A novel method of recording arm movements. A survey of common abnormalities

A novel technique uses a Schottky barrier photodetector to record abnormal movements of the arms in diseases of the nervous system. The method transduces displacement of the freely moving limbs, producing recordings that readily relate to clinical observation and provide quantification. This article gives examples of the use of the technique for examining ataxia in finger-to-nose testing, tremor, and cog-wheel phenomena in common neurological conditions.