title: Shoulder, elbow and wrist components of physiologic tremor amplitudeas measured using a laser penlight.
abstract: 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.
  
  
  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.
  
  
  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.
authors.affiliation: University of Iowa Hospitals and Clinics, Iowa City, IA, USA. davis9@valcom.net
authors.forename: B J
authors.initials: BJ
authors.lastname: Davis
authors.forename: J
authors.initials: J
authors.lastname: O'Connell
mesh_terms: D000328:Adult; D004550:Elbow; D005260:Female; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D010781:Photography; D012016:Reference Values; D012782:Shoulder; D014202:Tremor / Q000175:diagnosis*; D014953:Wrist