INTRODUCTION: Overactive bladder syndrome is defined by The International Continence Society as urgency, with or without incontinence, usually with increased urinary frequency and nocturia. It is difficult to estimate the prevalence of this syndrome because many patients do not seek medical help, despite considerable negative impact on quality of life. Lower urinary tract dysfunctions can be treated using electrical stimulation of the posterior tibial nerve. This therapy is conservative, effective, inexpensive and promotes high adhesion to treatment. It has good results, decreasing symptoms of urgency, urge-incontinence, urinary frequency and nocturia . Due to lack of consensus on the parameters of this technique, further research is necessary. OBJECTIVE: To compare the effectiveness of protocols for the electrical stimulation of the posterior tibial nerve for treatment of non-neurogenic overactive bladder. METHODS: The study was a blind randomized clinical trial. The study will accept up to 145 women with overactive bladder diagnosis for at least six months prior to the beginning of the study. The subjects will be divided into five groups: group TENS 0-1 (placebo group), group TENS 1-1 (electrical stimulation of one leg once a week), group TENS 1-2 (electrical stimulation of one leg twice a week), group TENS 2-1 (electrical stimulation of two legs one a week) and group TENS 2-2 (electrical stimulation of two legs twice a week). Physical evaluation will be done at the beginning and at the end of the treatment. Evaluation will be done using the King "s Health Questionnaire, the International Consultation Incontinence Questionnaire - Short Form, the Overactive Bladder Questionnaire, a three day urinary diary and a table for follow-up treatment.

Participants will be recruited from Urogynecology Physical Therapy Outpatient Clinic of a university hospital and randomly assigned using website www.randomization.com and distributed into five groups considering the sites of application and frequency of attendanc, listed above.

Data will be collected by the investigator using interview and physical examination and will be safely stored in computer.

For this study, in terms of urinary frequency, the standard deviation was estimated at 3.25 episodes of urinary urgency (SD=3.25). With 80% power and 95% confidence, the sample size calculation was 25 women in each group, plus a possible sample loss of around 20%, resulting in a sample size of 29 women per group, for a total of 145 patients in the study.

The chi-square test was used to assess whether there was an association between sample description variables and treatments. The analysis of variance F-test was used to assess whether there were differences in the numerical descriptive variables between treatment groups. The nonparametric Kruskal-Wallis test was used to compare treatments in terms of the difference between before and after for each quality of life and voiding diary variables. If there was statistical significance, the Dunn multiple comparison test was performed, with p-values of less than 0.05 considered significant. The analysis of variance model with repeated measures was used to compare data from the specific voiding diary according to the treatment groups and sessions. Significant comparisons were evaluated with Tukey post-hoc test. To approximate data to the normality, a 1/log (variable+1) transformation was done. For the follow up analysis, it was used the ANOVA three ways, with Holm Sidak post-hoc test for comparison of scores. All the statistical tests developed were based on a significance of 5%, i.e., the null hypothesis was rejected when the p-value was less than 0.05.

Inclusion Criteria:

• Women with 18 years of age or more;
• Cognitive level adequate for understanding orientations during treatment;
• Clinical diagnosis of overactive bladder syndrome for at least six months prior to the study.

Exclusion Criteria:

• Pregnant women or women who wish to get pregnant;
• Neurological disease;
• Urinary infection;
• Nephrolithiasis;
• Stress urinary incontinence;
• Mixed urinary incontinence;
• Women in pharmacological treatment for overactive bladder syndrome;
• Women undergoing hormone replacement therapy in the last six months;
• Peripheral neuropathy;
• Cystocele stage two or higher.