Autonomic dysfunction in Parkinson's disease.

We studied autonomic functions in 31 chronically treated patients with Parkinson's disease. They were tested twice: before a dose of medication and after medication. Before a dose of medication, when motor disability was maximal ("off"), patients had higher resting pulse rate, greater orthostatic fall in blood pressure, and decreased responses to Valsalva and cold pressor stimuli than their spouse-controls. To a heat stimulus, sweating was increased in the head and neck, and skin temperatures were cooler. After medication when function was optimal ("on"), the cardiovascular reflex abnormalities remained but were no worse. Skin temperature alterations and sweating abnormalities resolved.