Movement Disorders in Childhood [email protected] 66485438-66485457 Movement Disorders in Childhood Harvey S. Singer, MD Professor of Neurology and Pediatrics Haller Professor of Pediatric Neurological Diseases Director of Pediatric Neurology The Johns Hopkins Hospital Baltimore, Maryland Jonathan W. Mink, MD, PhD Professor of Neurology, Neurobiology and Anatomy, and Pediatrics Chief, Child Neurology University of Rochester Medical Center Rochester, New york Donald L. Gilbert, MD Director, Movement Disorder Clinic and Tourette’s Syndrome Clinic Associate Professor of Pediatric Neurology Cincinnati Children’s Hospital Cincinnati, Ohio Joseph Jankovic, MD Professor of Neurology Director, Parkinson’s Disease Center and Movement Disorders Clinic Department of Neurology Baylor College of Medicine Houston, Texas [email protected] 66485438-66485457 1600 John F. Kennedy Blvd. Ste 1800 Philadelphia, PA 19103-2899 MOVEMENT DISORDERS IN CHILDHOOD ISBN: 978-0-7506-9852-8 Copyright © 2010 by Saunders, an imprint of Elsevier Inc. All rights reserved. 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. Permissions may be sought directly from Elsevier’s Rights Department: phone: (+1) 215 239 3804 (US) or (+44) 1865 843830 (UK); fax: (+44) 1865 853333; e-mail: [email protected]. You may also complete your request on-line via the Elsevier website at http://www.elsevier.com/permissions. Notice Knowledge and best practice in this field are constantly changing. As new research and experience broaden our knowledge, changes in practice, treatment and drug therapy may become necessary or appropriate. Readers are advised to check the most current informa- Otion 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 the practitioner, relying on his or her own experience and knowledge of the patient, 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 assume any liability for any injury and/or damage to persons or property arising out of or related to any use of the material contained in this book. The Publisher Previous editions copyrighted 2010 Library of Congress Cataloging-in-Publication Data Movement disorders in childhood / Harvey S. Singer … [et al.].—1st ed. Includes bibliographical references. ISBN 978-0-7506-9852-8 1. Movement disorders in children. I. Singer, Harvey S. [DNLM: 1. Movement Disorders. 2. Child. WS 340 M9354 2010] RJ496.M68M685 2010 618.92′683—dc22 2009034376 Acquisitions Editor: Adrianne Brigido Development Editor: Taylor Ball Publishing Services Manager: Anitha Raj Project Manager: Mahalakshmi Nithyanand Design Direction: Louis Forgione Printed in the United States of America Last digit is the print number: 9 8 7 6 5 4 3 2 1 [email protected] 66485438-66485457 We dedicate this book to our patients, mentors, students, fellows, and other trainees for their inspiration and to our wives and families for their enduring support. [email protected] 66485438-66485457 [email protected] 66485438-66485457 [email protected] 66485438-66485457 Preface Movement disorders are a relatively new area of special- Chapters 1 to 4, includes basal ganglia and cerebellar ization within child neurology. For many years, move- anatomy, physiology, and pharmacology; standard def- ment abnormalities affecting the pediatric population initions; and diagnostic approaches. Subsequent chap- received little attention in adult-oriented textbooks, ters are disease oriented, based on age of presentation, and chapters were frequently written by adult neu- predominant motor phenomenology (hypokinetic or rologists. Over the past several decades, child neurolo- hyperkinetic), or clinical etiology (static encephalopa- gists have assumed a greater role in the care of children thy, metabolic disease, etc). Where possible, chapters with movement disorders and the investigation of their share a common format consisting of an overview, underlying etiologies and mechanisms. definition, review of clinical characteristics, neuron- The decision to produce a high-quality text devoted atomic localization, and pathophysiology, followed to movement disorders in children was based on a per- by a discussion of individual diseases and disorders. ceived need for an informative, useful resource that Lastly, we have included appendices with information would benefit the care of affected individuals. In the of general relevance to a clinician managing a child process of attaining this ultimate goal, several working with a movement disorder. Appendix A covers com- aims were established. First and foremost, each chapter mon medications used in the treatment of movement would be written by a board-certified child neurologist disorders (doses, side effects, and drug interactions). with a strong clinical and scientific background in the Appendix B provides a guide for diagnosing herita- field. Second, the number of authors would be limited, ble movement disorders, with tips on the use of the in order to maintain an active dialogue and compre- Online Mendelian Inheritance in Man (OMIM) and hensive review of each chapter. Lastly, recognizing that Genetests websites. Appendix C provides legends to written descriptions of abnormal movements are often the videos. limited and that visual aides are an essential teaching For all, this was a labor of pleasure and one of contin- tool, the inclusion of videos was a requirement. ued learning. We believe that this book provides a fun- Chapters were written by Harvey Singer, Jonathan damental background of neuronal circuitry, an approach Mink, and Donald Gilbert and reviewed by all authors. to patient evaluation, and a comprehensive review of dis- Patient videos, designed to illustrate and enhance the orders that should be acceptable to readers at all levels of described phenomenology, were provided by Joseph experience. We fully recognize that advances in pediatric Jankovic, who also reviewed and edited all the chapters. movement disorders continue to proceed at a rapid pace The book is organized in sections. The first section, and that future updates may be required. Harvey S. Singer, MD Jonathan W. Mink, MD, PhD Donald L. Gilbert, MD, MS Joseph Jankovic, MD Fall, 2009 vii [email protected] 66485438-66485457 [email protected] 66485438-66485457 Acknowledgments The authors would like to thank the staff at Elsevier for their assistance and flexibility. In particular, we acknowledge the efforts of Taylor Ball and Mahalakshmi Nithyanand. ix [email protected] 66485438-66485457 [email protected] 66485438-66485457 Basal Ganglia Anatomy, 1 Biochemistry, and Physiology O Introduction Striatum and Subthalamic Nucleus are the Input Nuclei The basal ganglia are large subcortical structures com- prising several interconnected nuclei in the forebrain, The striatum receives the bulk of extrinsic input to the diencephalon, and midbrain. Historically, the basal basal ganglia. The striatum receives excitatory input ganglia have been viewed as a component of the motor from virtually all of the cerebral cortex.1 In addition, system. However, there is now substantial evidence the ventral striatum (nucleus accumbens and rostroven- that the basal ganglia interact with all of the frontal tral extensions of caudate and putamen) receives inputs cortex and with the limbic system. Thus the basal gan- from the hippocampus and amygdala.2 The cortical glia likely have a role in cognitive and emotional func- input uses glutamate as its neurotransmitter and ter- tion in addition to their role in motor control. Indeed, minates largely on the heads of the dendritic spines of O 3 diseases of the basal ganglia often cause a combination medium spiny neurons. The projection from the cere- of movement, affective, and cognitive disorders. The bral cortex to the striatum has a roughly topographic motor circuits of the basal ganglia are better under- organization. It has been suggested that this topogra- stood than the other circuits, but because of similar phy provides the basis for a segregation of functionally organization of the circuitry, conceptual understand- different circuits in the basal ganglia.4 Although the ing of basal ganglia motor function can also provide topography implies a certain degree of parallel orga- a useful framework for understanding cognitive and nization, there is also evidence for convergence and affective function. divergence in the corticostriatal projection. The large dendritic fields of medium spiny neurons allow them 5 Components and Connections to receive input from adjacent projections, which arise of Basal Ganglia Circuits from different areas of cortex. Inputs to striatum from several functionally related cortical areas overlap and The basal ganglia include the striatum (caudate, puta- a single cortical area projects divergently to multiple men, nucleus accumbens), the subthalamic nucleus, striatal zones.6,7 Thus there is a multiply convergent the globus pallidus (internal segment, external seg- and divergent organization