Effect of a novel implantable tibial nerve stimulation system on overactive bladder in pigs.

Background: Overactive bladder (OAB) is a common and burdensome condition characterized by urgency, frequency, and urinary incontinence. While tibial nerve stimulation (TNS) has emerged as a minimally invasive neuromodulation therapy for OAB, current systems are limited by external devices, frequent hospital visits, and inconsistent stimulation. This study aims to investigate the safety and efficacy of a novel implantable TNS system for treating OAB in pigs.

Methods: Three male Bama miniature pigs (25-28 kg) received bilateral implantation of a novel battery-free, wireless implantable TNS system. The right-side device was activated as the treatment side, and the left-side device remained inactive as a control. Postoperative observations continued for 30 days, including assessments of general health, body weight, and X-ray monitoring of device position. OAB was induced by intravesical infusion of 5% acetic acid. Bladder pressure-volume curves were measured under baseline, OAB-induced (control), and TNS-stimulated (experimental) conditions. Histological examination of tissues surrounding the implants was conducted using hematoxylin and eosin staining to assess inflammation.

Results: All pigs remained in good health throughout the study, with stable weight gain and no adverse events. The implanted devices showed no migration and maintained stable function. Compared with baseline, bladder capacity was significantly reduced in the control group after OAB induction (P<0.05), and significantly increased in the experimental group after stimulation (average improvement of 24.4%, P<0.05). Histological analysis revealed no significant inflammatory reactions at electrode contact sites or in surrounding tissues between the experimental and control groups (P>0.05).

Conclusions: The novel implantable TNS system demonstrated excellent safety, biocompatibility, and efficacy in reducing OAB symptoms in pigs. These findings support its potential as a convenient and effective long-term neuromodulation therapy for OAB.