Enrolling too slowly due to insurance plans no longer covering the cost of the Percutaneous Tibial Nerve Stimulation treatment.

The null hypothesis for this study is that the combination of solifenacin and Percutaneous Tibial Nerve Stimulation (PTNS) is not different from PTNS alone. However the investigators anticipate a 20% improvement in patients receiving combination therapy as measured by the OAB-q (Overactive Bladder questionnaire) scores.

Inclusion Criteria:

1. 18 years of age or older
2. history of overactive bladder
3. history of inadequate response to prior or current treatment with anti- muscarinic medication, or unacceptable side effects from higher dose of anti-muscarinic medication
4. PTNS-naive
5. willing to discontinue the use of anti-muscarinic agents for 2 weeks before start of study medication ("washing out")
6. able to swallow and retain oral medication
7. able and willing to participate in the full duration of the study
8. able to read and write (health outcomes questionnaires are self-administered)and understand instructions related to study procedures and give written informed consent
9. OAB-q (items 1-8) score of 30 or higher

Exclusion Criteria:

1. presence of cardiac pacemaker and/or defibrillator
2. history of urinary retention
3. history of gastric retention
4. uncontrolled narrow angle glaucoma
5. any unstable, serious co-existing medical condition(s) including, but not limited to, myocardial infarction,coronary bypass surgery, unstable angina, cardiac arrhythmias, clinically evident congestive heart failure, or cerebrovascular accident within 3 months prior to Screening visit
6. abnormal liver function test (greater than 3 times the upper limit of normal for alanine aminotransferase [ALT], aspartate aminotransferase [AST], or alkaline phosphatase [ALP]); or bilirubin > 3 times the upper limit of normal
7. history of any illness (including psychiatric) that, in the opinion of the investigator, might confound the results of the study or pose additional risk to the subject
8. known hypersensitivity to solifenacin
9. participation in any investigational or marketed drug trial within the 30 days prior to the first dose of study drug or any time during the study period
10. pregnancy or trying to become pregnant
11. breast-feeding