OTTAWA — Continuous dorsal-genital nerve stimulation was effective for controlling overactive bladder symptoms in a feasibility study with 19 evaluable patients.
The next step is to test this new approach to treating refractory urge incontinence with an implantable device in a controlled pilot study, Dr. Jeffrey M. Mangel said while presenting a poster at the annual clinical meeting of the Society of Obstetricians and Gynecologists of Canada.
The implantable device already on the U.S. market for controlling urge incontinence by continuous electrical stimulation, Medtronic Inc.'s InterStim, works by stimulating the sacral nerve.
The possibility of achieving similar results by stimulating the dorsal-genital nerve, part of the pudendal nerve, should be attractive to gynecologists, said Dr. Mangel, director of the division of urogynecology and reconstructive pelvic surgery at MetroHealth Medical Center in Cleveland.
That's because the device and leads are implanted by a ventral approach, a surgery that gynecologists are comfortable doing. In contrast, the sacral-nerve stimulator leads require placement over the sacrum, an approach with which gynecologists are less familiar, Dr. Mangel said in an interview.
Placing a dorsal-genital nerve stimulator “could potentially be an in-office procedure,” he added.
Another possible advantage is that because the pudendal nerve is not a sensory nerve, patients may not experience the sensation of contraction that they feel with the InterStim device, he commented.
The dorsal-genital nerve stimulator that will be tested in future studies is made by NDI Medical, the company that sponsored the study presented by Dr. Mangel.
He disclosed that neither he nor his associates have any financial relationships with NDI beyond the company's funding of the study.
The study enrolled 21 women who had a primary diagnosis of urge incontinence and reflex-bladder contractions that had been confirmed by a cystometrogram, and who had not responded to medical therapies.
Seven patients each were enrolled at one of three centers: MetroHealth Medical Center, the Cleveland Clinic, and Duke University, Durham, N.C.
After a 5-day washout period and baseline measurements of incontinence, the women had electrodes placed on the dorsal-genital nerve using local anesthesia.
The electrodes were attached to an external generator that produced constant electrical stimulation of the nerve for 7 days.
The average age of the patients was 53 years, and the average duration of their incontinence was 6 years.
The impact of treatment was assessed based on patient diaries, the weight of pads used for incontinence, and reports of adverse events.
Outcome data were available for 19 patients.
Of the 19 patients, 13 had fewer urinary leak episodes per day, with 9 patients having improvements of 50% or more. The average number of leak events per day for all 19 patients fell from 4.7 at baseline to 2.6 after 7 days of treatment.
Also after 7 days, pad weight fell in 15 of 17 patients, by an average of 79%. Of these 17 patients, 8 had pads that were completely dry after a full day of use.
The electrical stimulation was well tolerated, and was described by patients as a thumping, tingling, or buzzing sensation.
Seven patients reported mild adverse effects that consisted of local erythema or a sensation of skin stimulation at the site of electrode implantation.