Persistence of therapeutic effect after repeated injections of botulinum toxin type A to treat incontinence due to neurogenic detrusor overactivity

Objectives. To study the effect of repeated botulinum toxin type A injections into the detrusor in patients with neurogenic detrusor overactivity and incontinence to determine the safety of repeated injections, the persistence of the clinical and urodynamic treatment efficacy, and potential changes in bladder compliance. Methods. Seventeen patients with neurogenic detrusor overactivity who had received three or more botulinum toxin type A injections into the detrusor were studied. The clinical and urodynamic data were analyzed at baseline (before the first injection), after the first injection, and after the last repeated injection. Results. No systemic side effects were observed for the total of 91 injections. The mean number of injections per patient was 5.4 (range 3 to 9). The mean number of incontinence episodes per day decreased from 2.6 at baseline to 0 after the first injection, and remained at 0 after the last injection. The maximal cystometric bladder capacity and reflex volume increased significantly after the first and last injection compared with at baseline. The maximal detrusor pressure decreased significantly after the first and last injection compared with at baseline. No difference in compliance was found from baseline to the first or last injection. Conclusions. Repeated injections of botulinum toxin A into the detrusor muscle are a safe and valuable treatment option for neurogenic detrusor overactivity. After repeated injections, the effect on the clinical and urodynamic parameters remained constant. Also, repeated injections did not decrease bladder compliance.