During the first 3 months postoperative patients will be randomized to either stimulation amplitude set at 90% of sensory threshold (control group) or 3 periods of stimulation at 0.05v (placebo), 50% and 90% of sensory threshold. Patients are randomized in a 1 to 2 pattern. After the initial 3 months the stimulation amplitude is increased to sensory threshold. After six months the project ends and the number of patients achieving the 50% improvement in incontinence episodes are evaluated.