The Physiological Significance of A-Waves in Early Diabetic Neuropathy: Assessment of Motor Nerve Fibers by Neurophysiological Techniques.

Qiong Cai,Lie-Hua Liu,Chao Wu,Guliqiemu Aimair,Yin-Xing Liang,Wen-Xiao Xu,Song-Jie Liao,Pei-Yao Xiao

doi:10.3389/fnsys.2021.633915

Abstract

Objective: This study aimed to investigate how early A-waves could occur in type II diabetes, and what it implied functionally.Methods: We performed conduction velocity distribution (CVD) test in peroneal nerves of 37 type II diabetic patients with normal nerve conduction study (NCS) and 22 age-matched controls. The electrophysiological data and clinical information were analyzed.Results: A-waves were observed in 45.9% of diabetic patients and only in 1 person in healthy controls, all detected in the tibial nerves. The diabetic patients with A-waves showed faster conduction velocity in all quartiles in the motor peroneal nerves compared to the patients without A-waves, and their CVD histograms were shifted to the right side, consisting of a significantly larger percentage of fast conducting fibers. There was no significant difference in the CVD values of the upper extremity nerves among the patients with and without A-waves and the healthy controls.Conclusion: A-waves could occur in type II diabetes as early as when NCS showed normal, and represented as a sign of neuropathy as well as a sign of rescued motor nerve function.

Highlights

A-wave is a late response following the compound muscle action potential (CMAP, M-wave) during routine motor nerve conduction studies (NCS)
The method to calculate the contribution of each nerve fiber group of different conduction velocities that makes up the compound muscle action potential, so called the conduction velocity distribution (CVD), is an accurate way to detect nerve damages and more sensitive for early diabetic neuropathy compared to routine NCS (Tuncer et al, 2011; Koszewicz et al, 2019)
We identified type II diabetic patients whose NCS was in normal range by using standard conduction techniques, and analyzed CVD of motor nerves in order to find the neurophysiological significance of A-waves in early diabetic peripheral neuropathy (DPN)

Summary

Introduction

A-wave is a late response following the compound muscle action potential (CMAP, M-wave) during routine motor nerve conduction studies (NCS). The method to calculate the contribution of each nerve fiber group of different conduction velocities that makes up the compound muscle action potential, so called the conduction velocity distribution (CVD), is an accurate way to detect nerve damages and more sensitive for early diabetic neuropathy compared to routine NCS (Tuncer et al, 2011; Koszewicz et al, 2019). CVD can detect the loss of motor fibers with different conductive velocities in diabetic patients when NCS remains normal, can serve as a supplement for routine NCS in early DPN (Kiziltan et al, 2007; Tuncer et al, 2011)

Results

Discussion

Conclusion