Randomized, controlled trial of anal electrical stimulation for fecal incontinence

Anal electric stimulation has been described as effective for fecal incontinence in several case series, but no study has addressed possible mechanism of benefit. We wished to examine whether anal electric stimulation, using an anal probe electrode, used on a daily basis at home for eight weeks, in the absence of any adjunctive exercises or advice, would improve symptoms of fecal incontinence and anal sphincter pressures when compared with "sham" electric stimulation.

Ninety patients (9 males, 81 females), with median age of 55 (range, 30-77) years were randomized, 47 to active anal stimulation at 35 Hz and 43 to "sham" stimulation at 1 Hz. Outcome measures included a one-week bowel diary, symptom questionnaire, manometry, and patients' evaluation of outcome.

Seventy patients completed the study. On an intention-to-treat analysis, there was no difference between the two groups on any of the outcome measures after eight weeks. Of those who completed stimulation, 44 (63 percent) felt the stimulation had improved their continence. Those with intact anal sphincters were not likely to rate their change more positively than those with sphincter disruption (P=0.71). Median patient rating of bowel control increased from 3 of 10 before stimulation to 5 of 10 after stimulation (P=0.001).

Eight weeks of anal electric stimulation was rated by patients as having improved their bowel control to a modest extent. There was no statistically significant difference detected between the groups, suggesting that 1 Hz was as effective as 35 Hz. This raises the possibility that the main effect is not sphincter contraction but sensitization of the patient to the anal area, or simply the effect of intervening per se. Home electric stimulation is a relatively cheap and generally well-tolerated therapy in the conservative treatment of fecal incontinence.