WESTPORT, CT (Reuters Health) Jan 02 - Sacral neurostimulation is an effective means of restoring voiding in patients with urinary retention that is refractory to other forms of therapy, according to a report published in the January issue of the Journal of Urology.
Dr. U. Jonas, from Medizinische Hochschule Hannover in Germany, and a multinational team assessed the voiding ability of 37 patients with refractory urinary retention who underwent early implantation of InterStim, a sacral nerve stimulation system, and 31 control patients who underwent delayed (after 6 months) implantation.
Prior to randomization, all patients had achieved a greater than 50% improvement in baseline voiding symptoms during a 3- to 7-day percutaneous test stimulation.
At 6 months, urine residual volume was significantly reduced in patients who had undergone implantation compared with control patients. In addition, catheterization was eliminated in 69% of implant patients, and a 50% or greater reduction in catheter volume per catheterization was achieved in an additional 14% of these patients.
Overall, the authors found that, at 6 months, successful voiding results occurred in 83% of the early implant group and only 9% of the control group. While residual volumes were significantly increased when nerve stimulation was temporarily inactivated, sustained efficacy of stimulation was noted up to 18 months after implantation.
"To our knowledge, how an intervention known to be effective for the treatment of frequency, urgency and urge incontinence can also restore voiding in some patients remains unknown," the investigators state.
One possibility is "that sacral nerve stimulation turns off excitatory outflow to the urethral outlet and so promotes bladder emptying, although the underlying cause of development of the abnormal reflex resulting in retention is unknown in most cases," they explain.
"The test stimulation procedure is an important diagnostic tool that allows the patient and physician to have the clinical effect of stimulation and make an informed choice about pursuing chronic implantable therapy," Dr. Jonas' team emphasizes. "This procedure offers a clinical advantage, as there are currently no consistent pretreatment factors that can accurately predict which patients will respond to therapy."
J Urol 2001;165:15-19.
2000 Reuters Ltd.