The emerging role of intravesical botulinum toxin therapy in idiopathic detrusor overactivity.

Recently there has been considerable original research into the use of the botulinum neurotoxins in idiopathic detrusor overactivity (DO). This common condition underlies the overactive bladder syndrome in a significant proportion of cases and was previously known as idiopathic detrusor instability. Failure of initial pharmacotherapy in this condition leaves few effective conservative/medical treatment options. Early reports of botulinum toxin (BoNT) therapy have been extremely promising, and the therapy appears to bridge the gap in such patients, before resorting to invasive surgical procedures. Approximately 30 studies have been reported often with widely differing techniques and some clinicians are beginning to administer BoNT for this unlicensed indication. This has led to the urgent need to critically review all available evidence to assess efficacy, safety and technique. In addition to performing a systematic Medline review, all abstracts presented to urological, urogynaecological and incontinence meetings that reported BoNT usage in idiopathic DO were analysed. Remarkable efficacy has been demonstrated in the vast majority of reported series and the treatment has also been used safely in paediatric and elderly populations. Side effects in all populations appear to be minimal and short lived. However, all the series are small and there remains a considerable number of fundamental questions to be answered. Hopefully large-scale robust randomised controlled trials will provide the necessary answers to facilitate the widespread adoption of this technique. Until then caution must be exercised in this unlicensed indication.