The measurement of abnormal movement: methods developed for Huntington's disease.

Clinical and laboratory methods were developed to detect motor abnormalities in patients with Huntington Disease. For clinical evaluation a quantitated neurological examination was used which factor analyzed into 2 scales: a chorea scale (a measure of involuntary movement) and a motor impairment scale (a measure of abnormalities of voluntary movement). Mechanized methods of measuring involuntary movement (accelerometer) and voluntary movement (reaction time, tapping speed, and movement time) were also developed. The motor abnormalities detected on the clinical and mechanical tests were not specific to HD but were also present in persons at 50% risk for HD and in patients with a variety of neurological disorders. The mechanized tests may be useful for screening for motor disorders in the population: they are non-specific, portable and do not require the services of an experienced clinician.