Repeated injections of botulinum toxin-A for idiopathic detrusor overactivity

Abstract

Objectives: To report the efficacy and safety of repeated injections of botulinum toxin-A (BTX-A) in treating idiopathic detrusor overactivity refractory to anticholinergics. Furthermore, we describe whether dose alteration in patients with poor responses or voiding dysfunction after initial treatment can improve outcomes.

Methods: A cohort of 34 patients who participated in a clinical trial was followed up and their progress reported. Twenty from this group had >1 BTX-A injection. Each patient received 200 U BTX-A initially, with subsequent injections between 100 and 300 U, administered by a trigone-sparing flexible cystoscopic technique. Efficacy was measured using voiding diaries and quality of life (QoL) assessed with Incontinence Impact Questionnaire-7 and Urogenital Distress Inventory-6 questionnaires. Urodynamic data were obtained for injections 1-3. All measurements were performed before and 3 months after injections.

Results: Twenty patients received a repeat injection and of these 9 subsequently received a third and fourth injection. Significant improvements in overactive bladder syndrome symptoms and QoL were observed after each injection as compared with baseline. Maximum cystometric capacity and bladder compliance increased with decrease in the maximum detrusor pressure during filling cystometry. When comparing overactive bladder symptoms, QoL, and urodynamic parameters 3 months after the first and last injections, no significant differences were found. Nine patients had their BTX-A dose altered, with better outcomes in 5. The commonest reported problems were difficulty in emptying the bladder and urinary tract infection.

Conclusions: BTX-A appears to be effective and safe after repeated administration in patients with idiopathic detrusor overactivity. Certain patients will benefit from dose optimization to improve efficacy or prevent voiding dysfunction.