New research may pave the way for a form of nerve stimulation for refractory overactive bladder that is home based and less invasive than current neuromodulation approaches.
Boston-New research may pave the way for a form of nerve stimulation for refractory overactive bladder (OAB) that is home based and less invasive than current neuromodulation approaches.
In a preliminary study presented at the AUA annual meeting in Boston, University of Pittsburgh researchers reported that the FootStim, which stimulates transcutaneous afferent nerves in the foot, showed symptom improvement that was comparable to that seen with percutaneous tibial nerve stimulation (PTNS). The study, designed to determine an ideal stimulation duration, found that 3 hours of daily stimulation per week led to better improvement in overall OAB symptoms than 30 minutes of daily stimulation.
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FootStim uses skin surface adhesive pad electrodes applied to the sole of the foot to deliver electrical pulses to branches of the tibial nerve. No needles are required. In an initial study published in 2014, the researchers sought to determine the impact of FootStim in healthy human subjects with no OAB. In eight subjects who underwent FootStim for 90 minutes, the authors reported a post-stimulation effect that resulted in an increase in bladder capacity of approximately 200 cc (J Urol 2014; 191:1009-13).
“This prompted us to continue our pursuit of FootStim as a treatment for OAB,” said principal investigator Christopher Chermansky, MD, assistant professor of urology at the University of Pittsburgh School of Medicine, who worked on the study with Changfeng Tai, PhD, and colleagues.
At the AUA annual meeting, Dr. Chermansky presented results from 38 women with refractory OAB who had 3.7 leaks per day at baseline. Nineteen of the patients underwent FootStim for 30 minutes every evening over the course of 7 days, while the other 19 patients underwent 3 hours of treatment over the same period. All patients went through a 2-week washout of OAB drug therapy prior to initiation of the study.
The study was performed over 3 weeks. Week 1 was used to obtain baseline voiding parameters, FootStim was applied during week 2, and week 3 was used to monitor the post-stimulation effect. Stimulation parameters included pulse frequency of 5 Hz and pulse width of 0.2 milliseconds; intensity of stimulation was set by patients at two to four times the minimal stimulation necessary to cause the great toe to twitch. A responder was defined as having a statistically significant improvement in one or more measured voiding parameters.
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Results showed that after 3 hours of daily stimulation per week, urge incontinence episodes decreased significantly from 3.7 to 2.8 leaks per day (p=.04), and a statistically significant improvement in urgency frequency was observed as well. With 30 minutes of daily stimulation, only the urge incontinence episodes decreased significantly-from 5.1 to 4.3 leaks per day (p=.03).
In the 3-hour group, 84% of patients (16 of 19) responded to at least one voiding parameter, versus 63% (12 of 19) in the 30-minute group. There were no adverse events, including redness, rash, or foot cramp, in either group. In both groups, foot stimulation effects persisted for about 4 days.
“Although this is an observational cohort study, testing different stimulation durations (3 hours or 30 minutes) did serve as a test to define the ideal stimulation duration,” Dr. Chermansky said.
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“We saw improvements in urgency urinary incontinence with both groups, with either 3 hours or 30 minutes per week. Yet, FootStim for 3 hours better improved the other OAB symptoms. Our results are comparable to PTNS,” he added, “but unlike PTNS, FootStim was able to be done at home.”
Dr. Chermansky said additional testing of FootStim is underway at the University of Pittsburgh with a 12-week randomized, sham-controlled trial in women with OAB
Study funding included a Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction Foundation neuromodulation grant and a Coulter Foundation grant at the University of Pittsburgh.
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