Abstract:
The objective of the present study was to characterize the motor control of idiopathic Parkinson's disease patients and normal subjects during orofacial nonverbal tasks. The fine force control associated with speechlike force magnitudes in three articulatory organs: Upper lip, lower lip, and tongue were examined by means of force transducers. Using visual feedback, subjects produced ramp-and-hold compression forces as rapidly and accurately as possible to end-point target levels ranging from 0.25 to 2 N. The relationship among several parameters of the ramp-and-hold force contraction and target force level was quantified in 14 Parkinsonian patients (7 males and 7 females) and 14 age- and sex-matched control subjects. All patients were successively evaluated in two conditions, that is, without and with levodopa therapy. The results demonstrated an abnormal isometric control force of the articulatory organs in patients with Parkinson's disease. Moreover, differences were observed between lip and tongue motor performance. Most of the results were not improved by L-dopa. This suggests that Parkinsonian dysarthria probably results from nondopaminergic lesions.