PORTABLE SYSTEM FOR QUANTIFYING MOTOR ABNORMALITIES IN PARKINSONS-DISEASE

In order to quantify motor disabilities in Parkinson's disease (PD), w e designed a compact, portable, neurophysiological system based upon a personal computer to measure tremor, bradykinesia, and muscle tone. T remor was detected by solid state accelerometers and translated into a digital signal. The system displayed the root mean square displacemen ts and frequency distribution of the tremor in the horizontal and vert ical planes, along with a reconstructed graphic image of the displacem ent. Bradykinesia was measured using a panel that detects release and depression of switches in response to auditory and visual signals; the system calculated subjects' reaction times and movement times in mill iseconds. Tone at the elbow was measured by strapping the upper extrem ity to a lightweight low-friction cradle and then passively moving the cradle with an instrumented handle. Signals representing torque and a rm angle were processed by the computer and displayed in real time on the screen with stiffness as a mean slope in Nm/degree. In clinical te sts, quantitative measures of tremor, movement time and rigidity were significantly abnormal in PD patients compared to control subjects. We conclude that this system is a convenient and accurate method to quan titate important aspects of the parkinsonian syndrome, and may be appl ied to quantitate other movement disorders.