Sympathetic sudomotor neural function in amyotrophic lateral sclerosis

Abstract

In patients with amyotrophic lateral sclerosis (ALS), sudomotor and vasomotor function have been considered to be impaired based on sympathetic skin response (SSR) or cutaneous blood flow measurements. We evaluated sympathetic sudomotor and vasoconstrictive neural function in ALS. We simultaneously recorded SSR, skin blood flow, and skin sympathetic nerve activity (SSNA) by microneurography in 20 patients with sporadic ALS and 20 healthy controls. Resting frequency of SSNA was significantly higher in ALS patients than in controls (p <0.05), but the increase of SSNA associated with mental arithmetic was smaller in ALS patients than controls (p <0.05). ALS patients also exhibited slight prolongation of SSNA reflex latencies compared with controls (p <0.05). In conclusion, sympathetic hyperactivity was observed in relation to sudomotor and vasoconstrictive skin responses. Since SSNA reflex latencies reflect central sympathetic function, the central autonomic pathways may be slightly impaired in patients with ALS.

Key words::

• Amyotrophic lateral sclerosis
• skin sympathetic nerve activity
• sympathetic skin response
• skin vasomotor reflex
• central autonomic pathway

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.