Malignant hyperthermia is a severe reaction to a dose of anesthetics. The reaction is sometimes fatal. It is caused by a rare, inherited muscle abnormality. Infrequently, extreme exercise or heat stroke can trigger malignant hyperthermia in someone with the muscle abnormality.
In people with the muscle abnormality, muscle cells have an abnormal protein on their surfaces. The protein does not affect muscle function significantly. That is, until the muscles are exposed to a drug that can trigger a reaction.
When a person with this condition is exposed to one of these drugs:
Calcium stored in muscle cells is released
The muscles contract and stiffen at the same time
There is a dramatic and dangerous increase in body temperature (hyperthermia)
Malignant hyperthermia usually occurs during or after surgery. But it can occur wherever anesthetic medications are used. This includes:
Intensive care units
Symptoms of malignant hyperthermia usually occur within the first hour after exposure to the trigger medication. However, the symptoms can be delayed for up to 12 hours.
Most cases occur in children and adults younger than 30.
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