Masseter muscle rigidity after vecuronium

Masseter muscle rigidity after suxamethonium, usually occurring in children induced with halothane, is associated with malignant hyperthermia. A case is reported in which masseter muscle rigidity occurred in an adult followin g vecuronium. From the limited data available, this and two similar reporte d cases, it appears that non-depolarizing muscle relaxants can, very rarely , cause masseter muscle rigidity in adults. This masseter muscle rigidity m ay complicate airway management, but is unlikely to progress to generalized rigidity and malignant hyperthermia.