Botulinum toxin therapy for neurologic disorders.

In the last 20 years, the therapeutic uses of botulinum toxin, a potent neurotoxin, have been investigated. The agent produces chemical denervation of muscle, thereby causing atrophy and weakness. Studies have shown that injection of this agent is an effective therapy for focal dystonias, particularly blepharospasm, hemifacial spasm, and torticollis. Investigation continues into the role of botulinum toxin in the treatment of anismus, detrusor-sphincter dyssynergia, writers' cramp, and other disorders in which focal weakening of selected muscles could be useful.