical biopsy of intrinsic brainstem tumors in children. Childs Nerv. Syst. 29(8), 1313–1319. Chaichana, K.L., Quiñones-Hinojosa, A., 2013. Neuro-oncology: paediatric brain tumours – when to operate? Nat. Rev. Neurol. 9(7), 362–364. doi: 10.1038/nrneurol.2013.97. Choux, M., Lena, G., Do, L., 2000. Brain stem tumors. In: Choux, M., Di Rocco, C., Hockley, A. (Eds.), Pediatric Neurosurgery. Churchill Livingstone, New York, pp. 471–491. Frazier, J., Lee, J., Thomale, U., et al. 2009. Treatment of diffuse intrinsic brainstem gliomas: failed approaches and future strategies. J. Neurosurg. Pediatr. 3, 259–269. Quiñones-Hinojosa, A., Gulati, M., Lyon, R., et al. 2002. Spinal cord mapping as an adjunct for resection of intramedullary tumors: surgical technique with case illustrations. Neurosurgery 51(5), 1199–1206; discussion 1206–1207. Quiñones-Hinojosa, A., Lyon, R., Du, R., et al. 2005. Intraoperative motor mapping of the cerebral peduncle during resection of a midbrain cavernous malformation: technical case report. Neurosurgery 56(2 Suppl), E439; discussion E439. Recalde, R.J., Figueiredo, E.G., de Oliveira, E., 2008. Microsurgical anatomy of the safe entry zones on the anterolateral brainstem related to surgical approaches to cavernous malformations. Neurosurgery 62(3 Suppl 1), 9–15; discussion 15–17.

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Cerebellar Tumors Kaisorn L. Chaichana, Jordina Rincon-Torroella, Salvador Manrique-Guzman and Alfredo Quiñones-Hinojosa To see Video 6, please go to ExpertConsult.com

Indications The suboccipital craniotomy is used for most lesions in the posterior fossa. Its indications are: • Brain tumors such as meningiomas, ependymomas, gliomas, medulloblastomas, acoustic neuromas and metastatic lesions. • Vascular lesions such as aneurysms, cavernous malformations, arteriovenous malformations and intraparenchymal hemorrhages. • Developmental anomalies such as Chiari malformations. • Posterior fossa infections.

Contraindications • Cervical spine pathology that would oppose flexion and reduction of the neck. • The sitting positioning is contraindicated in patients with patent foramen ovale (this position requires a preoperative echocardiogram to rule out patent foramen ovale). • If lesions extend above the tentorium, special consideration should be given to a combined approach, e.g. a supracerebellar and a supratentorial approach, to have good visualization of the lesion to be resected. • If the lesion extends from the posterior fossa to the middle fossa, a combined or staged lateral approach may be considered.

Surgical Procedure Patient Positioning • Various sitting positions can be used depending on the location of the lesion, patient’s body

habitus and other potential medical conditions (i.e. patent foramen ovale). • Park bench position (Figure 6.1): This is a modification of the lateral position, and used more commonly for more laterally positioned lesions including lesions of the lateral cerebellar hemisphere and cerebellopontine angle, as well as the far lateral approach (see Chapter 22). The head is flexed and the vertex of the head is tilted towards the floor. Excessive neck flexion and/ or side bending may impede venous return. The patient is well padded to avoid pressure injuries, especially to the ulnar nerve, brachial plexus and popliteal fossa. • Prone Concorde position (Figure 6.2): The position is more commonly used for midline lesions located caudally and at the craniocervical junction. The patient is anesthetized in the supine position and then turned prone and placed on chest rolls. For the Concorde position the head is flexed and reduced, the thorax is elevated, Trendelenburg position is applied and the legs flexed at the knees. • Sitting position: This is less frequently used because of its potential complications (e.g. air embolism, increased risk of pneumocephalus), but its advantages include improved venous drainage and gravity retraction of the cerebellar hemispheres. It can be used for pineal region tumors and/or a supracerebellar infratentorial approach. • Surgical navigation is registered after positioning. The surgical field should be perpendicular to the ground. The surgical field is sterilely prepped and local anesthetic is applied.

Chapter 6  •  Cerebellar Tumors

Figure 6.2 Concorde position for midline posterior fossa approaches. Neck flexion must be achieved. Bed tilting is required. © A. Quiñones-Hinojosa.

Figure 6.1 Park bench position for suboccipital approach: patient

positioning and padding. Caution is necessary to avoid brachial plexus injury. Several craniotomies can be performed to approach the cerebellar lesions. A small suboccipital approach is sufficient for localized lesions in the cerebellar hemisphere or vermis. A larger craniotomy will be required for larger pathology or pathology extending to the pineal region, venous sinuses or supratentorial space. The torcula and transverse sinus may be exposed and a supracerebellar–infratentorial or supracerebellar–transtentorial approach can be implemented. More lateral and ventral lesions would require a far lateral approach. Reproduced with permission from Pascual, J.M., Prieto, R., 2012. Surgical management of severe closed head injury in adults. In Quiñones-Hinojosa, A. (Ed.), Schmidek & Sweet, Operative Neurosurgical Techniques: Indications, Methods and Results, sixth ed. Saunders, Elsevier Inc., Philadelphia.

Incision

Asterion

Foramen magnum

Mastoid process Atlas

Skin Incision • The incision is made depending on the location of the lesion and the position of the patient. Options include midline or paramedian incisions, and the potential shapes can be a straight line, C- or S-shaped incision, or hockey stick incision. The shape depends on the area that needs to be exposed. • Straight midline: The patient is typically prone for a straight midline posterior fossa approach for centrally located or extensive lesions, or a lesion located caudally at the craniocervical junction. A linear skin incision is made in the midline extending from 4–5 cm above the inion down to the spinous process of the second cervical vertebra (C2). The length of the incision allows for wide lateral exposure of the posterior cervical fascia (Figure 6.3). A similar linear midline skin incision is made if the patient is in the sitting position. • Paramedian (lateral): A C- or S-shaped incision, as well as a straight line, can be made behind the ear for small localized, lateral lesions,

Figure 6.3 Suboccipital skin incision and bone landmarks. The skin

incision extends from 4–5 cm above the inion down to the spinous process of C2. Reproduced with permission from Raza, S.M., Quiñones-Hinojosa, A., 2011. Suboccipital craniotomy. In Jandial, R., McCormick, P., Black, P. (Eds.), Core Techniques in Operative Neurosurgery. Saunders, Elsevier Inc., Philadelphia.

especially those in the lateral brainstem. An S-shaped incision starts above the ear and extends down near the C2 spinous process, while a C-shaped skin incision arcs from the mastoid tip to above the ear. Both incisions allow exposure of the sigmoid sinus and sigmoid–transverse sinus junction. • The fascia is cut with a linear incision, and the suboccipital muscles are dissected en bloc from the skull and retracted laterally with selfretaining retractors. Craniotomy • The craniotomy is tailored to the lesion. For small, localized lesions, only a small craniotomy

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34

Section 1  •  Intra-Axial Tumors is needed. For larger lesions, a craniotomy that involves both cerebellar hemispheres and the torcula and transverse sinuses may be needed (Figure 6.4). If the venous sinuses have to be exposed, burr holes can be placed close to the transverse and/or the sigmoid sinus in order to complete a craniotomy. Then the craniotomy is done from the burr holes to either side of the foramen magnum. The last cut is the one that crosses over the transverse or sigmoid sinuses. The bone overlying the sinuses can be drilled by means of a burr or removed with a rongeur. This maneuver is done to prevent the transection of the sinuses with the craniotome during the craniotomy. • In both cases the craniotomy is performed carefully to preserve the underlying dura and dural sinuses. • A laminotomy or laminectomy at C1 allows for a wider dural opening, with a more inferior extension and more lateral mobilization of the dural flaps, as well as dural closure. It is useful for foramen magnum lesions and tonsillar herniation. In young patients the craniotomy may begin on one side of the foramen magnum, extend up to the transverse sinuses and finish on the other side of the foramen magnum, without requiring an initial burr hole. • Finally, the rim of the foramen magnum is rongeured to extend the opening laterally to the occipital condyles.

Dural Opening • Dependent on the extent of resection and/or the location of the lesion. • In the midline suboccipital craniotomy, the dura can be opened in a Y-shaped fashion. The superior limb of the dura extends to the inferior aspect of the transverse sinus. The inferior limb extends downwards to the foramen magnum. Care must be taken to avoid opening the venous sinuses. Large venous plexus and circular sinuses may be present in the foramen magnum area. Violation of those sinuses makes homeostasis more difficult and increases the risk of air embolism. • In the paramedian/lateral craniotomy, the dura is opened either in a cruciate form or in a U-shaped form with the attachment towards the sigmoid sinus. • Special care should be taken not to enter the transverse or the sigmoid sinus and hemostatic agents should be available. Intradural Dissection • Small superficial intra-axial tumors can be resected via a transcortical approach. Deeper lesions can be resected with the use of the tubular retractor. Ventricular lesions can be resected with tonsillar elevation if they are small or a telovelar approach for larger lesions.

Arachnoid (cisterna magna)

Transverse sinus Dura

Cerebellar tonsils

Tumor

Foramen magnum

Atlas

Atlas

A

B

Figure 6.4 (A) Dural opening: Y-shaped dural incision. (B) Opening of the arachnoid with exposure of the underlying cerebellar hemispheres,

cerebellar vermis and brainstem. Reproduced with permission from Raza, S.M., Quiñones-Hinojosa, A., 2011. Suboccipital craniotomy. In Jandial, R., McCormick, P., Black, P. (Eds.), Core Techniques in Operative Neurosurgery. Saunders, Elsevier Inc., Philadelphia.

Chapter 6  •  Cerebellar Tumors • The branches of the superior cerebellar artery, posterior inferior cerebellar artery and anterior inferior cerebellar artery must be preserved during the resection. If the brainstem is reached, the floor of the fourth ventricle and the brainstem may be protected with direct visualization and cottonoids as the tumor is resected. • In Chiari malformations and/or during removal of large tumors with tonsillar herniation, removing C1 allows a good decompression. The cisterna magna can be opened in order to fully visualize the tonsils and/or to be able to release cerebrospinal fluid for decompression. If there is a velum or arachnoid strip obstructing the fourth ventricle, it should be opened. • Intraoperative monitoring should be used to monitor brainstem and cranial nerve function. If changes are recorded, surgical resection should be paused. • After tumor resection, meticulous hemostasis should be obtained.

• The fascia and muscular layers are then closed with interrupted 0 Vicryl sutures. The wound should be closed in layers.

Pearls • The prone position does not provide optimal access to the airway but it has much lower incidence of air embolism compared to the sitting position. • The park bench position can increase venous pressure. Position the patient in order not to exert excessive neck flexion. • Avoid points of pressure to minimize chances of pressure injuries in any of these positions. • A cerebellar retractor placed on the superior aspect of the incision helps provide retraction during periosteal dissection. • Avoid the use of static parenchymal retractors. • Cautious and planned reconstruction optimizes operative and cosmetic results.

Closure • The dura is primarily closed with a 4-0 Nurolon running or interrupted sutures. • Depending on surgeon preferences, a piece of DuraGen or a sealant is placed over the dura. • The bone flap is then replaced and secured with titanium plates. There is a protracted debate about using a craniotomy vs. craniectomy in posterior fossa approaches. Craniectomy without replacement may be associated with increased risk of postoperative CSF leaks, headaches and wound revisions, but improves posterior fossa decompression. An intermediate option may be a craniectomy with replacement of the bone flap with a cranioplasty or titanium mesh.

Suggested Reading Chi, J.H., Lawton, M.T., 2006. Posterior interhemispheric approach: surgical technique, application to vascular lesions, and benefits of gravity retraction. Neurosurgery 59, ONS41–ONS49 [discussion ONS41–ONS49]. Lawton, M.T., Quiñones-Hinojosa, A., Jun, P., 2006. The supratonsillar approach to the inferior cerebellar peduncle: anatomy, surgical technique, and clinical application to cavernous malformations. Neurosurgery 59(4 Suppl 2), ONS-244–251; discussion ONS-251–252. Legnani, F.G., Saladino, A., Casali, C., et al. 2013. Craniotomy vs. craniectomy for posterior fossa tumors: a prospective study to evaluate complications after surgery. Acta Neurochir. (Wien) 155(12), 2281–2286. Quiñones-Hinojosa, A., Chang, E.F., Lawton, M.T., 2006. The extended retrosigmoid approach: an alternative to radical cranial base approaches for posterior fossa lesions. Neurosurgery 58(4 Suppl 2), ONS-208–214; discussion ONS-214.

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Cervicomedullary Tumors Jordina Rincon-Torroella, Karim Refaey, Kaisorn L. Chaichana and Alfredo Quiñones-Hinojosa To see Video 7, please go to ExpertConsult.com

Indications • In general, most focal cervicomedullary tumors are considered benign in pathology. Common tumors of the cervicomedullary region include low-grade astrocytomas, gangliogliomas and ependymomas. They are typically welldelineated and benign tumors, typically amen­ able to gross total resection.

Contraindications • Anaplastic astrocytomas with a diffuse growth pattern may also be encountered and are challenging to resect (biopsy can be done to establish a diagnosis). • Lesions that are stable clinically and radiographically, without signs of malignancy, may be initially managed in a non-operative manner with serial imaging and neurological evaluation.

Preoperative Considerations • The difficulty of surgical removal is correlated with the tumor’s growth pattern, pathology and involvement of surrounding structures. • Cervicomedullary tumors often extend from the lower two-thirds of the medulla to the superior aspect of the spinal cord. Some anatomical barriers (e.g. pyramidal decussation, medial lemniscus, etc.) confine these benign tumors in the cervicomedullary region making them more accessible and resectable (Figure 7.1). • Intraoperative monitoring and assessment of the functional integrity of neural pathways is typically recommended during surgery.

This includes somatosensory evoked potentials, brainstem auditory evoked potentials, spontaneous EMG of the lower cranial nerves and motor evoked potentials. • A cartouche stimulation probe can be used over the dorsal medulla to find a non-eloquent safe entry zone to access the cervicomedullary lesion. This allows for detection of functional neural tissue overlying the lesion and the proximity of functional tissue to the tumor.

Surgical Procedure Patient Positioning • The patient is placed in the prone position with the head flexed and fixed in a Mayfield threepoint fixation headholder. • For young children aged less than 3 years or patients with a very thin skull, a cerebellar headrest padded with soft gel rolls is typically recommended. • A semi-sitting position can be used while keeping in mind its potential complications, including venous air embolisms. Skin Incision • A standard midline skin incision is performed. • If the tumor is significantly eccentric, the skin incision is placed laterally as in a far lateral approach. Craniotomy • Cervicomedullary tumors are usually approached through a midline suboccipital craniotomy combined with C1 laminectomy. If the

Chapter 7  •  Cervicomedullary Tumors

Focal intrinsic tectal plate (Type II) Focal intrinsic midbrain (Type II) Dorsal exophytic pontine (Type III) Focal intrinsic pontine (Type II) Diffuse pontine (Type I) Dorsal exophytic medullary (Type III) Focal intrinsic medullary (Type II) Cervicomedullary (Type IV)

Figure 7.1 Classification of brainstem lesions based on CT and MRI by Choux et al. (2000). Type I: diffuse, Type II: focal intrinsic, Type III: focal exophytic, Type IV: cervicomedullary.

lesion extends caudally, the opening is comp­ lemented with additional necessary cervical laminectomies. • Laterally and/or ventrally located tumors are accessed through a dorsolateral approach (far lateral or retrosigmoid approaches). It is typically not necessary to perform extensive bone removal of the occipital condyle and/or the lateral mass of C1. Adequate exposure is obtained by the craniotomy and a C1 -hemilaminectomy. Only when necessary, partial drilling of the posterior third of the occipital condyle can be performed. • Often the cervical lamina can be replaced at the end of the procedure, and therefore cervical laminotomies can be considered instead of laminectomies.

Dural Opening • The dura mater is typically opened in a Y-shape. In the cervical portion a midline longitudinal incision is done under magnification with the operative microscope. Tenting sutures are used for dural traction. • Intraoperative ultrasound can be used to localize the lesion before or after dural opening. • A cartouche stimulation probe can be used over the dorsal medulla to find a non-eloquent safe entry zone.

Figure 7.2 Midline myelotomy.

Intradural Dissection • The surgical technique for tumor removal is similar to the methods used for intramedullary spinal cord tumors. • Less than 1 cm longitudinal myelotomy is typically performed at the surface of the cervicomedullary junction (Figure 7.2). This opening is placed over the tumor. The best approach is that which allows exposure of the tumor with the least risk of injury to surrounding structures.

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Section 1  •  Intra-Axial Tumors

Supracollicular

Infracollicular

Suprafacial Triangle

Infrafacial Triangle

Posterior Lateral Sulcus

Posterior Median Fissure Posterior Intermediate Sulcus

Figure 7.4 The tumor is gently explored with blunt microdissectors in

order to obtain an initial understanding of its relationship with the surrounding structures.

Figure 7.3 Brainstem safe entry zones. The midline is usually consid-

ered safe in the cervicomedullary region although it is not always selected as the myelotomy point. For instance, if the tumor has a cystic nature the region where the cyst is coming to the surface may be a preferred location for the myelotomy.

Anatomical knowledge, preoperative imaging and intraoperative mapping can be used to help select the safe entry zone (Figure 7.3). • Medially located tumors are accessed through a midline longitudinal myelotomy. The cervical cord may be rotated by the tumor pressure. It is advisable to locate the dorsal roots bilaterally and identify the midline to place the myelotomy without damaging the dorsal columns. • Laterally and/or ventrally located tumors are accessed through the posterior or the posterolateral sulci. A lateral incision may damage the dorsal columns. To decrease the risk of damage, the myelotomy is placed at the region where the tumor is closest to the pial surface. • The tumor is gently explored with blunt microdissectors in order to obtain an initial understanding of its relationship with the surrounding structures (Figure 7.4). • A biopsy is sent for immediate histological examination. • The tumor is removed in a piecemeal fashion. Resection starts with debulking the central portion of the tumor. It is advisable to keep the tissue manipulation inside the tumor cavity in

Figure 7.5 The tumor is cut with microscissors or reduced with ultrasonic aspiration.

order to minimize retraction of the surrounding parenchyma. Depending on its consistency, the tumor is cut with microscissors or reduced with ultrasonic aspiration (Figure 7.5). • Ultrasonic aspiration is carefully used at the lowest effective intensity and suction rate with a small handpiece.

Chapter 7  •  Cervicomedullary Tumors • The patient is transferred to the neurology critical care unit for at least 24 hours. The oral or nasal tracheal tube is maintained with mechanical ventilation and sedation as needed. • A CT scan can be performed postoperatively to exclude any early blood clotting, pneumocephalus and/or hydrocephalus, although such complications are rare.

Complications

Figure 7.6 Gentle microbipolar coagulation can be applied at the tumor margins followed by copious irrigation to prevent heat injury of the surrounding parenchyma.

• After debulking the central portion of the tumor, dissection continues to the upper and lower portions. When approaching the upper portion, care must be taken to avoid entering into the floor of the fourth ventricle. At this point, mapping the floor of the fourth ventricle can delimit the margins of the resection. • Tumor debulking must remain rigorously confined to the inside of the tumor and stopped when the interface with normal tissue becomes poorly defined. • Gentle microbipolar coagulation can be applied at the tumor margins followed by copious irrigation to prevent heat injury of the surrounding parenchyma. A cotton ball can be used inside the cavity to manipulate the tumor remnants (Figure 7.6). • The brainstem and spinal cord are very sensitive to manipulation. It is common to note some level of deterioration in the neuromonitoring recordings when attempting surgical resection. The anesthetic team should watch for transient changes and signs of cardiovascular instability (bradycardia and hypertension). • The use of the surgical microscope helps facilitate tumor identification and manipulation. Closure • The dura mater is closed watertight primarily. In cases where this cannot be achieved, pericranium or dural substitute can be used.

• It is common that some patients will have a transient worsening of function following the removal of an intra-axial cervicomedullary tumor. This requires a critical care environment. Permanent worsening is not uncommon. • Dysphagia, vocal cord paresis, sleep apnea, loss of cough and gag reflex, and transient motor loss can occur. • Cervical kyphosis and instability may be a longterm problem for pediatric patients undergoing extended cervical laminectomies. As a result, we typically prefer laminoplasties. Pearls • Cervicomedullary gliomas can be safely reached and totally removed, achieving good results.

• The operative approach and trajectory needs to be selected to minimize damage to healthy parenchyma while securing safe access to the lesion. • Intraoperative neurophysiological monitoring, mapping and neuronavigation are of prime importance to minimize morbidity.

Suggested Reading Chaichana, K.L., Quiñones-Hinojosa, A., 2013. Neuro-oncology: paediatric brain tumours – when to operate? Nat. Rev. Neurol. 9(7), 362–364. Choux, M., Lena, G., Do, L., 2000. Brain stem tumors. In: Choux, M., Di Rocco, C., Hockley, A. (Eds.), Pediatric Neurosurgery. Churchill Livingstone, New York, pp. 471–491. Di Maio, S., Gul, S.M., Cochrane, D.D., Hendson, G., Sargent, M.A., Steinbok, P., 2009. Clinical, radiologic and pathologic features and outcome following surgery for cervicomedullary gliomas in children. Childs Nerv. Syst. 25(11), 1401–1410. Epstein, F., Wisoff, J., 1987. Intra-axial tumors of the cervicomedullary junction. J. Neurosurg. 67(4), 483–487. Minturn, J.E., Fisher, M.J., 2013. Gliomas in children. Curr. Treat. Options Neurol. 15(3), 316–327. Quiñones-Hinojosa, A., Lyon, R., Du, R., Lawton, M.T., 2005. Intraoperative motor mapping of the cerebral peduncle during resection of a midbrain cavernous malformation: technical case report. Neurosurgery 56(2 Suppl), E439; discussion E439.

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Supracerebellar Infratentorial Approach Jordina Rincon-Torroella, Arnau Benet and Alfredo Quiñones-Hinojosa To see Video 8, please go to ExpertConsult.com

Indications

Preoperative Considerations

• This approach is well suited for midline tumors in the pineal region: germinoma, teratoma, pineocytoma, pineoblastoma, astrocytoma, metastasis, ependymoma, epidermoid tumor, cavernoma (Figure 8.1). • Tumors in the midline tectal region. • Midline pontomesencephalic lesions.

• This approach gives access to the midline and the resection can be extended laterally and rostrocaudally. The pineal region, quadrigeminal and ambient cisterns can be exposed through this route, which also gives access to the velum interpositum and the deep venous system. No normal parenchyma is transected en route to the tumor. • Because of the close location to the sylvian aqueduct, obstructive hydrocephalus is commonly present before surgery. CSF diversion may be necessary. • Preoperative MR venography is useful to study the relation between the tumor and the deep venous system and venous sinuses. • The goal of this approach is to achieve maximal relaxation of the cerebellum, with limited use of cerebellar retraction by taking advantage of the gravity.

Contraindications • The approach is not optimally suited if the tumor infiltrates laterally or superiorly above the tentorium. • Transcallosal interhemispheric or occipital transtentorial approaches are preferred under the following circumstances: • Tumors that extend superiorly, to the third ventricle or invading the corpus callosum (posterior transcallosal approach). • Tumors that extend laterally, around the fornix. • Tumors that extend inferiorly into the quadrigeminal plate or superior cerebellar peduncle. • Lesions located superiorly to the Galenic venous draining system and displacing the deep venous system in a ventral direction, e.g. meningiomas (occipital transtentorial approach). • Steeply angled tentorium (occipital transtentorial approach). • In tumors extending into the posterior part of the lateral ventricle, on the non-dominant side a transcortical transventricular approach is preferred.

Surgical Procedure Patient Positioning • The patient can be placed in the sitting position, the three-quarter-prone position, or the prone position. • The sitting or semi-sitting positions are the most used for the infratentorial supracerebellar approach. The patient is placed in the supine position. The back of the table is raised to its maximal angled position. The patient’s trunk is brought forward and the head is maximally flexed. The surgeon works over the patient’s shoulders in line with the tentorium in the posterior fossa.

Chapter 8  •  Supracerebellar Infratentorial Approach • This position provides good exposure of the pineal region. The sitting position is optimal for the surgical approach because the cerebellum falls away from the surgical view, gravity favors retraction and blood is not pooling in the surgical field. However, the sitting position has risk of air embolism. To prevent air embolism, the surgical table is tilted in order to keep the patient’s feet slightly above the head— which elevates venous pressure—until dural opening. After dural opening, the table is tilted to keep the feet at the level of the head. Bilateral jugular compression can be applied also during opening. • The three-quarter-prone position to the pinealtentorial region decreases the risk of air embolism and provides a more comfortable operating position to the surgeon but usually requires more marked cerebellar retraction. • The prone position is considered if the patient has a patent foramen ovale. • A Leyla bar and a self-retaining retractor system such as Greenberg’s retractors can be arranged at the operative table. • In those patients with obstructive hydrocephalus an intraventricular catheter is placed before starting the approach. Skin Incision • A linear midline incision is made from 3–4 cm above the inion to the spinous process of C2 or C3. Parietal interhemispheric Occipital transtentorial

• A myocutaneus flap, including the pericranium and the suboccipital muscles, is obtained through subperiosteal dissection, and can be elevated laterally on each side of the incision without disrupting the integrity of the muscles. Craniotomy • A wide rectangular suboccipital craniotomy is performed to include the transverse sinuses and torcula. The craniotomy does not extend to the foramen magnum but allows exposure of the cisterna magna (Figure 8.2). • The craniotomy is done with care to preserve the underlying dura. The burr holes are placed one at each side of the superior sagittal sinus (SSS) and superior and inferior to each transverse sinus lateral to the torcula. Some surgeons use the self-retaining burr hole maker, which is safer to use over the sinuses, thus placing one burr hole over the right and left transverse sinuses and one over the SSS. • A C1 laminectomy can be added if there is evidence of tonsillar herniation in the preoperative imaging. Dural Opening • The dura mater is opened with a semilunar, Y-shaped or cruciate incision. • The occipital sinus is ligated and transected. • The edges of the dural opening are elevated inferiorly and superiorly by proximal tenting sutures. • Retraction over the sinus should be modulated to avoid excessive compression that could produce blood stasis. Intradural Dissection

Infratentorial supracerebellar

Figure 8.1 Comparison between the occipital transtentorial and the

infratentorial supracerebellar approaches to the pineal region. The parietal interhemispheric approach gives access to the lateral and third ventricles. Adapted from Bruce, J.N., 2012. Management of pineal region tumors. In Quiñones-Hinojosa, A. (Ed.), Schmidek & Sweet: Operative Neurosurgical Techniques: Indications, Methods and Results, sixth ed. Saunders, Elsevier Inc., Philadelphia.

• The cerebellar falx and the occipital sinus can be ligated and divided. • The cisterna magna is opened to allow CSF drainage and relaxation of the cerebellum. This and gravity increase the working space. • At this point the operating microscope should be brought to the operating table. • The arachnoid in the incisura and around the quadrigeminal region and ambient cistern is usually thickened and tenaciously attached to the neurovascular structures. It may be dissected to allow wider opening to access the pineal region and recognize the vascular anatomy to preserve it (Figure 8.3A). • This approach avoids retraction or manipulation of the cerebral hemispheres. Retraction can

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Section 1  •  Intra-Axial Tumors be applied in the underside of the tentorium in the midline. Gentle retraction can be applied at the vermis if an extra surgical corridor is needed for good visualization of the lesion. Procedure 1. The

first step is disconnecting the inferior vermian veins bilaterally to gain access to the superior cerebellar surface. If the vermian veins

are dominant and have a large caliber, vascular clips can be used to clamp them before disconnecting. 2. The superficial bridging veins at the dorsal surface of the cerebellum between the superior surface of the cerebellar hemispheres and the tentorium are coagulated to free the cerebellum from the tentorium. 3. Visualization of the tentorial notch and the arachnoid membrane of the quadrigeminal cistern.

Superior Sagittal Sinus

Transverse Sinus

Torcula

Inferior Vermian Vein

PICA

Figure 8.2 Anatomy of the posterior fossa. A large occipital craniotomy was done to expose the contents initially encountered in the supracerebellar infratentorial approach. In this case, the craniotomy was expanded for educational purposes. (PICA, posterior inferior cerebellar artery.) © Arnau Benet.

1

3

1

3 4

4 5

5

6

6

8

7 9

10

2

2

A

B

Figure 8.3 Surgical anatomy of the cisterna quadrigemina as seen from the supracerebellar infratentorial approach. (A) The tentorial notch and

cerebellar hemispheres are retracted to gain surgical access to the cerebellar mesencephalic fissure. The superior vermian vein needs to be cauterized to facilitate the supracerebellar infratentorial corridor. The thick arachnoid membrane of the quadrigeminal cistern is incised very carefully to preserve the underlying venous system. (B) After removal of the arachnoid membrane and adhesions, the posterior venous system is exposed and the tumor dissection starts. 1, Tentorium. 2, Cerebellar hemispheres. 3, Vein of Galen. 4, Cerebellomesencephalic fissure vein (precentral cerebellar vein). 5, Basal vein of Rosenthal. 6, Tectal veins. 7, Internal cerebral vein. 8, Posterior cerebral artery. 9, Posterior medial choroidal artery. 10, Quadrigeminal plate. Reproduced with permission from Raza, S.M., Quiñones-Hinojosa, A., 2011. Supracerebellar infratentorial approach. In Jandial, R., McCormick, P., Black, P. (Eds.), Core Techniques in Operative Neurosurgery. Saunders, Elsevier Inc., Philadelphia.

Chapter 8  •  Supracerebellar Infratentorial Approach 4. Opening

of the arachnoid membrane of the quadrigeminal cistern with exposure of the deep venous complex. 5. The superior vermian vein and the vein of the cerebellomesencephalic fissure (aka precentral cerebellar vein) are coagulated and divided as far as possible from the vein of Galen. These can be recognized starting at the vermis and followed to Galen’s vein (Figure 8.3B). 6. Dissection of the adhesions of the lesion to the deep venous system. 7. Biopsy or central debulking of the tumor. Dissection of Pineal Tumors 1. Superior

portion: Dissection from the vein of Galen and the internal cerebral veins. Identification of the third ventricle and anatomy of the ventricular walls. Further superior exposure can be gained by incising the tentorium. 2. Lateral portions: If the lesion has a prominent lateral extension, that portion will not be well visualized. Complete visualization is obstructed by the tentorial edge and the straight nature of the corridor will make difficult lateral maneuverability. 3. Inferior portion: Visualization and preservation of the quadrigeminal plate. Resection of the tumor from lateral to medial, cauterizing the feeders from the posterior medial choroidal and superior cerebellar arteries (Figure 8.4). Closure • Before dural closure, the surgical cavity is thoroughly inspected for any venous bleeding or violation of the venous sinus. • The dura is primarily closed or a duraplasty is sutured to fill any dural gap. • The bone flap is reattached with miniplates.

Occipital Transtentorial Approach (Figure 8.5) This approach is used for pineal and posterior third ventricular lesions with either supratentorial and infratentorial components. The patient is usually placed in the sitting position. Retraction of the occipital lobe is necessary but has to be minimized. Usually there are no major bridging veins in this region, thus facilitating the surgical corridor. The transection of the tentorium is made 1 cm lateral to the midline and in a posterior to anterior direction. The tumor can be resected in the space between the basal vein and the internal cerebral vein. The thick arachnoid that gives access to the quadrigeminal cistern is encountered at the end of

Figure 8.4 (A, B) Cadaveric dissection of the pineal region. Galen’s

great vein and the internal cerebral veins (deeper) are usually above the pineal tumor and are not encountered until later stages of the arachnoid dissection. Laterally to the tumor the temporal lobe and Rosenthal’s basal veins can be seen as they course upward toward the torcula. The inferior resection is usually the most challenging and one must avoid the manipulation of the quadrigeminal plate and its surrounding structures. The trochlear nerve and superior cerebellar artery are usually not exposed during the resection. 1, Vein of Galen. 2, Basal vein of Rosenthal. 3, Cerebellomesencephalic fissure vein (precentral cerebellar vein). 4, Fourth cranial nerve. 5, Superior cerebellar artery. 6, Posterior cerebral artery. 7, Quadrigeminal plate. 8, Pineal gland. 9, Tentorium. 10, Occipital lobe. © Arnau Benet.

the corridor. Tumor resection can further proceed between the internal cerebral veins and Rosenthal’s basal vein. At this point the anterior portion of the falx cerebri can be transected, at or above 1 cm from the vein of Galen, after ligation of the inferior sagittal sinus. Cutting part of the falx cerebri will both provide more room for dissection and increase lighting and therefore visual control. Moreover, the splenium of the corpus callosum can be pushed superiorly to gain space to access the superior aspect of the tumor.

Complications • The transverse and sigmoid sinuses, torcula and the circular sinuses at the foramen magnum can be pierced inadvertently. In case of a small laceration, local hemostatics are applied to stop bleeding. In larger lacerations a vascular clip may be applied. • The sitting position increases the risk of air embolism if a venous sinus is inadvertently pierced. A Doppler probe, central venous catheter and end-tidal Pco2 are used to recognize and react quickly in case of air embolism. Moderate positive-pressure ventilation can be applied to avoid air embolism, especially during the bone opening or when the venous sinuses are exposed. The first maneuvers to avoid or limit an air embolism after sinus lesions include: • Copious irrigation with flooding of the area, and covering the sinus with cottonoids. At the

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Section 1  •  Intra-Axial Tumors • Some of the tumors of the pineal region can be tenacious, infiltrative and highly vascularized (e.g. pineal cell tumors). Complete resection may not be granted in those cases. Meticulous hemostasis is crucial in those tumors, especially if they are incompletely resected. To prevent bleeding from the remnant pieces, hemostatic agents like Surgicel can be used but should be placed carefully to avoid obstruction of the sylvian aqueduct. • Pineal apoplexy is a rare clinical presentation of pineal parenchymal tumors. • Patients may be transferred to the neurology critical care unit and closely watched for signs of hydrocephalus, bleeding or posterior fossa edema.

Superior Sagittal Sinus Tentorium Torcula

Tentorial Sinus

Posterior Temporal Vein

Posterior Occipital Vein

Figure 8.5 Occipital transtentorial approach. Reproduced with per-

mission from Alvernia, J.E., Mbabuike, N., Ware, M.L., 2011. Occipital craniotomy. In Jandial, R., McCormick, P., Black, P. (Eds.), Core Techniques in Operative Neurosurgery. Saunders, Elsevier Inc., Philadelphia.

same time, the anesthesia team immediately places the patient in the Trendelenburg position, moving the head down. • A large bubble of air in the heart will present with a constant “machinery” murmur discovered by the Doppler ultrasound. Special attention and coordination with anesthesia must be planned. Specific maneuvers related to patient positioning can entrap the air bubble in the heart, allowing endovascular access to aspirate the air: • The Trendelenburg position keeps a leftventricular air bubble away from the coronary arteries. • The left lateral decubitus position may prevent the progression of the air bubble into the pulmonary artery and also prevents the air from passing through a potentially patent foramen ovale. • The resection of the inferior portion of the tumor is usually challenging. The tumor can be adherent to the dorsal midbrain, especially in the collicular region. Caution is needed in this region, since the interface between the tumor and the quadrigeminal plate may be difficult to distinguish. Postoperative visual abnormalities and ocular movement disturbances (e.g. lack of accommodation, upward gaze palsy, interocular palsy) are common after irritation of the quadrigeminal region. Those deficits improve gradually during weeks or months.

Pearls • Initial maneuvers help to achieve maximal cerebellar relaxation: • Large craniotomy, reaching the transverse to sigmoid sinus junction bilaterally. • Opening the cisterna magna. • Cauterization and division of all the bridging veins between the superior cerebellar surface and the tentorium. • Many of the tumors in this region extend into the third ventricle, requiring long instruments to reach the anterior portions of the tumor. • A Cavitron ultrasonic aspirator with a long, curved tip can be helpful for debulking tumors of firm consistency. • Endoscopic supracerebellar infratentorial approaches to this region have also been recently developed.

Suggested Reading Chibbaro, S., Di Rocco, F., Makiese, O., et al. 2012. Neuroendoscopic management of posterior third ventricle and pineal region tumors: technique, limitation and possible complication avoidance. Neurosurg. Rev. 35, 331–338. Giordano, M., Wrede, K.H., Stieglitz, L.H., Samii, M., Lüdemann, W.O., 2007. Identification of venous variants in the pineal region with 3D preoperative computed tomography and magnetic resonance imaging navigation: a statistical study of venous anatomy in living patients. J. Neurosurg. 106, 1006–1011. Hart, M.G., Santarius, T., Kirollos, R.W., 2013. How I do it – pineal surgery: supracerebellar infratentorial versus occipital transtentorial. Acta Neurochir. 155, 463–467. Hernesniemi, J., Romani, R., Albayrak, B.S., et al. 2008. Microsurgical management of pineal region lesions: personal experience with 119 patients. Surg. Neurol. 70, 576–583. Kawashima, M., Rhoton, A.L., Jr., Matsushima, T., 2002. Comparison of posterior approaches to the posterior incisural space: microsurgical anatomy and proposal of a new method, the occipital bi-transtentorial/falcine approach. Neurosurgery 51, 1208–1221. Shahinian, H., Ra, Y., 2013. Fully endoscopic resection of pineal region tumors. J. Neurol. Surg. B Skull Base 74(3), 114–117.

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Intraoperative Assessment of Extent of Resection Jordina Rincon-Torroella, Eibar Ernesto Cabrera-Aldana and Alfredo Quiñones-Hinojosa To see Video 9 (Part 1 and Part 2), please go to ExpertConsult.com

Introduction • Neuro-oncological surgery has rapidly emerged and developed as a new field in neurosurgery focused on the treatment of tumors affecting the brain, cord and the peripheral nerves. It has undoubtedly relied on a parallel advance with technology. • With the introduction of computerized tomography (CT) and magnetic resonance imaging (MRI), neurosurgeons can plan the safest and most direct approach preoperatively. In addition, obtaining functional data through imaging is also possible. Some examples of these advancements are the functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). • Intraoperative electrophysiological function surveillance and intraoperative mapping are immediate and precise tools that have helped to increase resection of intra-axial tumors adjacent to areas of presumed eloquence. • There is growing evidence that extensive surgical resection of tumors is associated with prolonged survival. Consequently, during the last decade, the primary goal in tumor surgery has been to maximize resection without inflicting new neurologic deficits. • Imaging improvements and software developments allow the possibility to have real-time imaging feedback and semi-automatized volumetric analysis to evaluate the extent of resection and residual volume of intra-axial lesions. • Surgical resection is the initial treatment for most patients with high-grade gliomas (HGG).

Current literature reports that in HGG surgery, i.e. glioblastoma (GB), resections of >70–95% of amenable enhancing tumor or residual volumes 5 mm in thickness extending from the surgical cavity into the brain parenchyma with welldiscriminated borders. A continuous echogenic rim 1 cm). • Symptoms related to pituitary adenomas include: • Large lesions might present suprasellar and parasellar extensions, associated with optic chiasm compression and visual field defects as well as dysfunction of the cranial nerves in the cavernous sinus (III, IV, VI, V1 and V2). • Hormone-secreting lesions are associated with different clinical syndromes, such as acromegaly, Cushing’s disease and hyperprolactinemia • The evaluation of pituitary adenomas must include: • CT scan for evaluation of the bone anatomy, calcifications within the lesion and preoperative evaluation of the different subtypes of sphenoid sinus that might be encountered. • Sellar MRI scan for analysis of the location of the lesion and its relation to surrounding structures such as the internal carotid artery,

optic chiasm and cavernous sinus. Dedicated pituitary MRI scans, with thin coronal cuts and dynamic contrast evaluation, are recommended in cases of microadenomas. • Endocrine evaluation to determine the presence of hormonal dysfunctions. • Ophthalmological evaluation to study the patient’s preoperative visual field accuracy and acuity.

Indications • Treatment options include clinical follow-up, medical treatment, surgery and radiotherapy/ radiosurgery. • Clinical follow-up with periodic MRI scan is recommended for most nonfunctioning adenomas smaller than 1 cm (microadenomas), which usually are asymptomatic lesions incidentally found in MRI scans. • Medical treatment is the gold standard treatment in cases of prolactinomas. Drug therapy with bromocriptine and/or cabergoline is effective to achieve tumor remission in most cases. In cases of large GH-secreting adenomas, neoadjuvant or adjuvant treatment with octreotide may be useful to improve the hormonal control rate after surgery. In some cases, after medical therapy with cabergoline and/or octreotide the tumor may present a fibrous consistency, which may increase the complexity of the resection. This may be considered before the introduction of neoadjuvant medications.

Chapter 24  •  Pituitary Adenomas Stereotactic fractionated radiotherapy and radiosurgery may be useful in the treatment of recurrent adenomas and residual lesions in the cavernous sinus. • Indications for surgery include: • Non-functioning adenomas that present with development of new visual or ocular movement deficit. • Lesions with progressive enlargement during follow-up. • GH- and ACTH-secreting pituitary ad­enomas. • Prolactinomas that did not respond to drug therapy or in those cases presenting with major side effects secondary to the medical treatment. •

Surgical Procedure Patient Positioning • The patient is placed in a 3-point head fixation system (Mayfield skull clamp or similar) in a slightly extended position to angle the sphenoid sinus and sella rostrally. Additionally, the head is rotated 5–10° towards the right shoulder so the nasal cavity is parallel to the surgeon’s working angle. • The perinasal skin and nasal cavity are prepared with use of povidone iodine. • After adequate prepping and draping, the nasal cavity is packed for approximately 2 minutes with afrin-soaked pledgets to reduce the bleeding originated by nasal mucosa manipulation.

septum and exposing the bone structure of the posterior nasal septum and the rostrum sphenoidale (Figure 24.1). • The posterior attachment of the nasal septum to the rostrum is detached and the septum is deviated to the contralateral side with use of a Penfield No. 2 dissector. • Wide bilateral opening of the sphenoid sinus is then performed, with preservation of the inferior portion of the vomer, an important midline anatomic landmark to guide the surgeon throughout the approach. Sellar Phase • Identification of the sella and its surrounding structures is necessary before the drilling of the sellar floor (Figure 24.2).

Sphenoidal Ostium

Middle Turbinate

Sphenoidal Ostium

Sphenoidal Rostrum

Nasal Septum

Nasal Phase • A paraseptal approach decreases tissue damage and provides optimal visualization of the sella. In most of cases of pituitary adenomas, a single nostril approach is used in order to reduce potential nasal complications secondary to surgical manipulation. • With a 0° endoscope the surgeon identifies the anatomic landmarks of the nasal cavity, including the inferior, middle and superior turbinates, nasal septum, coana and ostium sphenoidale. • Lateralization of the middle turbinate is performed to enlarge the working field in the nasal cavity. Resection of the middle turbinates is avoided in order to preserve the olfactory and nasal function. • The sphenoid ostium is identified 1 cm superior and medial to the middle turbinate. • With use of a monopolar electrocautery a vertical cut in the mucosa is done at the posterior part of the nasal septum. The mucosa is then pushed laterally dissecting it from the nasal

Figure 24.1 Exposure of the sphenoidal rostrum. Once the posterior

part of the nasal septum is pushed laterally, the sphenoidal rostrum  is exposed. The sphenoid ostia are superior and lateral to the rostrum. © A. Quiñones-Hinojosa.

Sphenoidal Crest Optic-carotid recess

Optic-carotid recess Sella

Carotid

Carotid Clivus

Vomer

Figure 24.2 Exposure of the sellar floor. Before drilling the sellar floor,

identification of the anatomic landmarks of the sella and parasellar region is recommended, including: sella, carotid prominences, opticocarotid recess and clivus. © A. Quiñones-Hinojosa.

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Section 5  •  Endoscopic Approaches to Skull Base Tumors • The septations inside the sphenoid sinus may be carefully studied in the preoperative CT scan. They are carefully undermined with the use of a drill or a rongeur. This maneuver is carefully performed since some of these septations may point towards the carotid arteries. • The limits of the sellar floor opening are: laterally until the carotid prominences, superiorly up to the tuberculum sellae and inferiorly until

the posterior portion of the sellar floor. With a thorough knowledge of the endoscopic anatomy and experience, the drilling can be extended to any direction for the expanded approaches (coronal and sagittal expansions). • In cases of large adenomas with important suprasellar and parasellar extensions, an extended approach with drilling of the tuberculum and planum sphenoidale may be useful.

Separation of dura from capsule of pituitary gland Inspecting anterior and lateral surfaces of pituitary

Removing bone of anterior sella

Dura Capsule Pituitary gland

A

Identifying tumor site and edge of tumor Dissection at interface of tumor capsule and pituitary

B

Incising pituitary capsule to identify capsule of tumor at its interface with normal gland

Posterior surface of tumor separated

Extracapsular removal

C Figure 24.3 Endoscopic resection of microadenomas. (A) Exposure of the tumor. (B) Technique for resection of microadenomas. (C) Extracap-

sular en bloc removal of pituitary microadenomas. Reproduced with permission from Oldfield, E.H., Vortmeyer, A.O., 2006. Development of a histological pseudocapsule and its use as a surgical capsule in the excision of pituitary tumors. J. Neurosurg. 104, 7–19.

Chapter 24  •  Pituitary Adenomas Dural Opening • After the bone removal, the durotomy is usually performed in a cross-shaped manner with a micro-blade. The dural opening must be tailored according to the size and location of the lesion. Unnecessary large dural openings are avoided to reduce the incidence of intra- and postoperative CSF leaks. Intradural Dissection and Tumor Resection • Large macroadenomas (>10 mm) • Large lesions may be identified immediately after dural opening. • Most of the pituitary adenomas (95%) are soft lesions that can be easily debulked. Once the lesion is identified, debulking of the inferior part of the tumor is performed with use of ring curettes. • The tumor is progressively removed in stages. After approaching the inferior part of the lesion, the dissection continues superiorly and laterally, until identification of the diaphragma sellae and normal pituitary gland. • Careful removal of tumor portions close to the diaphragma sellae is done with gentle use of upward ring curettes. At this point, a 30° endoscope may improve the visualization of the surgical field and blind corners and facilitate the tumor removal. If traction is required, it is performed carefully and progressively in order to avoid injuries to the diaphragm and subsequent intraoperative CSF. • In lesions with large suprasellar residual components, a Valsalva maneuver can be used to increase the intracranial pressure to attempt to bring the suprasellar portion of the lesion into the sellar space. Drainage of CSF or injection of 1–2 mL of air via a lumbar drain are maneuvers that have been also used to achieve this objective. • Complete removal of a macroadenoma may require extended endoscopic approaches (e.g. sagittal expansions: transtuberculum/ transplanum) or a staged/combined approach. These may be planned in advance with the use of the preoperative imaging. For staged approaches, the first stage can be the endoscopic transsphenoidal resection and the second stage can be a new endoscopic procedure (if the suprasellar component has descended to the sella in the follow-up MRI) or a transcranial approach, according to the location of the residual adenoma after the initial debulking.

• Microadenomas (