Spinal Cord Lower Urinary Tract Control in Humans.

Background and objective: Although there have been significant advancements in functional magnetic resonance imaging (fMRI) studies that have enhanced our understanding of brain control over bladder function in humans, a notable gap still exists in exploring spinal cord involvement in real-time. The objective of this study was to develop and validate an fMRI protocol to assess innate spinal cord activity in humans within regions associated with bladder function.

Methods: Twenty healthy adult participants 9 men, 11 women underwent functional magnetic resonance imaging (fMRI) of the spinal cord during implementation of a natural bladder filling protocol and simulated bulbocavernosus reflex (sBCR). Anatomical images were obtained, followed by resting-state and task-based fMRI assessments during both full and empty bladder states. Functional spinal neuroimaging data were analyzed using a custom pipeline comprised of Spinal Cord Toolbox, FSL, and MATLAB scripts for preprocessing and analysis.

Key findings and limitations: Our preliminary findings revealed activation in 15 participants (7 men, 8 women), exhibiting diverse patterns of activity across the T10-S5 neuronal segments during task-fMRI sessions conducted with both empty and full bladder conditions during sBCR. The identified activated regions included sympathetic (T10-L2), parasympathetic (S2-S4), and somatic nuclei (S2-S4), previously implicated in facilitating lower urinary tract (LUT) control. Notably, our preliminary findings suggest that sex differences may influence these activation patterns, though further investigation and second-level analysis are warranted to confirm this observation.

Conclusions: Although preliminary, our findings demonstrate, for the first time, the efficacy of our fMRI protocol in detecting task-induced activity in the lumbosacral spinal cord, underscoring our capability to precisely target specific regions responsible for regulating LUT function.