Treatment of REfractory Overactive BLadder With the AXonics Sacral Neuromodulation System (RELAX-OAB)

Inclusion Criteria: * Diagnosis of OAB as demonstrated on a 3-day voiding diary defined as ≥ 8 voids/day, and/or a minimum of 2 involuntary leaking episodes in a 72-hour period * Positive motor response on at least two implanted electrodes during intraoperative test * Failed, or are not a candidate for more conservative treatment (e.g., pelvic floor training, biofeedback, behavioral modification, oral pharmacotherapy) * No changes to current regimen of medications that affect bladder function for at least 4 weeks prior to beginning the baseline voiding diary * Willing and capable of providing informed consent * Capable of participating in all testing associated with this clinical investigation Exclusion Criteria: * Primary stress incontinence or mixed incontinence where the stress component overrides the urgency component * Current urinary tract mechanical obstruction such as benign prostatic enlargement or urethral stricture * Interstitial cystitis or bladder pain syndrome as defined by either AUA or EAU guidelines * History of any pelvic cancer * Any significant medical condition that is likely to interfere with study procedures, device operation, or likely to confound evaluation of study endpoints * Any psychiatric or personality disorder at the discretion of the study physician * PHQ-9 Patient Depression Score ≥ 10 * Current symptomatic urinary tract infection (UTI) or more than 3 UTIs in past year * Any neurological condition that may interfere with normal bladder function, including stroke, multiple sclerosis, Parkinson's disease, clinically significant peripheral neuropathy, or spinal cord injury (e.g., paraplegia) * Severe or uncontrolled diabetes (A1C \> 8, documented in the last 3 months) or diabetes with peripheral nerve involvement * Treatment of urinary symptoms with botulinum toxin therapy in the past 12 months * Treatment of urinary symptoms with tibial nerve stimulation in the past 3 months * Previously implanted with a sacral neuromodulation device or participated in a sacral neuromodulation trial * Subject with a documented history of allergic response to titanium, zirconia, polyurethane, epoxy, or silicone * Knowledge of planned MRIs, diathermy, or high output ultrasonic exposure * Any other active implanted devices including neurostimulators (e.g., cochlear implant, pacemaker) and/or drug delivery pumps, whether turned on or off * Passive implants (e.g., prostheses) are allowed, but no implanted metal should be at the Neurostimulator implant site * A female who is breastfeeding or of child-bearing potential with a positive urine pregnancy test or not using adequate contraception * Participation in a current clinical trial or within the preceding 30 days