The evaluation of an ultrasound detector (UD) in the measurement of oro-facial dyskinesia.

An ultrasound detector (UD) was compared with a clinical rating (CR) scale in the assessment of oro-facial movements in 23 chronic schizophrenic patients and 23 normal subjects over a period of 4 weeks. The apparatus distinguished well between normal volunteers and dyskinetic patients. There were also highly significant correlations between UD scores and clinical ratings. The results thus confirm both the construct and concurrent validity of the technique. Nevertheless, there was significant variation in the UD scores for some patients between assessments. A technical problem was the inability of some patients to cooperate for more than 30 seconds. The scores of the normal subjects were consistent. With further development and repeated 30-second assessments the technique might be of value in the ascertainment of early dyskinesia in patients at risk and also in measuring drug effects.