Small Fiber Assessment by Cutaneous Silent Period

Our primary objective in this study is to investigate the cutaneous silent period (CSP) in normal subjects in the Egyptian population, as it was not carried out before in Egypt. The aim was to carry out the test in our unit to study the appropriate method, technique, and parameters of this new test so that we can apply it in future research. In addition, to obtain preliminary normative data of the test; onset latency, end latency, duration, and latency difference (LD) of CSP, as well as assess the effect of age, height, upper limb length, and gender on CSP values.

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).