Selective motor stimulation of the pudendal nerve using multi-contact cuff electrodes: a pre-clinical study in feline and ovine models.

Introduction: Pudendal nerve stimulation is a promising therapy for urinary incontinence, however stimulation can evoke off-target activity. We aimed to determine whether multi-contact cuff electrodes can selectively recruit motor fibers of the pudendal nerve trunk in preclinical feline and ovine models. Methods: Multi-contact cuff electrodes were implanted around the pudendal nerve in anesthetized felines and ovines. Structured variations in electrode contact configurations and stimulation amplitudes were applied to evoke external urethral sphincter (EUS) and external anal sphincter (EAS) pressure responses. We calculated selectivity indices, EUS Scores, and EAS Scores to quantify selective recruitment and the magnitude of evoked pressure changes. Results: We achieved selective motor activation, with preferential recruitment of the EUS or EAS in all three feline experiments and one of three ovine experiments. In felines, at least four electrode combinations selectively evoked EUS responses (EUS Score 0.5) and at least one combination targeted the EAS. In ovines, one EUS-selective and six EAS-selective combinations obtained comparable scores. In preliminary tests, we observed functional increases in leak point pressure and incontinence prevention with selective stimulation. Conclusions: This study shows that multi-contact cuff electrodes can selectively activate EUS and EAS motor fibers in the pudendal nerve. Future work should focus on optimizing stimulation parameters to enhance selectivity and assess the translational potential of this approach for restoring pelvic organ control.