Control of bladder function by electrical stimulation of pudendal afferents

Spinal cord injury (SCI) and other neurological disorders can cause urinary dysfunction that can cause serious health problems and reduce quality of life. Current methods for treating urinary dysfunction have major limitations or provide inadequate improvement in symptoms. Pudendal nerve stimulation is a potential means of restoring control of bladder function. Bladder contraction and relaxation can be evoked by pudendal afferent stimulation, and peripheral pudendal afferent branches may be ideal targets for a bladder control neural prosthesis. This dissertation investigates control of bladder function by selective electrical stimulation of pudendal afferents.;This study investigated the ability to improve both urinary continence and micturition by both direct and minimally-invasive electrical stimulation of selected pudendal afferents in α-chloralose anesthetized male cats. Direct stimulation of the pudendal afferents in the dorsal genital nerve (DGP), percutaneous DGP stimulation, and intraurethral stimulation were used to quantify the bladder response to selective activation of pudendal afferents. Finite element modeling of the cat lower urinary tract was used to investigate the effects of intraurethral stimulation location and intraurethral electrode configuration on the complement of pudendal afferents that was activated. The contribution of sympathetic bladder innervation to bladder activation by pudendal afferent stimulation was assessed through pharmacological and surgical block of sympathetic activity to clarify the mechanisms of bladder contraction evoked by pudendal afferent stimulation.;The DGN is an ideal target for restoring urinary function because stimulation at low frequencies (5-10 Hz) improves urinary continence, while stimulation at high frequencies (33-40 Hz) improves urinary voiding. Intraurethral stimulation is a valid method for clinical investigation of bladder responses to selective activation of the DNP or cranial sensory branch (CSN) of the pudendal nerve. In the cat, intraurethral stimulation can activate the bladder via two distinct neural pathways, a supraspinal pathway reflex activated by the CSN and a spinal reflex activated by the DNP. Finite element modeling revealed that intraurethral electrode location (rather than electrode geometry) is the primary factor in determining whether the DNP and CSN can be selectively activated by intraurethral stimulation. Finally, the sympathetic bladder pathway does not play a significant role in mediating bladder activation by DNP stimulation. These findings imply that selective pudendal afferent stimulation is a promising approach for restoring control of bladder function to individuals with SCI or other neurological disorders.