Intravesical botulinum A toxin in children with refractory non-neurogenic overactive bladder
Annemarth Lambregts, MD, Anka Nieuwhof-Leppink, PhD, Aart Klijn, PhD, Rogier Schroeder, PhD.
University Medical Centre Utrecht, Utrecht, Netherlands.
BACKGROUND: Overactive bladder (OAB) with urinary incontinence poses a great impact on daily activities and quality of life. Sometimes OAB can be unresponsive to specific urotherapy and antispasmodic medication. Due to its successful outcomes in the treatment of neurogenic bladder, intravesical botulinum-A toxin (BtA) came as a possible solution for children refractory to treatment. The aim of this study is to analyse the outcomes of intravesical BtA injections on bladder volume and incontinence in children with refractory OAB.
METHODS: The charts of children diagnosed with refractory non-neurogenic OAB who underwent BtA treatment in our centre since 2011 were retrospectively analysed. By rigid cystoscopy a varying number of injections of the solution (BtA diluted in normal saline 0.9%, dose varying from 100-300 international units) were inserted in the detrusor muscle. Injections were equally distributed over de bladder wall. The functional bladder volume (FBV) is computed with the maximum voided volume (MVV) expressed as a percentage of EBC for age. Response on incontinence was defined according to the ICCS-criteria in complete response, partial response (more than 50% reduction of symptoms) and no response (less than 50% reduction of symptoms). Both complete and partial response was noted as successful. Dependent variables were compared using Wilcoxon Signed Rank test. Multivariate logistic regression was used to identify predictors of the response on urinary incontinence. RESULTS: Fifty children (41 boys) with a median age of 9.9 years were included. On the short term, there was a significant increase in FBV after initial BtA treatment from a median of 52.9% to 70% (p = 0.000). 72% and 46% showed improvement of continence on the short (< 6 months) and long term (> 6 months), respectively. Male gender and small baseline FBV predict a positive outcome on continence on the long term. The most prevalent complications were urinary tract infections occurring in 6 cases (12%).
CONCLUSIONS: Our study showed a significant increase in bladder volume on the short term after BtA treatment. Improvement of continence was seen in 72% of the children on the short term and in 46% on the long term. Safety of BtA therapy was good with only few complications. Boys with a small baseline FBV appear to respond better to the treatment. Prospective studies are necessary to determine long-term efficacy and to enable selection of the appropriate population for BtA treatment. An analyses comparing efficacy between BtA and the currently available drug combination with an anticholinergic agent and Mirabegron should be included. 
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