Sacral nerve modulation for urinary disorders: Overactive bladder

Abstract

Overactive bladder (OAB) syndrome is a combination of complex urinary symptoms, and is defined as urinary urgency with or without urgency incontinence, usually accompanied by frequency and nocturia, in absence of urinary tract infection or other obvious pathology. Treatment of patients with OAB is complex and international guidelines suggest life style interventions, pelvic floor re-education, bladder retraining and antimuscarinic drugs as first-line treatment option. Sacral neuromodulation (SNM) has been approved by Food and Drug Administration (FDA) in 1997 and more than 150,000 patients have already received this treatment worldwide. SNM is currently recommended by expert panels for the treatment of intractable OAB syndrome. Seven randomized trials have reported results in publications and are consistently in favour of SNM. In more than the 40 case series studies, about 39 % of patients with urgency urinary incontinence were cured following implantation, and 67% of patients achieved 50 % or greater improvement in incontinence symptoms. Studies comparing the effectiveness of the SNM versus botulinum toxin (BTX) injection have produced conflicting results, but studies comparing the cost-effectiveness of SNM suggested that SNM treatment strategy was more expensive but also more effective than BTX injections in the first 2 years. However, a recent study showed that SNM treatment was cost-effective after 5 years compared to BTX injection. Currently SNM stands as the single licensed second-line treatment for OAB, but more research is needed to improve the selection of patients and the identification of more prognostic factors and clarify the reduction in effectiveness over time.