Electrical stimulation in overactive bladder.

Electrical stimulation is an effective and well-tolerated treatment for overactive bladder. Initial work in animals indicated the potential of this treatment, and early clinical experience in Europe further supported its likely efficacy. Although the mechanism of action of electrical stimulation remains unproven in humans, it is believed to be a neuromodulating therapy which affects the neural signaling that controls continence. There is also strong evidence that electrical stimulation affects striated muscle. The therapy can cause hypertrophy of skeletal muscle fibers, possibly by the recruitment of faster-conducting motor units, which would not normally be recruited during voluntary efforts. In addition, electrical stimulation can alter the expression of myosin isoforms, favoring a conversion to type I muscle. Despite our incomplete understanding of the mechanism of action of electrical stimulation, clinical devices have been developed quickly. Case series have been reported throughout Europe. These were followed by controlled clinical trials in the United States. There is good evidence that the use of vaginal electrical stimulators can reduce the occurrence of symptoms of overactive bladder in about half of the patients treated. Multiple uses of nonimplanted stimulation, including thigh stimulation, anal stimulation, and direct pelvic muscle stimulation, have been reported. In these trials, it is common for objective findings to be poorly correlated with subjective reports of improvements or cure. Patients frequently report that the urge-to-leak time improves, but this is difficult to measure objectively. The use of nonimplanted devices is effective and well tolerated, and should precede the use of implanted devices. A direct comparison with other effective methods of treatment for overactive bladder is warranted.