Peripheral Silent Period In Cervical and Generalized Dystonia

Objective: Dystonia is a movement disorder described by continuous or alternating muscle contractions causing unusual postures or insistent motions. Abnormal sensorimotor integration and abnormalities in inhibitory pathways are thought to have a role in pathogenesis. This paper aims to research the state of inhibitory pathways in the spinal cord in dystonia through documenting a silent period (SP) through cutaneous stimulation (CuSP) or mixed nerve stimulation (MnSP). Methods: 23 patients with dystonia were included in the study. Also, 19 healthy subjects were included in the study as a control group. Ages were similar between two groups. (p=0.092). CuSP and MnSP are recorded through abductor pollicis brevis and median nerve at the wrist respectively. Results: Onset latency, time, and suppression index of CuSP were equivalent between two groups. Moreover, the initiation and terminate latencies of MnSP, also duration, were similar between these two groups. I2 suppression index was lower in generalized dystonia patients compared to patients with cervical dystonia (100.0 vs 86.7±21.4%; F=4.252, 0.035). Conclusions: The most striking result to emerge from the data is that there was lower suppression during CuSP in generalized dystonia patients. Our results suggest that spinal inhibitory circuits are less active if only there is clinical involvement of the relevant segment.