Parasympathetic assessment in Parkinson's disease.

There is little evidence of autonomic dysfunction in PD, although autonomic disturbance was included in the original description by J. Parkinson. In addition, there are no data for de novo PD patients. We selected 14 de novo parkinsonians (seven men and seven women), aged 62.7 +/- 8.2 years, with mild disease (stage 1 through 2 on the Hoehn and Yahr's scale), without history of diabetes, heart disease, or alcoholism, and without neuropathy or orthostatic hypotension. Fourteen age- and sex-matched normal persons were controls. We found a highly significant difference in the respiratory sinus arrhythmias during deep breathing (p less than 0.01); the basal heart rate, the respiratory sinus arrhythmias during quiet breathing, and the Valsalva ratios did not differ statistically, however. In the absence of neuropathy and orthostatic hypotension and in the presence of normal Valsalva ratios, we believe that the abnormality found by us may apply only to parasympathetic dysfunction, perhaps at a central level. In addition, the abnormality seems to be independent of stage and therapy.