Transcutaneous Tibial Nerve Stimulation for Urinary Incontinence After Radical Prostatectomy

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).

Inclusion criteria

• Male patients aged 18-80 years
• Urinary incontinence greater than 8 g on the 24-hour pad test after radical prostatectomy
• Postoperative catheter removed, between 2 weeks and 1 year after surgery
• Willing to complete study questionnaires and able to understand the procedures, benefits, and possible side effects
• Able to provide written informed consent

Exclusion criteria

• History of urinary incontinence prior to radical prostatectomy
• History of conservative treatment after prostatectomy, including tibial nerve stimulation, magnetic stimulation, or electrical stimulation
• Prolonged indwelling urethral catheterization (more than 15 days)
• Anatomical/post-traumatic malformations or active skin conditions at electrode sites preventing electrode application or stimulation
• History of prior urological surgery
• Inability to voluntarily contract pelvic floor muscles on digital rectal examination per ICS terminology
• Currently receiving or having received radiotherapy
• Urethral stricture or active urinary tract infection
• Heart failure, pacemaker, or implanted defibrillator
• History of transurethral resection of the prostate (TURP) for benign prostatic hyperplasia
• Use of medications that may affect bladder function (antimuscarinics, duloxetine, tricyclic antidepressants, etc.)
• History of neurogenic bladder or peripheral/central neurological pathology
• Inability to attend treatment sessions regularly due to distance or physical limitations