Botulinum toxin: Basic science and clinical uses in otolaryngology

The role of botulinum toxin as a therapeutic agent is expanding rapidly in otolaryngology. Botulinum toxin is a protease that blocks the release of ac etylcholine from nerve terminals. Its effects are transient and nondestruct ive, and largely limited to the area in which it is administered. These eff ects are also graded according to dose, allowing for individualized treatme nt of patients and disorders. Botulinum toxin has been used primarily to tr eat disorders of excessive or inappropriate muscle contraction. In the fiel d of otolaryngology, these include spasmodic dysphonia, oromandibular dysto nia, and blepharospasm; vocal tics and stuttering; cricopharyngeal achalasi a; various tremors and tics; hemifacial spasm; temporomandibular joint diso rders; and a number of cosmetic applications. Botulinum toxin treatment has recently begun to show some benefit in the control of pain from migraine a nd tension headache. It may also prove useful in the control of autonomic d ysfunction, as in Frey syndrome, sialorrhea, and rhinorrhea. In over 20 yea rs of use in humans, botulinum toxin has accumulated a considerable safety record, and in many cases represents relief for thousands of patients unaid ed by other therapy.