Ephaptic crosstalk in Painful Diabetic Neuropathy: an electrodiagnostic study.

Abstract

Painful Diabetic Neuropathy (PDN) is a common complication of diabetes mellitus (DM) which significantly causes pain and distress in patients. Release of factors from degenerating fibers activating adjacent fibers to produce ephaptic crosstalk have been proposed as one of the pain mechanism in PDN. Here we aim to detect ephaptic crosstalk between small fibers and large fibers in PDN subjects by comparing the electrodiagnostic result of patients with PDN and patients without PDN. This study used cohort prospective design. Patients with type 2 DM or impaired glucose tolerance (IGT) without PDN from several health facilities in Yogyakarta were followed for 12 months for the occurrence of PDN. Demographic, clinical, laboratory and electrodiagnostic data from all patients were collected and analyzed. One hundred and forty-one subjects (58 men, 83 women) with an average age of 51 years (range, 40–61 years), were enrolled in this study. After 48 weeks of observation, 12 subjects were found to have PDN. The differences of distal latency between PDN and non-PDN group were significant when measured in median sensory nerve (4.47 ms ±2.43 versus 3.39 ms ±1.79, p = 0.002), tibial motor nerve (6.96 ms ±3.07 versus 5.90 ms ±2.17, p = 0.041), and sural sensory nerve (6.02 ms ±3.56 versus 3.55 ms ±2.90, p <0.001). Among all parameters measured in this study, the H-reflex had higher abnormality persentage compared to other electrodiagnostic variable (H latency = 30%, H amplitude = 71%, H/M Ratio = 88%, and H-M IPL = 15%). Our result shows that small fiber neuropathy in PDN can be detected by electrodiagnostic study which measures large fibers function. This indicates that ephaptic crosstalk between small fiber and large fiber happens in PDN.