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Shoulder, elbow and wrist components of physiologic tremor amplitudeas measured using a laser penlight
1University of Iowa Hospitals and Clinics, Iowa City, IA, USA. davis9@valcom.net
Objective:
To measure the amplitude of physiological tremor in normal subjects using a novel method in an attempt to characterize some of the components of physiological tremor.
Background:
Current methods of measuring tremor are limited in their capability of measuring the contributions of various limb segments to physiologic tremor.
Design And Methods:
Subjects were asked to hold a laser penlight aimed at a target. Photographs with an exposure of 1 s were taken to record the path of the light. The angle of deflection was calculated under various conditions by averaging the results from four trials spaced at 15-second intervals.
Results And Conclusions:
The maximum amplitude under all conditions tested was less than 0.25 degrees. Contributions from the wrist and fingers were significantly greater than contributions from the elbow or shoulder. Rotational movements were significantly more prominent than movements in other planes at the shoulder but not the elbow or wrist.