Hypothesis / aims of study
Tibial nerve stimulation is an effective third line treatment for patients with bothersome overactive bladder, urgency symptoms and nocturia. However, the 30-minute once a week standard protocol likely under delivers stimulation time or “dosage” and can also represent significant patient burden. The technological advance of wireless stimulation allows placement of the lead in a smaller area where historically a pulse generator would not fit. An implantable tibial nerve technology with wireless energy delivery allows programmable nerve stimulation to previously unacessable targets. Patient controlled home stimulation may also provide longer, daily stimulation time at home and more rapid clinical improvement. This prospective study evaluates two office-based tibial nerve treatments for UI; percutaneous tibial nerve stimulation (PTNS) and chronic tibial nerve stimulation (CTNS) via a wireless neuromodulation system.
Study design, materials and methods
Women reporting bladder symptoms for at least 6 months and experiencing a minimum of 1 urge incontinence episode per day were randomized (1:1) to receive 12 weeks of standard percutaneous tibial nerve stimulation treatments or an implanted chronic tibial nerve stimulation device. Chronic tibial nerve stimulation is an investigational office based procedure under local anesthesia. A wireless lead is placed parallel to the tibial nerve using a novel retrograde approach and confirmed with motor and sensory response. All patients are taught how to wear an ankle bracelet / sleeve and confirm a motor / sensory response. In this study patients were instructed to stimulate the tibial nerve for 6-8 hours a day.
After percutaneous tibial nerve stimulation women had the option of having the chronic tibial nerve stimulation device placed. Voiding diaries, the OAB-q symptom questionnaire and the I-QOL quality of life questionnaire were completed, and safety was assessed. Descriptive statistics were performed.
Nine women were enrolled; 5 to the chronic tibial nerve stimulation arm and 4 to the percutaneous tibial nerve stimulation arm. 2 percutaneous tibial nerve stimulation patients choose to undergo chronic tibial nerve stimulation device implant after percutaneous tibial nerve stimulation for a total of 7 chronic tibial nerve stimulation devices implanted. There was one device explant done at 2 years in a woman who had excellent symptomatic response, the explant was for complete resolution of her symptoms after adrenal surgery. The device was removed in the office without incident. The other 6 remain active study participants. Data includes all 7 completing the 6 month visit, and 3 completing the 12-month visit (Table). All percutaneous tibial nerve stimulation and chronic tibial nerve stimulation patients reported improvements in UI episodes per day, OAB symptoms and QOL. Most chronic tibial nerve stimulation improvement were observed by 4 weeks vs. percutaneous tibial nerve stimulation improvement at 13 weeks. Positive treatment effects continued through 12-months post-implant. To date, 5 study-related adverse events (AE's) have been reported, all were minor and have resolved.
Interpretation of results
The retrograde approach tibial nerve lead placement technique was safe and well tolerated in the office setting under local anesthesia.
Tibial nerve stimulation was effective for both groups, and though the numbers are low in this early clinical trial, we observed that chronic tibial nerve stimulation group had a more rapid clinical improvement. This clinical improvement was sustained.