Assessment of sudomotor dysfunction in early Parkinson's disease.

We performed a quantitative sudomotor function test on 10 patients with early Parkinson's disease (PD) and 11 age-matched control subjects. Thermal warming increased the sweat rate in both PD and controls. There was no difference in sweat rate between the forearm and the thigh in either PD or controls. In PD, thyrotropin-releasing hormone (TRH) did not increase the sweat rate, whereas it did so in the controls. These results suggest that sudomotor dysfunction in early PD is minor but that there may be an impairment of TRH-induced sympathetic response in the early stages of PD.