Symptoms and implications

The genetic defect involves one or more genes associated with skeletal muscle calcium homoeostasis. Genetic predisposition, usually referred to as malignant hyperthermia susceptibility, is not usually associated with any symptoms during every day life and nor does MH susceptibility have any manifestations unless the individual is exposed to the triggering drugs.

The triggering drugs are the potent inhalational anaesthetics (isoflurane, sevoflurane, desflurane, etc) and the depolarising neuromuscular blocking drug suxamethonium.

For most patients, the potent inhalational anaesthetics are the drugs of choice used by the majority of anaesthetists for most surgical procedures. MH susceptible patients should not receive the MH triggering drugs. Alternative anaesthetic agents are available.

When the possibility of malignant hyperthermia has been raised or when there is a family history of malignant hyperthermia, it is important to clarify an individual patient’s risk. Without doing so it is impossible to provide the safest form of anaesthesia for them in the future. For an index case, this is especially important because the diagnosis has ramifications for the whole family.