Unilateral versus Bilateral PTNS for the Treatment of Overactive Bladder

Objectives: Posterior Tibial Nerve Stimulation (PTNS) is an advanced therapy option for overactive bladder (OAB) that uses neuromodulation of the posterior tibial nerve, with a minimal side effect profile. Previous studies have examined the efficacy of bilateral sacral neuromodulation, however there is no data on bilateral PTNS for the management of OAB. We sought to determine whether bilateral PTNS stimulation was more effective than unilateral PTNS at improving OAB symptoms.

Methods: We performed a randomized-controlled study of participants with overactive bladder at two tertiary medical centers between April 2018 and June 2023. Participants were randomized to either bilateral or unilateral PTNS and followed for 12 weeks. OAB questionnaire short form (OABq SF) and Incontinence Impact questionnaire (IIQ) were administered at baseline and every 4 weeks through week 12. Participants also filled out a 2-day voiding diary weekly. Our primary outcome was change in OABq SF from baseline to completion of study. Secondary outcomes included change in IIQ score, number of daily voids, nocturia and incontinence episodes as obtained from the 2-day voiding diary. Score changes were compared using ANOVA and pairwise t-test. A sample size estimate of 23 per group was calculated based on improvement in the OABq SF of 36.7 (+/-21.5) in the unilateral PTNS arm and an estimated 50 % better response in the OABq SF in the bilateral group as compared to the unilateral group for 80% power. The study was ceased prematurely due to low enrollment.

Results: We randomized 36 women, mean age 68.7 (range 32-90) years. Overall, baseline OABq SF scores were 64.6 +/-21.6 and IIQ was 56.1 +/- 26.2 with no differences between the groups. Both groups showed improvement in OABq SF at 12 weeks or to the last measurement (Table 1). While both groups showed improvement in IIQ, only the bilateral group’s improvement was statistically significant. There was no difference in number of daily voids, nocturia or incontinence episodes in either group. Although in Table 1 and Figure 1, the mean and median differences in OABq SF, IIQ, and incontinence episodes were lower in the bilateral group, the differences between the groups were not significant. In addition, while the number of daily voids and nocturia episodes improved in the bilateral group, this was not statistically significant.

Conclusions: Both unilateral and bilateral PTNS led to a significant decrease in OABq SF. There was a significant decrease in IIQ score in the bilateral group but not in the unilateral group. However, the differences between the unilateral and bilateral groups in OABq SF and IIQ scores were not statistically significant. A study with a larger population is needed to assess superiority. Our findings suggest that Bilateral PTNS is an option for the management of overactive bladder.