Defined as a core (oesophageal, tympanic) temperature above 40.5°C. Hyperthermia may be an extreme form of pyrogen-induced fever associated with infection, inflammation, neoplasia or CVA

Heat stroke

Heat Stoke is a life-threatening illness characterized by:

Pathophysiology of Heat Stroke

At risk  - very young and elderly, obese and those undertaking unaccustomed or prolonged muscular activity, grand mal fitting, athletes, marathon runners and armed forces recruits. 

Predisposing factors include:

Clinical features







Poor Prognostic Factors in Heat Stroke

Malignant hyperthermia

Rare, autosomal dominant, drug-induced myopathy associated with a Ca++ transfer defect in patients receiving volatile anaesthetics, muscle relaxants, antidepressants, alcohol or Ecstasy. Heat production is increased by muscle catabolism, spasm and peripheral vasoconstriction.

The neuroleptic malignant syndrome

Laboratory Investigations

A drug induced hyperthermic syndrome secondary to antipsychotics - especially dopamine antagonists such as haloperidol, thioridazine and chlorpromazine. It is associated with muscle rigidity, extra pyramidal signs, dyskinesia, impaired consciousness and autonomic dysfunction and continues for 1-2 weeks.

Features NMS

Management of hyperthermia

Mortality from heat stroke approaches 80% if prompt, effective treatment is not undertaken

Differential Diagnosis of Heat Stroke

Content by Dr Jon Dallimore, Dr Íomhar O' Sullivan 10/02/04. Reviewed by Dr ÍOS 10/02/05. Reviewed by Dr IOS 25/04/2007. Last reviewDr. ÍOS 9/10/12.