Peripheral Neuromodulation for the Treatment of Overactive Bladder

defined by the International Continence Society [1] as “urgency with or without urge incontinence, usually with frequency and nocturia, in the absence of other pathologic or metabolic conditions to explain these symptoms.” Most cases of OAB are idiopathic and many respond to behavioral modification or antimuscarinic medications. However, it is not uncommon for patients to not respond to these interventions and to be classified as having refractory OAB symptoms. One such refractory case is illustrated below. Case 1 . A 46-year-old white female presents with complaints of urinary urge incontinence. She leaks in moderate amounts generally on her way to the bathroom, but also with changes in position such as getting out of a chair or bed. She has been tried on various combinations of anticholinergic and tricyclic medications with mild improvement, but the medications further worsened her constipation, which already is a significant problem for her. She has been taught guarding maneuvers, behavioral modification, and pelvic floor rehabilitation without satisfactory improvement in her symptoms. Past medical history is otherwise unremarkable and past surgical history is remarkable for appendectomy and hysterectomy (for large fibroids). There is no history of back problems or neurological disease. Physical examination is unremarkable and urogenital examination reveals a normal meatus, minimal cystourethrocele, and normal neurological examination including normal perianal sensation and rectal sphincter tone. Voiding diary reveals a functional bladder capacity of 300 ml, average voided volume of ~160 ml, and two to three moderate volume leakage episodes daily. Urodynamic studies in the standing position at a fill rate of 60 ml/min with room temperature sterile contrast material reveal phasic detrusor overactivity starting at volumes of 160–180 ml with moderate volume leakage. Bladder is normally oriented and the patient is able to void to completion with low voiding pressures. Although this patient responded to some degree to anticholinergic therapy, she could not tolerate it due to side effects especially constipation. Although frequency–urgency syndromes and urge incontinence are quite common and many patients can be adequately managed with combinations of behavioral therapy, pelvic floor rehabilitation, and pharmaceutical therapy, a significant minority of patients do not respond adequately to these measures or cannot tolerate the side effects and desire further treatment. Options generally are limited and require major surgical procedures such as augmentation cystoplasty, which often can result in incomplete emptying and need for intermittent catheterization, an alternative not acceptable for many such patients. While sacral neuromodulation (SNS) has been used in the treatment of refractory OAB with reasonable success rates in appropriately selected patients and is addressed in detail elsewhere, for many patients it represents a more invasive treatment option than they would like. Prior to considering sacral neuromodulation, which is more invasive and significantly more expensive, patients