Neurological Differential Diagnosis Neurological Differential Diagnosis A Prioritized Approach Roongroj Bhidayasiri, MD, MRCP(UK), MRCPI Department of Neurology David Geffen School of Medicine at UCLA and Parkinson Disease Research, Education and Clinical Center (PADRECC) of West Los Angeles Veterans Affairs Medical Center Los Angeles, CA Michael F. Waters, MD, PhD Department of Neurology David Geffen School of Medicine at UCLA Los Angeles, CA Christopher C. Giza, MD UCLA Brain Injury Research Center Divisions of Neurosurgery and Pediatric Neurology David Geffen School of Medicine at UCLA Los Angeles, CA © 2005 Roongroj Bhidayasiri, Michael F. Waters and Christopher C. Giza Published by Blackwell Publishing Ltd Blackwell Publishing, Inc., 350 Main Street, Malden, Massachusetts 02148-5020, USA Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK Blackwell Publishing Asia Pty Ltd, 550 Swanston Street, Carlton, Victoria 3053, Australia The right of the Author to be identifi ed as the Author of this Work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. 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, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. First published 2005 Library of Congress Cataloging-in-Publication Data Bhidayasiri, Roongroj. Neurological differential diagnosis : a prioritized approach / by Roongroj Bhidayasiri, Michael F. Waters, Christopher C. Giza. p. ; cm. Includes index. ISBN-13: 978-1-4051-2039-5 (alk. paper) ISBN-10: 1-4051-2039-8 (alk. paper) 1. Nervous system--Diseases--Diagnosis--Handbooks, manuals, etc. 2. Diagnosis, Differential--Hand- books, manuals, etc. [DNLM: 1. Nervous System Diseases--diagnosis--Handbooks. 2. Diagnostic Techniques, Neurological- -Handbooks. ] I. Waters, Michael F. II. Giza, Christopher C., 1965- III. Title. RC348.B485 2005 616.8’0475--dc22 2005001189 ISBN 13: 978-1-4051-2039-5 ISBN 10: 1-4051-2039-8 A catalogue record for this title is available from the British Library Set in 10/13 pt Minion by Sparks, Oxford – www.sparks.co.uk Printed and bound in India by Gopsons Papers Limited, New Delhi Commissioning Editor: Stuart Taylor Development Editor: Kate Bailey and Katrina Chandler Production Controller: Kate Charman For further information on Blackwell Publishing, visit our website: http://www.blackwellpublishing.com The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp processed using acid-free and elementary chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board used have met ac- ceptable environmental accreditation standards. Although every effort has been made to ensure that drug doses and other information are presented accurately in this publication, the ultimate responsibility rests with the treating physician. Neither the publishers nor the authors can be held responsible for any consequences arising from the use of infor- mation contained herein. Any product mentioned in this publication should be used in accordance with the prescribing information prepared by the manufacturers. Dedication To my loving grandmother, Pranom Chivakiat, my parents, Mitr & Nisaratana Bhidayasiri, all my teachers of neurology, and lastly all my patients who have taught me much about neurology. RB I would like to dedicate this work to my family, friends, and colleagues, especially Alejandra, for helping to keep my tank full. MFW To my wonderful wife, Rosanne, who gave me our son and greatest joy, Vincent, and my parents, Chester & Yueh-hua who started me on my journey. CCG Contents Foreword, ix Preface, xiii Acknowledgements, xiv How to Use this Book, xv 1 Neuroanatomy and Neuropathology, 1 2 Clinical Syndromes, 62 3 Vascular Neurology, 107 4 Paroxysmal Disorders, 149 5 Neuropsychiatry and Dementia, 173 6 Movement Disorders, 202 7 Infectious, Infl ammatory, and Demyelinating Disorders, 239 8 Peripheral Neurology, 268 9 Neuro-ophthalmology and Neuro-otology, 294 10 Neuro-oncology, 323 11 Pediatric Neurology, 345 12 Neurogenetics, 382 13 Neuroradiology, 403 14 Spinal Cord Disorders, 443 15 Diagnostic Tests, 462 Appendix A: Clinical Pearls, 509 Appendix B: Abbreviations, 523 Index, 525 vii Foreword Every time a physician encounters a patient for the purpose of diagnosis and treatment, a complicated process occurs. It is obvious that this process must be successful if a physician is to choose an optimal therapy in a timely fashion. Such reasoning requires the physician to identify important facts in the history from the patient, family members, and, in some cases, witnesses. The appearance of the pa- tient and the physical examination confi rm suspicions identifi ed from the history. The importance of signs and symptoms must be ranked in terms of their relative importance to the diagnosis at hand, eliminating artifactual information as well as true fi ndings that are irrelevant to the current diagnosis, such as those related to prior diagnoses. The resulting set of facts must then be applied to a large store of possible disorders weighted by the patient’s demographic features such as gender, age, ethnicity, habits, and geographical factors as well as the time-intensity relation- ship (e.g. acute, subacute, chronic) and temporal pattern (e.g. progressive, episodic, relapsing) of the onset of the medical problem at hand. The nervous system provides a unique set of deductive reasoning opportunities in that its architecture is not homogeneous but compartmentalized by functional systems composed of groups of cell bodies and the fi ber tracts that connect them. This information can then be applied to possible diagnoses constrained by ana- tomical localization, temporal features, and demographics. What emerges is a short, prioritized list by likelihood, and, most importantly, concern for possibilities that could be life threatening or produce irreparable damage to the nervous system. This working diagnosis is then confi rmed, fi rst during the physical examination itself, and later by laboratory methods including electrophysiological tests, imaging, and analysis of body fl uids or biopsy material. Once confi rmed, treatment may begin. Thus, a large body of information is sifted down to the salient facts and con- verging in overlapping indicators that allow the selection of this short differential diagnostic list. In many ways, this is an exercise in probability. In fact, numerous attempts have been made to reduce the diagnostic decision-making process to a mathematical one. Computers are especially well suited to help in collecting and processing clinical information. They can be used to retain large lists with the ca- pability of convergence on the most likely answer, with special attention to those diagnoses that may be life threatening. The applications of symbolic logic, prob- ix x Foreword ability theory, value theory, and Boolean algebra have all been employed in these au- tomated strategies. Such approaches have taught us what we see and know from the clinic on an everyday basis. Medical diagnostics should emphasize the fundamental importance of considering combinations of symptoms or symptom complexes. This is important because all too often an evaluation is made of a sign or symptom by itself, without respect to the other features of the disorder, often leading to errors. The consideration of a combination of signs and symptoms that a patient does and does not have, in relation to possible combinations of disease, is a most effective and effi cient approach to the diagnostic process. This text is a marvelous example of providing the practical and probabilistic approach to patients with disorders of the nervous system. It emphasizes prob- ability because a neurological diagnosis can rarely be made with absolute certainty at the bedside, but rather a short list of the ‘most likely’ diagnoses is made and then one is later confi rmed. At the same time, the authors have made the important contribution of also identifying those potential diagnoses that would acutely be life threatening or result in irreparable damage to the brain, spinal cord, or peri- pheral nerves. The importance of this strategy is self-evident. By clustering their approach in accordance with the usual categories of neurological disorders, the process of identifying a complex of patient symptoms, signs, demographic factors, and temporal relationships leading to the appropriate diagnosis is simplifi ed for the reader. The authors have done a superb job in producing a text that is effi cient, easy to use, practical, and accurate. Their motivation comes from practical experience. The clinician, particularly the clinician in training, needs to be able to fi nd and quickly assess information about the patient with whom they are concerned at that mo- ment. It is their job to sift through the facts and artifacts, as noted above, and bring the salient information to be merged with the compendium of lists and diseases provided in this text. Great diagnosticians, from experience and through their ability to generate an instant rapport with the patient, arrive at accurate diagnoses in a remarkably ef- fi cient fashion. Great diagnosticians also have an excellent memory for the facts of their fi eld. Good memory alone and the ability to effi ciently prioritize data provided by the patient are not enough, however. It is the ability to rapidly converge those data sets to a short list or a fi nal diagnosis that makes a good physician a great diagnosti- cian. This text provides a vehicle to help the reader think in that fashion and move toward that role model. The authors have done a masterful job in facilitating the process. I am certain they can be persuaded to apply these strategies to future projects and to expand this approach within the fi elds of neurology and neurosurgery. A fi nal comment: diagnoses, diseases, signs, and symptoms, along with their probabilities, life threatening potentials, and other quantifi able variables are all part of the practice of medicine. These issues are the factors that allow us to determine what is wrong with a patient and provide treatments for their benefi t. The patient Foreword xi with an illness is also a human being in trouble who seeks the help of another person with special knowledge and training. That distinction and the compassion required to help both the person and the patient is as important as any drug or procedure that we as physicians can provide. John C. Mazziotta, MD, PhD Los Angeles, California March 30, 2004 Preface This book has its roots in our perceived need for a concise text to assist the practi- tioner in prioritizing likely diagnoses when encountering a patient complaining of neurological problems or defi cits. Though many references exist on neurological disease and differential diagnoses, few offer easily referable likely diagnoses based on common complaints and presentation. When one approaches differential di- agnosis in neurology, there is frequently a feeling of overwhelming information. It is often one’s fi rst appreciation of the complexities of neurological disease and the elegance of the neurological system when realizing that seemingly ‘anything can cause anything’. When constructing a neurological differential diagnosis, it is often inevitable that a page-long laundry list is quickly compiled. And, although it is true that one cannot make a diagnosis that one doesn’t think of, it is also true that the overwhelming majority of diagnoses can be made by considering the top fi ve or so possibilities. Common things are commonly seen. Moreover, it is also true that one practices today in an environment of limited time and limited resources. Therefore, shouldn’t one be considering the most likely diagnoses fi rst, working up those pos- sibilities, and moving forward if that approach fails to yield the answer? The caveat, of course, is that dangerous or disabling diagnoses must be considered early on to limit death and disability. These principles have directed the construction of this book. While many of the differentials are somewhat lengthy, they are arranged to direct the reader to consider the most likely and most dangerous possibilities fi rst, saving the lesser possibilities for those instances when a comprehensive differential is required for an accurate diagnosis. This book is not, nor is it intended to be, an exhaustive reference. It is, however, an attempt to rationally focus one’s attention in a ‘high-yield’ manner. In writing this text, we are seeking to strike a balance between being comprehensive and being practical. It is our hope that you will fi nd this book a valuable resource when confronted with the task of formulating a neurological differential diagnosis. Collectively, we all wish we had had it during our training, particularly on those late nights in the emergency department. Roongroj Bhidayasiri, Michael F. Waters, Christopher C. Giza xiii