Malignant hyperthermia – what do we know in 2019?

Malignant hyperthermia (MH) is a life-threatening syndrome caused by sudden, uncontrolled skeletal muscle hypermetabolism in response to inhalation anaesthetics and depolarizing muscle relaxants.
MH is related to an abrupt, massive release of calcium from the endoplasmic reticulum. False diagnosis and lack of targeted therapy are associated with high mortality rates; therefore, continuous education and knowledge updating are required. Our aim was to present the most recent data concerning epidemiology, genetics, pathophysiology, clinical course, treatment, and diagnosis of MH.
The search on PubMed database was performed in March 2019, using key words such as: malignant hyperthermia, hyperthermia, ryanodine receptor, dantrolene. Studies published between 2004 and 2019 were selected for this review. Guidelines and recommendations of European Malignant Hyperthermia Group (EMHG) and Malignant Hyperthermia Association of the United States (MHAUS) were also included.

EPIDEMIOLOGY

The estimated incidence of MH is between 1 : 10,000 and 1 : 250,000 anaesthetic procedures [1]. All ethnic groups are affected, all over the world. MH develops more frequently in young individuals and in males than in females [2–4]. The susceptibility to MH is thought to be inherited as an autosomal dominant trait. The prevalence of mutations of genes associated with MH susceptibility ranges from 1 : 2000 to 1 : 3000 [1, 5, 6].
Discrepancies between potential predisposition to MH and its incidence are associated with incomplete penetrance, implying that the genetic defect either requires some additional factors for the phenotype to occur or other factors can prevent its occurrence [6].
In the 70-ties, the mortality after a malignant hyperthermia crisis was 64% [7]. Thanks to the introduction of dantrolene and advances in intraoperative monitoring techniques, the mortality rates significantly decreased. Based on the data of 1987–2006, Larach et al. [4] assessed the North America mortality to be 1.4%. In Japan, the mortality was reduced from 40% to 5.9% over four decades [8].
According to the data presented by Mayzner-Zawadzka in 2004, 10 cases of MH were observed annually in Poland [9]. Because reporting episodes of MH is not obligatory, current incidence of MH in Poland is not known.

GENETICS

MH is caused by the mutation in the receptors involved in the mechanism of muscle contraction [1]; the mutation concerns the gene...


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