Temporal control of voicing in Parkinson's disease and tardive dyskinesia speech

Basal ganglia disorders are associated with a set of clinical syndromes characterized by various motor disabilities. The hypocinetic syndromes, of which Parkinson's disease (PD) is the prototype, are mainly marked by a paucity and a slowing down of motor function, while the hypercinetic disorders, and among them tardive dyskinesia (TD), are mainly distinguished by involuntary and abnormal movements. The abnormal speech motor control is part of the parkinsonian semiology, but little is known about the specific speech alterations in TD. In the present acoustic study, the motor control capabilities of PD and TD subjects were compared in a sentence production task. Three temporal measures were used: sentence duration, total number of pauses, and ratio of total pause duration to total sentence duration. Analyses of data revealed a significant decrease of voiceless speech periods in the two clinical groups, relative to controls, but most markedly in TD subjects. These data indicate that TD is not only characterized by involuntary movements but also by a disturbance of voluntary motor control. The results also revealed that, in spite of their clinical and neurophysiological differences, PD and TD also share similar patterns of deficits. (C) 1999 Academic Press.