Subjects will be randomized at baseline to either CAN-Stim or SNS InterStim® after inclusion and exclusion criteria have been met, 150 subjects will be randomized in to either arm of the study (89 subjects each arm).

At the following visit, CAN-Stim subjects will be immediately implanted unilaterally with a permanent device (implantation side up to investigators discretion). During implantation, the subject should feel pulsation in their foot with or without toe flexion, confirming stimulation of the tibial nerve. Subjects not achieving this motor response will not have the device implanted and will be exited from the study. Implanted subjects will be educated on the use of the transmitter and programmer. Programming parameters will be set and therapy will be delivered for a minimum of 8 hours per day for 2 weeks. Programming changes can be done as needed during this time period to maximize clinical response. At the 2-week visit, diaries will be reviewed and confirmed for accuracy and discrepancies and the number of urgency incontinence episodes will be calculated and compared to baseline diaries. Subjects who are considered a responder at the 2-week follow-up visit (\>50% improvement in urgency related incontinence episodes) will continue therapy and followed for a total of 12 months with primary outcomes assessed at 3 months. Non-responders will be offered an explant of the device and will exit the study. Subjects having less than 50% improvement may choose to keep the device. These subjects will be followed for adverse events with phone calls at 3, 6 and 12 months.

Subjects randomized to SNS will have their Stage I device implanted and tested during a 2-week period. Stage I will have a tined, quadripolar lead placed in the S3 (preferred) or S4 (alternate) foramen in the standard fashion using fluoroscopic guidance and motor response. Motor responses can include a contraction of the levators ("bellows" response) with or without plantar flexion of the great toe. Subjects who are not demonstrating an appropriate motor response will not have the device implanted and will be exited from the study. Subjects, who respond intraoperatively, will have the extension lead connected and externalized in the standard fashion. Subjects may have their InterStim® activated 24 hours/day, but a minimum of 8 hours per day for 2 weeks is required to remain in the study. Programming changes can be done as needed during this time period to maximize the clinical effect. At the 2-week visit, diaries will be reviewed and confirmed for accuracy and clarified for discrepancies and the number of urgency incontinence episodes will be calculated and compared to baseline diaries. Patients achieving a clinical response (\>50% improvement in urgency related incontinence episodes) will undergo implantation of a pulse generator and removal of the percutaneous extension lead. The IPG will be programmed in the standard fashion using settings that were working for the patient during the 2-week trial. Subjects implanted with the InterStim® device will be monitored for a total of 12 months with primary outcomes assessed at 3 months. Non-responders will be offered an explant of the device and will exit the study. Subjects having less than 50% improvement may choose to keep the device. These subjects will be followed for adverse events with phone calls at 3, 6 and 12 months.