Sympathetic sudomotor neural function in amyotrophic lateral sclerosis

Area of Science:

• Neurology
• Autonomic Neuroscience
• Skeletal Muscle Disorders

Background:

• Sudomotor and vasomotor functions are often impaired in amyotrophic lateral sclerosis (ALS).
• Previous assessments relied on sympathetic skin response (SSR) or cutaneous blood flow.
• A comprehensive evaluation of sympathetic neural function in ALS is needed.

Purpose of the Study:

• To evaluate sympathetic sudomotor and vasoconstrictive neural function in patients with sporadic ALS.
• To compare autonomic responses between ALS patients and healthy controls.

Main Methods:

• Simultaneous recording of SSR, skin blood flow, and skin sympathetic nerve activity (SSNA) using microneurography.
• Inclusion of 20 sporadic ALS patients and 20 healthy controls.
• Assessment of SSNA during resting conditions and mental arithmetic tasks.

Main Results:

• ALS patients exhibited a significantly higher resting frequency of SSNA compared to controls (p < 0.05).
• The increase in SSNA during mental arithmetic was attenuated in ALS patients (p < 0.05).
• ALS patients showed slight prolongation of SSNA reflex latencies compared to controls (p < 0.05).

Conclusions:

• Sympathetic hyperactivity is present in ALS patients, linked to sudomotor and vasoconstrictive skin responses.
• Prolonged SSNA reflex latencies suggest potential subtle impairment in central autonomic pathways in ALS.
• Findings indicate a role for autonomic dysfunction in the pathophysiology of ALS.