A First-In-Human Feasibility Study of a New Implantable Tibial Nerve Stimulator for Overactive Bladder Syndrome

Overactive bladder (OAB) remains a prevalent and often debilitating syndrome, affecting millions worldwide. Despite numerous treatment options, including behavioral modifications, pharmacologic therapies, and third-line interventions such as botulinum toxin injections and sacral neuromodulation, many patients either fail to respond adequately or discontinue treatment due to adverse effects.

Percutaneous tibial nerve stimulation (PTNS) has emerged as an effective neuromodulatory approach, but its requirement for frequent office visits limits long-term adherence. This first-in-human (FIH) feasibility study examines the use of a novel implantable tibial nerve stimulator (ITNS) with a long-lasting battery as a long-term treatment for patients with symptoms of OAB.

Study Overview and Key Findings
This pilot study enrolled ten patients with refractory OAB, seven of whom experienced urgency urinary incontinence (OAB-wet) and three with urgency without incontinence (OAB-dry). Following implantation of the ITNS device, participants underwent daily stimulation for two weeks, followed by weekly stimulation for 13 weeks. The study primarily aimed to establish safety and understand preliminary efficacy.

The results demonstrated statistically significant improvements in various OAB symptoms assessed throughout the study. Notably, 80% of participants met the responder criteria, defined as an improvement in at least one OAB symptom by ≥50%, while all patients reported subjective symptom improvement on the Global Response Assessment (GRA), with a median score of 6. The mean number of daily voids during waking hours decreased from 8.5 to 6.3 (p = 0.016), and daily urgency-related voids reduced from 7.6 to 3.0 (p < 0.001). Incontinence episodes saw a dramatic decline from 2.5 to 0.3 per day (p < 0.001). No significant safety concerns were seen in the trial, with no serious adverse events reported. Adverse events, such as incision-site redness and transient discomfort, were effectively managed without sequelae.

Randomized Controlled Trial is Ongoing
An ongoing, larger randomized controlled trial is underway examining the use of the Intibia™ System for patients with Urgency Urinary Incontinence (UUI), results of which will be reported in due course.

Conclusions
ITNS therapies represent an exciting advancement in the neuromodulation landscape for OAB syndrome. By addressing some of the key limitations of PTNS and other third-line therapies, ITNS devices have the potential to improve treatment adherence and long-term outcomes for patients struggling with symptoms of OAB.

Written by: Parminder Sethi, MD, John Muir Urology, San Ramon, CA

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