Peripheral autonomic surface potential. A quantitative technique for recording sympathetic conduction in man

Area of Science:

• Neuroscience
• Autonomic Nervous System Research
• Biomedical Engineering

Background:

• The peripheral autonomic nervous system's electrical activity is challenging to measure non-invasively.
• Previous methods for assessing sympathetic nerve function have limitations.

Purpose of the Study:

• To define and characterize a novel skin potential, the peripheral autonomic surface potential (PASP).
• To investigate the diagnostic utility of PASP in conditions affecting autonomic function, such as diabetes and post-sympathectomy.

Main Methods:

• Utilized electromyography (EMG) equipment with time-locked recording and averaging.
• Recorded PASP from palmar and plantar surfaces following median nerve stimulation.
• Administered atropine via iontophoresis to confirm the cholinergic nature of PASP.
• Compared PASP in healthy subjects, diabetic patients, and patients with sympathectomy.

Main Results:

• Successfully recorded a biphasic PASP in normal subjects with distinct latencies and amplitudes for palmar and plantar sites.
• Calculated a mean sympathetic conduction velocity of 1.28 m/s.
• Demonstrated significantly reduced PASP amplitudes in diabetic patients compared to controls.
• Observed absent or markedly reduced PASP on the side of sympathectomy.

Conclusions:

• PASP is a reliable, non-invasive electrophysiological marker of peripheral sympathetic nerve activity.
• PASP measurement offers a sensitive tool for detecting autonomic dysfunction, particularly in diabetic neuropathy.
• The findings support the use of PASP in clinical assessment of autonomic disorders.