EFFECTS OF LEVODOPA ON FINGER AND OROFACIAL MOVEMENTS IN PARKINSONS-DISEASE

1. The objective of this study is to compare the efficacy of levodopa on finger and orofacial movements in Parkinson's disease. The sensitiv ity of the orofacial and finger systems to levodopa would suggest the involvement of dopaminergic lesions. 2. The production of isometric fo rce was estimated in both conditions, without and with levodopa, in 14 patients with idiopathic Parkinson's disease (mean duration of sympto ms: 9 +/- 3 years). 3. Forces generated by the upper and lower lips, t ongue, right and left forefingers in the presence of visual feedback w ere measured by means of force transducers. 4. The target force levels used in the present study included 0.25, 0.5, 1 and 2 newtons corresp onding to fine forces presumably involved in speech production. Moreov er, motor disability of patients was assessed in each condition, using the motor examination of the Unified Parkinson's disease rating scale and a hand-tapping test. 5. Fourteen control subjects also participat ed in this study. 6. The beneficial effect of levodopa on finger movem ents was observed as indicated by an improvement in motor scores and p roduction of forces. In contrast, the production of orofacial forces w as either not improved, or aggravated by levodopa. 7. These results su ggest that cerebral non dopaminergic lesions participate to the impair ments of parkinsonian speech.