Companion to Clinical Neurology, Second Edition

Companion to Clinical Neurology,

Second Edition

WILLIAM PRYSE-PHILLIPS

MD, FRCP (Lond.), FRCP (C), DPM

OXFORD UNIVERSITY PRESS

Companion to Clinical Neurology

Second Edition

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Companion to Clinical Neurology

SECOND EDITION

WILLIAM PRYSE-PHILLIPS

MD, FRCP (Lond.), FRCP (C), DPM

Professor of Medicine (Neurology) Memorial University St. John’s, Newfoundland, Canada

1

2003

1

Oxford New York

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Copyright © 2003 by William Pryse-Phillips

Published by Oxford University Press, Inc.

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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 Pryse-Phillips, William.

Companion to clinical neurology / William Pryse-Phillips.—2nd ed.

p. ; cm. Includes bibliographical references.

ISBN 0-19-515938-1 1. Neurology—Dictionaries. I. Title.

[DNLM: 1. Neurology—Dictionary—English.

2. Nervous System Diseases—Dictionary—English.

Wl 13 P973c 2003] RC334 .P79 2003 616.8
03—dc21 2002029294

2 4 6 8 9 7 5 3 1 Printed in the United States of America

on acid-free paper

Preface to the Second Edition

The kind comments of those who wrote reviews of the first edition of my Compan-

ion delighted me. I am particularly pleased that what was written originally for my

own use as a practicing clinical neurologist was also found appropriate by so many of my colleagues and I was further honored when Japanese colleagues called for an edition in their own language.

The format of the book has not changed in this second edition. I have continued to list certain items twice if either of their two names seems likely to be the word or phrase that requires authentication, and have selected from some thousands of jour- nal articles scanned only those definitions, criteria, or comments that were most meaningful to me. I have made comments that may not amuse the General Staff, but they come from where the action is: in the trenches.

Advances in neurology are occurring at least as fast as in any other area of med- icine and I recognize that in the year between the delivery of my manuscript and its publication, new information will have been presented that will make some of my definitions passé. I ask the reader’s forbearance. I also must restate the comment I made in preparing the first edition of my Companion: “I have aimed [only] for rea- sonable completeness,” suitable for almost all (but of course not quite all) the situ- ations that the clinical neurologist is likely to meet in which an authoritative defi- nition is required. The decisions on what to include and to exclude were mine, based on my experience and my enthusiasms, so this is a very personal compilation, stem- ming from my insights (and sometimes probably the lack of them) into the neurol- ogy of today that rides upon yesterday’s shoulders. I offer it with the hope that it will inform and occasionally divert my colleagues and that it will benefit their patients.

St. John’s, Newfoundland W.P-P.

Canada

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Preface to the First Edition

A confused and equivocal terminology is the fruitful parent of con- fused and equivocal thinking.

—Sir Francis Walshe, 1947

One of the most difficult tasks for the beginning neurologist is that of understand- ing the jargon of the subject. It has been estimated that over 20,000 new words are learned or at least interpreted by a mature physician; a high percentage of them must be used in neurology. Not only derivations from Latin and Greek, but also epony- mous disorders, names of chemicals, acronyms, neologisms, and pet-names spill re- peatedly from neurologists’ lips. Because they are not all widely known they often cloud meaning and impair communication although their original intent was to de- fine, to categorize, or to distinguish concepts, clinical experience, or scientific truths.

Who were all these people whose names are attached to syndromes or diseases or tests? How do dysphagia and dysphasia differ? Why isn’t Bell’s phenomenon the same as Bell’s palsy and why doesn’t it involve the long thoracic nerve of Bell? Is there common ground in the definition of criteria for this or that condition? Such questions are naive to a neurologist, but need an answer when asked by students or by physicians who are not so trained, or by professional workers in allied disciplines.

Companion to Clinical Neurology is a personal endeavour to provide answers to ques-

tions like these. I have tried to incorporate within it some science, some art, some his- tory, some practical experience. It is also a hive in which nest numerous bees formerly resident in my bonnet and which needed more Lebensraum. It is designed for the bed- side and, I hope, for a reasonably low shelf in a room where a physician does his or her work. At least one reference is included for most of the entries delineating diseases, usually representing that publication on the subject which brought the material first to attention or one to which the interested reader may turn in order to receive more precise directions along the road to further knowledge; but in some instances it is to that paper on the subject which I enjoyed reading most.

The Companion is designed as a guide wherein the menu of neurological practice is laid out and from which suggestions for further reading may be obtained. I have assembled what I believe to be the best published definitions of neurological phe- nomena, and where none is available, have provided a brief description of my own.

This is not a treatise on differential diagnosis; only, when a word or a phrase is en- countered which is not fully understood. I trust that it will have been given a defi- nition here, and in certain cases, some background to reinforce memorization.

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My selection of items or names for inclusion has been on the basis of what prob- lems I think a neurologist might expect to meet over the years of clinical practice.

The major entry is in each case that name which I believe to be the one most com- monly used, and therefore the most recognizable. Bracketed thereafter are synonyms also in recent use. Where words other than major entries are printed in boldface, this indicates that the item is itself a separate entry; italics indicate foreign words, emphasis, journals, or variants not entered elsewhere. Where two or more authors have given their names to a condition, the reference given is to that paper first ap- pearing, or occasionally to that which corrected the errors of the first with such dex- terity that the alternate eponym is preferable—as with Jakob and Creutzfeldt. How- ever, where usage of the two (or three or, God help us, more) names has led to numerous variations depending on the order in which those names are placed, only that combination which seemed to me to be the most familiar has been included.

The same restriction applies to the seemingly endless permutations of derived La- tinisms, only a few of which appear. To save the bother of incessant turning of pages, brief summaries of some conditions are also included under their alternative names.

In this Companion I have aimed for reasonable completeness, but realize that neu- rology is too large a subject for one head to contain. Among the readers of this book there will be many with special knowledge which could lead to improvements upon some of the definitions that I have attempted here; their kind offers of contributions would be accepted with delight and acknowledged with gratitude.

W.P-P.

viii PREFACE TO THE FIRST EDITION

Foreword to the First Edition

In these days of publish-or-perish, novelty seldom rises above the flat sea of new re- views and books that simply confirm what’s already well known. Dr. Pryse-Phillips, however, has chosen a new tack and, in the process, brought us an astonishingly large, clinically oriented compendium of things neurological. In form, Companion

to Clinical Neurology takes its place alongside such source references as the renowned

and informative Oxford Companions. Its contents describe at varying length but with great clarity the phenomenological world of clinical neurology from its hesitant be- ginning over a century ago to its current vigorous strength. Ranging between brief, identifying sentences defining minor neurological facts to longer descriptions about diseases and their classifications, Pryse-Phillips depicts or explains neurology’s by- gone leaders as well as its symptoms, signs, syndromes, diseases, eponyms, opera- tive procedures, and diagnostic tests. In the breadth of its topics the book has a gen- tly nostalgic, British-Continental flavor of a more relaxed scientific day. Nevertheless, it by no means ignores American sources or recent contributions, including genetic classifications.

Certain features stand out. The Companion gives special attention to the clinical expressions and electrophysiological mechanisms of the epilepsies. The text also in- terestingly and informatively reflects Pryse-Phillips’ longstanding interest in neu- rology’s cognitive and behavioral aspects. But these are just a few of its extraordi- nary riches. Did you, the reader, know that although Munchausen’s syndrome was named by Ascher in 1951, the disorder’s content had been described by Meige in his graduation thesis (Paris) in 1893? Or that the condition has three synonyms and three subsets? I didn’t. Would you be surprised to find that ataxia has been defined in 41 different forms, or that it is included in 40 different identified syndromes? I was. These historic pearls and many others await the reader’s eye, whether to en- tertain as nightly pre-sleep browsing or to act as a sourcebook from which to iden- tify past foundations of tomorrow’s neuroscience.

Companion to Clinical Neurology provides a remarkably thorough, pithy view of

the world of clinical neurology and its close co-disciplines. With well over 15,000 entries and 5,000 references, it successfully reflects the prodigious (and nowadays rare) scholarship of its author. Within these pages the novitiate will discover the past richness of clinical neurology, and experienced neurologists will find informative explanations about all kinds of common and arcane aspects of their discipline’s heritage.

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In short, Companion to Clinical Neurology provides the best compact source I know in which one can quickly refresh one’s memory about a fact well known or dig out a hitherto unknown item about the most philosophically and biologically interest- ing of all the medical specialties.

Fred Plum, M.D.

x FOREWORD TO THE FIRST EDITION

Acknowledgments

During the years that I wrote the first edition of this book, many people gave me help and advice. In particular I was fortunate in being able to access the private col- lection of medical biographies compiled by (the late) Mr. Austin Seckersen, formerly of the Bodleian Library at the University of Oxford. His generosity greatly speeded the completion of the work. The initial writing was done during a sabbatical year from Memorial University. I thank Lord Walton, then Warden of Green College, and Professor John Newsom-Davis of the University of Oxford for providing me with a visiting scholarship at Green College and with membership of the Depart- ment of Neurology.

Substantial assistance in the writing of the first edition was provided by Drs. Mil- ton Alter, Peter Dunne, Roger Duvoisin, Joseph Foley, Anita Harding, Andrew Kertesz, Wayne Massey, David Neary, Charles Poser, R. Mark Sadler, Patrick Sweeney, P.K. Thomas, and James Woodrow. Mr. Theo Dunnett of the Bodleian Li- brary provided skilled help without limit in the location and selection of sources, particularly in the production of the illustrations in this second edition.

The writing of this second edition was done during another sabbatical year from Memorial University and I thank Dr. Ian Bowmer, Dean of Medicine, for provid- ing this essential opportunity. Huge assistance was lent by Dr. Heather Arnold, Dr. Bijal Mehta, and Dr. Scott Sloka in scrutinising the neurological papers pub- lished in English since the first edition, while they were studying medicine at Memo- rial. Many corrections and additions were suggested by Dr. Homer J. Moore, of San Diego, CA, to whom I offer my hearty thanks.

Items substantially contributed by others acknowledged here are followed by their initials in the text.

This compilation required the reproduction of items from some hundreds of in- dividual sources, for which today fees are commonly required. I thank the Ameri- can Academy of Sleep Medicine, the American Medical Association, the American Psychiatric Association, Blackwell Science, the British Medical Association, the Cana- dian Journal of Neurological Sciences, Elsevier Science, the United States Govern- ment, John Wiley and Sons Inc., and the World Health Organization in particular for waiving such fees; without their gracious support of an academic endeavor such as this, the book would have been impossible to produce.

The material from the American Association of Electrodiagnostic Medicine’s Glos-

xi

sary of Terms in Electrodiagnostic Medicine © 2001 is used freely by kind permis- sion of the AAEM (Nomenclature Committee: Lawrence H. Phillips II, M.D., Chair, Andrew J. Haig, M.D., William Litchy, M.D., Chair; Mark Hallett, M.D., Raymond G. Auger, M.D., Charles K. Jablecki, M.D., Ernest M. Baran, M.D., M.S.B.M.E., Dale J. Lange, M.D., Francis J. Bonner Jr., M.D., Janice M. Massey, M.D., M.E. Brand- stater, M.B.B.S., Ph.D., FRCP, Lawrence R. Robinson, M.D., Daniel Dumitru, M.D., Ph.D., Margaret A. Turk, M.D., Bjorn Falck, M.D., Ph.D., Jacqueline J. Wertsch, M.D., Andrew J. Gitter, M.D., and Asa J. Wilbourn, M.D.). Again, I offer my sin- cere thanks.

The lines from “voices to voices, lip to lip” are reprinted as an envoi from Com-

plete Poems, 1904–1962, by E. E. Cummings, edited by George J. Firmage, by per-

mission of Liveright Publishing Corporation. Copyright © 1926, 1954, 1991 by the Trustees for the E. E. Cummings Trust. Copyright © 1985 by George James Fir- mage.

In some instances an original reference was not available to me; I acknowledge again with pleasure (and with admiration) the work of Dr. Michael Baraitser and Dr. Robin Winter and their colleagues that led to the publication of the Neuroge- netic Database; this and the encyclopedic works of Dr. Victor McKusick and (through his superb website) Dr. Alan Pestronk provided me with data on and analyses of a number of disorders that I would have missed otherwise.

I am especially grateful to my new editor, Fiona Stevens, Nancy Wolitzer, Jerri Hurlbutt, and the Oxford University Press for their confidence in me and in my book and for their labors in making it as good as it could be.

And I thank my family, Gwyneth, Amy, and Sam for their continual support, and for understanding the realities of an academic life.

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xii ACKNOWLEDGMENTS

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Companion to Clinical Neurology

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AAA syndromes See Allgrove syndrome.

A band Dark, anisotropic thick filaments in muscle which with the I bands make up a myofibril. Upon them is a dark transverse M line surrounded by a lighter H- zone.

A pattern deviation A nonparalytic form of hori- zontal strabismus or tropia in which the visual axes are directed to closer objects (esotropia) as the subject looks up or separate (exotropia) as the subject looks down. Thus the horizontal deviation of the visual axes varies with the vertical position of the eyes.³³³⁰See also V pattern deviation, which is the reverse of this.

A test (Random Letter Test) A simple test of vigilance in which the examiner reads out a random series of let- ters, and the patient is required to tap on the table with a pencil whenever a specific letter such as A is spoken.

A wave A compound muscle action potential that fol- lows the M wave, evoked consistently from a muscle by submaximal electric stimuli and frequently abolished by supramaximal stimuli. Its amplitude is similar to that of an F wave, but the latency is more constant. The A wave usually occurs before the F wave, but may oc- cur afterwards. It is thought to be due to extra dis- charges in the nerve, ephapses, or axonal branching.

This term is preferred over axon reflex, axon wave, or axon response. Compare with the F wave.¹⁰(From the 2001 Report of the Nomenclature Committee of the American Association of Electromyography and Elec- trodiagnosis. Used by permission, copyright © 2001, AAEM.)

A1, A2 electrodes The conventional terms in elec- troencephalography for recording electrodes placed re- spectively on the left and right ears.

Ac electrode The conventional term in electroen- cephalography for a recording electrode placed on the contralateral ear with respect to any other electrode.

Aase-Smith syndrome A congenital dysmorphic syndrome characterized by cardiac and skeletal abnor- malities, adrenal tumors, holoprosencephaly, Dandy- Walker malformation, and hydrocephalus.¹⁶ AB variant A form of gangliosidosis characterized by deficiency of GM2activator factor, leading to the accu- mulation of GM2ganglioside. See GM2gangliosidosis.

Abadie, Charles A. (1842–1932) French ophthal- mologist who practiced in Paris. He described alcohol injection of the Gasserian ganglion for trigeminal neu- ralgia as well as the Abadie sign (Dalrymple sign), re- traction of the upper lid as a result of contraction of the levator palpebrae muscles in hyperthyroidism.¹⁷ Abadie, Jean-Louis-Irenée-Jean (1873–1946) French neurologist and psychiatrist who graduated with a the-

sis on the internal capsule and who became professor of nervous and mental diseases in Bordeaux. He de- scribed the Abadie sign in 1905; his other publications dealt with such topics as hysterical polyuria, epilepsy, tabes, and diabetes insipidus.

Abadie sign Loss of deep pain sensation, shown by insensibility to hard pressure upon the Achilles’ tendon in patients with tabes dorsalis; it was said to have been the third most common sign in that condition. See also Biernacki sign and Pitres sign, each of which are also typically positive in tabes.

abasia An inability to maintain an upright posture, as described with astasia by Blocq in patients with hys- terical disorders.⁶⁰⁶

abasic gait apraxia A syndrome resulting from small hemorrhages into the posterior internal capsule and/or putamen bilaterally, manifesting clinically as an inabil- ity to maintain the upright stance or to walk, although the muscle actions underlying these activities are unaf- fected when the subject makes the same movements while lying down.⁵¹¹⁴

ABC syndrome (angry backfiring C nocioceptor syn- drome) A fanciful term for what is likely to be the com- plex regional pain syndrome.

Abdallat neurocutaneous syndrome A congenital dysmorphic syndrome characterized by patchy depig- mentation of skin and hair, spasticity, and sensorimo- tor peripheral neuropathy.³³⁷

abdominal epilepsy The occurrence of abdominal pain or vomiting as the sole or major manifestation of a partial seizure in children.¹⁵⁰³

This nonconvulsive seizure disorder occurs princi- pally in children and is characterized by brief attacks of borborygmi, vomiting, pallor or flushing of the face, perspiration, and severe colicky periumbilical pain, fre- quently associated with altered consciousness and brief and simple automatisms. Coexisting EEG abnormali- ties include bilateral spike-and-wave, polyspike-and- wave, low-voltage fast, and 10-Hz fast activity.⁵⁶ abdominal migraine Recurrent attacks of abdomi- nal pain, vomiting, pallor, and sometimes fever in school-age children who have a family history of mi- graine and who, in many cases, later go on to develop more typical migrainous features.³⁵⁹The pain is usu- ally a diffuse burning or aching in periumbilical or epi- gastric regions, and may have been preceded by well- recognized prodromal symptoms of migraine.

abdominal neuroblastoma See neuroblastoma.

abdominal pain–nerve entrapment syndrome Uni- lateral segmental pain felt in the abdominal wall and due to entrapment of cutaneous nerves as they pass

A

1

through its muscular layer, usually at the outer border of the rectus sheath. The origin of the pain is localized to a point below the examining finger, and it is wors- ened by tensing the abdominal muscles, as with trunk flexion in the supine position.

abdominal paradox Inward movement of the ab- dominal wall during inspiration, as seen in some cases of neuromuscular disease leading to ventilatory failure.

abdominal (muscle) reflex Contraction of the rec- tus abdominis and other muscles of the abdominal wall in response to a tap on the muscle itself or at the up- per or lower end of the rectus abdominis. The reflex is not always found in the normal subject, but may be in- creased in patients with pyramidal lesions above T6.

Numerous sites for the elicitation of the reflex have been described, including the rectus abdominis lateral to the umbilicus, the nipple, the symphysis pubis, the anterior superior iliac spine, the costal margin, or the thoracic wall. Another method described is to insert the finger into the umbilicus and to tap it.³³²⁴

abdominal (skin) reflex Contraction of the muscles of the abdominal wall such that the umbilicus is drawn slightly towards the site of a gentle scratch of the over- lying skin in any of the four quadrants. It was first de- scribed by Rosenbach in 1876.³³²⁴

This represents a spinal polysynaptic reflex that is normally present, but it may be absent in pyramidal le- sions at sites above T6, and in multiple sclerosis, be- cause of diminished excitability of the spinal reflex cen- ter.³¹⁸² It is seldom present after pregnancies, in the very obese, and in those who have had numerous ab- dominal operations. When the cord lesion is at T10, the reflex will only be present over the upper half of the ab- domen. Further localization of a spinal cord lesion ac- cording to the presence of the reflex in upper, middle, and lower abdominal regions is of more theoretical than practical value.

abdominal reflex dissociation Augmentation of the abdominal muscle reflex with disappearance of the abdominal skin reflex; a sign of an upper motor neu- ron lesion above T6.³³²⁴

abducens (Lat, to lead away from) The sixth cranial nerve, described by Eustachius in 1564, and so called because it supplies the lateral rectus muscle which draws the eye to the side, away from the midline.

abduction The movement by which part of the body is drawn away from the sagittal line or a digit is drawn aside from the medial line of the hand. See also (ocu- lar) duction.

abduction nystagmus (ataxic nystagmus, internu- clear ophthalmoplegia) A form of dissociated nystag- mus in which the abnormal movement is seen in the abducting eye either exclusively or else far more obvi- ously than in the other eye, which may fail to adduct normally. See internuclear ophthalmoplegia.

abductor digiti quinti sign Slight abduction of the fifth finger on one side when patients with mild hemi- paresis extend the arms out in front of them. When this is seen bilaterally, however, the sign has no signifi- cance.¹²⁸

The phenomenon was noted by Wartenberg, but he ascribed it to cerebellar disease. The Souques sign, in which all the fingers are separated, is similar, as is the pinky finger sign.

abductor laryngeal paralysis A dominantly inher- ited congenital syndrome manifesting as hoarse voice and dysphagia.³³⁷

Abercrombie, John (1781–1844) Scottish physician who published the first book devoted to the neu- ropathology of both the central and the peripheral nerv- ous systems, in which he classified three types of apoplexy (1828). He was also the first to describe sub- dural empyema.

Aberfeld syndrome A recessively inherited syn- drome of myotonia, dwarfism, multiple joint contrac- tures, facial dysmorphism, blepharophimosis, poor muscle development, and bone disease, resembling Morquio-Brailsford disease.²⁴

aberrant regeneration The inappropriate redirec- tion of fibers sprouting from a site of injury. This has been described most typically in compression of the third cranial nerve by an intracavernous meningioma.

In this situation retraction of the upper eyelid on down- ward gaze or adduction of the eye, restricted upward movement of the globe, and impairment of the pupil- lary light response are found.⁶²³

abetalipoproteinemia (Bassen-Kornzweig syndrome) A recessively inherited, progressive ataxic syndrome of early childhood, due to a deficiency of apoprotein B, which is an important factor in transporting lipids from the intestine to the plasma. The responsible gene is lo- cated on chromosome 2 at 2p24. The accompanying neuropathy is probably due to vitamin E deficiency.

Clinically, the disease resembles Friedreich ataxia, with cerebellar signs, ptosis, ophthalmoplegia, and sen- sorimotor neuropathy, but in addition pigmentary retinopathy and steatorrhea are found, low-density lipoproteins are absent from the plasma, triglyceride and cholesterol levels and chylomicron counts are low, and acanthocytes are found in fresh smears.²⁴³⁹See also cerebellar ataxias (variants).

abiotrophic dementia See Creutzfeldt-Jakob dis- ease.

abiotrophy (Gr, lack of organism  turn) De- rived by Sir William Gowers, this term signifies the ces- sation of growth of an organ. It is used to label a process whereby the previously normal metabolism of certain cell lines ceases, frequently as an age-related process.

The word was first used by Gowers in his discussion of the spinocerebellar degenerations.

2 ABDOMINAL PARADOX

Diseases labeled abiotrophic include Huntington chorea, adult-onset acid maltase deficiency, Parkinson disease, amyotrophic lateral sclerosis, and many more, but as the infective, genetic, or other etiologies of neu- rological diseases are progressively discovered, the blan- ket term seems to have less and less usefulness. Proba- bly the last condition to warrant the name of abiotrophy will be such age-related changes as cortical cell loss pro- ducing memory impairment.

able autism See Asperger syndrome.

ablepharon Absence of the eyelids. In the most se- vere form, the skin of the forehead and the skin of the face are fused but the condition may be incomplete or unilateral. Autosomal recessive inheritance has been shown in many cases.

abluminal Outside the lumen of a vessel, such as a blood vessel.

abnormal illness behavior See hysteria.

abnormal involuntary movement scale A five-point scale for the evaluation of abnormal involuntary move- ments affecting the face and mouth, the extremities, and the trunk, with an added global judgement of severity.

The assessment is based upon a formal examination in which subjects remove their shoes and socks and sit with their legs apart, their feet flat on the floor and their hands on their knees or hanging unsupported. Open- ing of the mouth; protrusion of the tongue; tapping the thumb with each finger as fast as possible; standing; ex- tending both arms in front; walking; and alternate flex- ion and extension of the arms are then observed and the abnormalities rated between 0 (none, normal) and 4 (severe). The muscles of facial expression, lips and pe- rioral regions, jaw, tongue, upper and lower limbs, and trunk are examined separately, and a global assessment is made of the severity of any abnormal movements and of the incapacity which they induce.⁴⁵⁴¹

abnormal swallowing syndrome Brief awakenings from normal sleep as a result of aspiration of normal secretions that have not been swallowed efficiently, leading to choking and coughing²³²³(see also sleep dis- orders²³⁴).

abortive disseminated encephalitis (Redlich en- cephalitis) See encephalitis lethargica.

abscess, cerebral A circumscribed collection of pus.

The first accurate account of the phenomenon was that of Hermann Lebert (1813–1878), a French physician, in 1856, although Sauveur Morand (1697–1773), a French surgeon, is credited with a successful drainage procedure for temporosphenoidal abscess in 1752.⁴⁹⁷⁹ MacEwen performed the first modern procedure.³⁵⁴⁸ An historical review was published by Garfield.²⁰²⁹See also epidural abscess, spinal subdural abscess.

absence epilepsy (petit mal epilepsy, centrencephalic epilepsy, minor motor seizures, myoclonic-astatic

seizures, myokinetic epilepsy, typical absence attacks, pyknolepsy) A seizure disorder in which the seizures consist typically of frequent brief (2–15 seconds) alter- ations in consciousness without motor accompani- ments apart from fluttering of the eyelids, automatisms, or association with myoclonic or atonic seizures (com- plex absences). In all cases there is an immediate return to normal activity and mentation at the end of the at- tack. In simple absence attacks, there is only impairment of consciousness, although simple and limited motor activity such as eyelid fluttering may occur. A heredi- tary tendency is notable in some families.³⁵¹⁵

The following diagnostic criteria of the ILAE have been reviewed:⁶⁷⁹

1. A form of epilepsy with onset before puberty (childhood AE), or before age 17 years (juvenile AE)

2. Occurring in previously mentally and neurologically normal children

3. Absences are the initial type of seizures

4. Very frequent absence seizures of any kind occur, except myoclonic absences

5. Absence seizures are associated on the EEG with bilat- eral, symmetric, and synchronous discharge of regular 3/second spike-and-wave complexes on a normal back- ground activity. Less regular spike–wave activity is pos- sible, when compatible with a diagnosis of typical ab- sences.

Typical and atypical forms are recognized. In the typ- ical form, the clinical manifestations are as above, and the EEG shows generalized, synchronous, symmetrical 2.5-Hz (or more) spike-and-wave or multiple spike- and-wave activity. In the atypical form (see atypical ab- sences), such activity is at 2.5 Hz or is 2.5 Hz but with irregular frequency or asymmetrical voltage; clin- ically the duration is greater, and abnormal interictal records, multiple seizure types including myoclonus and loss of postural tone, mental retardation, and de- velopmental delay are all more common while au- tomatisms are less so. Substantial overlap occurs be- tween the two varieties.

In further variant forms, myoclonic jerks, versive movements, or atonic periods are associated, in which case the tendency for the typical or complex absence at- tacks to cease at puberty is not manifest. Generalized tonic-clonic seizures may also occur in patients with typical absence attacks,²⁶³¹as may myoclonus.

The term was first employed to describe temporary mental confusion by Louis-Florentin Calmeil (1798–

1895), a French physician, in his graduate thesis on epilepsy.

absence seizures Generalized nonconvulsive epileptic seizures expressed mainly by disturbances of conscious- ness with little if any motor activity. Typical absence seizures are characterized by symmetrical and synchro- nous 3-Hz spike–wave complexes; atypical absences are associated with other EEG patterns including spike–wave complexes at slower rates, small-amplitude fast activity, or rhythmic, high-voltage 10-Hz activity.¹⁶⁹⁴

ABSENCE SEIZURES 3

absence status (petit mal status, spike–wave stupor, non-convulsive status, minor status) An epileptic syn- drome characterized by clouding of consciousness, ap- athy, or stupor with fluctuating confusion, interspersed with atonic or myoclonic head nods, fluttering of the eyelids, or slight erratic myoclonus of the face or seg- ments of the limbs, lasting from hours to days. These behavioral changes are accompanied by generalized continuous or near-continuous EEG abnormalities, usually comprising complexes of spikes and slow waves occurring at 3 Hz (2.5–6 Hz) and representing a change from the usual interictal EEG pattern. Incoordination resembling that of cerebellar ataxia may also occur. The condition is usually found in subjects with preexisting generalized epileptic syndromes, such as the Lennox- Gastaut syndrome. See also twilight states, status epilepticus, complex partial status.

In a variant form, similar features appear in adults without any preexisting seizure disorder, who show rhythmic irregular spike–wave discharges on the EEG.⁵⁵⁴²

absent muscles The congenital absence of certain muscles such as the pectoralis, serratus anterior, latis- simus dorsi, trapezius, supraspinatus, or thenar mus- cles.

The more usual occurrence of deficiency in the right rather than the left pectoralis is unexplained. See Souques syndrome.

absolute refractory period That interval following depolarization of a nerve or muscle during which it can- not be excited by further stimuli.

abstraction ability The ability to discern the mean- ing or significance of ideas. The ability to think in non- representative rather than in concrete terms, to form concepts, use categories, generalize from a single in- stance, apply procedural rules, and distinguish the properties of a part from the mass of the whole.

Abul Quasim Arabian physician of the tenth century, whose writings contained the first known account of experiential hallucinations in epilepsy.

abulia (Gr, without will) A state in which the pa- tient manifests lack of initiative and spontaneity, with preserved consciousness. An apathetic blunting of feel- ing, drive, mentation, and behavior such that all actions are performed slowly after a delay.

Clinically, it is a sign of lesions such as a tumor af- fecting the under side of the frontal lobes, bilateral la- cunar strokes, or normal pressure hydrocephalus.³⁸⁵² Academy of Neurological and Orthopedic Medicine and Surgery A professional society. Address: 522 Rossmore Drive, Las Vegas, NV 89110. Tel: 702-452- 9538.

acalculia Difficulties in calculating, with or without problems in the identification and naming of printed

figures, but usually accompanied by inability to copy (acopia). The condition was described and named by Henschen in 1919. Lesions of the dominant frontal or parieto-occipital lobes are responsible. Hécaen²⁵⁰⁵de- fined three forms:

Aphasic acalculia Impaired comprehension and writing of numbers due to a lesion of the dominant hemisphere.

Visuospatial acalculia Defective alignment of numbers and of arithmetic grammar, yet normal comprehension of the numbers themselves.

Anarithmic acalculia An inability to comprehend numera- tion and the principles of mathematics, often accompa- nied by other evidence of dominant hemisphere lesions.

See also anarithmia.

acanthamoebocytosis Infection with Acanthamoeba polyphaga, usually acquired from swimming in infected pools. The neurological complications include menin- goencephalitis.

acanthocytes (Gr, thorn cells) Red cells with a spiky outline, seen only in fresh blood smear prepara- tions.

acanthocytosis The presence of acanthocytes (spiky red cells) in the blood; a finding in abetalipopro- teinemia, familial hypobetalipoproteinemia, amyo- trophic chorea with acanthocytosis, HARP syn- drome, Hallervorden-Spatz disease, mitochondrial cytopathies, Wolman disease, and the McLeod phe- notype.^2435,5350See neuroacanthocytosis.

acatalasemia A peroxisomal disorder without neu- rological features.

acataposis (Gr, not to swallow) Dysphagia.

acceleration injury An injury resulting from sudden movement of the head and neck in relation to the rest of the body. The older term, whiplash, though more evocative to a jury, has now been superseded.

acceleration injury syndrome An alleged post- traumatic syndrome of persistent neck pain, headache, dizziness and disequilibration, impaired concentration, irritability, and emotional lability following such an in- jury, usually caused by a motor vehicle accident. The underlying pathology, if any, is not determined.

accelerator nerves The sympathetic nerves to the heart.

accessory nerve The eleventh cranial nerve, so named by Thomas Willis in his Cerebri Anatome (1664) because he realized that it receives additional fibers from the C2–3 spinal roots.

accessory nerve palsy A focal motor neuropathy causing weakness and wasting of the sternomastoid and/or trapezius muscles.

The most common cause is surgical trauma at the time of lymph node biopsy; blunt trauma is etiologi- cally less common.⁵²³

accident neurosis See disability neurosis.

4 ABSENCE STATUS

accommodation 1. In neuronal physiology, a rise in the threshold transmembrane depolarization required to initiate a spike, when depolarization is slow or a sub- threshold depolarization is maintained. In the older lit- erature, the observation that the final intensity of cur- rent applied in a slowly rising fashion to stimulate a nerve was greater than the intensity of a pulse of cur- rent required to stimulate the same nerve. The latter may largely be an artifact of the nerve sheath and bears little relation to true accommodation as measured in- tracellularly. (From the 2001 Report of the Nomen- clature Committee of the American Association of Electromyography and Electrodiagnosis.¹⁰ Used by permission, copyright © 2001, AAEM.)

2. In the older literature, accommodation was used to describe the observation that the final intensity of cur- rent applied in a slowly rising fashion to stimulate a nerve was greater than the intensity of a pulse of cur- rent required to stimulate the same nerve. The latter may largely be an artifact of the nerve sheath and bears little relation to true accommodation as measured in- tracellularly.

3. (ocular) The process whereby the lens changes its shape to refract more, and the pupil constricts as the eyes converge, in order to improve the focusing of ob- jects at a short range. Retinal blur is diminished and, as in the case of cameras, the smaller aperture improves the depth of focus. The power of accommodation de- creases with age because of decreased power of the cil- iary muscle and decreased elasticity of the lens. The phenomenon was first described by Thomas Young (1773–1829), an English physician, at the age of 20.

accommodation curve See strength–duration curve.

accommodative effort syndrome Blurring of images with persisting near fixation, due to impaired ocular di- vergence with a normal near point for accommodation and convergence, and with an esophoria during near vision, which is relieved by plus lenses.⁴⁶⁰⁵

accommodative insufficiency Impairment of ac- commodation for near vision, as a result of congenital or of acquired causes, the latter including disorders both of the eye and of the central and peripheral nerv- ous systems and muscles.

acephalgic migraine (migraine equivalent) The oc- currence of a migraine aura without the succeeding headache, more commonly seen in patients of advanced age. Symptoms of cortical or brainstem dysfunction oc- cur, with gradual onset, and are less than an hour in duration. In childhood, occipital seizures may cause the same symptoms. See also migraine without aura. A fa- milial form has been described.⁵¹²⁵

aceruloplasminemia A recessively inherited syn- drome affecting iron metabolism manifesting cerebel- lar ataxia, early dementia, involuntary movements, reti-

nal dystrophy, and diabetes, and with absence of ceru- loplasmin in the plasma.³⁴⁵⁷

acervuli See psammoma bodies.

acesis (from Gr, to heal) A cure.

acetylcholine Acetyl trimethyl-␤-acetyl-ethylammo- nium hydroxide, a transmitter substance liberated from terminals of the vagus nerve (Otto Loewi, 1921), from parasympathetic synapses, and from motor nerve end- ings (Sir Henry Dale, 1933, 1936).

acetylcholine deficiency A variant syndrome of childhood myasthenia gravis, in which a deficiency of acetylcholine at the nerve terminals is due to a defect in resynthesis at that site.²⁴⁶⁹

acetylcholine receptor deficiency A recessively in- herited myasthenia-like syndrome characterized by a marked deficiency of acetylcholine receptors and pre- senting clinically as bulbar, limb, and ocular muscle weakness from infancy and electrically marked by small, miniature end-plate potentials.¹²⁰²

acetylcholinesterase deficiency A rare variant syn- drome of infantile myasthenia gravis in which the acetylcholine is not hydrolyzed after its release at the end plate, leading to prolonged depolarization and repetitive potentials following a single stimulus.¹⁶⁶⁸

The clinical features resemble those of other forms of myasthenia, with weakness and fatigability of the bul- bar, extraocular, and spinal musculature, but EMG studies reveal repetitive muscle action potentials in re- sponse to single nerve stimulation as well as the usual decrementing response to repetitive stimuli.

achalasia Failure of relaxation of any kind of hollow tube, as in the case of degeneration of Auerbach’s plexus in the esophagus, which leads to impaired esophageal contractions presenting clinically as dysphagia or vom- iting. The condition usually occurs in infancy.³⁹⁰⁴ achalasia and microcephaly A congenital syndrome characterized by this disorder of esophageal motility, with accompanying microcephaly and mental and de- velopmental delay.³³⁷

Achard-Foix-Mouzon syndrome Reduction of the number of lumbar or sacrococcygeal vertebrae, usually associated with a conus medullaris syndrome and sometimes causing leg weakness as well.³⁰

achee See akee.

Achilles reflex (triceps surae reflex) The ankle jerk.

Achilles tendon The gastrocnemius tendon inserting into the calcaneum, so named because of the associa- tion with Achilles’ heel.

The fable underlying the nomenclature is that the mother of this Greek hero held him by the heel when dipping him into the river Styx, a procedure conferring invulnerability to all those parts touched by the water.

ACHILLES TENDON 5

The heel was not protected and it was a wound to this region delivered by his enemy Paris that killed him. In these days of flourishing neuromythology, it is unwise to scoff at this kind of story.

Achillodynia (Albert disease, Swediaur disease) Pain in the heel due to Achilles tendonitis. It was first de- scribed in 1893 by Edward Albert (1841–1900), an Aus- trian surgeon.⁴⁹⁷⁹

achondroplasia A craniofacial dysplasia in which the formation of enchondral bone is also deficient. The condition is dominantly inherited in 20% of cases. The major clinical features are facial dysmorphism, dwarfism, tripod hands, and lumbar lordosis. See also Jeune syndrome and Ellis-van Creveld syndrome, which are similar.

The condition was described by Parrot in 1878 and in greater detail by Pierre Marie in 1880.

ACHOO See photic sneeze reflex.

Achor-Smith syndrome A syndrome of acute skele- tal muscle degeneration with profound weakness in the setting of prolonged nutritional deficiency with features of pernicious anemia, sprue, and pellagra, complicated by acute diarrhea resulting in hypokalemia and severe renal insufficiency.

achromasia (Gr, lack of color) The impaired up- take of chemical stains by cells undergoing chromatol- ysis.

achromatic Having or producing no color; a term applied to those lenses which cause no color dispersion.

achromatopsia (Gr, lack of color  eyesight) (color blindness, cortical or central achromatopsia) An acquired disorder of color perception involving all or part of the visual field, with preservation of vision for form. The retinal color receptors are not affected. The condition is frequently associated with visual agnosia and with a field defect. It is caused by focal damage to the visual association cortex or its subjacent white mat- ter.¹²⁶⁰See also dyschromatopsia, cone dystrophy.

In a variant form, the same problem is inherited as a sex-linked deficit.

acid albumen turbidity test A screening test for the detection of mucopolysaccharides in blood or urine.

acid maltase (D-1,4- and D-1,6-glucosidase) A lyso- somal enzyme which hydrolyzes glycogen, maltose, and other oligosaccharides to yield free glucose.

acid maltase deficiency See glycogen storage dis- eases.

acid phosphatase deficiency A recessively inherited syndrome of intermittent vomiting, hypotonia, lethargy, opisthotonus, and death in early infancy due to defi- ciency of lysosomal acid phosphatase.⁴⁰⁵⁷

acidemia See organic acidemia.

Ackerman’s angle A measurement at the skull base, considered characteristic in encephalocele and hydro- cephalus but not now in use. It was described in 1882 by Konrad Ackerman (1825–1896), a German pathol- ogist who was a professor at Rostock.

acne fulminans with inflammatory myopathy A syn- drome characterized by the sudden onset of severe ul- cerative acne of the chest, back, and face, associated with fever and leukocytosis and accompanied by pain in the pelvic girdle muscles with wasting, myalgia, and arthral- gia but with normal serum creatine kinase levels.⁴¹⁶⁹ acopia Difficulty in making a copy on paper from a printed or written text, regardless of whether reading is affected or not.

acoria (aplestia) Inability to attain satiety after eating.

Acosta disease See acute mountain sickness.

acoustic EMG (AMG; acoustic myography) A record of the sounds emitted by muscles during their con- traction as a result of mechanical vibrations set up within the muscle. The mean frequency of the sounds increases in parallel with the contractile force derived.

The technique is used in monitoring fatigue and force of contraction, and in the control of prosthetic de- vices.^10,375

acoustic myography See acoustic EMG.

acoustic neuroma A benign tumor of the vestibular portion of the eighth cranial nerve, and actually a schwannoma. It was first described by Cushing in 1917¹²²⁹and accounts for 5%–10% of all intracranial tumors.

Clinically, hearing loss, tinnitus, and dysequilibrium lead to headache, incoordination and imbalance, in- volvement of adjacent cranial nerves, and eventually symptoms of increased intracranial pressure and bul- bar symptoms. The use of computerized axial tomog- raphy, magnetic resonance imaging, and brainstem auditory evoked responses in the diagnosis of the con- dition has been reviewed.²⁴⁶⁷

Acoustic Neuroma Association A charitable organ- ization in this field. Address: 600 Peachtree Parkway, Suite 108, Cumming, GA 30041. E-mail: anausa@aol.

com. Web site: http://www.anausa.org.

Acoustic Neuroma Association of Canada A chari- table organization. Address: PO Box 369, Edmonton, Alberta, Canada T5J 2J6. Tel: (403) 428-3384. Web site:

http://www.anac.ca.

acoustic reflex Contraction of the stapedius muscles bilaterally in response to a loud sound, recorded by measuring the acoustic impedance in the ear. The qui- etest sound producing such a contraction is known as the acoustic threshold; it is elevated in lesions of the cochlear nerve, but also with seventh cranial nerve or middle ear disease.

6 ACHILLODYNIA

acoustic startle reflex Violent muscle jerks following an unexpected sound stimulus, as in stiff person syn- drome and hyperekplexia.

acoustic threshold See acoustic reflex.

acousticomotor seizures See startle epilepsy.

acousticopalpebral reflex See palpebral reflex.

acquired central alveolar hypoventilation A syn- drome of hypoventilation occurring during sleep, typ- ically related to bilateral posterolateral medullary le- sions, which are most often vascular occlusions.¹⁴²³ acquired epileptic aphasia See Landau-Kleffner syndrome.

acquired fixation nystagmus See acquired nystag- mus, fixation nystagmus.

acquired hepatocerebral encephalopathy (por- tosystemic shunt encephalopathy, non-Wilsonian he- patocerebral degeneration) A cerebral degenerative dis- ease complicating chronic liver failure and producing a syndrome of drowsiness, impaired memory, ataxia, dysarthria, asterixis, choreoathetosis, and progressive dementia. The pathological hallmarks of the disorder are the presence of plump (Alzheimer type II) astro- cytes in the striatum, cortex, and dentate nucleus and of spongy changes in the third cerebral cortical layer in laminar distribution.

The condition was described by Victor and Adams in 1965, although F. Morel had noted a similar condi- tion in 1939.³⁹⁷¹

A variant condition is early childhood hepatocerebral degeneration, in which progressive liver disease (the Huttenlocher variant of Alpers disease) and brain dis- ease are manifest by recurrent partial, secondarily gen- eralized seizures followed by mental and motor regres- sion. The liver disease is exacerbated by valproic acid administration.⁵⁴⁹

In another variant form, the clinical appearances are those of Wilson disease but the metabolic disorder af- fecting copper is distinct.²¹⁴⁶See also non-Wilsonian extrapyramidal disease.

acquired horizontal jerk nystagmus The most com- mon form of acquired nystagmus, subdivided between vestibular and gaze-evoked or gaze-paretic forms.

acquired immunodeficiency syndrome (AIDS) In- fection with the human immunodeficiency virus (HIV), a lentivirus that causes systemic and neurological disease, the latter by primary infection, malignancy, or through opportunistic infection. The various neurological syn- dromes produced have been classified:^3728,5662

Chart A–1. Neurological Complications of Acquired Immunodeficiency Syndrome

Opportunistic Infection CNS toxoplasmosis Cryptococcal meningitis

Progressive multifocal leukoencephalopathy Herpesvirus infections

Malignancy

Primary CNS lymphoma Systemic lymphoma

Primary Infection

AIDS-related dementia (see HIV encephalopathy) HIV encephalopathy

HIV myelopathy Acute atypical meningitis Acute sensory neuropathy AIDS radiculopathy

See also HIV-associated conditions.

acquired inflammatory demyelinating polyneu- ropathies Inflammatory demyelinating diseases of the peripheral nerves and nerve roots, often with ex- tensive secondary axonal degeneration and resulting from immunological disturbances. Acute (acute inflammatory demyelinating polyneuropathy), chronic (chronic inflammatory demyelinating poly- neuropathy), and dysproteinemic or paraneoplastic (gammopathic neuropathy) forms are described.⁷⁷ acquired mutism A condition of complete absence of speech that is not associated with other aphasic symptomatology or alteration of consciousness. See mutism, cerebellar mutism.

acquired myotonia See idiopathic neuromyotonia.

acquired pendular nystagmus A rare form of hori- zontal, vertical, or rotatory nystagmus in which the phases are similar in duration in each direction, as a re- sult of which there is no “jerk” component. It leads to complaints of burred vision with oscillopsia and is of- ten associated with a head tremor. The usual causes are cerebellar or brainstem disease, most likely due to vas- cular or demyelinating pathologies.²²⁷⁸It is also a fea- ture of the syndrome of oculopalatal myoclonus.²⁷² acquired slow-channel syndrome See myasthenia gravis.

acquired verbal–auditory agnosia with convulsive disorder See Landau-Kleffner syndrome.

acrocallosal syndrome (Nelson syndrome, Schinzel syndrome) A dysmorphic syndrome characterized by unusual facial appearance, mental retardation, absent corpus callosum, duplication of the halluces, and men- tal retardation.⁴⁰⁹⁷Macrocephaly and clinodactyly are also common, and hyperreflexia with hypotonia is usual.⁴⁹⁷⁰

acrocephalopolysyndactyly The combination of cranial vault abnormality with polysyndactyly. At least four forms are differentiated:³³⁵

Type I (Noack syndrome, Pfeiffer syndrome) A (domi- ACROCEPHALOPOLYSYNDACTYLY 7

nantly inherited?) syndrome of acrocephaly, large toes with syndactyly, and brachydactyly of the toes and some- times of the fingers.

Type II (Carpenter syndrome) The combination of acro- cephaly, polysyndactyly, short stature, obesity, mental re- tardation (usually), and congenital cardiac defects.⁴⁷³¹ Type III The combination of acrocephaly, syndactyly of fin-

gers and toes, and other skeletal abnormalities.⁴⁸⁸² Type IV A congenital dysmorphic syndrome characterized

by acrocephalopolysyndactyly, and craniosynostosis.³³⁵ Hootnick-Holmes syndrome is a further variant form characterized by webbed fingers, polysyndactyly and craniostenosis.²⁶⁴¹

See also acrocephalosyndactyly, Apert syndrome.

acrocephalosyndactyly Dominantly inherited syn- dromes characterized by the occurrence of both tower skull and fusion of digits. The distinction between some of the syndromes that follow may be artificial.³³⁵

Type I See Apert syndrome.

Type II Probably the same as Apert syndrome.

Type III (Saethre-Chozen syndrome) A congenital dys- morphic syndrome characterized also by low frontal hair- line, ptosis, facial asymmetry, and soft tissue syndactyly of the hands.⁵⁴⁴

Type IV (Waardenburg syndrome) A rare congenital dys- morphic syndrome characterized by genital, digital, and cardiac anomalies, acrocephaly, and craniosynostosis.⁵⁵²² Type V (Pfeiffer syndrome) A rare congenital dysmorphic syndrome characterized by acrocephaly, hypertelorism with normal intelligence, and soft tissue syndactyly of the hands.³⁶⁶¹See Pfeiffer syndrome.

Other variants without CNS findings are recorded.³³⁵ See also Carpenter syndrome.

acrocephaly (Gr, pointed head) A developmental defect in skull shape such that the anteroposterior di- ameter is reduced, the occiput is flattened, and the fore- head is high, as with fusion of both of the coronal or of all the cranial sutures. See also Crouzon syndrome.

acrodermatitis chronica atrophicans (Hopf syn- drome) A chronically progressive dermatological disease of young adults, probably of spirochetal origin and tick- borne, leading to widespread livid blue-red discoloration of the skin and later dermal atrophy.²⁶⁴⁴It is often com- plicated by an asymmetric sensory polyneuropathy.⁴¹⁶⁹ acrodermatitis enteropathica See subacute myelo- opticoneuropathy.

acrodynia (Gr, the extremities pain) 1. See Pink disease. 2. The distal limb pain felt in nutritional neu- ropathies and in ergotism. The term is now seldom used.

acrodysostosis A congenital dysmorphic syndrome characterized by short stature, psychomotor retarda- tion, brachycephaly, thick calvarium, and hydro- cephalus.⁵¹⁸⁸

acrodystrophic neuropathy A sensory neuropathy causing painless plantar ulcers or trophic changes, of- ten with destruction of the bones, hands, and feet.

In this group are the hereditary sensory and auto- nomic neuropathies and some acquired neuropathies such as those due to leprosy, diabetes, and alcoholism.⁴⁸⁷⁸ acrofacial dysostosis See orofaciodigital syndrome 2.

acrofacial syndrome See fetal hydantoin syn- drome.

acromegalic myopathy A syndrome of mild proxi- mal muscle weakness with elevated levels of serum cre- atine kinase and associated with hypertrophy of both type 1 and type 2 muscle fibers in patchy distribu- tion,³⁶⁸⁵ sometimes seen in this condition of excess growth hormone production.

In a variant form, muscle hypertrophy is the only ab- normality.

acromegalic neuropathy An uncommon, severe, de- bilitating, progressive peripheral neuropathy compli- cating hypothyroidism, with marked enlargement of the peripheral nerves and characterized by endoneur- ial hypertrophy and axonal degeneration.⁵³⁵¹Features of the carpal tunnel syndrome may be the earliest pres- entation.

acromial reflex Flexion of the elbow in response to a tap on the coracoid or the acromion, present in up- per motor neuron lesions affecting that limb⁴⁷²³ and probably resulting from transmitted vibrations rather than from direct stretch of any tendon.

acromicria A skeletal deformity appearing in many congenital syndromes, characterized by smallness of the extremities.

acro-osteolysis with osteoporosis See osteopetrosis.

acroparesthesia Tingling sensations in the distal parts of the limbs, the classic complaint of people with carpal tunnel syndrome, but also voiced by some with sensory polyneuropathies.

acroparesthesia syndrome See carpal tunnel syn- drome.

acropathy Disfiguring damage sustained by the most distal parts of the body—the digits, ears, and nose, for example. This is seen in many mutilating sensory neu- ropathies⁵⁵³⁴ such as hereditary sensory and auto- nomic neuropathies and leprosy, as well as with cord lesions interrupting pain pathways, such as syringo- myelia.

acrus The term of Hippocrates for the state of the body when it is at the height of its well-being.

acrylamide An industrial polymer used to form slur- ries, which is toxic to axons since it impairs the process of fast (bidirectional) axonal transport, leading to dying-back neuropathies.

Acta Neurochiurgica A neurosurgical journal. Web site: http://link.springer.de/link/service/journals/00701/

about.htm.

8 ACROCEPHALOSYNDACTYLY

Acta Neurologica Belgica (Acta Neurol. Belg.) A neu- rological journal. Address: Association des Sociétés Sci- entifiques Medicales Belgiques, 43 rue des Champs Elyssées, B-1050 Brussels, Belgium. Web site: http://

www.ulb.ac.be/medecine/loce/Acta_Medica_Belgica/

journal/Acta_Neurologica_Belgica.htm

Acta Neurologica Scandinavica (Acta Neurol.

Scand.) A neurological journal published by Blackwell/

Munksgaard. Web site: www/blackwellmunksgaard.com/

actaneurologica.

Acta Neuropathologica A neuropathological journal.

Web site: http://link.springer.de/link/service/journals/

00401/index.htm.

actin A structural protein in vertebrate muscles.

action myoclonus (intention myoclonus) Brief, sud- den, arrhythmic, fine, or coarse myoclonic jerks followed by a period of inhibition, excited by willed movements and startle, affecting variable muscle groups but usually those activated voluntarily and leading to fragmentation of contraction. It is the characteristic finding in the Lance-Adams syndrome.³²⁴⁰See also myoclonus.

action myoclonus–renal failure syndrome A reces- sively inherited syndrome characterized by severe pro- gressive action myoclonus, finger tremor, ataxia, dysarthria, seizures, and renal failure requiring trans- plantation by the third decade, but without mental in- volvement.¹⁶⁶

action myotonia Delayed muscle relaxation follow- ing voluntary contraction of the muscle.

action potential (AP) The brief regenerative electric potential that propagates along a single axon or mus- cle fiber membrane. An all-or-none phenomenon;

whenever the stimulus is at or above threshold, the ac- tion potential generated has a constant size and con- figuration. See also compound action potential, mo- tor unit action potential. (From the 2001 Report of the Nomenclature Committee of the American Associ- ation of Electromyography and Electrodiagnosis.¹⁰ Used by permission, copyright © 2001, AAEM.) action tremor 1. Physiological tremor accentuated by muscle contraction, as seen both in normal subjects and in those with Parkinson disease. 2. Any tremor or vol- untary contraction of muscles, including postural, kinetic, and isometric tremors.¹⁴²²See also cerebellar tremors.

activated protein C resistance factor (Leiden) A dominantly inherited disorder resulting in an increased liability to stroke and due to a mutation at 1q23.

activation 1. In physiology, a general term for the ini- tiation of a process. 2. The process of motor unit ac- tion potential firing. The force of muscle contraction is determined by the number of motor units and their fir- ing rate. (From the 2001 Report of the Nomenclature Committee of the American Association of Elec-

tromyography and Electrodiagnosis.¹⁰Used by permis- sion, copyright © 2001, AAEM.)

activation procedure A technique used to detect de- fects of neuromuscular transmission during repetitive nerve stimulation testing. Most commonly a sustained voluntary contraction is performed to elicit facilitation or postactivation depression. (From the 2001 Report of the Nomenclature Committee of the American Associ- ation of Electromyography and Electrodiagnosis.¹⁰ Used by permission, copyright © 2001, AAEM.) activator mutant A form of gangliosidosis with two variants:

Infantile (AB variant) A disorder presenting similarly to Tay- Sachs disease (GM₂gangliosidosis) with the infantile onset of myoclonus, seizures, hypotonia, and, later, spasticity, de- mentia, and death. A cherry-red retinal spot is present.⁴⁹⁰⁶ Adult (AB variant) A syndrome of adult-onset normal- pressure hydrocephalus, seizures, and dementia with in- creased hexosaminidase A and B activity.³³⁵

active continence The maintenance of bladder out- let closure at rest through increased reflex activity in the pudendal nerve, which causes increased activity in the striated muscle around the urethra and thus in- creases the resistance to fluid flow.

active electrode (exploring electrode, input terminal 1, grid 1, G1) The recording electrode close to the source of the activity to be recorded. In EEG, the first of two inputs to a differential amplifier. [RMS] See also recording electrode.

active sleep A sleep stage in newborn children, sim- ilar to REM sleep.

activities of daily living (ADL) The range of those behaviors which are normally required for personal self-maintenance and independent life within a com- munity. These activities are usually divided between two categories. Physical ADL represents the most basic personal care tasks, such as feeding, excretion (bowels, bladder), toileting, dressing, cleanliness (grooming, bathing), and motility (transfers, wheelchair, walking, stairs). Instrumental ADL embodies more complex ac- tivities, including handling of personal finances, preparing meals, shopping, using the telephone, trav- eling and housework.

Items included within extended ADL include the fol- lowing:³⁴⁹

Getting About Household Activities Other Activities Carrying a hot Washing up Gardening

drink

Working outside Washing clothes Managing money Crossing roads Housework Going out socially Getting in/out Shopping Employment/work

of a car

Using public Making hot drinks/ Hobbies/leisure

transport snack

Driving a car Reading Telephoning Writing

ACTIVITIES OF DAILY LIVING 9