SENSITIVITY TO VECURONIUM AFTER BOTULINUM TOXIN ADMINISTRATION

When used to treat focal dystonias, botulinum toxin may cause a transi ent impairment of neuromuscular transmission in muscles distant from t hose injected. These systemic effects are not clinically evident, but should not be ignored when patients are exposed to other drugs or cond itions that also impair neuromuscular transmission. A patient is descr ibed who underwent general anesthesia twice during treatment with botu linum toxin for a long history of blepharospasm. On both occasions, th e neuromuscular block produced by vecuronium (0.05 mg kg(-1)) was moni tored in the abductor digiti minimi muscle. Compared with that observe d in 24 individuals who were free from neuromuscular problems, the pat ient's sensitivity to vecuronium was low 90 days after the seventh tre atment with toxin and normal 8 days after the ninth. The possibility i s considered that repeated treatments with the toxin may cause continu ous remodeling of neuromuscular junctions and may cause the patient to develop some tolerance to the action of neuromuscular blockers.