Inclusion Criteria:
* Is male or female 22 years of age or older.
* Has a diagnosis of UUI for greater than or equal to 6 months prior to the screening baseline visit date.
* Has failed, could not tolerate (stopped taking medication due to lack of efficacy or intolerable side effects), or not a good candidate for (as determined by treating physician) at least one (1) antimuscarinic or β3 adrenoceptor agonist medication.
* Is willing and able to washout (at least five half-lives) from OAB medications for a period determined appropriate based on type of OAB medication prior to the baseline bladder diary and remain off OAB medications through the study duration OR must be willing to maintain medication through the study duration.
* Has a diagnosis of UUI with at least 4 UUI episodes on a 72-hour diary.
* Has a positive stimulation trial with a 50% reduction in UUI episodes.
Exclusion Criteria:
* Has a contraindication for the Neuspera SNM System per the device labeling.
* Has a hemoglobin A1c of \>8%.
* Has glucosuria.
* Has diabetic neuropathy.
* Has interstitial cystitis or bladder pain syndrome as defined by either American Urological Association (AUA) or European Association of Urology (EAU) guidelines, chronic pelvic pain, or recurrent symptomatic urinary tract infections.
* Has skin, orthopedic, neurological, or hematological (bleeding disorder) or anatomical limitations that could prevent successful placement of the neurostimulator.
* Has broken, blistered skin or compromised circulation in the area of the neurostimulator implant.
* Has neurogenic bladder dysfunction such as traumatic or atraumatic myelopathy, multiple sclerosis, Parkinsonism, or history of cerebrovascular accident.
* Has documented urinary retention within 6 months prior to the screening baseline visit date.
* Has clinically significant bladder outlet obstruction.
* Is currently undergoing or has previously undergone pelvic irradiation.
* Is a subject with a mechanical obstruction such as benign prostatic hypertrophy, urethral stricture, or cancer.
* Has current grade 3 or 4 pelvic organ prolapse including cystocele, rectocele, enterocele, procidentia or vaginal vault prolapse.
* Has received tibial nerve stimulation (TNS) in the past 3 months for the treatment of overactive bladder or unwilling to stay off TNS therapy for the study duration.
* Has received treatment of urinary symptoms with any botulinum neurotoxin type-A (BoNT-A) agent in the past 6 months; (e.g. obotulinumtoxinA, Botox,® abobotulinumtoxinA, Dysport® IncobotulinumtoxinA, Xeomin®).
* Is a woman who is pregnant or planning to become pregnant during this clinical study or is a woman of child-bearing potential who is not using a medically acceptable method of birth control. Women of child-bearing potential must undergo a pregnancy test, with clear negative result.
* Has previously had SNM therapy.
* Has active implantable medical devices such as neurostimulators, drug pumps, pacemakers, or internal defibrillators since compatibility has not been assessed.
