Supranormal Sensory Nerve Action Potential Amplitude Correlates of Sensory Symptoms

Patients presenting with pain, numbness, or paresthesias frequently have normal electrodiagnostic studies. Supranormal sensory nerve action potential amplitudes may be a potential biomarker of sensory nerve hyperexcitability.

A retrospective chart review of 400 consecutive patients with normal electromyography reports between July and November 2016 was performed. Patients were divided into tertiles based on the degree of sensory nerve action potential amplitudes above lower limits of normal (<2×, 2-3×, and >3×). Patient demographics and sensory symptom quality were assessed. Multivariate analysis assessed for an association between sensory symptoms and sensory nerve action potential amplitudes, age, or gender.

After controlling for age and gender, subjects in the 2-3× and >3× normal tertiles had a higher association with multifocal symptoms, whereas those in the >3× normal tertile had a lower association with distal symptoms compared with the <2× normal tertile.

The association of supranormal sensory nerve action potential amplitudes with multifocal symptoms may be an indicator of diffuse hyperexcitability.