Bladder-wall and pelvic-plexus stimulation with model microstimulators: Preliminary observations

Severe urinary retention is not a common condition, but may occur following some pelvic surgeries or other medical conditions. Electrical stimulation of the bladder has been exam- ined as a means of managing this difficult problem. We con- ducted preliminary investigations in cats to prove the hypothesis that pelvic-plexus (bladder-neck) stimulation would produce greater micturition response with reduced side effects, such as animal movement or discomfort, than bladder-wall stimulation with electrodes implanted higher on the bladder wall. We used model microstimulators that mimic the look and function of commercial microstimulators, but that we constructed. We instrumented four female cats during a survival surgery. Ani- mals recovered well and studies were conducted over a 1-month period in the conscious animal and under anesthesia. We per- formed a variety of studies with different stimulation parame- ters and electrode locations to evaluate our hypothesis. In the active animal, we supplied only low currents, but two animals responded to stimulation with bladder contractions and voiding. Following anesthesia, higher stimulating currents resulted in greater bladder contractions during stimulation in two of the three animals. In two cases, pelvic-plexus (bladder-neck) stimu- lation induced greater micturition responses than direct bladder- wall stimulation. In conclusion, we learned from these prelimi- nary observations that stimulation at the pelvic plexus (bladder neck) may induce a better micturition response than stimulation higher on the bladder-wall. Newly available commercial micro- stimulators should be further studied for the treatment of urinary retention.