Introduction to Clinical Neurology This page intentionally left blank Introduction to Clinical Neurology Fourth Edition Douglas J. Gelb, MD, PhD Department of Neurology University of Michigan Medical School Ann Arbor, Michigan 1 2011 1 Oxford University Press, Inc., publishes works that further Oxford University’s objective of excellence in research, scholarship, and education. Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Shanghai Taipei Toronto With offi ces in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Thailand Turkey Ukraine Vietnam Copyright © 2011 by Oxford University Press, Inc. Published by Oxford University Press, Inc. 198 Madison Avenue, New York, New York 10016 www.oup.com Oxford is a registered trademark of Oxford University Press All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. Library of Congress Cataloging-in-Publication Data Gelb, Douglas James, 1957– Introduction to clinical neurology / Douglas J. Gelb. – 4th ed. p.; cm. Includes bibliographical references and index. ISBN 978-0-19-973484-9 1. Neurology. 2. Nervous system—Diseases. I. Title. [DNLM: 1. Nervous System Diseases. WL 140 G314i 2011] RC346.G45 2011 616.8–dc22 2010011749 The science of medicine is a rapidly changing fi eld. As new research and clinical experience broaden our knowledge, changes in treatment and drug therapy occur. The author and publisher of this work have checked with sources believed to be reliable in their efforts to provide information that is accurate and complete, and in accordance with the standards accepted at the time of publication. In light of the possibility of human error or changes in the practice of medicine, however, neither the author, nor the publisher, nor any other party who has been involved in the preparation or publication of this work warrants that the information contained herein is in every respect accurate or complete. Readers are encouraged to confi rm the information contained herein with other reliable sources, and are strongly advised to check the product information sheet provided by the pharmaceutical company for each drug they plan to administer. 9 8 7 6 5 4 3 2 1 Printed in the United States of America on acid-free paper To my father, the best teacher I know This page intentionally left blank Preface In the fi ve years since the publication of the third edition of this book, con- trolled trials and systematic reviews have helped to resolve or clarify many longstanding clinical debates. The current edition incorporates recent evi- dence regarding such topics as the role of steroids in treating Bell’s palsy, surgical vs. non-surgical treatment of lumbar disc herniation, the relative value of clopidogrel and aspirin/extended-release dipyridamole in stroke prevention, the comparative effectiveness of glatiramer and interferons in treating multiple sclerosis, and the relative risks and benefi ts of carotid endarterectomy and angioplasty/stenting. In the same time period, the FDA has approved four new anti-epileptic drugs, a drug for Huntington’s dis- ease, and a new symptomatic medication for multiple sclerosis. There have also been recent revisions to the defi nitions of some fundamental neuro- logic conditions, notably “transient ischemic attack” and “epilepsy.” The current edition includes all of these developments. Although the details have been thoroughly updated, the overall organi- zation and focus of the book remain unchanged. As before, the emphasis is on diagnosis and management, stressing general principles and a system- atic approach. I have tried to maintain a consistent tone throughout the book, but to make sure that the discussion did not become too tainted by my personal biases and idiosyncrasies, I asked some of my colleagues to review chapters in their areas of expertise. I am grateful to Jim Burke, Ron Chervin, Kelvin Chou, Praveen Dayalu, Simon Glynn, Kevin Kerber, Steve Leber, Dan Leventhal, Linda Selwa, Jonathan Trobe, and Darin Zahuranec for many helpful comments. Of course, I was too stubborn to follow all of their advice, so any fl aws that remain in the book are my fault, not theirs. As with all three previous editions of the book, I want to thank my wife, Karen, and my daughters, Elizabeth and Molly, for helping me avoid distractions when deadlines loomed and for providing the best possible distractions at other times. D.J.G. This page intentionally left blank Preface to the First Edition Is neurology obsolete? Two current trends prompt this question. First, dra- matic biologic and technologic advances have resulted in increasingly accurate diagnostic tests. It is hard to believe that CT scans have only been widely available since the 1970s; MRI scans, PET scans, and SPECT scans are even more recent, and they are constantly being refi ned. While chess- playing computers have not quite reached world champion status yet, neurodiagnostic imaging studies have long since achieved a degree of sensitivity that neurologists cannot hope to match. There is more than a little truth to the joke that “one MRI scan is worth a roomful of neurolo- gists.” Moreover, advances in molecular genetics and immunochemistry now permit more accurate diagnosis of many conditions than could have been imagined 25 years ago. Some conditions can even be diagnosed before any clinical manifestations are evident. With tests this good, what is the point of learning the traditional approach to neurologic diagnosis, in which lesion localization is deduced from patients’ symptoms and signs? The second major trend challenging the current status of neurology is health care reform. As of this writing, the fi rst great national legislative debate concerning health care reform has ended, not with a bang but a whimper. Yet the problem itself has not disappeared. The already unac- ceptable costs of health care will continue to escalate if the current system remains unchanged. While the various reform plans that have been pro- posed differ in many fundamental respects, there appears to be a consen- sus that there should be more primary care physicians and fewer specialists. Indeed, several forces are already pushing the medical profession in that direction even in the absence of a comprehensive national legislative plan. As a concrete example, it is anticipated that the number of residency train- ing positions in neurology will drop, perhaps to only half of the current level. With so much nationwide emphasis on primary care, what is the point of studying neurology? x PREFACE TO THE FIRST EDITION Ironically, these two trends together provide a compelling reason to study neurology. In coming years, there will be increasing pressures on primary care physicians to avoid referring patients to specialists (and there will be fewer specialists in the fi rst place). One response of primary care physicians might be to order more diagnostic tests. Unfortunately, the only thing more impressive than the sensitivity of the new tests is their price tag. Just at the time when diagnostic tests are reaching unprecedented levels of accuracy, the funds to pay for the tests are disappearing. Rather than replacing neurologists with MRI scans and genetic testing, primary care physicians will have to become neurologists (to some degree) themselves. In short, the role currently played by neurologists may well be obsolete, but neurology itself is not. All physicians, regardless of specialty, must become familiar with the general principles of neurologic diagnosis and management. That is the rationale for this book. The purpose of this book is to present a systematic approach to the neu- rologic problems likely to be encountered in general medical practice. The focus throughout the book is on practical issues of patient management. This is a departure from the traditional view of neurologic diseases as fas- cinating but untreatable. Neurologists are often caricatured as pedants who will pontifi cate interminably on the precise localization of a lesion, produce an obscure diagnosis with an unpronounceable eponym, and smugly declare the case closed. In years past, this stereotype was not wholly inaccurate. Even when therapeutic options existed, there were few con- trolled studies of effi cacy, so it was easy to take a nihilistic approach to therapy. “First do no harm” could often be legitimately interpreted to mean “Do nothing.” This was obviously a frustrating position for physi- cians, and even more so for patients, but at least it kept things simple. All this has changed. Controlled trials of both new and traditional therapies are being conducted with increasing frequency. In the two years since the original versions of some of the current chapters were fi rst prepared, sumatriptan has been approved for treatment of headache, beta interferon for use in multiple sclerosis, ticlopidine for stroke, and tacrine for Alzheimer’s disease. Felbamate has appeared and (practically) disappeared. Gabapentin and lamotrigine have been approved for use in epilepsy. The long-term results of a large cooperative study of optic neuritis have chal- lenged traditional practices involving the use of steroids for that condition and for multiple sclerosis. Preliminary reports have appeared concerning the value of endarterectomy for asymptomatic carotid stenosis, a new preparation of beta interferon for MS, and Copolymer I for MS. These are exciting developments, but many of the studies raise as many questions as PREFACE TO THE FIRST EDITION xi they answer. They certainly change the way physicians have traditionally approached many neurologic diseases. This book refl ects that change. Esoteric diagnostic distinctions with little practical relevance are avoided. Distinctions that affect treatment are emphasized. In most chapters, the available treatment options and general approach to management are presented fi rst, to clarify which diagnostic distinctions are important and why.