Diurnal variability of orofacial dyskinetic movements

Objective: Instrumental methods to measure tardive dyskinesia (TD) have been introduced in the last few years to try to eliminate the differences in inter-rater reliability. After eliminating variations attributed to the use of different raters, it is clear that TD frequently shows fluctuations in severity contributing to a low test-retest reliability. In the present study the diurnal variability of dyskinetic movements was explored by a computerized technique using digital imaging processing to measure orofacial movements. Method: Ten patients with persistent tardive dyskinesia were assessed three times a day once a week for four consecutive weeks. Results: Four patients had significant diurnal variations in the severity of dyskinetic movements and six did not have significant variations. The period of time between waking and the assessment, the severity of dyskinetic movements, and smoking were significantly different between these two groups. Conclusion: Diurnal variations, particularly in relation to sleeping and smelting patterns, may need to be taken into account during longitudinal studies of tardive dyskinesia.