Neurosurgery Board Review: Neurosurgery chapter

Colen Publishing

www.colenpublishing.com ©™

Colen Publishing Colen Publishing, L.L.C. PO Box 36536 Grosse Pointe Woods, MI 48236 Author and Editor: Chaim B. Colen, M.D., Ph.D. Editorial Assistant: Roxanne E. Colen, PA-C COPYRIGHT © 2008 by Colen Publishing, L.L.C. This book, including all parts thereof, is legally protected by copyright. Any use, exploitation, or commercialization outside the narrow limits set by copyright legislation without the author’s consent if illegal and liable to prosecution. This applies in particular to photostat reproduction, copying, mimeographing or duplication of any kind, translating, preparation of microfilms, and electronic data processing and storage. Some of the product names, patents, and registered designs referred to in this book are in fact registered trademarks or proprietary names even though specific reference to this fact is not always made in the text. Therefore, the appearance of a name without designation as proprietary is not to be construed as a representation by the publisher that it is in the public domain. Permissions may be sought directly from Colen Publishing, L.L.C. by writing to the above address. Printed in China Colen Flash-Review: Neurosurgery, 2nd Edition ISBN Volume 1: 1-935345-01-X Volume 2: 1-935345-02-8 2 Volume Set: 1-935345-00-1 Note: Knowledge in medicine is constantly changing. The author has consulted sources believed to be reliable in the effort to provide information that is complete and in accord with the standards at the time of publication. However, in view of the possibility of human error by the author in preparation of this work, warrants that the information contained herein is in every respect accurate and complete, and that the author is not responsible for any errors or omissions or for the results obtained from use of such information. The reader is advised to confirm the information contained herein with other sources. This is especially important in connection with new or infrequently used drugs. In such instances, the product information sheet included in the package with each drug should be reviewed.

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Glossary COPYRIGHT-------------------------------------------------PREFACE -----------------------------------------------------HOW TO USE THIS CARD REVIEW-------------------CONTRIBUTORS-------------------------------------------GLOSSARY--------------------------------------------------NEUROSURGERY-----------------------------------------NEUROLOGY -----------------------------------------------NEUROPATHOLOGY-------------------------------------NEUROANATOMY----------------------------------------NEUROCRITICAL CARE---------------------------------NEURORADIOLOGY--------------------------------------NEUROBIOLOGY------------------------------------------BONUS BIOSTATISTICS----------------------------------

1 1 1 4 1 110 86 238 57 80 73 64 6

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Preface •

The idea to undertake such a large Flashcard review spawned from watching my wife Roxanne study for her Physician Assistant Boards. Diligently every day she would create a set of 7-10 flashcards from her study material that she would take with her to work. Later on, when I was studying for my written Neurosurgery Board examination, I gleaned information from various texts and other study guides and wrote down the most relevant material on cards for quick review while at work. It was amazing how much time during the day would be available to review these cards. If there was a delay in a OR case, a long lunch-line, a traffic jam (especially the i94 on a Friday afternoon) or waiting for my wife at her OB/GYN appointment -these little cards were specially handy. Always ambitious in life, the thought of giving this study tool to the busy neurosurgery resident was captivating. My expectation is to enable the resident with a quick yet informative review of basic neuroscience principles. With positive encouragement from my fellow residents on the 1st edition, I cautiously proceed here with updating information, adding new images, improved illustrations and clarification of neuroscience concepts. May this endeavor serve to better our wonderful science inherited through the legacy of Harvey Cushing, Neurosurgery. Chaim

September 9, 2008

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The Colen Flash-Review Author and Editor Chaim B. Colen, M.D., Ph.D. Department of Neurological Surgery Wayne State University School of Medicine Detroit, Michigan Assistant Editor Roxanne E. Colen, M.S., PA-C Colen Publishing, LLC Grosse Pointe, Michigan

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Acknowledgements I would like to give thanks to a great many wonderful persons whose efforts, although not inscribed in these cards, were instrumental in making this monumental task possible. One exceptional individual to whom I owe special thanks is my mother in-in-law, Colleen Johns, who babysat my daughter Emily and son Joshua for hours on end, while my wife and I toiled through hundreds of pages of various textbooks and journal articles, formatted questions, and drew computer illustrations. To my daughter Emily Rivka, who incessantly tugged at my pants trying to get my attention to the squirrel in our backyard ;and that big bright smile from my son Joshua that continually sent me optimism. To Mahmoud and Abhi who spent hours at my home assisting with typing, researching and editing; Naomi whose positive attitude in life is exceptionally brightening and uplifted the group’s 2 am brainstorming sessions when I still had to wake up early to work the next day, all the pathologists, especially Doha, who assisted in taking photographs, Dr. William Kupsky, for allowing us access to his collection of unique neuropathology, and to all the medical students especially Kristyn, whose hard work is admirable. There are those whose names are not here but did assist in some way, thank you. I am forever indebted to my training program, the Wayne State University neurosurgery program, my Chairman Dr. Murali Guthikonda, and Associate Chairman Dr. Setti S. Rengachary whose moral support over the last five years has kept me on this educational drive. For this second edition, there were fellow residents that gave me input and new insight that has helped to improve this edition over the first. To my parents Joseph and Leila, educators of true dedicated quality, and to whom I owe my homeschooling education and self-motivation. Lastly to my wife Roxanne, whose patience with my ambitiousness knows no boundaries. ©™ Thank you All, Chaim September 9, 2008

How to use this Flashcard review •

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These cards are intended to cover most of the aspects of the Neurosurgery Board Examination. They are not a COMPLETE review and therefore they are not intended to replace textbooks. We would advise using these cards during the last couple of weeks before your board exam except for the pathology section which you should go through all year to better remember the photographs in it (heavily encountered during the boards!). BOARD FAVORITE questions are of extreme importance and most likely to bump into during the boards, so make you sure you know how to answer them right. Good luck! Chaim B. Colen, M.D., Ph.D. ©™

Faculty Reviewers Murali Guthikonda, MD Professor and Chairman Department of Neurological Surgery Wayne State University School of Medicine Detroit, Michigan Setti Rengachary, MD Associate Chairman Department of Neurological Surgery Wayne State University School of Medicine Detroit, Michigan William, J. Kupsky, MD Department of Neuropathology Wayne State University School of Medicine Detroit, Michigan

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Forward •

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With ever increasing scope and complexity of knowledge base, the current day trainee or practitioner of neurosurgery finds it difficult to keep up with the explosion of neurosurgical information. This is compounded by a healthy growth in specialization in various branches of neurosurgery. Chaim has made an attempt to make life simpler by incorporating small quanta of knowledge on flashcards accompanied by clear and simple illustrations. The user may review as few or as many cards as his/her time will allow. Although not meant to be substitutes for standard comprehensive texts and atlases, these cards help to refresh the information learned from the bedside, operating room and standard books. Each card represents a mini-examination with instant access to appropriate answers. This is a fun way to recall neurosurgical information especially before an upcoming test. Setti S. Rengachary, M.D. Department of Neurological Surgery

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Physician Contributing Authors Rivka R. Colen, MD Department of Radiology The Massachusetts General Hospital Harvard Medical School Boston, Massachusetts Doha Itani, MD Department of Pathology WSU School of Medicine Detroit, Michigan

Mahmoud Rayes, MD Department of Neurological Surgery WSU School of Medicine Erika Peterson, MD UT Southwestern, Department of Neurological Surgery Dallas, Texas

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Contributing Medical Students Darmafall, Kristyn Wayne State University School of Medicine Class of 2012

Galinato, Anthony Wayne State University School of Medicine Class of 2012

Larson, Sarah Wayne State University School of Medicine Class of 2012

Davis, Naomi Wayne State University School of Medicine Class of 2011

Gotlib, Dorothy Wayne State University School of Medicine Class of 2009

Martinez, Derek Wayne State University School of Medicine Class of 2011

Dub, Larissa Wayne State University School of Medicine Class of 2012

Kozma, Bonita Wayne State University School of Medicine Class of 2008

Matthew Smith Wayne State University School of Medicine Class of 2011

Faulkiner, Rodney Wayne State University School of Medicine Class of 2012

Lai, Christopher Wayne State University School of Medicine Class of 2010

Matto, Shereen Wayne State University School of Medicine Class of 2012 ©™

Contributing Undergraduates Jeffrey P. Kallas Wayne State University Class of 2010 Abhinav Krishnan Wayne State University Class of 2010 Peter Paximadis Wayne State University Class of 2008

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Q? •

Neurosurgery

When the interpeduncular cistern is filled with blood secondary to a ruptured posterior communicating aneurysm, which of the following choices describes the safest surgical approach? A. Superior to the posterior communicating artery, because there is only one perforating arterial branch and so this area is safe B. Opening the membrane of Lilliequist above the posterior communicating artery to avoid injury to the perforators that may be covered with blood C. Opening the membrane of Lilliequist below the posterior communicating artery to avoid injury to the superiorly directed perforators that may be covered with blood D. The membrane of Lilliequist should not be opened

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Neurosurgery

The correct answer is C. It is safer to open the membrane of Lilliequist below the PComA to avoid injury to the superiorly directed perforators that may be covered with blood. The posterior communicating artery (PComA) usually gives off 2–10 perforators which begin approximately 2 to 3 mm from its origin. Branches, the anterior thalamoperforating arteries, run postero-medially into the interpeduncular cistern and supply the inferior optic chiasm, optic tract, tuber cinereum, mammillary bodies, subthalamus, posterior hypothalamus, and the anterior thalamus. An important point is that aneurysms almost always arise from the superior medial aspect of the PComA so that when the interpeduncular cistern is filled with blood, in case of a ruptured intracranial aneurysm, it is safer to open the membrane of Lilliequist below the PComA to avoid injury to these superiorly directed perforators that may be covered with blood. Of these perforators, the largest and most constant one is referred as the premamillary artery or thalamotuberal artery. Zeal AA, Rhoton AL Jr. Microsurgical anatomy of the posterior cerebral artery. J. Neurosurg. 1978 (48) 534–559.

Classification: Neurosurgery, Ruptured Posterior Communicating Aneurysm, Surgical Approach

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Q?

Neurosurgery

• Which of the following choices best describes the Wartenberg’s sign? A. Ulnar nerve compression B. Adduction of the index finger C. Weakness of the third palmar interosseous muscle D. Inability to flex the thumb

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A. • •

Neurosurgery

BOARD FAVORITE!

The correct answer is C, weakness of the third palmar interosseous muscle Wartenberg’s sign is one of the earliest signs of ulnar nerve entrapment. It is the result of the weakness of the third palmar interosseous muscle, which leads to abducted posture of the small finger.

• Ulnar nerve compression locations: • Upper arm: arcade of Struthers – aponeurotic band anterior to the medial head of the triceps (NOT STRUTHER’S LIGAMENT which is a ligament connecting the medial epicondyle and the supracondylar process). • Elbow/Forearm: in the cubital tunnel between the two heads of the flexor carpi ulnaris. MOST COMMON LOCATION (see neuroanatomy section) • Wrist: Guyon’s canal (see neuroanatomy section)

Wartenberg’s sign

A. M. Richards. Key Notes on Plastic Surgery. Blackwell Publishing. 2002. p. 215. H. Richard Winn, M.D. Youman’s Neurological Surgery 5th Edition. Philadelphia, PA: Elsevier 2004. p. 3925.

Classification: Neurosurgery, Clinical findings, Wartenberg’s Sign

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Q? •

Neurosurgery

When should an open craniotomy be used to eliminate a vein of Galen malformation in an infant or older child? A. Yasargil I and II B. Yasargil II and IV C. Yasargil I and IV D. Yasargil III and V

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A. • • •

Neurosurgery

The correct answer is A, open craniotomy should be used with Yasargil types I and II. Vein of Galen aneurysmal malformation is a rare congenital anomaly of the cerebral circulation. It makes up approximately 1% of intracranial vascular malformations, but they represent 30% of pediatric intracranial vascular malformations. Two methods of classifications had been used extensively in the literature. The first classification divided it into mural and choroidal type. The choroidal type is where there are multiple shunts communicating with the anterior dilatation of the median prosencephalic vein. The mural type is where the arteriovenous shunt is in the wall of the dilated vein. The second classification described by Yasargil divides into type I to IV in which type I corresponds to mural types and type II and III correspond to the choroidal type. vein of Galen aneurysmal malformation

Angiogram showing a mural type vein of Galen aneurysmal malformation supplied  by the right posterior choroidal artery.

C.A. Raybaud, C.M. Strother, J.K. Hald. Aneurysms of the vein of Galen: embryonic considerations and anatomical features relating to the pathogenesis of the malformation. Neuroradiology 1989;31:109-128. H. Richard Winn, M.D. Youman’s Neurological Surgery 5th Edition. Philadelphia, PA: Elsevier 2004. p. 3442.

Classification: Neurosurgery, Vein of Galen Malformation, Open Craniotomy

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Q? •

Neurosurgery

According to this cervical x-ray which of the following statements is most accurate? A. You must surgically fuse this fracture. B. Most of these fractures will heal without surgical fusion C. It is likely due to flexion injury D. It is due to fracture of the pedicles

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A.

Neurosurgery

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The correct answer is B. Most hangman’s fractures heal with immobilization and do not warrant surgical intervention. In general, type 1 injuries are treated with a rigid collar for 8 to 12 weeks. Type 2 injuries are initially reduced with traction in slight extension followed by a halo vest for 12 weeks. A halo vest in compression and slight extension is used for type 2A injuries. Immediate surgery is required for type 3 injuries to stabilize the C2/C3 facet joint.

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The hangman's fracture consists of bilateral pars interarticularis fractures involving the C2 vertebral body. Anterior subluxation or dislocation of the C2 vertebral body will often occur in consequence to a hangman’s fracture, which itself occurs secondary to hyperextension injuries seen during automobile accidents or hangings. Levine AM, Edwards CC. The management of traumatic spondylolisthesis of the axis. J Bone Joint Surg Am.1985;67:217-226.

Classification: Neurosurgery, Hangman’s Fracture, Treatment

BOARD FAVORITE!

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Q? •

Neurosurgery

In order to be directly above the foramen of Monro, where would the corpus callosum need to be incised? A. At the genu B. 1 cm behind the genu C. 2.5 cm behind the genu D. 5 cm behind the genu E. 2.5 cm anterior to the splenium

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A. •

Neurosurgery

The correct answer is C. The foramen of Monro is directly beneath the corpus callosum at around 2.5 cm behind the genu. genu of the corpus callosum

right hemisphere

2 cm

foramen of Monro

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Classification: Neurosurgery, Corpus Callosum Incision, Foramen of Monro

Q?

Neurosurgery

• The most appropriate next step in management for the abnormality seen in this image would be to: A. Embolize B. Inject alcohol C. Consider coiling D. Consider surgery E. No intervention at this time

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A. • •

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Neurosurgery

The correct answer is E, no intervention at this time. The angiogram seen here depicts the classical findings seen in venous malformations (VM), caput medusa. VM consist of a large cortical draining vein receiving a collection of medullary veins that usually occurs near the angle of the ventricle. They rarely hemorrhage. Thus, when diagnosed, they do not require intervention. 30% are associated with cavernous malformations. There may be multiple angiomas in blue nevus syndrome.

Perrini P, Lanzino G. The association of venous developmental anomalies and cavernous malformations: pathophysiological, diagnostic, and surgical considerations. Neurosurg Focus. 2006 Jul 15;21(1):e5. Review.

Classification: Neurosurgery, Venous Malformations, Management

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Q? •

Neurosurgery

The strength of a screw is proportional to: A. The length L B. The outside diameter (thread diameter)3 C. The inside diameter (ID)3 D. The product of the ID and length squared (ID x L) 2 E. All of the above

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A.

Neurosurgery

• The correct answer is C, the inside diameter (ID)3

OD

ID ©™

Classification: Neurosurgery, Screw Strength

Q? •

Neurosurgery

The order of structures traversed when doing Deep Brain Stimulation (DBS): A. Zona incerta, thalamus, subthalamic nucleus, substantia nigra B. Thalamus, zona incerta, subthalamic nucleus, substantia nigra C. Thalamus, subthalamic nucleus, zona incerta, substantia nigra D. Subthalamic nucleus, thalamus, zona incerta, substantia nigra

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Neurosurgery

BOARD FAVORITE!

The correct answer is B, thalamus, zona incerta, subthalamic nucleus, substantia nigra The thalamus (shown in green), subthalamic nucleus (in yellow) and the substantia nigra (in red) are also included in the basal ganglia. The putamen (in blue) can also be seen in this diagram. The zona incerta is the white area just inferior to the thalamus. The arrow depicts the trajectory traversed during DBS.

Fraix V, Pollak P, Van Blercom N, Xie J, Krack P, Koudsie A, Benabid AL (2000) Effect of subthalamic nucleus stimulation on levodopa-induced dyskinesia in Parkinson s disease. Neurology 55:1921–1923.

Classification: Neurosurgery, Deep Brain Stimulation, Structures

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Q?

Neurosurgery

• In doing deep brain stimulation of the subthalamic nucleus, going posterolateral will cause: A. Tetonic muscular contraction B. Dysesthesias C. Tremor reduction D. Double vision

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A. • •

Neurosurgery

BOARD FAVORITE!

The correct answer is B, dysesthesias. NOTE –This is an important board question! – Anterolateral: tetonic muscular contraction Æ internal capsule – Dorsal: decrease in tremor Æ zona incerta – Posterolateral: dysesthesias, sweating Æ medial lemniscus – Medial: double vision, changes in pupils Æ CN III, IV

Fraix V, Pollak P, Van Blercom N, Xie J, Krack P, Koudsie A, Benabid AL (2000) Effect of subthalamic nucleus stimulation on levodopa-induced dyskinesia in Parkinson s disease. Neurology 55:1921–1923.

Classification: Neurosurgery, Deep Brain Stimulation, Posterolateral to Subthalamic Nucleus

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Q? •

Neurosurgery

A 76 year-old male presents to your clinic in consultation with results of a recent angiogram that suggest carotid stenosis with 45% occlusion by NASCET criteria. He denies current visual changes, headaches or weakness, but says that 2 weeks ago he did have “loss of sight” in the left eye for one day . You would recommend: A. Medical therapy (ie, antiplatelet agents and cardiovascular risk factor control/prevention) B. Recommend carotid endarterectomy after considering the patient's risk factor profile and comorbidities C. Recommend endarterectomy without considering the patient's risk factor profile and comorbidities D. Carotid endarterectomy plus antiplatelet therapy and cardiovascular risk factor control/prevention ©™

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Neurosurgery

BOARD FAVORITE!

The correct answer is A, medical therapy. (ie, antiplatelet agents and cardiovascular risk factor control/prevention). NASCET criteria for carotid stenosis: Symptomatic (TIA or minor stroke) Lower-grade carotid stenosis (