Symptoms of overactive bladder affect a large portion of the world population, especially the elderly. Sacral neuromodulation (SNM) is an effective third-line therapy in patients with overactive bladder. The working mechanism of SNM can be explained by the neural connections of the lower urinary tract. It is proposed that SNM does not work directly on the central components of the micturition reflex, but on cortical and subcortical areas, which in turn inhibits the micturition reflex components in the caudal brainstem. The clinical use and outcomes of SNM are described for several forms of bladder dysfunction. Furthermore, some recent new developments in SNM are discussed, such as expanded indications, more effective use of existing nonrechargeable neuromodulators and the introduction of a rechargeable device. Conservative treatment of overactive bladder (OAB) with or without urinary incontinence consists of pelvic floor exercises, medication and lifestyle intervention, including fluid restriction and timely voiding. If these conservative interventions fail, it is possible to offer electrical stimulation therapies, such as sacral neuromodulation (SNM). In patients suffering from urinary urgency, frequency and urgency incontinence, electrical stimulation of the sacral nerve significantly reduces urinary symptoms and improves patient quality of life. SNM is also used effectively for other forms of bladder dysfunction, such as underactive bladder and bladder pain syndrome (BPS). The increased use of minimally invasive SNM has decreased the need for more open surgical procedures such as ileocystoplasty and urinary diversion. SNM uses an implanted electrode to the third or fourth sacral spinal nerve to deliver a nonpainful electrical stimulus. The brain of the patient perceives this stimulus and, in turn, effectively restores bladder function and alleviates the patients' symptoms. Due to the system-oriented, and not organ-oriented, approach, SNM not only treats urinary disorders, but may also have a beneficial effect on bowel and sexual dysfunction as well as on pelvic pain.
Normal control of the lower urinary tractIn order to understand the role of the brain in the control of the urinary bladder and its sphincter, one can make a distinction between structures and axonal tracts in the caudal brainstem and spinal cord, which are intrinsic part of the micturition and continence reflex, and structures and pathways, located in the forebrain and mesencephalon, which modulate these micturition and continence areas. Most of the clinical therapies aimed at functional bladder disorders are not specifically targeted to the micturition reflex areas, but influence cortical and subcortical brain areas, which, in turn, modulate the micturition reflex components. Examples of such therapies are pelvic floor physiotherapy, biofeedback, transcutaneous electrical nerve stimulation, posterior tibial nerve stimulation and SNM. Currently, there is no effective behavioral, chemical or electrical treatment which works directly and specifica...