New Pharmacologic and Minimally Invasive Therapies for the Overactive Bladder

Michael Franks, MD, Emmanuel Chartier-Kastler, MD, Michael B. Chancellor, MD

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In This Article

Sacral Nerve Stimulation

Before the approval of sacral nerve stimulation (SNS), urologists had been limited to pharmacologic, behavioral, or biofeedback therapy for OAB. If these regimens failed, the remaining treatment alternatives involved major surgery. Intestinal bladder augmentation is very successful in treatment of OAB symptoms; however, this is major surgery that involves the risk for significant morbidity. This surgery offers an irreversible change of lifestyle that few non-neuropathic patients are willing to accept. Beyond bladder augmentation, we simply do not have any good surgical treatments. Subtrigonal phenol injection or denervation procedures have been described, but the success rates are not high, and there is little enthusiasm in the urologic community for these procedures.

With the introduction of SNS (Medtronic, Inc), a new surgical technique developed by urologists for urologists is now available. SNS placement is minimally invasive and nondestructive. Most important, this technique is reversible and is associated with lower morbidity than the other surgical treatments. If SNS does not work, it causes no permanent damage, nor does it preclude the patient or urologist from any other mode of therapy. This method should be reserved for the patient with intractable urgency and urge incontinence unhelped by other methods of treatment.[50]

The SNS treatment itself consists of a trial implant with a temporary stimulation unit. The temporary testing trial is generally called the percutaneous nerve evaluation (PNE). If the temporary unit provides relief of the symptoms, a permanent implant is placed. During the initial PNE, the electrodes are usually inserted percutaneously through the S3 sacral foramen as an outpatient procedure with local anesthesia. These electrodes are then attached to a small portable transcutaneous electrical nerve stimulation unit, which is similar to a pulse generator. The trial period lasts for a week and, if successful, a permanent pacemaker unit is placed onto the electrode for permanent stimulation. The parameters of stimulation are modulated by noninvasive change of the pacemaker parameters.

The principles behind SNS in the treatment of OAB can be summarized as somatic afferent inhibition of sensory processing in the spinal cord. The SNS simply blunts the overactivity that the patient with OAB experiences and relieves symptoms. SNS stimulates pudendal afferent input to the sacral spinal cord, and it inhibits supraspinally mediated, hyperactive voiding by blocking ascending sensory mechanisms.[51] Interestingly, SNS input can also restore micturition in patients with idiopathic urinary retention. Idiopathic urinary retention is thought to be due to overactivity of the guarding reflexes with the clinical manifestation of pelvic floor spasticity and functional detrusor sphincter dyssynergia. Sacral inhibition by SNS allows pelvic floor relaxation and subsequent micturition in patients with idiopathic urinary retention caused by an overactive guarding reflex.

It is not difficult to implant SNS. Urologists with proper training have all the skills and background needed to perform this procedure. A focused course and hands-on mentoring are recommended for the first few cases. SNS belongs in the hands of the urologists. It is important for the vitality of the field of urology to expand its arsenal and the scope of cutting-edge treatment options. SNS provides a unique and exciting treatment option that the urologist can provide to patients who have benefited from conventional treatment options. We encourage urologists with special interest in voiding dysfunction and urinary incontinence to consider learning SNS. This treatment can be proposed for other chronic and refractory voiding disorders like idiopathic retention or selected cases of pelvic pain.

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