Injection of Botulinum toxin into the detrusor muscle is a treatment for urinary incontinence secondary to neurogenic detrusor overactivity while injection into the external urethral sphincter is a treatment for detrusor-sphincter dyssynergia and high post void residual urines.
Five pre-post studies (n=132) (Dykstra et al. 1988; Schurch et al. 2000; Chen et al. 2008; Kuo 2008; Chen & Kuo 2012) found injection of Botulinum toxin into the detrusor muscle or bladder sphincter to be an effective method for treating urinary incontinence or retention secondary to neurogenic detrusor overactivity and bladder sphincter dyssynergia. In these conditions, injections of the Botulinum toxin either allowed increased urinary bladder capacity (i.e. reduced overactivity of the bladder) or facilitated improved evacuation of urine (reduced bladder sphincter dyssynergia). The duration of effect was reported to last up to 9 months (Schurch et al. 2000). All studies were level 4 and showed positive effects. In fact, following treatment with Botulinum toxin, 3 individuals reported fewer episodes of AD (Kuo 2008), 4 individuals reported decreased frequency and intensity of AD (Chen et al. 2008), 3 individuals who experienced severe AD during bladder emptying reported disappearance of these symptoms altogether (Schurch et al. 2000), 3 individuals reported AD was completely resolved (Chen & Kuo 2012), and 18 individuals experienced improvement in AD symptoms (Chen & Kuo 2012). While the evidence suggests that Botulinum toxin may be a viable treatment for neurogenic detrusor overactivity, the evidence supporting the application of Botulinum toxin specifically for the prevention of AD is inconclusive.
There is level 4 evidence (from 5 pre-post studies: Dykstra et al. 1988; Schurch et al. 2000; Chen et al. 2008; Kuo 2008; Chen & Kuo 2012) that Botulinum toxin injections into the detrusor muscle or external urethral sphincter seem to be a safe and valuable therapeutic option in SCI patients who perform clean intermittent self-catheterization and have incontinence resistant to anticholinergic medications.