Development of an implant technique and early experience using a novel implantable pulse generator with a quadripolar electrode array at the tibial nerve for refractory overactive bladder.

OBJECTIVES: Tibial nerve stimulation is an effective treatment for overactive bladder (OAB) and has been utilized as an in-person recurring session treatment option for many years. The primary objective of this study was to evaluate the safety and efficacy of a long-term implantable device and the method of utilizing a retrograde approach to place the device (a percutaneous implantable pulse generator [pIPG] with integrated quadripolar electrodes) at the tibial nerve (Protect PNS; Uro Medical Corp.).

METHODS: A novel retrograde implant technique was developed through multiple cadaveric dissections to percutaneously implant a chronic, wireless, minimally invasive pIPG device with integrated quadripolar electrodes (now licensed to Uro Medical) at the tibial nerve. A proof-of-concept pIPG device approved as part of an FDA IDE was designed to gain early experience in subjects with refractory OAB. The pIPG was implanted in the office under local anesthesia using the novel retrograde approach, and stimulation was activated using an external wireless energy source called a transmitter. Initially, a pilot study was designed to compare outcomes in subjects randomized to either percutaneous tibial nerve stimulation (PTNS) or Protect PNS. However, due to the small sample sizes available at this time, it was not possible to compare the two groups. Thus, the purpose of this manuscript is to describe the outcome of subjects who underwent implantation of the Protect PNS system. Twelve-month safety and efficacy were evaluated.

RESULTS: Nine subjects were enrolled in the randomized pilot study; 5 to the pIPG group and 4 to PTNS, and all completed the 13-week primary endpoint. Subsequently, two subjects in the PTNS group chose to cross over and have the pIPG implanted after 13 weeks. Outcomes of the seven subjects who underwent implantation of the pIPG are described. No complications related to the office procedure were noted. Two of the older model pIPG devices became nonresponsive at 1 and 4 weeks and were replaced. Six minor adverse events were reported and resolved. Subjects reported improvement in urge urinary incontinence (UUI) episodes, OAB symptoms, and quality of life. Subjects impanted with a pIPG reported a 50% reduction in UUI as early as 1 week.

CONCLUSIONS: Results of this pilot study suggest that retrograde percutaneous implantation of a pIPG is a safe, minimally invasive one-stage office procedure for treatment for urge incontinence related OAB symptoms, without significant complications after 12 months follow-up. Future studies will be required to compare outcomes among treatment modalities.