Systemic Weakness After Therapeutic Injections of Botulinum Toxin A: A Case Series and Review of the Literature

摘要

The use of intramuscular injections of Botulinum neurotoxin A (BoNT-A) is common in the treatment of hypertonicity and movement disorders. While most side effects are mild, systemic effects, manifested by generalized weakness distant from the site of injection, have been reported. Previously reported occurrences are discussed, and three new cases of patients who developed systemic weakness following administration of BoNT-A (Botox®), despite having tolerated similar injections on several prior occasions, are presented. A review of the literature and reported cases indicate that risk of developing systemic effects does not appear to be related to dose based on body weight. It may be more likely that risk for systemic effects is related to total injection dose and injection frequency. The results of our three patients would indicate that injections of greater than 600 units of Botox with follow-up injections occurring every three months may lead to an increased risk. We would recommend careful consideration of re-injection frequency if injections of greater than 600 units of Botox are given. Reduction in systemic side effects may occur if re-injection frequency occurs in intervals of four months or greater in these individuals.