Facilitation of Nerve Conduction by Distant Muscle Contraction in Stroke Patients

ABSTRACT

OBJECTIVE: To investigate the effect of distant muscle contraction on the sensory and motor nerve conduction and F-wave studies in stroke patients. METHOD: During isometric contraction of contralateral hand, sensory nerve action potential (SNAP), compound muscle action potential (CMAP) and F-wave of median nerve were recorded at submaximal and supramaximal stimulus intensity. The subject group consisted of 15 stroke patients and 10 control subjects. RESULTS: At submaximal stimulation, the amplitude and area of SNAP were significantly increased during muscle contraction in both groups (p <0.05). However there were no changes in parameters of SNAP and CMAP at supramaximal stimulation in both groups. The latency of F-wave was prolonged, and the amplitude was increased in the stroke group than those in the control group at resting state (p <0.05). The shortening of F-wave latency and increment of F-wave amplitude were observed in the control group during distant muscle contraction, but not in the stroke group. CONCLUSION: The distant muscle contraction might facilitate the nerve conduction. In addition F-wave elicited during voluntary contraction can be used as a monitor of upper motor neuron disorders.