Multimodal neuroimaging insights into central mechanisms of overactive bladder with an empty bladder: a cross-sectional study.

BACKGROUND AND OBJECTIVE: Overactive bladder (OAB) is a complex condition involving central nervous system (CNS) processes that are not fully understood. We conducted a detailed neuroimaging study to investigate the CNS role in OAB, focusing on the bladder emptying state. METHODS: This cross-sectional study included 168 OAB patients and 133 matched controls. Participants underwent resting-state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging (DTI) during the bladder emptying state. Data were analyzed using tract-based spatial statistics (TBSS), graph theory, functional connectivity, and structure-function coupling. The Overactive Bladder Symptom Score (OABSS) and the Overactive Bladder Questionnaire Short Form (OAB-q SF) were also utilized. KEY FINDINGS AND LIMITATIONS: TBSS revealed three white matter tracts with higher fractional anisotropy in OAB patients; the largest of these, including the body of the corpus callosum (bCC) and bilateral anterior corona radiata (ACR), correlated positively with OAB-q scores. Functional connectivity analysis indicated increased connectivity between the left dorsolateral superior frontal gyrus (SFGdor.L) and bilateral supplementary motor areas, and reduced connectivity between the left middle temporal gyrus (MTG.L) and the right inferior temporal gyrus (ITG.R). The left amygdala (AMYG.L) exhibited enhanced structure-function coupling, which was positively associated with OABSS and OAB-q scores. However, the study's cross-sectional design precludes determining causal relationships due to the lack of longitudinal data. CONCLUSIONS AND CLINICAL IMPLICATIONS: This study identified distinct functional and structural brain alterations in OAB patients during the bladder emptying state. These findings offer new perspectives for investigating innovative treatment strategies. Trial registration This study was registered on the UK's Clinical Study Registry (ISRCTN11583354).