Skin nerve sympathetic activity reflex latency in Parkinson's disease

Using a microneurographic method, skin nerve sympathetic activity (SSA) reflex latency was measured in 16 patients suffering from idiopathic Parkinson's disease (PD) and 11 age-matched normal subjects. The mean latency in patients with PD was significantly delayed (0.821 s, p less than 0.01), when compared with that in normal subjects (0.676 s). Reflex latency showed a significant positive linear correlation with arm length. By determining the SSA reflex latency, conduction velocities in post-ganglionic skin sympathetic nerve were measured indirectly. Averaged conduction velocities in PD and normal subjects, 1.76 m/s and 1.86 m/s, respectively, did not differ significantly (p greater than 0.1). This data suggests that the reflex pathway of SSA is disturbed in patients with PD and that the increased reflex latency is caused by a central/preganglionic delay.