Use of a neuromuscular stimulator to increase anal sphincter pressure

Objectives: The objective of this study was to determine if short periods o f electrical stimulation with perianal electrodes could increase anal press ures. Material and methods: Anorectal responses to electrical stimulation were ev aluated in five healthy SCI patients. Anorectal pressures were recorded wit h a small pressure-recording balloon before, during, and immediately follow ing stimulation. A battery-powered stimulator with self-adhering surface el ectrodes, two inches in diameter was used. Stimulating parameters consisted of 300 mus 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 stim ulations. Results: Four of the five subjects had strong anal contractions with perian al 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 shor t periods of stimulation used here, fatigue was apparent. There was an aver age drop of 11% in anal pressure over the 13 s of stimulation. Rectal press ures were unchanged with perianal stimulation. Conclusions: Perianal stimulation with surface electrodes is an approach th at might be considered in the future for management of fecal incontinence i n individuals with spinal cord injury. Further studies are needed to assess the feasibility of using chronic perianal surface electrical stimulation t o sustain anal sphincter contractions.