Malignant hyperthermia (MH) is a hypermetabolic response to certain inhaled anesthetic drugs with sudden, intense temperature elevation (hyperthermia) and muscle rigidity. Sustained contraction of skeletal muscles generates more heat than the body can dissipate. Other signs include hyperkalemia, tachycardia, tachypnea, acidosis, elevated carbon dioxide, increased oxygen consumption, and rhabdomyolysis. MH crisis constitutes a medical emergency. Incidence in the general population is estimated at 1:100 000 anesthetics administered.
Monitoring core temperature during surgical use of inhaled anesthetics can identify early MH.
MH crisis can be treated by immediately stopping the triggering anesthetic, administering dantrolene, treating hyperkalemia (hyperventilating), and lowering body temperature. Failure to treat MH crisis immediately leads to severe organ damage and death.
A predisposition to MH crisis is associated with an autosomal dominant pattern of inheritance caused by mutations in RYR1 and CACNA1S genes. Genetic skeletal muscle receptor abnormalities allow excessive calcium accumulation in response to anesthetic agents. Central core disease, King-Denborough syndrome, and central nuclear myopathy are also conditions that predispose patients to MH crisis.
Potentially life-threatening emergency
Malignant hyperthermia
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Synopsis

Codes
ICD10CM:
T88.3XXA – Malignant hyperthermia due to anesthesia, initial encounter
SNOMEDCT:
405501007 – Malignant Hyperthermia
T88.3XXA – Malignant hyperthermia due to anesthesia, initial encounter
SNOMEDCT:
405501007 – Malignant Hyperthermia
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Differential Diagnosis & Pitfalls
- Neuroleptic malignant syndrome
- Serotonin syndrome
- Sepsis
- Meningitis (viral, bacterial, fungal)
- Encephalitis
- Thyrotoxicosis
- Pheochromocytoma
- Drug intoxication
- Hypothalamic tumor or injury
- Rhabdomyolysis
- Anaphylaxis
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Drug Reaction Data
Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.
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Last Reviewed:06/19/2019
Last Updated:01/19/2022
Last Updated:01/19/2022