Nerve Stimulation Device Improves Tough-to-Treat Overactive Bladder Symptoms

Jill Stein

June 02, 2010

June 2, 2010 (San Diego, California) — Percutaneous tibial nerve stimulation (PTNS) is an effective treatment for patients with overactive bladder (OAB) who have failed conservative therapy, according to the results of a multicenter trial released here at the American Urological Association 2010 Annual Scientific Meeting.

The 23-center Study of Urgent Percutaneous Versus Sham Effectiveness in Treatment of Overactive Bladder Symptoms (SUMIT) also provides level 1 clinical evidence that the therapeutic effect of PTNS is not the result of a placebo effect; rather, stimulation of the tibial nerve resulted in significant improvement in OAB symptoms, the investigators said.

"Although there have been multiple open-label studies in the past using tibial nerve stimulation for the treatment of overactive bladder, the criticisms have been lack of a validated sham," principal investigator Kenneth M. Peters, MD, professor and chair of urology at Oakland University William Beaumont School of Medicine in Royal Oak, Michigan, told Medscape Urology. "This is the first multicenter, randomized, sham-controlled trial proving that tibial nerve stimulation is very safe and effective for the treatment of OAB symptoms."

He added that PTNS should be considered an alternative to antimuscarinic therapy for the treatment of OAB. "Over 75% of patients treated with OAB meds quit taking these within the first year because of a combination of side effects, cost, and lack of efficacy. Tibial nerve stimulation provides an excellent alternative."

Patients with primary stress urinary incontinence and pregnant patients are not suitable candidates for PTNS, he said.

Neuromodulation Targets Nerves That Control Bladder Function

PTNS is a type of neuromodulation therapy that uses electrical stimulation to target specific nerves in the sacral plexus that control bladder function. The treatment targets the sacral plexus from an accessible minimally invasive entry point into the nervous system — the posterior tibial nerve. It is intended for office-based treatment of OAB symptoms.

For the trial, 220 patients from 23 sites were randomized, after a 2-week antimuscarinic washout period, to the PTNS intervention, which involved 12 weekly 30-minute therapy sessions, or to a validated sham intervention.

Trial participants were men and women 18 years of age or older who had a score of 4 or more on the short form of the OAB questionnaire for urgency, at least 10 voids per day, and OAB symptoms for at least 3 months. All had failed multiple types of conservative treatment.

The primary end point was an intent-to-treat analysis of the participants' 7-point global response assessment (GRA), a patient self-report measure of overall treatment effectiveness.

Improvements Seen on Multiple Measures

Overall, 54.5% of PTNS patients and 20.9% of sham patients reported moderate or marked improvement in overall bladder symptoms at 13 weeks (P < .001).

PTNS was associated with statistically significant improvements, compared with sham therapy, in all GRA subset components: urgency (42.7% vs 22.9%; P = .003), frequency (47.6% vs 21.9%; P < .001), and urge incontinence (37.9% vs 22.1%; P = .02).

On diary entries, PTNS also produced a statistically significant improvement in voiding parameters, including frequency, nighttime voids, moderate to severe urgency, and urge incontinence after 12 weeks of treatment, compared with sham therapy.

Quality-of-life scores on the OAB questionnaire showed statistically significant improvement, compared with the sham group, 13 weeks from baseline in the PTNS group.

The active treatment was associated with minimal adverse effects. Six of the 110 patients in the PTNS group (5.5%) developed adverse effects, including ankle bruising, discomfort at the needle site, bleeding at the needle site, and tingling in the leg, compared with 0 of the 110 patients in the sham group. There were no serious adverse events related to either treatment.

Dr. Peters also said that the study found, surprisingly, that a subset of patients with fecal incontinence along with OAB also had an improvement in their fecal incontinence symptoms. More studies are needed to examine this association, he added.

"The study is extremely provocative, in that it was carefully constructed to have a double-blind sham control, which is not very common in device trials," Neal Shore, MD, FACS, director of Carolina Urologic Research Center/Atlantic Urology Clinics in Myrtle Beach, South Carolina, said in an interview. "The validity of the sham control was very well thought out and was not discoverable by the patient populations."

More importantly, he added, "their results demonstrate the significant effectiveness of an outpatient therapy for patients with refractory OAB symptoms."

Dr. Shore said that he uses the therapy in his own practice and noted that it is ideally suited for patients who have failed or who are intolerant of oral anticholinergics. "The next step for many of these tough-to-treat patients is a device that is implanted during a surgical procedure, and PTNS offers patients an opportunity for benefit using a nonsurgical office-based procedure."

Uroplasty, Inc. provided funding for the study. Dr. Peters is a consultant for Uroplasty, Inc. Dr. Shore has disclosed no relevant financial relationships.

American Urological Association (AUA) 2010 Annual Scientific Meeting: Abstract 1515. Presented June 1, 2010.