Heat stroke.

Heatstroke is the most severe form of the heatrelated illnesses and is caused by an excessive rise in deep body temperature due to thermoregulatory failure. It is characterized primarily by hyperthermia usually with core temperature above 40.6o C (105o F), central nervous system dysfunction, metabolic derangement and coma. Heat stroke is the least common but most serious form of heat disorder. It needs to be distinguished from heat exhaustion, a benign condition. Unlike heat exhaustion, it carries a high mortality if effective treatment is not given immediately (Table 1). Two forms of heatstroke exist, ‘classical’ nonexertional heatstroke (NEHS) and Exertional heatstroke (EHS).