DIRECT BLADDER STIMULATION WITH SUTURE ELECTRODES PROMOTES VOIDING INA SPINAL ANIMAL-MODEL - A TECHNICAL REPORT

To determine the efficacy of a new electrode for direct bladder stimul ation, five male cats were instrumented during anesthesia. Multistrand ed, 316LVM, stainless-steel, wire electrodes were implanted on the bla dder wall serosa above the trigone area. The electrodes were made with a needle attached to the end that was cut off after suturing the elec trode in place. Additional instrumentation included tubes for pressure recording and filling, and hook electrodes for leg and pelvic floor E MG recording. Bladder filling and stimulation studies were conducted i n tethered animals 1 to 2 weeks following recovery. Chronic studies we re conducted following recovery in tethered animals. To test these ele ctrodes in a spinal cord injury (SCI) model, a T-1 level complete lesi on was performed on the above instrumented animals. Spinal animals had successful direct bladder stimulation that induced active contraction s and voiding both before and after SCI, but voiding rates were higher more than 2 weeks after SCI and at larger initial bladder volumes. Op timum stimulation parameters consisted of 40 pulses per second, 300 mu s to 1 ms pulse duration, a stimulation period of 3 to 4 s, and 10 to 40 mA. Urethral resistance, indicated by a urethral function measure, showed that stimulation had no adverse effect on urethral function, a nd fluoroscopy showed an open membranous urethra during stimulation an d voiding. The cat has a small penile urethra that is the flow rate co ntrolling zone. The suture electrode did not corrode, erode into the b ladder, or become dislodged, and appears suitable for chronic implanta tion.