Malignant Hyperthermia Testing and Information Facility

Summary

Malignant hyperthermia or MH, is an inherited condition of the skeletal muscles that only becomes apparent on exposure to many of the commonly used general anaesthetic agents. When a person with this condition is exposed to these so called "triggering agents" an abnormal process starts, which causes the muscle cells to become flooded with calcium ions resulting in uncontrolled muscle contraction and energy consumption. If this process is not stopped rapidly by withdrawal of these triggering agents and administration of the specific antidote - dantrolene, severe muscle damage or even death may occur. Severe complications from MH are now rare because anaesthetists are trained to recognize and treat this condition.

Testing facilities in Australasia

At present there are only 4 testing facilities, these being located in Sydney, Melbourne, Perth and Palmerston North in New Zealand.

The unit in Sydney was established by Drs Street, Baines and Overton in 2002 in response to a lack of available testing in NSW. This unit is funded by a very generous donation from a local business, Sound Isolation Systems owned by Mr Geoff Grimish.

Who should attend the MH clinic?

The gene defect thought to cause MH is present in about 1 in 5,000 to 10,000 of the population. An affected person will only be aware that they may carry this gene defect if they, or a family member has suffered an adverse response under general anaesthesia. Thus most people using this service will have a letter from their anaesthetist or local doctor outlining their abnormal response, requesting clarification of their MH status. More rarely some of the muscle disorders such as the muscular dystrophies or exercise induced muscle breakdown (rhabdomyolysis), are associated with MH.

It should be noted that the testing available at present is not suitable as a general screening test for people without a history of MH who are about to undergo anaesthesia and surgery.