© 2007 THE AUTHOR JOURNAL COMPILATION © 2 0 0 7 B J U I N T E R N A T I O N A L | 1 0 1 , 4 1 7 – 4 2 3 | doi:10.1111/j.1464-410X.2007.07233.x 417 Review Article SACRAL NEUROMODULATION FOR OVERACTIVE BLADDER AND URINARY RETENTION CHARTIER-KASTLER Sacral neuromodulation for treating the symptoms of overactive bladder syndrome and non-obstructive urinary retention: > 10 years of clinical experience Emmanuel Chartier-Kastler Faculté Pierre et Marie Curie, Université Paris VI, Hospital Pitié-Salpêtrière, Assistance Publique Hôpitaux de Paris, France Accepted for publication 13 July 2007 KEYWORDS efficacy, overactive bladder, quality of life, randomized controlled trials, sacral neuromodulation, safety, urinary retention INTRODUCTION Overactive bladder (OAB) syndrome is a common condition affecting millions of people in the Western world. It is typically associated with urgency, with or without urge urinary incontinence (UUI), usually with frequency and nocturia [1]. The International Consultation on Incontinence (ICI), and other international guidelines, currently recommend diet and lifestyle modifications and behavioural therapy (e.g. pelvic floor muscle training, bladder retraining or biofeedback) in combination with antimuscarinic therapy as first-line treatment for patients with OAB [2]. However, in many patients conservative therapy does not sufficiently alleviate the symptoms of OAB. A study conducted in 2002 in 21 362 patients showed that at 1 year after the first prescription, only 15% of patients remained on OAB medication (Fig. 1) [3]. In most cases, patients stop taking medication because of lack of efficacy or side-effects. A survey among 1447 people receiving treatment for UI showed that younger patients ( < 50 years old) are twice as likely to stop using antimuscarinic agents as are older patients [4]. Up to a few years ago the only alternative therapies for these patients were invasive and irreversible surgical procedures, e.g. augmentation cystoplasty and urinary diversion. These procedures are associated with significant short- and long-term risk and morbidity, and in many cases the treatment becomes more bothersome than the condition itself. Therefore, surgery (as bladder enlargement) should be considered as a last resort when all other treatment options have failed. The same problems apply to urinary retention (UR), for which immediate treatment usually consists of intermittent catheterization [5]. Until recently, the only second-line treatment for patients with UR was surgery, which is associated with significant morbidity. If not treated, UR can have serious health consequences, e.g. reflux, upper urinary tract damage, infection and overflow UI. As previous reports showed an acute effect of afferent stimulation in modulating detrusor overactivity [6], neuromodulation (NM), and particularly sacral NM (SNM) has emerged as a valuable minimally invasive treatment option for patients with lower urinary tract dysfunctions such as OAB and non- obstructive UR in whom conservative treatments have failed. SNM SNM involves continuous electrical stimulation of the sacral nerves to inhibit or activate the neural reflexes that influence the bladder, sphincter and pelvic floor. Basically, a pacemaker-like implantable neurostimulator (INS) sends mild electrical pulses to electrodes that are usually placed next to the third sacral nerve (S3). Since its first description by Schmidt et al. in 1979 [7], SNM has developed from an elaborate procedure to a minimally invasive technique that can be easily done under local anaesthesia in an outpatient setting. Unlike surgery, SNM is a reversible technique that does not preclude other treatment options. In the most recent 2004 ICI guidelines, SNM was proposed as an option for patients with UUI to be considered when conservative therapy fails [2]. SNM with the InterStim TM device (Medtronic, Inc., Minneapolis, MI, USA) was CE-marked in Europe in 1994 and approved by the Food and Drug Administration (FDA) for treating refractory UUI in October 1997, and for idiopathic UR and symptoms of urgency- frequency in 1999. Over the past decade, InterStim therapy has gained global acceptance in urological practice and > 35 000 patients have been treated worldwide. MODE OF ACTION OF SNM In adults, certain brain pathways are critical for controlling the sphincter and urethral guarding reflexes to allow micturition. When these brain mechanisms are damaged by spinal cord injury, this can lead to inefficient bladder emptying. Dysfunctional voiding can