Tardive dyskinesia and abnormal tongue movements.

Forty-two subjects, 20 with and 22 without clinically diagnosed tardive dyskinesia (TD), were rated for TD on the scale of Simpson et al. They also performed a tongue protrusion test and had the presence of tongue movements within the buccal cavity observed. Fifty per cent of the severe or definite TD subjects as classified by rating scale were unable to maintain tongue protrusion for a minimum of 30 seconds, and 85 per cent of them had abnormal tongue movements. In 45 per cent of the possible TDs and in 9 per cent of the doubtful subjects, the movement test was also positive.