Cutaneous Silent Period in the Evaluation of Small Nerve Fibres

INTRODUCTION High intensity cutaneous stimulus transiently suppresses tonic voluntary muscle activity resulting in cutaneous silent period (CSP). AIM The aim of our study was to evaluate the normal values of an onset latency L1, a late latency L2 and a duration of CSP after stimulating sensory fibres of the median nerve. MATERIAL AND METHODS This prospective study was performed at the Neurology Department, Clinical Center of Sarajevo University in period from January 1st 2013 to December 1st 2013. In our study we examined 61 subjects. The group included our relatives, coworkers and friends. The informed consent from testing subjects was obtained. RESULTS The origin of silent period is stimulation of small A-delta nerve fibres. The pre-synaptic or post-synaptic interruption of the electrical volley to motor neurons is discussed. Median values of muscle activity suppression in healthy female is 55.0 ms (45.0-74.0) and 59.0 ms (52.0-67) male subjects. There is a correlation between the onset latency L1 and the late L2 latency (p < 0.03). In the on-going study it seems that delay of L1 and shorter muscle activity suppression might provide a sign of small nerve fibres involvement. CONCLUSION The use of CSP improves the value of neurophysiology examination.