Malignant hyperthermia in France: characteristics of 93 diagnosed patients in one French reference centre

BACKGROUND: Malignant hyperthermia (MH) is a rare but potentially fatal complication of general anaesthesia, triggered by volatile anaesthetics and depolarising muscle relaxants in genetically predisposed individuals. Although outcomes have improved with better monitoring and dantrolene administration, diagnosis remains challenging. This study aimed to describe patients referred after suspected MH crises in France and to compare clinical features and Larach grading between MH-susceptible and non-susceptible patients. MATERIAL: We conducted a retrospective, monocentric study of patients referred to a French MH reference centre between 1968 and 2020. Clinical, biological and anaesthetic data from suspected MH crises were analysed. MH susceptibility was determined using genetic testing and/or in vitro contracture testing. The diagnostic performance of the Larach clinical grading scale was assessed using receiver operating characteristics curve. RESULTS: Of 1258 patients evaluated, 182 experienced a suspected MH crisis, of these 93 were fully investigated; 49 were confirmed as MH-susceptible (MHS) and 44 MH-negative (MHN). The specific triad (Hyperthermia, hypercapnia and muscle rigidity) was observed in 86% of the MHS patients. Adequate treatment with Dantrolene was given in 64% of cases after 2000. The threshold of 45 on Larach's score exhibited a specificity of 90% [87 to 93%] and a sensitivity of 59% [54 to 94%]. CONCLUSION: In this French cohort of 93 cases fully evaluated for MH susceptibility, the typical triad was present in 86% of MHS patients. Performance of Larach score as determined by this study was similar to its original description.