What is Malignant Hyperthermia?

Malignant hyperthermia (MH) is a condition triggered by exposure to particular drugs used in general anesthesia such as halothane, and the neuromuscular blocking agent succinylcholine. In MH individuals, these drugs can induce an uncontrolled and very drastic increase in metabolism. Skeletal muscles start to contract increasing the need for oxygen. This causes an increase in respiration as the body struggles to remove carbon dioxide, and regulate temperature. This may eventually lead to circulatory collapse and even death of the patient if not treated quickly and efficently.

 MH is a rare autosomal disorder which the ryanodine receptor gene (RYR1) is most likely to be affected, (please see 'RYR1 gene-what is it?' on this website for more information). MH susceptibility is phenotypically and genetically related to central core disease (CCD), which is also an autosomal dominant disorder diagnosed by both MH symptoms and myopathy.

MH usually goes unoticed in the patient until it unmasked under anesthesia due to the fact that there is generally very little else that can trigger it. There is no way of telling if a person may have MH unless there is a family history of this disorder. Today there is a diagnosis criteria which is listed on this website which help surgeons to predict if a patient may have this disorder before the operation. 

If a member of the family has been noted tro have MH then it is important to notify the hospital  before an operation.

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