The impact of transcutaneous tibial nerve stimulation on brain function in patients with overactive bladder: a prospective longitudinal self-controlled study.

OBJECTIVE: This study aimed to explore brain activity and functional connectivity changes associated with transcutaneous tibial nerve stimulation (TTNS) in patients with neurogenic overactive bladder (OAB), alongside changes in clinical symptoms. METHODS: This prospective longitudinal self-controlled trial, conducted at the China Rehabilitation Research Center from 2024 to 2025, enrolled 15 adults with symptom-defined neurogenic OAB associated with spinal cord injury or multiple sclerosis. Resting-state functional magnetic resonance imaging (fMRI) was performed before and after standardized TTNS under full- and empty-bladder conditions. The primary imaging outcomes were fractional amplitude of low-frequency fluctuations (fALFF) and functional connectivity (FC). RESULTS: TTNS significantly enhanced clinical outcomes, reducing 24 h urinary frequency from 15.53 ± 2.97 to 12.87 ± 2.88 (p < 0.001) and decreasing OABSS from 9.67 ± 1.50 to 8.53 ± 1.41 (p < 0.001). Neuroimaging indicated improvements were supported by notable increases in neural activity during bladder fullness, particularly in the fALFF of the left cerebellum posterior lobe (pFWE < 0.001) and right medial frontal gyrus (pFWE = 0.004). Additionally, FC between the left cerebellum posterior lobe and left fusiform gyrus was strengthened (pFWE = 0.005). Correlation analysis revealed that higher functional connectivity was associated with lower OAB symptom scores (p = 0.001). Importantly, Baseline fALFF differences between bladder states no longer met the corrected significance threshold after treatment (p < 0.05). CONCLUSION: In this cohort, 1 month of TTNS was associated with reductions in urinary frequency and OABSS and with changes in fALFF and FC. These preliminary findings do not establish neuroplasticity, normalization, or a causal TTNS-specific mechanism and require confirmation in adequately powered sham-controlled studies. CLINICAL TRIAL REGISTRATION: https://www.chictr.org.cn/hvshowprojectEN.html?id=300046&v=1.0, Identifier: ChiCTR2600122960.