The application of video image processing to quantitative analysis of extremity tremor in humans

A new method for the detection and quantification of extremity tremor is described, based on video image processing. A single CCD camera recorded the movement of the extremity. A passive marker in the shape of a black annulus was placed on the forearm and the movement of the annulus analysed. The framestore digitised the video signal at a sample rate of 10 Hz. The time period of the movement analysis was delta t = 6.4 s. A total of 32 adults with alcoholism and 22 controls participated in this study. The movement of the extremity was recorded during the usual neurological test (sitting posture, feet together, upper extremities directly in front of subject) for both extremities. In this study, it was assumed that the probability density function f(d) of some variable D is characteristic of the tremor. This function is formed by a finite mixture of bivariate continuous distributions. The results suggest that f(d) characterises patients with alcoholism and distinguishes them from control subjects with only physiological tremor. The results demonstrate the capacity of the measuring system based on video imaging to quantifying motor impairments in clinical neurology.