A Potential Urodynamic Classification of Voiding Patterns in Neurogenic Lower Urinary Tract Dysfunction Due to...

Objectives: To characterize urodynamic findings after lower-level spinal cord injury (LSCI) and to evaluate a new pressure-based classification framework-the bladder-sphincter dyscoordination syndrome (BSDS)-for describing voiding patterns. We also introduce a descriptive "neurogenic bladder outlet obstruction" (NBOO) phenotype for straining-dependent voiding difficulty. Methods: We retrospectively analyzed the first urodynamic studies (December 2020-August 2024) in 81 men with LSCI (injury at T10 or below). Key urodynamic measures included detrusor and intravesical pressures during filling and voiding, bladder volumes (first desire to void and capacity), compliance, maximum flow rate (Q_max), post-void residual (PVR), voiding efficiency, and the ratio of detrusor to abdominal pressure rise (ΔPdet/ΔPabd). We compared cases with detrusor overactivity (DO) versus those without DO. Among those with voiding discoordination, we distinguished classical detrusor-sphincter dyssynergia (DSD) from a proposed NBOO phenotype (characterized by abdominal straining pressure ≥ 40 cmH₂O, detrusor pressure < 20 cmH₂O, incomplete emptying, and no anatomic obstruction). We further classified discoordination cases using the BSDS framework into four subtypes-dual high-pressure (DHP), detrusor-muscle predominant (DMP), dual low-pressure (DLP), and abdominal-pressure predominant (APP)-based on reference pressure thresholds (detrusor 20 cmH₂O; abdominal 40 cmH₂O). Results: Patients with DO (43.2%) showed significantly higher detrusor pressures during filling (at first desire to void and at capacity) and a lower first desire volume than non-DO patients, while maximum capacity was similar (p = 0.105). During voiding, DO cases had lower PVR and higher emptying rates, although the detrusor-vs-abdominal pressure contribution (ΔPdet/ΔPabd) was comparable between groups. Among 63 patients with voiding discoordination, 32 (50.8%) met NBOO criteria; these NBOO cases exhibited lower detrusor and intravesical voiding pressures but worse emptying (higher PVR) compared to classical DSD cases. Overall, 76 of 81 patients (93.8%) fit within the BSDS classification-distributed as 22 DHP, 13 DMP, 15 DLP, and 26 APP patterns. Conclusions: The BSDS framework (and the NBOO descriptor when conventional indices cannot be applied) offers a novel way to describe voiding patterns after LSCI. It links urodynamic observations to potential management strategies (by identifying whether the bladder or outlet is the primary issue). Prospective studies are needed to validate this framework against outcomes such as upper tract integrity, continence, and dependence on catheterization.