RESUMO
BotuLinum toxin A (Botox, Allegan) is a potent neurotoxin that blocks the release of acetylcholine at the neuromuscular junction of cholinergic nerves. Botulinum toxin was introduced to clinical medicine in 1980. Since then it has become a major therapeutic drug in many medical sub-specialties and its use for facial rejuvenation has become increasingly popular. Diplopia after botulinum toxin injection for facial rejuvenation is a rare and transient complication which is related to chemodenervation of adjacent muscle groups. We would like to report 3 cases of double vision related to extra-ocular muscle paresis after an injection of botulinum toxin for facial rejuvenation and blepharospasm. In all 3 cases recovery occurred, without any treatment, over 3 to 4 months (apparently from regeneration of inactivated proteins necessary for degranulation of acetylcholine vesicles). The clinicians engaged in botulinum toxin injections for facial rejuvenation or blepharospasm, should be aware of the possible complications, and inform the patients about the risk of developing double vision. The clinicians should take into account and ask about Botox when treating patients complaining of diplopia.
