Portable magnetic stimulator shows no benefit in OAB

December 1, 2005

Montreal--Trans-sacral magnetic stimulation using a portable device appears to yield no discernible benefits over a sham device in patients with overactive bladder, according to results of an Australian study. It remains unclear, said the authors, whether this failure is due to the particular manner in which the device delivered the magnetic field or whether magnetic stimulation in general is simply an ineffective treatment for this condition.

Montreal-Trans-sacral magnetic stimulation using a portable device appears to yield no discernible benefits over a sham device in patients with overactive bladder, according to results of an Australian study. It remains unclear, said the authors, whether this failure is due to the particular manner in which the device delivered the magnetic field or whether magnetic stimulation in general is simply an ineffective treatment for this condition.

Dr. Achtari was recently a fellow at Mercy Hospital for Women in Melbourne, where the study was conducted. He is currently a urogynecologist at Centre Hospitalier Universitaire Vaudois in Lausanne, Switzerland.

Encouraged by positive results with transcutaneous electrical nerve stimulation and implantable sacral neuromodulators, the researchers investigated whether they could achieve similar efficacy with a portable device.

"We have developed a portable electromagnetic device with a corresponding sham unit delivering a trans-sacral magnetic stimulation of the S3 and S4 sacral nerve roots using a small coil device incorporated into this belt," Dr. Achtari explained.

Sixty-three patients with OAB underwent a 2-week washout period and were randomized to treatment with the portable trans-sacral magnetic stimulation device or a sham device. Patients were instructed to use the device at home for 20 minutes a day over 12 weeks. Outcomes measures included a 3-day voiding diary, 1-hour pad test, visual analog score for symptom impact, the King's Health Questionnaire, and the validated Australian Quality of Life Questionnaire.

Outcomes measured at 6 and 12 weeks revealed no difference between the two groups or between baseline and outcome measures on any of the outcome parameters. There was no difference between the active and sham groups or the baseline and outcomes measures with respect to frequency, nocturia, or quality of life. There was, however, a nonsignificant increase in maximum volume voided when baseline and post-treatment values were compared in the active treatment group.

"Our conclusion is that trans-sacral electromagnetic stimulation, when used in a double-blind, controlled trial, has no statistically significant effect on the symptoms of overactive bladder," Dr. Achtari said.

He told Urology Times, however, that the failure of the portable device used in his study may also be explained by the fact that it delivers the electromagnetic stimulation differently than a commercially available electromagnetic chair device.

"The chair delivers magnetic stimulation to the pelvic floor muscles or to the nerve endings," he said. "Apparently there is nothing happening in the sacral roots [with the chair]."

Other possible reasons for failure suggested by audience members at the presentation were failure of patients to use the device as instructed, need to use the device differently (eg, for longer periods of time or whenever patients begin to sense urgency), and the possibility that the electrical coils were not placed in the correct position on the sacral nerves. Dr. Achtari explained that the standard toe flexion test that confirms the position of the coils could not be conducted, as patients would then know that they were in the treatment group rather than the placebo group.