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  Vol. 55 No. 2, February 1998 TABLE OF CONTENTS
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How Normal Is ‘Normal'?

Mild Tremor in a Multiethnic Cohort of Normal Subjects

Elan D. Louis, MD, MS; Blair Ford, MD; Seth Pullman, MD; Keren Baron

Arch Neurol. 1998;55:222-227.

Background  While many "normal" subjects exhibit mild clinically detectable tremor, the extent to which this tremor is present has received little attention.

Objective  To characterize the prevalence and clinical characteristics of mild, clinically detectable tremor in a multiethnic cohort of normal subjects.

Methods  Normal control subjects (n=36) and their relatives (n=67) were enrolled in a community-based case-control study of the familial aggregation of essential tremor. Subjects underwent a tremor interview and videotaped tremor examination. Two neurologists independently rated the severity of tremor during different postures and tasks, and a total tremor score (maximum score, 36) was calculated for each subject. Eight subjects were randomly selected to undergo quantitative computerized tremor analysis.

Results  In 103 normal subjects (36 control subjects and 67 relatives of control subjects) the mean total tremor score was 4.8 (range, 0-12.5). Ninety-nine (96%) of 103 subjects had tremor, as defined by a total tremor score of 0.5 or higher. For most tasks, the mean tremor score was greater in the nondominant than in the dominant arm. The total tremor score correlated highly with age (r=0.28; P=.004). There were no sex or ethnic differences in the mean total tremor scores. On tremor analysis, the amplitude and frequency of the tremor differed from that in a group of similarly studied subjects with essential tremor.

Conclusions  Normal subjects almost uniformly have a clinically detectable tremor that is mild and age dependent. Characterization of this tremor helps to establish standards for normal tremor. These standards are crucial for accurate diagnostic classification in population-based studies of essential tremor.


From the Department of Neurology (Drs Louis, Ford, and Pullman and Ms Baron), and the Gertrude H. Sergievsky Center (Dr Louis), College of Physicians and Surgeons, Columbia University, New York, NY.



THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

Mild Tremor in Relatives of Patients With Essential Tremor: What Does This Tell Us About the Penetrance of the Disease?
Louis et al.
Arch Neurol 2001;58:1584-1589.
ABSTRACT | FULL TEXT  

Evidence for familial aggregation of tremor in normal individuals
Louis et al.
Neurology 2001;57:110-114.
ABSTRACT | FULL TEXT  

Clinical Subtypes of Essential Tremor
Louis et al.
Arch Neurol 2000;57:1194-1198.
ABSTRACT | FULL TEXT  

Validity of a Performance-Based Test of Function in Essential Tremor
Louis et al.
Arch Neurol 1999;56:841-846.
ABSTRACT | FULL TEXT  

Diagnostic Criteria for Essential Tremor: A Population Perspective
Louis et al.
Arch Neurol 1998;55:823-828.
ABSTRACT | FULL TEXT  





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