Effective methods of pelvic plexus nerve and bladder stimulation in anesthetized animal model

Abstract

Abstract-Urinary retention is a serious urological problem associated with spinal cord injuries (SCIs) and other pelvic disorders. Effective methods of pelvic nerve stimulation were investigated for this problem. Following anesthesia in five dogs, the bladder was surgically exposed. Bladder and anal sphincter pressures were recorded. Testing was first conducted with probe electrodes. Barb electrodes were then implanted with a needle near the pelvic plexus nerves and the bladder wall. We tested different electrode arrangements and stimulating parameters to induce bladder contractions without skeletal muscle stimulation. The pelvic plexus nerves near the bladder were identified, and the barb electrodes were effectively implanted. Stimulation with bipolar and bilateral electrodes induced pressures over 30 cmH 2 O without skeletal muscle activation. Common stimulation parameters were 40 pps, 400 microseconds pulse duration, and 15 to 25 mA stimulating current applied for 3 s. Effective electrode implantation methods were shown. Also identified were electrode arrangements and stimulating parameters that induced strong bladder contractions without skeletal muscle activation. However, voiding studies were not conducted. Further studies with barb electrodes are warranted, and these methods may have applications for bladder stimulation following SCI.

Evaluation of Bipolar Permaloc™ Electrodes for Direct Bladder Stimulation

“…In our prior of cats and dogs studies we observed higher bladder pressures to stimulation [14][15][16][17][18][19]. In our most recent study of dogs, we used similar but fewer bipolar barb electrodes on the bladder wall than were used in this study.…”

“…For the remaining four animals, we made replica bipolar electrodes ( Fig. 1) modeled after the bipolar Permaloc TM electrodes [14]. The replica electrodes consisted of multistranded, stainless-steel wires insulated with Teflon ® (Model X, Cooner wire Inc, Chatworth, CA) in which five mm of Teflon R insulation was stripped from the end of the lead and then was bent back over a 20 G needle to create a barb electrode.…”

“…In a few initial tests, a lower current of 10 mA was tested first when there was a concern about possible leg muscle contractions. Other stimulation parameters were set to levels reported to induce maximal bladder pressures including 400 s pulses, 40 Hz stimulating frequency and 5 s stimulation periods [14,[16][17][18][19].…”

“…We have been investigating optimal methods of bladder wall stimulation [14][15][16][17][18][19]. Recently we reported that bipolar barb electrodes with little separation between the two stimulating surfaces were effective for inducing high bladder pressures in anesthetized dogs [14].…”

“…Recently we reported that bipolar barb electrodes with little separation between the two stimulating surfaces were effective for inducing high bladder pressures in anesthetized dogs [14]. In this study, we purchased Permaloc ™ bipolar electrodes (Synapse Biomedical Inc, Oberlin OH) that also had little separation between the stimulating surfaces, in contrast to the wide seperation used by Magasi et al [12,13], and tests were conducted with bladder wall stimulation in swine.…”