The pathogenesis of widespread pain and increased tenderness in Fibromyalgia (FM) are still unknown. Recently, the role of central nervous system hyperexcitability is emphasized in pathogenesis of FM. The central sensitization was demonstrated with decrease in nociceptive flexion reflex (NFR) threshold in patients with FM. The NFR and cutaneous silent period (CuSP) are excitatory and inhibitory parts of the same spinal protective reflex, respectively. The aim of this study was to evaluate the changes in CuSP in FM.
Twenty-eight patients with FM and 18 healthy volunteers were subjected to the study. CuSPs on right abductor pollicis brevis muscle evoked by electrical stimulation of the right fifth digit were recorded.
The CuSP onset latencies were significantly longer in patients with FM. There was not any significant difference in CuSP duration between patients and controls.
The latency elongation of the CuSP shows that there is some delay in the development of the inhibitory part of the spinal protective reflex in patients with FM. The observed changes in CuSP of the patients with FM may suggest some abnormalities in the circuits of sensorimotor integration at spinal and supraspinal levels. The results regarding the changes observed in the CuSP in patients with FM should be confirmed by further studies.