A computational model of the pudendal nerve for the bioelectronic treatment of sexual dysfunctions

A large population of both males and females is affected by sexual dysfunctions, while presently existing treatments have several drawbacks. Novel electroceutical approaches could be promising alternatives. Genital arousal is known to be controlled by autonomic and somatic activity. Most of the nerve fibers involved in these processes origin from the second to fourth sacral nerve, namely the efferent parasympathetic fibers and the afferent sensory fibers carrying the stimuli responsible of triggering reflex arousal, later forming the pudendal nerve. The latter is a reasonable target for implants since it follows a repeatable course and can be exposed via well-known surgical approaches. We compared existing implantable electrodes, the Interstim quadripolar lead and a multipolar cuff, in terms of thresholds and selectivity, which are the first requirement to deliver effective stimulation without inducing pain, spasms, or other collateral phenomena. We employed a hybrid modeling approach: the target nerve was 3D-modeled on real histological cross-sections. FEM modeling was performed to simulate current injection into the fascicles. The fascicles were then populated with compartmentalized axons and neurophysiological simulations using the MRG model were performed. We estimated whether, and at which injected charge level, each axon fired along its length and computed parameters of interest, resulting in hints to guide the development of a future bioelectronic solution.