Use of botulinum toxin in neuro-ophthalmology.

Botulinum toxin produces a temporary chemical denervation, which initially was used to reduce the diplopia associated with paralytic strabismus. Subsequently, the drug was found to be effective in the management of dystonias, including hemifacial spasm and blepharospasm. More recently, there is evidence that botulinum toxin may lessen the pain associated with some movement disorders, tension headache, and migraine. The effect of botulinum toxin in temporary, but the therapeutic benefit usually is maintained even after repeated injections. The form of botulinum toxin used in clinical practice is the A serotype. Other serotypes may have a therapeutic role in the future. The mode of action and the clinical experience of botulinum toxin in neuro-ophthalmology is discussed.