Botulinum toxin-A (BoNT-A) injections into the external urethral sphincter are an established therapeutic procedure for reducing bladder outlet obstruction in patients with detrusor sphincter dyssynergia (DSD) due to spinal cord injury (SCI). Given the paucity of data on patients with DSD but without SCI, we aimed to assess the efficacy of intrasphincteric BoNT-A injections in this cohort. For this retrospective study, we screened all patients who underwent their first intrasphincteric BoNT-A injection at our institution between 2015 and 2021. The inclusion criteria were patients aged 18 years or older with neurogenic detrusor overactivity (NDO) and DSD with a maximum detrusor pressure (Pdetmax) of >40 cmH2O, confirmed via video-urodynamic studies (VUDS). The primary outcome was a reduction in Pdetmax and detrusor overactivity leak point pressure (DOLPP) during NDO-associated urinary incontinence posttreatment. The secondary outcome was a reduction in patients relying on indwelling urinary catheters posttreatment. We included 13 eligible patients (all male, median age 31 years, with different underlying neurological disorders, except SCI). All underwent intrasphincteric BoNT-A injections with either 100 (n = 7) or 150 (n = 6) units, respectively. Pdetmax during voiding was significantly reduced posttreatment (median 105 vs. 54 cmH2O, p = 0.006), whereas DOLPP remained unchanged (i.e., median 50 cmH2O). While seven patients relied on indwelling urinary catheters pre-treatment, all were catheter-free posttreatment. Intrasphincteric BoNT-A injections in patients with non-SCI related DSD appear feasible for reducing bladder outlet obstruction to a certain degree in this cohort and subsequently for reducing the rate of indwelling catheters.
Keywords: botulinum toxin-A; detrusor sphincter dyssynergia; electromyography; external urethral sphincter; non-spinal cord injury.