Instrument measurement of lingual force variability reflects tardive tongue dyskinesia.

Tardive tongue dyskinesia is often under-diagnosed or misdiagnosed. Instrument measurement of lingual force variability may be a valid and reliable method for assessing tardive tongue dyskinesia. Instrument measurement of lingual force variability was compared to the clinical level of tardive tongue dyskinesia and total body dyskinesia as measured by the Abnormal Involuntary Movement Scale (AIMS) in 35 subjects: 23 patients with a psychiatric disorder using antipsychotics, of which 11 were with and 12 were without tardive tongue dyskinesia, and 12 age- and gender-matched healthy controls. Lingual force variability correlated with tardive tongue dyskinesia (Spearman r = 0.56; p < 0.01) and with total dyskinesia (r = 0.47; p = 0.02); there was no association with age, antipsychotic dose, or psychiatric diagnosis. Instrument test-retest reliability corresponded with an ICC of 0.85 p < 0.0001. Instrument measurement of lingual force variability is a valid and reliable method for assessing tardive tongue dyskinesia.