An association between certain congenital abnormalities and the malignant hyperthermia trait.

Although an association between malignant hyperthermia (MH) and congenital abnormalities has been recorded, no prospective study has been attempted to investigate this relationship. Standardised in vitro muscle tests were performed, because of impending anaesthesia for corrective surgery, on 25 children with birth defects similar to those induced by hyperthermia in laboratory animals, and in whom excessive pyrexial reactivity to anaesthesia, drugs or stress were recorded. Fifteen of the 25 children were MH positive by responding abnormally to the administration of halothane/caffeine. Five of these patients reacted positively to both caffeine and halothane, while the remainder manifested a contractile response to halothane only. This study underlines the existence of an anaesthetic risk factor associated with certain congenital abnormalities and neurodevelopmental delay and emphasises the need for further research to elucidate the possible importance of heat stress during fetal development in genetically susceptible individuals.