Small Fiber Assessment by Cutaneous Silent Period

Nerve conduction studies performed routinely in electromyoneurography laboratories deal mainly with large myelinated fast conducting nerve fibers. A reliable method allowing the study of small peripheral nerve fibers (Aδ \& C) would be of interest (Jovita et al., 2006). As they are initially affected and maybe the earliest exhibited sign of neuropathy. In recent years, the cutaneous silent period (CSP) has received increased attention in health and disease. The CSP is an inhibitory spinal reflex that appears following strong electrical stimulation of the cutaneous nerve and causes suppression of voluntary muscular contraction for a certain period of time (Kofler et al., 2019). This action presents a reciprocal action to the nociceptive flexor withdrawal response (FWR) which serves as an 'excitatory reflex' increasing activity in primary flexor muscles. When taken into context, the interplay between the CSP and FWR can clearly be seen. The evaluation of the CSP represents a useful electrophysiological method for investigating the function of small fibers by using standard electromyography equipment (Eckert et al., 2018).