A bladder control system for spinal cord injured (SCI) patients is needed that can be implanted with
minimally invasive methods. New Permaloc bipolar electrodes consisting of 6 mm helical, wire, stimulating surfaces
separated by 3 mm and a polypropylene securing barb (Synapse Biomedical Inc) were developed for this application.
They are implanted on the bladder wall with a 16 gauge needle, a minimally invasive method.
Seven swines were anesthetized, the lower urinary tract exposed and instrumented with pressure transducers.
Four PermalocTM electrodes were implanted following identification of effective bladder wall stimulation sites next to the
ureters and dorsal neurovascular bundle. Bladder stimulation to induce high pressures was conducted at 40 Hz, 400 s
pulses, 5 s stimulation periods and a high stimulating current of 40 mA.
At the high stimulating current peak bladder pressures were low, ranging from 12±2 to15±3 cm H20, insufficient
to induce urination. Urethral sphincter contractions occurred during high bladder pressure. A spinal reflex role for high
sphincter pressures during stimulation was shown by similar high pressures recorded during a bladder squeeze test
Stimulation with PermalocTM bipolar electrodes at high currents produced insufficient bladder pressures for
urination. Further modifications of the electrode such as greater separation of the bipolar stimulating surfaces or changes
in the testing methods such as alternative animal models are needed to induce high bladder pressures without side effects.