SACRAL ROOT STIMULATION FOR CONTROLLED DEFECATION

Selective rectal or sphincter neurostimulation aiming at controlled de fecation was performed in 10 dogs. While the dogs were under anesthesi a, the rectal and rectal neck pressures, balloon expulsion as well as external anal sphincter (EAS) response to stimulation of the second sa cral ventral nerve root (S2) and its autonomic and somatic branches we re determined. Each of these nerves was stimulated separately using bi polar platinum cuff electrodes. S2 stimulation resulted in rectal and rectal neck pressure elevation as well as increase of EMG activity of EAS without balloon expulsion. Autonomic branch stimulation effected r ectal pressure increase and balloon expulsion, while somatic branch st imulation caused increase of rectal neck pressure and EAS EMG activity with no balloon expulsion. S2 stimulation with somatic branch transec tion produced rectal pressure elevation and balloon expulsion. In cont rast to rectal pressure, the rectal neck pressure increased with incre asing stimulus frequency. In conclusion, rectal evacuation and sphinct eric control could be induced by selective sacral root electrostimulat ion: S2 stimulation with transection of the somatic branch for the for mer and pudendal branch stimulation for the latter.