Transcutaneous Tibial Nerve Stimulation for Urinary Incontinence After Radical Prostatectomy

Overview

Urinary incontinence (UI) after radical prostatectomy (RP) is a common postoperative complication that significantly affects quality of life. This study aims to evaluate the efficacy of active transcutaneous tibial nerve stimulation (TTNS), added to standard pelvic floor muscle training (PFMT), compared with sham TTNS, in patients with UI after RP. The study uses a randomized, double-blind, sham-controlled design. The primary outcome is incontinence severity measured by the 24-hour pad test. Secondary outcomes include voiding diary parameters, pelvic floor muscle strength (perineometry), quality of life, sexual function, and anxiety/depression levels.

The incidence of UI after RP ranges from 17-77% at 1 month, 7-53% at 3 months, and 3-38% at 6 months postoperatively, with full continence recovery typically taking up to one year. PFMT is the most commonly used conservative approach for managing post-RP UI; however, exercise protocols reported in the literature (contraction number, duration, position) are not standardized. In recent years, peripheral neuromodulation techniques, particularly TTNS, have increasingly been studied as an adjunct to PFMT. Existing literature on this topic is limited to retrospective studies without sham control groups, leaving it unclear whether the observed clinical improvement reflects a true neuromodulatory effect or the natural recovery process. This study is the first prospective, randomized, double-blind, sham-controlled clinical trial comparing the efficacy of active TTNS added to PFMT versus sham TTNS added to PFMT. Design: Participants are stratified by postoperative time (1-3 months, 3-6 months, 6-12 months) and randomized within each stratum using blocks of four at a 1:1 ratio into two groups. Interventions - Group 1 (n=52): PFMT + Active TTNS, delivered via Enraf Nonius Myomed 932 at 20 Hz, 200 microseconds pulse width, continuous mode; once weekly, 30 minutes per session, for 12 weeks. Group 2 (n=52): PFMT + Sham TTNS, identical device/duration/frequency, using a four-electrode masking protocol with brief initial sensory stimulation followed by gradual current reduction to zero. Both groups also follow a 12-week progressive home-based PFMT program. Blinding: This is a double-blind trial. The participant and the outcome-assessing/data-collecting investigator are blinded to treatment allocation, and the statistician analyzes coded group labels blinded to group identity. The treating clinician, who monitors the motor threshold during stimulation, cannot be blinded but is fully isolated from clinical assessment processes. Assessment time points: Baseline (T0) and end of 12 weeks (T1). Sample size: Based on an a priori power analysis (Yamanishi et al. reference data), effect size d=0.585, alpha=0.05, 80% power yielded a minimum of 47 patients per group; accounting for 10% dropout, the final sample size was set at 104 (52 per group).