Brain Activity Changes During Bladder Filling in Women With Overactive Bladder After Percutaneous Tibial Neuromodulation

Purpose: Percutaneous tibial neuromodulation (PTNM) is a standard third line therapy for patients with overactive bladder (OAB). While the therapy has demonstrated efficacy, its exact mechanism of action is unclear. Functional neuroimaging is employed to understand brain activity changes during the micturition cycle in women with OAB. In this study, we measure brain perfusion using functional MRI (fMRI) during bladder filling at discrete bladder volumes in women with OAB pre and post PTNM. We also assess brain perfusion at discrete bladder volumes in healthy women without OAB. Materials and Methods: Women with and without OAB were enrolled. All participants completed validated urinary symptom questionnaires. Subjects underwent an fMRI exam with arterial spin labeling (ASL) fMRI while their bladders were filled through a urethral catheter at discrete bladder volumes. Subjects with OAB underwent a second ASL fMRI after treatment with PTNM. Results: Twelve women with OAB and 13 women without OAB were enrolled. Patients with OAB had increased bladder filling sensations at lower bladder volumes compared to women without OAB. Anterior cingulate cortex (ACC), insula and supplemental motor area (SMA) perfusion during bladder filling did not increase in a linear fashion in healthy women nor women with OAB; there were changes in ACC, insula, and SMA perfusion during bladder filling at set bladder volumes, which changed after a single session of PTNM. Conclusions: Perfusion of the ACC, insula, or SMA does not change linearly during bladder filling in women, irrespective of OAB. After a single session of PTNM, perfusion changes during bladder filling in the ACC, Insula, and SMA in a non-linear fashion.