Masseter muscle rigidity or spasm may occur in children and other patients undergoing general anesthesia. Some patients have evidence of malignant hyperthermia.
Clinical features:
(1) administration of a volatile agent (halothane, sevoflurane) plus succinylcholine
(2) development of masseter muscle spasm, which in some patients may progress to severe rigidity
Features suggesting risk of malignant hyperthermia:
(1) generalized rigidity (rather than limited to the masseter muscles)
