In vitro human masseter muscle hypersensitivity: a possible explanation for increase in masseter tone

No response to trigger agents in a malignant hyperthermia-susceptible patient

Malignant hyperthermia susceptibility is an inherited disorder, where a life-threatening condition can result from exposure to a trigger agent or agents. Succinylcholine and volatile anaesthetic agents are well established to be trigger agents in anaesthetic practice. We describe a case of a previously investigated malignant hyperthermia-susceptible patient who did not declare his status and was exposed to both succinylcholine and isoflurane, without any detectable reaction. Possible explanations for the lack of reaction include a subnormal temperature when exposed to isoflurane, and a significant interval between exposure to succinylcholine and isoflurane. Absence of a reaction to trigger agents on this occasion is not thought to indicate an incorrect diagnosis and labelling.