Botulinum toxin for spastic gastrointestinal disorders.

Botulinum toxin (BTX) is one of the most potent inhibitors of acetylcholine from nerve endings, and this accounts for its toxic properties as well as its therapeutic application in a variety of neuromuscular syndromes. This review focuses on the growing use of BTX in the so-called 'spastic' disorders of the gastrointestinal tract. These include achalasia, for which the short-term efficacy of the intrasphincteric injection of BTX has been well established. However, because of the chronicity of this condition, repeated injections of the toxin may be required at regular intervals. In contrast, the relatively short duration of action may be an advantage in disorders such as chronic anal fissure, where the benefit of this therapy has now been demonstrated in hundreds of patients. There are many other sphincteric and non-sphincteric syndromes in the gut for which the efficacy of this agent is being actively tested. These include non-cardiac chest pain, post-operative pylorospasm and sphincter of Oddi dysfunction. Skeletal muscle sphincters, such as the upper oesophageal sphincter or the external anal sphincter/puborectalis muscle, may also be targeted, with good effect. In some of these conditions, the local injection of BTX may serve as a useful therapeutic trial, facilitating the decision to institute more invasive forms of therapy. The cumulative short-term experience with BTX in the gut to date suggests that it is a relatively simple and safe therapy. The use of BTX represents a novel approach for gastrointestinal motility disorders, and the rapidly expanding list of successful applications holds promise for a more widespread use of similar agents in the future. Additional studies on long-term outcome are eagerly awaited.