Feasibility of replacing a tibial nerve neuromodulation implant. A case series

Introduction: Implantable tibial neuromodulation (iTNM) is a minimally invasive treatment for lower urinary tract dysfunction. In a previously reported study, patients received the first-generation Renova iStim SystemTM, which consists of an implantable electrode powered by an external wearable unit. Following study completion, a second-generation wearable, non-compatible with the original implant, was developed, necessitating surgical revision to maintain therapy. This is the first report detailing the surgical, technical, and clinical aspects of such a revision. Methods: Five patients with overactive bladder (OAB) who had completed a three-year follow-up in the original study opted for implant revision due to device incompatibility. The new implant was activated four weeks post-surgery, with efficacy assessed three months post-revision using a three-day voiding diary and compared to original baseline and 36-month data. Patient satisfaction was evaluated after six months using the Patient Global Impression of Improvement (PGI-I). Complications were monitored throughout routine follow-up. Results: All patients originally received the implant in 2015; revisions were performed in 2022 without difficulties or complications. Mean operating time was 48 min. Leak episodes per day were 7.67 (SD 4.43) at baseline, 1.27 (SD 2.27) at 36 months, and 3.13 (SD 4.82) post-revision. Mean PGI-I score was 3 (SD 1.79). One patient required and responded well to device reprogramming. Conclusion: Revision surgery for iTNM proved safe, easily performable, and restores clinical effectiveness and patient satisfaction, making it a promising long-term therapeutic option for OAB.