Neural Mechanisms of Poststroke Urinary Incontinence: Results From an fMRI Study.

BACKGROUND

Urinary incontinence after a stroke significantly affects patient outcomes and quality of life. It is commonly associated with uninhibited detrusor contractions, but the underlying neural mechanisms remain poorly understood. This study aimed to explore the brain activity patterns associated with volitional and involuntary bladder contractions in stroke survivors.

METHODS

This cohort study enrolled 15 stroke survivors with documented urinary incontinence and 9 healthy controls. Participants underwent simultaneous blood oxygen level-dependent functional magnetic resonance imaging of the brain and urodynamics, capturing 25 involuntary and 23 volitional bladder emptying events in patients with stroke and 35 volitional voiding events in healthy individuals. We used general linear modeling in functional magnetic resonance imaging analysis to discern neural activity patterns during these events and in the phases leading up to them, aiming to identify neural mechanisms underlying involuntary versus volitional urinary control. Statistical significance for neuroimaging analyses was set at P<0.005 with a minimum cluster size of 25 voxels.

RESULTS

During volitional emptying events, both healthy controls and stroke survivors exhibited increases in activation in regions implicated in sensorimotor control and executive decision-making, such as the brainstem, cingulate cortex, prefrontal cortex, and motor areas. In contrast, involuntary emptying events were associated with minimal changes in brain activity, suggesting minimal cortical involvement. Bladder filling preceding volitional contractions was associated with activity in the salience network (insula, anterior cingulate gyrus) in stroke survivors and healthy controls. Conversely, although there was an increase in overall blood oxygen level-dependent signal, activation of the salience network was conspicuously absent during bladder filling preceding involuntary contractions.

CONCLUSIONS

The findings suggest that the salience network plays an important role in maintaining urinary continence in stroke survivors. The inability to activate the salience network may underpin the pathophysiology of poststroke urinary incontinence. Interventions aimed at modulating this network could potentially ameliorate lower urinary tract symptoms in this patient population.

REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05301335.