To evaluate clinical outcomes of implantable tibial nerve stimulation (ITNS) in patients with refractory idiopathic overactive bladder (OAB) who previously responded to posterior tibial nerve stimulation (PTNS), and to explore whether prior PTNS response predicts treatment success.

We conducted a retrospective case series of five patients with refractory idiopathic OAB who had previously demonstrated a positive response to PTNS but subsequently experienced symptom recurrence or discontinued therapy due to non-compliance. All patients underwent baseline clinical evaluation, including urodynamic studies where available, prior to intervention. ITNS was performed using the Bioness StimRouter system under local anesthesia, with the stimulation lead placed subcutaneously at the level of the ankle along the posterior tibial nerve distribution. This configuration enabled patient-controlled, home-based therapy.

Clinical outcomes were assessed using the validated Overactive Bladder Questionnaire (OAB-q), as well as subjective patient-reported symptom improvement. Follow-up duration ranged from 3 to 9 months. Safety outcomes, including procedural and post-procedural adverse events, were also recorded.

All five patients reported clinically meaningful symptomatic improvement, with estimated response rates ranging from 70% to 90%. A consistent reduction in OAB-q scores was observed across the cohort, indicating improved quality of life. 

The procedure was well tolerated in all cases. No intraoperative complications were encountered, and no major adverse events were reported during the follow-up period. All patients were able to successfully utilize the device for home-based therapy without technical difficulties or discontinuation.

ITNS appears to be an effective and minimally invasive treatment option for patients with refractory OAB, particularly in those who previously responded to PTNS. The observed symptomatic improvement and favorable safety profile support its role as a maintenance or alternative therapy in patients unable to sustain PTNS due to compliance limitations.

Prior response to PTNS may serve as a useful predictor of treatment success with ITNS. These preliminary findings support the use of PTNS responsiveness as a potential patient selection tool; however, larger prospective studies are required to confirm this relationship.