Predictors of successful outcomes of urethral sphincter botox injection in women with non-neurogenic voiding dysfunction.

[OBJECTIVE] Non-neurogenic voiding dysfunction is a bothersome urological condition that has a wide range of causes and limited treatment options. The current study retrospectively analyzed the treatment outcomes of botulinum toxin A (BoNT-A) injection and the predictive factors of successful therapeutic outcomes in women with non-neurogenic voiding dysfunction.

[METHODS] This study included women diagnosed with non-neurogenic voiding dysfunction, including dysfunctional voiding (DV), poor relaxation of external sphincter (PRES), bladder neck dysfunction (BND), and detrusor underactivity (DU). Videourodynamic study (VUDS) was performed on all patients before treatment. In total, 100 U of BoNT-A was injected at 5 sites periurethrally in each patient. Treatment outcome was assessed by global response assessment (GRA) to improvement of voiding difficulty at 3 months after treatment.

[RESULTS] In total, 368 patients received urethral BoNT-A injections. The mean age was 54.1 ± 19.8 years. At baseline VUDS, DV was noted in 246 (66.8%) patients, PRES in 112 (30.4%), BND in 5 (1.4%), and DU in 5 (1.4%). The overall success rate by GRA ≥ 2 was 47.8%, including 91.5% in patients with DV, 8.5% in patients with PRES, and none in patients with BND or DU. A higher voiding detrusor pressure (Pdet > 28.5 cmHO) and a lower post-void residual volume (PVR < 222 mL) at baseline could be predictors of successful outcomes after urethral sphincter BoNT-A injections.

[CONCLUSIONS] Urethral sphincter BoNT-A injection is effective in treating non-neurogenic voiding dysfunction caused by DV, but not BND or DU in women. A higher Pdet and a lower PVR at baseline indicate sustainable detrusor contractility and true urethral sphincter dysfunction rather than DU or PRES. Moreover, they may be predictors of a successful therapeutic outcome.