Clinical Use of Botulinum Toxin

Botulinum toxin is a complex protein produced by the anaerobic bacteriumClostridium botulinum. Previously known only as a cause of a serious and often fatal paralysis acquired through ingestion of contaminated food, the toxin causes paralysis by blocking the presynaptic release of acetylcholine at the neuromuscular junction. Advantage can be taken of this neuromuscular blocking effect to alleviate muscle spasm due to excessive neural activity of central origin or to weaken a muscle for therapeutic purposes. In therapeutic applications, minute quantities of botulinum neurotoxin type A are injected directly into selected muscles. Local injections of botulinum toxin are effective in the treatment of strabismus, essential blepharospasm, and hemifacial spasm. The Food and Drug Administration has recently approved botulinum toxin for these indications. Clinical studies indicate that botulinum toxin injections can also provide useful symptomatic relief in a variety of other conditions characterized by involuntary spasms of certain muscle groups, notably