Botulinum toxin for detrusor overactivity and symptoms of overactive bladder: where we are now and where we are going.

Botulinum toxin (BTX) treatment for overactive bladder and detrusor overactivity is becoming increasingly recognized as an excellent therapeutic option for treating patients refractory to anticholinergic agents. Results from open-label studies have suggested that this therapy is effective in neurogenic and idiopathic detrusor overactivity, yet validating evidence from randomized, placebo-controlled trials has been unavailable. The exact mechanism of action of BTX in the bladder is controversial, although evidence suggests that apart from preventing the presynaptic release of acetylcholine from the parasympathetic innervation to the bladder, it might have an effect on sensory mechanisms. The latter hypothesis could in part explain its effect on symptoms such as urgency. The purpose of this Review is to present the results of randomized, placebo-controlled trials in which BTX treatment for detrusor overactivity was investigated. Also the evidence supporting its potential dual mechanism of action in the bladder will be considered. In addition, the various techniques of administration of BTX are discussed and avenues for further research suggested.