Studies on the feasibility of urinary bladder evacuation by direct spinal cord stimulation. II. Poststimulus voiding: a way to overcome outflow resistance.

Electrical stimulation of the spinal cord micturition center is effective in inducing strong detrusor contraction. Simultaneous sphincteric contraction, however, prevents voiding from occurring. At the end of stimulation a sharp drop in sphincteric activity takes place, with a concomitant and slower drop in intravesical pressure--resulting in a short poststimulus phase where bladder pressure exceeds urethral resistance and a spurt of urine is passed. This brief period was put to use by applying a train of short stimuli of 1-sec duration and separated by 1-sec intervals, following which complete bladder emptying could be obtained in an average time of 30 sec. This poststimulus voiding was constantly observed after high spinal cord transection. It can be accomplished without the need for neurectomy, sphincterectomy, or drug-induced muscular blockade.