malignant hyperthermia

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Related to malignant hyperthermia: Dantrolene


1. greatly increased temperature; see also fever. Called also hyperpyrexia. adj., adj hyperther´mal, hyperther´mic.
2. a nursing diagnosis accepted by the North American Nursing Diagnosis Association, defined as the state in which an individual's body temperature is elevated above his or her normal range.
malignant hyperthermia a syndrome affecting patients undergoing general anesthesia, marked by rapid rise in body temperature, signs of increased muscle metabolism, and usually rigidity. The sensitivity is inherited as an autosomal dominant trait.

ma·lig·nant hy·per·ther·mi·a

rapid onset of extremely high fever with muscle rigidity, precipitated by exogenous agents in genetically susceptible people, especially by halothane or succinylcholine. Compare: futile cycle.

malignant hyperthermia (MH)

a rare genetic hypermetabolic condition characterized by severe hyperthermia and rigidity of the skeletal muscles, occurring in affected people exposed to inhalation anesthetics and succinylcholine. It is a life threatening emergency and must be treated immediately. Treatment includes discontinuation of the inhalational anesthetic, the administration of dantrolene sodium, administration of 100% oxygen, cooling, cessation of surgery, and correction of acidosis and hyperkalemia. Patients susceptible to malignant hyperthermia must be informed of the condition and susceptible relatives screened. The family is referred to the Malignant Hyperthermia Registry of the Malignant Hyperthermia Association of the United States (MHAUS). Individuals with confirmed malignant hyperthermia should wear a medical alert wrist band. Compare neuroleptic malignant syndrome.

malignant hyperthermia, susceptibility to, 1

An autosomal dominant (OMIM:145600) condition of variable penetration in which a patient, when subjected to certain anaesthetics (halothane, diethyl-ether, cyclopropane, enflurane and psychotropics), develops a potentially fatal reaction (up to 70% mortality in acute episodes), which occurs in 1/15,000 administrations of anaesthesics in children and 1/50–100,000 in adults; 1/2 of cases had not been previously sensitive to anaesthesia. Anaesthetised patients may develop high fever and muscle rigidity with rhabdomyolysis, release of myoglobin, renal damage and acute renal failure. 

Clinical findings
Tachycardia, tachypnoea, cyanosis, labile blood pressure, muscle rigidity, rapid and marked hyperpyrexia, acidotic, hyperkalemic, possibly DIC, renal failure; similar reactions may be evoked in these patients by warm weather, exercise, emotional stress or without known environmental cues, and are initiated by muscular hypermetabolism due to an idiopathic increase in sarcoplasmic calcium occurring under general anaesthesia. 

Muscle contraction test with halothane or caffeine challenge.
Hypothermia, hydration, sodium bicarbonate infusion, mechanical hyperventilation, diuretics to increased urine flow, dantrolene (an agent that blocks excitation-contraction coupling between T tubules and sarcoplasmic reticulum). 

Molecular pathology
Caused by defects in RYR1, which encodes ryanodine receptor 1, a calcium channel that mediates the release of Ca2+ from the sarcoplasmic reticulum and plays a key role in triggering muscle contraction.

ma·lig·nant hy·per·ther·mi·a

(mă-lig'nănt hī'pĕr-thĕr'mē-ă)
Rapid onset of extremely high fever with muscle rigidity, precipitated by exogenous agents in genetically susceptible people, especially by halothane or succinylcholine.

malignant hyperthermia

A rare inherited muscle disorder that leads to dangerously high fever from intense muscle contraction when the affected person is given a general anaesthetic drug such as halothane, cyclopropane or ethyl ether, or a muscle relaxant drug such as succinylcholine. Emergency treatment to cool the patient, to neutralize the rapid rise in blood lactic acid from the muscles, and to reverse the abnormal muscle response, is needed to save life.

Malignant hyperthermia

A type of reaction (probably with a genetic basis) that can occur during general anesthesia in which the patient experiences a high fever, the muscles become rigid, and the heart rate and blood pressure fluctuate.

ma·lig·nant hy·per·ther·mi·a

(mă-lig'nănt hī'pĕr-thĕr'mē-ă)
Rapid onset of extremely high fever with muscle rigidity, precipitated by exogenous agents in genetically susceptible people.


1. greatly increased body temperature. May have effect as teratogen.
2. heat therapy. Used in the treatment of tumors, often in conjunction with chemotherapy or radiation. Whole body, regional or localized hyperthermia is induced with electromagnetic radiation, radiofrequency current heating or ultrasonic heating.

epidemic hyperthermia
poisoning by Neotyphodium (Acremonium)coenophialum.
idiopathic hyperthermia
term applied in error to the effects of ergotism under conditions of high ambient temperature. See also rye ergot, Neotyphodium(Acremonium) coenophialum.
malignant hyperthermia
a drug induced stress syndrome of pigs which have been treated with halothane or suxamethonium. Isolated cases have been reported in dogs and cats. The clinical syndrome includes muscle rigidity and hyperthermia. It is fatal and susceptibility to it is inherited. See also porcine stress syndrome.


tending to become progressively worse and to result in death; having the properties of anaplasia, invasiveness and metastasis; said of tumors.

malignant aphtha
see contagious ecthyma.
malignant carbuncle
a form of anthrax in humans.
malignant catarrhal fever (MCF)
an acute highly infectious, fatal herpesvirus disease of cattle, farmed deer and occasionally pigs characterized by an erosive stomatitis and gastroenteritis, erosions on the mucosa of the upper respiratory tract, keratoconjunctivitis, encephalitis, and lymphadenopathy. There are at least two viruses involved. A wildebeest-associated form of the disease is caused by alcephaline herpesvirus 1. It occurs in most African countries in cattle which co-mingle with clinically normal wildebeest and hartebeest. It is epizootic and seasonal. It can also occur in zoological gardens in other countries. Sheep-associated MCF is caused by a poorly characterized virus, presumably ovine herpesvirus 2 (OvHV-2). Cases mostly occur when cattle have had contact with lambing ewes and usually start 1-2 months later. Goats can also act as a source of OvHV-2 infection for cattle. Cases without apparent or recent exposure to sheep do occur but are uncommon. Called also bovine malignant catarrh.
malignant edema
an acute infection of wounds by Clostridium septicum, C. chauvoei, C. perfringens, C. sordellii or C. novyi. The inflammation causes severe swelling and discoloration of skin and exposed tissues. There may be local subcutaneous emphysema and a frothy exudate, depending on the identity of the invading organism. There is a high fever and a profound toxemia; death follows within a few hours if treatment is not provided. Special occurrences are when a large number of animals are affected at one time. These include involvement of the vulva in recently lambed ewes, of shearing or docking wounds, and of the umbilicus or eyes of recently born lambs.
malignant fibrous histiocytoma
a rare aggressive tumor of dogs and cats; composed of densely packed fibroblasts and histiocytes.
malignant head catarrh
see malignant catarrhal fever.
malignant histiocytosis
see malignant histiocytosis.
malignant hyperthermia
see malignant hyperthermia, porcine stress syndrome.
malignant lymphoma
malignant pustule
see malignant carbuncle (above).
malignant theileriasis
theileriasis caused by Theileria hirci.
References in periodicals archive ?
Correlations between genotype and pharmacological, histological, functional and clinical phenotypes in malignant hyperthermia susceptibility.
Patients with malignant hyperthermia demonstrate an altered calcium control mechanism in B lymphocytes.
The drug was introduced into clinical practice and once a usable compound had been produced, recommended for the first line treatment of malignant hyperthermia in 1980.
Should all children with suspected or confirmed malignant hyperthermia susceptibility be admitted after surgery?
Preparation of the Siemens KION anesthetic machine for patients susceptible to malignant hyperthermia.
Myoglobinuria, malignant hyperthermia, neuroleptic malignant syndrome and serotonin syndrome.
Identification of a mutation in porcine ryanodine receptor associated with malignant hyperthermia.
Even with proper treatment, malignant hyperthermia has a high mortality rate.
Malignant hyperthermia in infancy and identification of novel RYR1 mutation.
Steele confirmed that both had died from malignant hyperthermia, which can be "pharmacologically induced".
The anesthesiologist, suspecting that Susie has malignant hyperthermia (MH), responds quickly, knowing that if the infant is not treated rapidly she may die.
Because ZEMURON is always used with other agents, and the occurrence of malignant hyperthermia during anesthesia is possible even in the absence of known triggering agents, clinicians should be familiar with early signs, confirmatory diagnosis and treatment of malignant hyperthermia prior to the start of any anesthetic.

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