MH is a reaction to commonly used anaesthetic drugs where the body produces too much heat. If it is not recognised and treated in its early stages, MH can lead to death. When someone is known to be at risk of developing MH, there are safe alternative anaesthetic drugs that can be used. The risk of developing MH is associated with a change in the genes that are responsible for controlling the release of calcium in skeletal muscle cells.

A person at risk of MH can be diagnosed by removing a small piece of muscle (using safe anaesthesia) in an operation called a muscle biopsy, and then exposing small strips of their muscle to the anaesthetic gases under carefully controlled conditions in our MH laboratory.

Is MH common?

No. An MH reaction is a rare event, occurring in about one in every ten thousand general anaesthetics. Possibly about 1 in every 500 persons in the population is potentially susceptible (has a genetic change that may make them more likely to have MH).

I have had an uneventful anaesthetic in the past.  Does this mean I do not have MH?

No. Triggering anaesthetics do not necessarily cause an MH crisis every time someone at risk is given them. There is one patient who had 13 general anaesthetics before they had an MH reaction, although on average, a person develops a reaction on the third exposure.