BoNT-A injection has been widely used in treatment of neurogenic or non-neurogenic detrusor overactivity refractory to antimuscarinic therapy. Patients with neurogenic detrusor sphincter dyssynergia (DSD), non-neurogenic dysfunctional voiding (DV), or detrusor underactivity (DU) with an open bladder neck have also been treated by urethral sphincter BoNT-A injection. However, clinical researches of the efficacy of BoNT-A injection on the BND are limited. This study retrospectively analyzed the treatment outcome of BoNT-A injection on BND, and searched for predictive factors for a satisfactory or failed treatment outcome.

A total of 41 patients with different LUTDs received transurethral bladder neck BoNT-A injection for their voiding dysfunction. The patients received videourodynamic study (VUDS) and a tight bladder neck was demonstrated with or without a high voiding detrusor pressure (Pdet) or DO. Bladder neck BoNT-A injection was performed under intravenous general anesthesia. A total of 100U of BoNT-A dissolved in 5ml of normal saline was injected at 5 sites of the bladder neck. The treatment outcome was assessed by self-reported global response assessment (GRA) for the improvement of voiding efficiency and difficulty. The treatment outcome was assessed by self-reported global response assessment (GRA, scored from -3 to +3, indicating from got worse to excellent) for the improvement of voiding efficiency and difficulty.

A total of 41 patients (33 men and 8 women) who had VUDS proven BND received bladder neck 100U BoNT-A injection for the voiding dysfunction. The mean age was 43.6 ± 17.1 (4 – 74) years. Among the patients 35 (85.4%) had normal detrusor contractility and 6 (14.6%) had DU or DA. At 6 months after the BoNT-A injection, 11 (26.8%) patients had a successful treatment outcome, 16 (39.0%) had an improved outcome, and 14 (34.1%) failed the treatment. The overall satisfactory rate was 65.9% at 6-month follow-up. Analysis of the baseline VUDS parameters of patients with normal detrusor contractility, those with non-neurogenic BND had the highest satisfactory outcome (81.8%), whereas those with neurogenic BND had a lower satisfactory outcome (50% for NBND and 55.6% for NBND plus DSD). (Table 2). Patients with normal detrusor contractility and a failed treatment outcome had a higher BOO index than those with a satisfactory treatment outcome (52.5 ± 30.8 vs. 27.7 ± 23.8 cmH2O, p = 0.047). (Table 2). Logistic regression analysis revealed that a higher PVR at baseline predicts a failed treatment outcome of BoNT-A BN injection for patients with BND. However, the p value is only marginal (p = 0.053). (Table 3)

Only 26.8% of patients had a successful treatment outcome, 39.0% had an improved outcome, and 34.1% failed after bladder neck BoNT-A injection for treatment of BND associated voiding dysfunction. Patients with a high Pdet at baseline and those with spinal cord injury and DSD might have a less favorable outcome after treatment.