Early urodynamic profiles predict lower urinary tract recovery after spinal cord injury in female rats

Bladder dysfunction is a major complication after spinal cord injury (SCI) and effective treatment remains challenging. Neurogenic bladder can be difficult to treat because of its heterogeneous and dynamic symptoms. We aimed to (1) characterize heterogeneity in bladder recovery from acute to chronic phases and (2) predict chronic urinary function using early urodynamic parameters. We performed continuous longitudinal urodynamic monitoring in 10 complete T9 SCI and 10 control rats over 4 weeks. A novel metabolic cage system enabled 24/7 tracking of voiding behavior. Key parameters, including voiding efficiency (VE), post-void residual (PVR), and ureter flow rate (UFR), were measured continuously throughout recovery. Unsupervised clustering identified three distinct spinally mediated reflexive voiding phenotypes in the chronic phase (days 20-30), defined by VE and PVR: good (robust efficient voiding), moderate (partial voiding efficiency), and poor (minimal voiding efficiency). No single acute-phase urodynamic parameter (3-10 days post-injury) differed significantly between phenotypes. In contrast, multivariate generalized linear models incorporating parameter interactions, particularly VV × VE and UFR × VE², predicted chronic phenotype with high accuracy (R² = 0.90, p < 0.001). These findings underscore the prognostic importance of interactions among early urodynamic features in determining the severity of long-term neurogenic bladder outcomes after SCI and identify a critical window for individualized intervention.