Trial of Maintenance Therapy With Posterior Tibial Nerve Stimulation for Overactive Bladder

This study has 2 parts. Part 1 is a 12-week observational study of weekly Posterior Tibial Nerve Stimulation (PTNS) treatment for women with overactive bladder. Part 2 is a randomized, controlled trial of monthly maintenance PTNS therapy versus no therapy in subjects who were successfully treated by PTNS in Part 1. Part 1: 12-week observational study of weekly PTNS treatment. The primary aim of Part 1 is to determine the efficacy of a 12-week course of PTNS in the treatment of overactive bladder. Secondary aims are to determine the changes in voiding frequency and quality-of-life measures after the 12-week treatment. Part 2: Randomized, controlled study of monthly PTNS compared to no PTNS after 12-week treatment The primary aim is to determine time-to-failure after 12 weeks of PTNS in subjects who receive maintenance therapy compared to those who do not, in order to ascertain if there is a need for maintenance therapy after 12 weeks of PTNS. The investigators' secondary aims are to compare the long-term efficacy and quality of life impact in patient receiving maintenance PTNS compared to those that do not and to determine the efficacy of rescue maintenance PTNS in subjects who have symptom recurrence in the no maintenance therapy arm. Hypothesis: There will be no difference in time to failure between women randomized to monthly maintenance PTNS compared to no maintenance PTNS.