A Neurophysiologic Study of External Anal Sphincter Muscle Using Magnetic Stimulation

ABSTRACT

OBJECTIVE: To examine the nerve supply of external anal sphinctor muscle which contributes for the anal or urinary continence. METHOD: In the present study, sacral arc reflex was examined by an electrical stimulation of the penile shaft and recording of the compound muscle action potential from the external anal sphincter muscle with surface electrode, and pudendal nerve conduction was done by using a magnetic stimulation of proximal and distal cauda equina and recording from the external anal sphincter muscle. RESULTS: The results showed that the mean sacral arc reflex latency was 36.88+/-3.59 msec, and mean amplitude was 223+/-51.86 V with an electrical stimualtion. The mean latency by a magnetic stimulation of the proximal cauda equina was 6.34+/-1.29 msec, and the mean amplitude was 138+/-56 V. The mean latency by a magnetic stimualtion of the distal cauda equina was 3.67+/-0.44 msec, mean amplitude was 534+/-380 V. CONCLUSION: The pudendal nerve conduction study using a magnetic stimulation is a useful evaluation tool for the fecal incontinence of peripheral type, and neurogenic bladder.