title: Is there a link between exertional heat stroke and susceptibility to malignant hyperthermia?
abstract: OBJECTIVE
  The identification of a predisposition toward malignant hyperthermia (MH) as a risk factor for exertional heat stroke (EHS) remains a matter of debate. Such a predisposition indicates a causal role for MH susceptibility (MHS) after EHS in certain national recommendations and has led to the use of an in vitro contracture test (IVCT) to identify the MHS trait in selected or unselected EHS patients. The aim of this study was to determine whether the MHS trait is associated with EHS.
  
  
  METHODS
  EHS subjects in the French Armed Forces were routinely examined for MHS after experiencing an EHS episode. This retrospective study compared the features of IVCT-diagnosed MHS (iMHS) EHS subjects with those of MH-normal EHS patients and MH patients during the 2004-2010 period. MHS status was assessed using the European protocol.
  
  
  RESULTS
  During the study period, 466 subjects (median age 25 years; 31 women) underwent MHS status investigation following an EHS episode. None of the subjects reported previous MH events. An IVCT was performed in 454 cases and was diagnostic of MHS in 45.6% of the study population, of MH susceptibility to halothane in 18.5%, of MH susceptibility to caffeine in 9.9%, and of MH susceptibility to halothane and caffeine in 17.2%. There were no differences in the clinical features, biological features or outcomes of iMHS EHS subjects compared with those of MH-normal or caffeine or halothane MHS subjects without known prior EHS episode. The recurrence rate was 12.7% and was not associated with MH status or any clinical or biological features. iMHS EHS patients exhibited a significantly less informative IVCT response than MH patients.
  
  
  CONCLUSIONS
  The unexpected high prevalence of the MHS trait after EHS suggested a latent disturbance of calcium homeostasis that accounted for the positive IVCT results. This study did not determine whether EHS patients have an increased risk of MH, and it could not determine whether MH susceptibility is a risk factor for EHS.
authors.affiliation: French Military Hospital Laveran, Marseille, France; Val de Grâce Military School, Paris, France; Unité mixte de recherche 7291, laboratoire de neurosciences cognitives, Aix Marseille University, Marseille, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Sagui
authors.affiliation: French Military Hospital Laveran, Marseille, France; Val de Grâce Military School, Paris, France.
authors.forename: Coline
authors.initials: C
authors.lastname: Montigon
authors.affiliation: French Fire Brigade Health Service, Courbevoie, France.
authors.forename: Amandine
authors.initials: A
authors.lastname: Abriat
authors.affiliation: French Military Hospital Laveran, Marseille, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Jouvion
authors.affiliation: Armed Forces Epidemiological and Public Health Center, Marseille, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Duron-Martinaud
authors.affiliation: Val de Grâce Military School, Paris, France; Armed Forces Biomedical Research Institute, Brétigny/Orge, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Canini
authors.affiliation: Val de Grâce Military School, Paris, France; French Military Hospital Clermont-Tonnerre, Brest, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Zagnoli
authors.affiliation: Unité mixte de recherché 7339, Center for Magnetic Resonance in Biology and Medicine, Aix Marseille University, Marseille, France.
authors.forename: David
authors.initials: D
authors.lastname: Bendahan
authors.affiliation: Service d'anatomie pathologique et de neuropathologie, Timone hospital, assistance publique/hôpitaux de Marseille, Marseille, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Figarella-Branger
authors.affiliation: French Military Hospital Laveran, Marseille, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Brégigeon
authors.affiliation: French Military Hospital Laveran, Marseille, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Brosset
mesh_terms: D000328:Adult; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D003286:Contracture / Q000139:chemically induced / Q000503:physiopathology; D004198:Disease Susceptibility; D005260:Female; D006221:Halothane / Q000494:pharmacology; D018883:Heat Stroke / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008305:Malignant Hyperthermia / Q000175:diagnosis / Q000503:physiopathology*; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D018685:Anesthetics, Inhalation; D002110:Caffeine; D006221:Halothane