Pudendal nerve stimulation for overactive bladder. (Experimental Device).
Afferent pudendal nerve stimulation has been shown to inhibit the micturition reflex, abolish uninhibited detrusor contractions, and increase bladder capacity; said Dr. Buller, chief of urogynecology at Walter Reed Army Medical Center, Washington.
Pudendal stimulation offers several advantages over currently available sacral neuromodulation: The device can be placed under local, rather than general, anesthesia.
It stimulates three sacral segments instead of one, thereby providing increased afferent input, which is believed to be important for neuromodulation.
Also, stimulating a peripheral nerve rather than a nerve root eliminates unpleasant stimulation of nerves in the buttocks and lower extremities, he said.
"Chronic pudendal nerve stimulation may provide a more precise and less invasive form of neuromodulation. ... I believe this thing has a lot of promise," Dr. Buller said of the device, which is known as the BION and is manufactured by Advanced Bionics Corp., Sylmar, Calif.
In a study sponsored by the company, a percutaneous stimulation test-using a stimulating electrode placed through the perineum to the pudendal nerve--was performed in seven women who had refractory overactive bladder.
Six had a positive response, with a mean 39% increase in maximum cystometric capacity.
Five of those six potential candidates underwent placement of the BION under local anesthesia. The device was inserted transperineally through a small introducing trocar, using a vaginal finger to guide it into place near the pudendal nerve at the ischial spine.
There were no perioperative complications, Dr. Buller reported at the meeting, which was cosponsored by Loyola University.
Patients received stimulation an average of 11.5 hours per day.
At 45 days, volume at first urge had increased by 31% and maximum cystometric capacity by 60%.
Voiding diaries revealed decreases of 57% in incontinent episodes, 23% in daytime voids, and 47% in nighttime voids, he said.
Pad use dropped from an average of 3.4 to 1.1 per day.
These clinical responses, though dramatic, did not reach statistical significance because of the small sample size. Study parameters returned to baseline after the stimulation was stopped, Dr. Buller noted.
The prototype microstimulator that was used in this trial had an external coil worn around the patient's hips and a controller worn around the shoulder or waist.
Future studies will be done using an entirely self-contained, implantable version of the device.
The company hopes to begin the final phase of testing in 2002.
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|Author:||Tucker, Miriam E.|
|Publication:||OB GYN News|
|Date:||Feb 1, 2002|
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