Hyperthermia Syndromes
Hyperthermia is elevation of body temperature to more than 41.5°C (106.7°F). It is also called hyperpyrexia. There are many causes of hyperthermia, which are different from that of the causes of fever. The causes of hyperthermia or hyperpyrexia are Heat Stroke, Drug-induced hyperthermia, Malignant hyperthermia, Neuroleptic Malignant Syndrome, Endocrinopathy, Central Nervous System Damage, Serotonin Syndrome etc.
Heat stroke:
Heat stroke which is association with a warm environment may be categorized as exertional or nonexertional. Exertional heat stroke typically occurs in individuals exercising at elevated ambient temperatures and/or humidity. In a dry environment (with maximum efficiency), sweating can dissipate approximately 600 kcal/hour, which require the production of more than 1 liter of sweat. Even in healthy individuals, dehydration or the use of common medications (like over-the-counter antihistamines with anticholinergic side effects) may precipitate exertional heat stroke. Nonexertional heat stroke typically occurs in either very young or elderly individuals, particularly during heat waves due to medicines like anticholinergics, including antihistamines; antiparkinsonian drugs; diuretics; phenothiazines. The elderly, the bedridden, persons taking anticholinergic or antiparkinsonian drugs or diuretics, and individuals confined to poorly ventilated and non-air-conditioned environments are susceptible to non exertional heat stroke.
Malignant hyperthermia:
Malignant hyperthermia occurs in individuals with an inherited abnormality of skeletal-muscles. Elevated temperature, increased muscle metabolism, muscle rigidity, rhabdomyolysis, acidosis, and cardiovascular instability develop within minutes in these individuals with muscular abnormality. This rare condition is often fatal. The neuroleptic malignant syndrome occurs during use of neuroleptic agents (antipsychotic phenothiazines, haloperidol, prochlorperazine, metoclopramide) or the withdrawal of dopaminergic drugs and is characterized by “lead-pipe” muscle rigidity, autonomic dysregulation, and hyperthermia. This disorder appears to be caused by the inhibition of central dopamine receptors in the hypothalamus, which results in increased heat generation and decreased heat dissipation.
Hyperthermia due to Serotonin Syndrome:
The serotonin syndrome, seen with selective serotonin uptake inhibitors (SSRIs), MAOIs, and other serotonergic medications, has many overlapping features, including hyperthermia, but may be distinguished by the presence of diarrhea, tremor, and myoclonus rather than the lead-pipe rigidity of the neuroleptic malignant syndrome. Thyrotoxicosis and pheochromocytoma can also cause increased thermogenesis.
Related posts:
