Video Urodynamic Predictors of Outcomes After Urethral Sphincter Botulinum Toxin A Injection in Spinal Cord-Injured Patients with Detrusor Sphincter Dyssynergia

<b>Purpose:</b> Detrusor sphincter dyssynergia (DSD), a common lower urinary tract condition in patients with suprasacral spinal cord injury (SCI), can lead to urological complications and reduced quality of life. Urethral sphincter botulinum toxin A (BoNT-A) injection has been used to promote spontaneous voiding, albeit with limited success. This study aimed to identify predictive factors for treatment success. <b>Methods:</b> This retrospective analysis included 207 patients (157 males and 50 females) with chronic SCI and varying DSD grades treated with urethral sphincter BoNT-A injection. Each received 100 U of onabotulinumtoxinA via transurethral sphincter injection. The primary outcome was voiding efficiency (VE) and symptom improvement, assessed via global response evaluation 3 months post-treatment. Baseline videourodynamic parameters were used to predict success. <b>Results:</b> Successful outcomes were observed in 33.8% of patients. These patients were older and had higher voiding pressure, maximum flow rate (Qmax), voided volume, bladder contractility index, and VE, as well as lower post-void residual (PVR) volume and bladder outlet obstruction index. Patients with SCI and DSD grade 1 had the highest success rate (65.7%) compared to those with DSD grade 2 (14.3%) or 3 (7.1%). Patients with DSD grade 3 had the highest failure rate (55.8%). Multivariate analysis showed that higher Qmax and lower PVR significantly predicted success, consistent with lower DSD grades. <b>Conclusion:</b> Grade 1 DSD, higher Qmax, and lower PVR were associated with higher success after urethral BoNT-A injection, whereas grade 3 DSD predicted failure. Thus, careful patient selection is essential for effective DSD treatment with urethral BoNT-A injection.