Dr. Dean S. Elterman, MD, MSc, FRCSC, Attending Urologic Surgeon, Toronto Western Hospital, University Health Network, Assistant Professor, Division of Urology, Department of Surgery, University of Toronto, Toronto, ON.
Harkiran K. Sagoo, BSc(Hons), 4th Year Medical Student at GKT School of Medicine, King's College London, U.K.

Abstract
Sacral Neuromodulation (SNM) is a FDA-approved minimally invasive surgical therapy offered as a third-line treatment for refractory overactive bladder (OAB). Studies report improvements in continence, mean number of voids/day, quality of life, depression and sexual function in patients receiving SNM compared to medical therapy, with treatment success sustained long-term and with few adverse events. SNM is recommended by CUA and AUA guidelines in the treatment of OAB in carefully selected patients.
Key Words: Neuromodulation, Neurostimulation, Overactive, Bladder, Incontinence.

Introduction
Overactive Bladder
Overactive Bladder (OAB) is defined as "the presence of urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence, in the absence of UTI or other obvious pathology".¹

OAB is prevalent in approximately 18% of men and women aged ≥35 in Canada, and continues to rise with the ageing population.² OAB is associated with a reduction in patients' health-related quality of life (HRQOL), increase in healthcare costs, urinary tract infections and increased risk of falls in the elderly.^3,4 Patients may remain untreated as they may be reluctant to discuss their symptoms due to their embarrassing nature.⁵

Symptoms & Diagnosis of OAB
Symptoms of OAB are neuromuscular in origin and caused inappropriate contraction of the detrusor muscle during bladder filling, referred to as detrusor overactivity (DO). DO may occur as a result of neurological illness or injury, or from idiopathic causes exclusive of underlying neurological, metabolic, inflammatory, obstructive, neoplastic or infectious conditions of the bladder.

CUA and AUA guidelines recommend a detailed history, physical examination and urinalysis as minimum requirements for patients with urinary incontinence (UI) to elicit OAB symptoms and exclude other causes.^6,7 Assessing the severity of bladder symptoms in terms of storage, voiding and post-micturition may assist in establishing the type and severity of incontinence and degree of bother. Urine cultures and/or post-void residual assessment may be performed in some patients, with additional information provided from bladder diaries/symptom questionnaires.⁶

In men with OAB, a symptom and quality of life assessment is recommended together with digital rectal examination (DRE) and prostate-specific antigen (PSA) measurement.⁷ Urodynamics, cystoscopy and diagnostic renal and bladder ultrasound are not recommended during initial assessment of uncomplicated cases.⁶