Parasympathetic and Sympathetic Monitoring Identifies Earliest Signs of Autonomic Neuropathy

Area of Science:

• Autonomic Nervous System Disorders
• Neurology
• Cardiology

Background:

• Autonomic dysfunction, progressing from peripheral autonomic neuropathy (PAN) to cardiovascular autonomic neuropathy, elevates morbidity and mortality risks.
• PAN, often involving small fiber disorder (SFD), represents the earliest stage of autonomic neuropathy.
• Galvanic skin response (GSR) is a common, minimally invasive diagnostic test for SFD and PAN.

Purpose of the Study:

• To evaluate the concordance and diagnostic utility of parasympathetic and sympathetic (P&S) monitoring and SweatC™ sudomotor testing in diagnosing autonomic dysfunction.
• To assess the effectiveness of these tests in identifying early stages of autonomic neuropathy, including PAN and SFD.

Main Methods:

• A prospective, observational study of 340 consecutive patients under 60 years old at an autonomic clinic.
• Patients underwent P&S Monitoring (cardiorespiratory analyses) and SweatC™ sudomotor testing (GSR-based).
• Data were collected and analyzed from February 2018 through May 2020.

Main Results:

• SweatC™ and P&S Monitoring showed 90.0% concordance (306/340 patients) across all stages of autonomic neuropathy.
• The negative predictive value for P&S disorder was 89.4% with negative sudomotor testing; positive predictive value was 90.4% with positive sudomotor testing.
• P&S Monitoring demonstrated high sensitivity, specificity, and predictive values, comparable to sudomotor testing in detecting early autonomic neuropathy.

Conclusions:

• Both SweatC™ and P&S Monitoring are reliable for risk stratification in patients with suspected autonomic dysfunction, including early PAN and SFD.
• These testing modalities, particularly with normal findings, effectively aid in excluding underlying autonomic nervous system dysfunction.
• Either testing method can be utilized for diagnosing and managing autonomic neuropathy.