Botulinum toxin interferes with acetylcholine release from periopheral motor nerve terminals, resulting in temporary paralysis of the injected muscles. Minute doses of botulinum toxin are injected around the eyelid and facial area with a fine needle. The effect usually occurs within the first few days and lasts an average of 3 to 4 months, at which time another injection is given. Repeated treatment generally remains effective over a prolonged period in most patients. However, in some individuals, botulinum toxin injections may become less effective over time, possibly because of a resprouting of motor endplates or the development of an antitoxin.
Side effects are infrequent and transient.
They include ptosis, blurred vision, double vision, ocular irritation and tearing. These side effects resolve spontaneously in a matter of days to weeks. The procedure for the upper lids involves a meticulous dissection and removal of the orbicularis, corrugator and procerus muscles through an eyebrow incision. The myectomy procedure requires hospitalization for 2 to 3 days. The healing process following a myectomy may take up to a year.