Electrically stimulated smooth muscle neosphincter

Most patients undergoing total anorectal reconstruction suffer some degree of incontinence despite the incorporation of an electrically stimulated gracilis neosphincter. As smooth muscle has the ability to maintain prolonged contraction without fatigue, the aim of this study was to assess the feasibility of developing an electrically stimulated smooth muscle neosphincter.

Electrical stimulation of the rabbit colon was performed via intramural wire electrodes using a constant voltage DC stimulator. Contractile activity was recorded by serosal strain gauges and an intraluminal pressure probe.

Basal colonic pressure was 4-13 (median 11) cmH2O. Peak pressures generated by stimulated contractions (10 V, 1 ms, 10 Hz) ranged from 14 to 37 (median 26, n = 36) cmH2O and were significantly higher than those with spontaneous contractions (P = 0.005). During continuous stimulation contractions lasted for 45-96 (median 74) s. Intermittent stimulation using trains of electrical pulses of 1-2-min duration at 1-2-min intervals produced repeated contractions. Alternative contractions were produced when intermittent electrical stimulation was performed at two sites alternately with two pairs of electrodes more than 2.5 cm apart, producing a sustained high-pressure zone.

An electrically stimulated smooth muscle neosphincter is feasible. It has potential applications in the management of faecal incontinence.