Bursting stimulation of proximal urethral afferents improves bladder pressures and voiding

Reflex bladder excitation has been evoked via pudendal nerve, pudendal nerve branch and intraurethral stimulation; however, afferent-evoked bladder emptying has been less efficient than direct activation of the bladder via sacral root stimulation. A stimulation method that improves activation of the urethra-bladder excitatory reflex with minimal sphincter recruitment may lead to improved bladder emptying. Fine wire electrodes were placed in the wall of the urethra in five cats. Placement of electrodes near the proximal urethra evoked bladder contractions with minimal sphincter activation. On these electrodes, lower frequency burst-patterned stimuli evoked greater bladder voiding efficiencies (71.2 +/- 27.8%) than other stimulus patterns on the same electrodes (50.4 +/- 41.5%, p > 0.05) or any stimulus pattern on electrodes that elicited urethral closure (16.5 +/- 12.7%, p < 0.05). Fine wire electrodes specifically targeted afferent fibers in the urethra, indicating the feasibility of clinical evaluations using the same method. This work may improve the translation of next generation neuroprostheses for bladder control.