Oral tardive dyskinesia: validation of a measuring device using digital image processing.

The present study was performed to investigate the reliability and validity of a new device for the assessment of oral dyskinesias by means of digital image processing. Twenty schizophrenic patients with tardive dyskinesia (TD) and ten healthy controls were studied. In patients instrumental scores were compared to different clinical rating scale scores. Measurements were repeated after 2 weeks under the same circumstances to assess test-retest stability. Instrumental scores discriminated well between normal subjects and dyskinetic patients and correlated significantly with clinical ratings (r = 0.63). The test-retest correlations showed a correspondence not larger than 40%, detecting thus the fluctuation of the TD intensity over time. These results suggest that our device is a reliable and easy to handle technique for the assessment of TD. Furthermore, the ability of the device to analyze the frequency distribution of movements makes it a useful tool for the quantitative and qualitative analysis of TD.