Introduction: Hemispheric differences in brain function account for the differential effects of stroke laterality on various domains of cognition, sensory-motor function, and decision making. Similarly, the size and location of stroke determine the type and severity of bladder dysfunction in patients with neurogenic lower urinary tract dysfunction (NLUTD). However, the changes in functional brain activity in relation to the side of stroke are yet to be understood. This study aimed to determine the differential patterns of micturition-related neural activity in right- vs. left-sided strokes. Methods: Patients with a history of chronic (>1yr) ischemic or hemorrhagic strokes and NLUTD were enrolled. Patients underwent urodynamic assessment while micturition-related brain activity was simultaneously assessed using functional magnetic resonance imaging with the blood-oxygen-level-dependent (BOLD) technique. Statistical parametric mapping (SPM) was used to assess the changes in BOLD signal during a 10-second period of maximum urgency. The signal intensity was compared between left- versus right-sided strokes, with age, gender, and time since stroke as covariates. Statistically significant clusters were identified using a p value of <0.001 and cluster size of >25 voxels. Results: A total of 23 patients (16 men, 69.57%; mean age 53.61±9.82) were enrolled, of whom 16 (69.57%) suffered from right-sided strokes. Analysis of the BOLD signal changes during the period of maximum urgency yielded increased intensity in patients with left-sided strokes in eight areas spanning the anterior cingulate (Brodmann area 32), inferior frontal gyrus, middle frontal gyrus, and limbic area (cingulate gyrus) on the left hemisphere; frontal sub-gyral area on the right; and superior frontal gyrus (Brodmann area 8) bilaterally. Two clusters located in the left cerebellar anterior lobe and right limbic lobe (posterior cingulate) showed decreased BOLD signal in left-sided strokes compared to right-sided counterparts. Conclusions: This study demonstrated the differences in micturition-related brain activity between left- and right-sided strokes and identified ten areas of differential activity. Patients with right-sided strokes demonstrated markedly diminished brain activity in several brain regions that are known to play a role in LUT control. Consistent with the inherent functional differences across the brain hemispheres, stroke laterality is correlated with the changes in brain activation during micturition. SOURCE OF Funding: Urology Care Foundation
