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PURPOSE: Electrical sacral root stimulation induces defecation in spinal cord injury patients and is currently under examination as a new therapy for fecal incontinence. In contrast to electrical stimulation, magnetic stimulation is noninvasive. To gain more insight into the mechanism of action of sacral root stimulation, we studied the effects of magnetic sacral root stimulation on anorectal pressure and volume in both fecal incontinence and spinal cord injury patients. METHODS: Three groups were examined: 14 healthy volunteers, 18 fecal incontinence patients, and 14 spinal cord injury patients. Repetitive magnetic sacral root stimulation was performed bilaterally using bursts of five seconds at 5 Hz. Anal and rectal pressure changes and rectal volume changes were measured. RESULTS: An increase in anal pressure was seen in 100 percent of the control subjects, in 86 percent of the spinal cord injury patients, and in 73 percent of the fecal incontinence patients (P=0.03). The overall median pressure rise after right-sided and left-sided stimulation was 12 (interquartile range, 8–18.5) and 13 (interquartile range, 6–18) mmHg at the mid anal level. A decrease in rectal volume was provoked in 72 percent of the control subjects, in 79 percent of the spinal cord injury patients, and in 50 percent of the fecal incontinence patients. Overall median volume changes after right-sided and left-sided stimulation were 10 (range, 5–22) and 9 (range, 5–21) percent from baseline volume. An increase in rectal pressure could be measured in 56 percent of the control subjects, 77 percent of the fecal incontinence patients, and 43 percent of the spinal cord injury patients. Median pressure rises after right-sided and left-sided stimulation were 5 (range, 3–12) and 5 (range, 3–5) mmHg. CONCLUSIONS: Magnetic sacral root stimulation produces an increase in anal and rectal pressure and a decrease in rectal volume in healthy subjects and patients with fecal incontinence or a spinal cord injury.

PURPOSE: The aim of this controlled study was to examine whether it was feasible to use magnetic stimulation as a new diagnostic tool to evaluate the motor function of the sacral roots and the pudendal nerves in patients with fecal incontinence. PATIENTS AND METHODS: Nineteen consecutive patients (17 females) with a median age of 67 (range, 36–78) years referred for fecal incontinence and 14 healthy volunteers (six females) with a median age of 42 (range, 23–69) years were examined. Latency times of the motor response of the external anal sphincter were measured after electric transrectal stimulation of the pudendal nerve and magnetic stimulation of the sacral roots. RESULTS: The success rates of pudendal nerve terminal motor latency and sacral root terminal motor latency measurements were 100 and 85 percent, respectively, in the control group and 94 and 81 percent, respectively, in the fecal incontinence group. Median left pudendal nerve terminal motor latency was 1.88 (range, 1.4–2.9) milliseconds in the control group and 2.3 (range, 1.8–4) milliseconds in the fecal incontinence group (P