Sympathetic sudomotor and vasoconstrictive neural function in patients with Parkinson's disease

To evaluate sympathetic sudomotor and vasoconstrictive neural function in Parkinson's disease (PD), we simultaneously recorded sympathetic skin response (SSR) and skin blood flow (SVR; skin vasomotor reflex), as well as skin sympathetic nerve activity (SSNA) measured in peroneal nerves by microneurography, comparing 12 patients with idiopathic PD with 16 healthy controls. Resting SSNA frequency (8.8 ± 4.3 bursts/min) was significantly lower in PD patients than in controls (p < 0.01). Frequency increases in response to performing mental arithmetic were slightly smaller in PD patients than in controls. PD patients exhibited normal SSNA reflex latencies compared with controls. Although no significant relationship was found between resting SSNA frequency and disease duration or degree of disability, a significantly negative correlation between increases in SSNA with mental arithmetic and PD duration was observed. Occurrence of SSR and SVR following SSNA bursts induced by electrical stimuli was reduced in PD (p < 0.05). In patients with PD, sympathetic sudomotor and vasoconstrictive neural function was decreased at rest, but SSNA reflex latencies in the legs were nearly normal. Since responses of peripheral target organs may be impaired, both central and peripheral factors may contribute to autonomic symptoms in PD.