Use of a neuromuscular stimulator to increase anal sphincter pressure

The objective of this study was to determine if short periods of electrical stimulation with perianal electrodes could increase anal pressures.

Anorectal responses to electrical stimulation were evaluated in five healthy SCI patients. Anorectal pressures were recorded with a small pressure-recording balloon before, during, and immediately following stimulation. A battery-powered stimulator with self-adhering surface electrodes, two inches in diameter was used. Stimulating parameters consisted of 300 micros pulse duration, 35 Hz stimulating frequency. A current response study was conducted by using short periods of electrical stimulating with currents from 0-100 mA until a maximal pressure was recorded. Each current setting was conducted for 13.2+/-9.7 s before increasing to the next higher current, and fatigue was reduced by including a 5-minute rest between stimulations.

Four of the five subjects had strong anal contractions with perianal stimulation. Increases in pressure ranged from 38 to 125 cm H2O based on maximal responses at currents ranges of 60 to 100 ma. Even during the short periods of stimulation used here, fatigue was apparent. There was an average drop of 11% in anal pressure over the 13 s of stimulation. Rectal pressures were unchanged with perianal stimulation.

Perianal stimulation with surface electrodes is an approach that might be considered in the future for management of fecal incontinence in individuals with spinal cord injury. Further studies are needed to assess the feasibility of using chronic perianal surface electrical stimulation to sustain anal sphincter contractions.