Long-term effects of repeated intradetrusor botulinum neurotoxin A injections on detrusor function in patients with neurogenic bladder dysfunction.

OBJECTIVE To evaluate the influence of repeated botulinum neurotoxin A (BoNT-A) treatments on detrusor function in patients with neurogenic detrusor overactivity (DOA) due to spinal cord lesions. PATIENTS AND METHODS In a retrospective study, urodynamic evaluations of 27 consecutive patients with neurogenic DOA due to spinal cord lesions who received at least five BoNT-A treatments were analysed. RESULTS After the first BoNT-A treatment, bladder capacity, reflex volume, continence status and detrusor compliance were significantly improved and maximum detrusor pressure (Pdetmax) was significantly reduced. The mean number of BoNT-A treatments was 7.1. Compared with the results of the first treatment, the incontinence rate (seven patients) and the number of patients with an elevated Pdetmax (five patients) were slightly increased after the final BoNT-A treatment. The long-term success rate was 74%. Every fourth patient needed a major surgical intervention. There was a significant decrease in Pdetmax before BoNT-A treatments, indicating that detrusor contraction strength did not completely recover after treatment. CONCLUSIONS Our study confirmed the long-term efficacy of repeated BoNT-A treatments in patients with neurogenic DOA. However, in long-term follow-up, every fourth patient required surgical interventions. Moreover, our data give the first hint that BoNT-A may lead to impaired detrusor contraction strength, which could influence future treatment options. Prospective studies are necessary to elucidate the impact of repeated BoNT-A treatments on detrusor function and the interactions with future treatment options.