Malignant Hyperthermia (MH)

What is malignant hyperthermia?

High body temperature is known as hyperthermia. Malignant hyperthermia (MH) is a familial inherited disease in which a person experiences a rapid response to certain drugs that are used during surgeries (especially anaesthetic gases). Malignant hyperthermia is observed in the form of severe muscle contractions and a swift rise in the body temperature. The hyperthermia seen in this condition differs from that in other medical emergencies such as infection or a heat stroke.

What are its main signs and symptoms?

The common signs and symptoms of MH include:

• Body temperature that rises to 105°F (40.6°C) or even higher (Read more: Fever treatment)
• Muscle stiffness, rigidity and ache (due to an unknown cause)
• Rapid heart rate
• Acidosis
• Bleeding
• Discolouration of the urine, which could be dark brown

What are its main causes?

MH can be caused by:

• Inheritance of the condition (Even one parent carrying the disease can lead to a child developing MH).
• Other inherited muscle diseases such as:
  • Multiminicore myopathy
  • Central core disease

Both these diseases affect skeletal muscles, leading to muscle weakness.

How is it diagnosed and treated?

This condition is generally revealed after a person is given anaesthesia during surgery. An individual suffering from MH experiences fast and often irregular heart rate and sometimes unexplained death during anaesthesia. Hence, a family history of MH is taken by the physician before administering anaesthesia. Some of the tests that could be advised to diagnose this condition include:

• Blood tests such as:
  • Clotting tests: Prothrombin time (PT) and partial thromboplastin time (PTT)
  • Blood chemistry panel, which includes creatinine phosphokinase (CPK)

• Urine test to evaluate the levels of myoglobin, which is a muscle protein.
• Genetic testing
• Muscle biopsy

Management of MH includes:

• Administration of dantrolene, which is considered to be a drug of choice during an episode of MH.
• Reducing the fever or risk of further serious complications by wrapping the person in a cooling blanket.
• The person is given fluids through a vein (intravenously) during an episode of MH, which helps to prevent damage to the kidneys, thereby preserving their function.

1. MedlinePlus Medical Encyclopedia: US National Library of Medicine; Malignant hyperthermia.
2. National Institutes of Health; [Internet]. U.S. National Library of Medicine. Malignant hyperthermia.
3. Tobin JR, Jason DR, Challa VR, Nelson TE, Sambuughin N. Malignant hyperthermia and apparent heat stroke.. JAMA. 2001 Jul 11;286(2):168-9.
4. Larach MG, Brandom BW, Allen GC, Gronert GA, Lehman EB. Malignant hyperthermia deaths related to inadequate temperature monitoring, 2007-2012: a report from the North American malignant hyperthermia registry of the malignant hyperthermia association of the United States.. Anesth. Analg. 2014 Dec;119(6):1359-66.
5. National Organization for Rare Disorders. [Internet]. Danbury; Malignant Hyperthermia.