Electrical stimulation induced sphincter fatigue during voiding.

The stimulation of the sacral nerves to induce voiding is often associated with simultaneous contraction of the striated sphincter rendering micturition difficult or impossible. Rhizotomy of some sacral nerves was found to be necessary to facilitate voiding with stimulation. An main objective in the present experiment was to evaluate the feasibility of achieving the same result using electrical stimulation to fatigue the sphincter. In order to compare the effect of rhizotomy and fatiguing striated sphincter, the bladder outlet resistance was measured. S2 nerves were stimulated with 3 V, 35 Hz and 100 microseconds duration for 5 to 10 sec. Following S2 nerves stimulation the pudendal nerve was stimulated till we obtained sphincteric fatigue. The optimal parameter to induce sphincter fatigue were 3 V, 100-500 Hz and 100 microseconds. for 15-20 sec. The combined pressure-flow studies showed that fatiguing the sphincter via the pudendal nerve using these parameters was as good as cutting it in achieving bladder emptying with stimulation.