How is exertional heat stroke clinically defined?

• A. Mild heat illness with dehydration but normal core temperature.
• B. Fever due to infection causing mild symptoms.
• C. Severe heat illness with CNS dysfunction and core temperature typically above 40°C during physical exertion.
• D. Heat cramps without CNS involvement.

Answer: (C)

Exertional heat stroke is a severe heat illness that occurs during strenuous exercise, showing marked dysfunction of the central nervous system (such as confusion, agitation, seizures, or coma) and a core body temperature typically above 40°C (104°F). The key idea is the combination of CNS impairment with extreme hyperthermia arising from exertion, not from infection. This sets it apart from milder heat illnesses, which may involve dehydration or cramps without CNS symptoms, and from fever due to infection, which is not caused by failing thermoregulation during exercise. Rapid cooling is essential because the CNS injury and hyperthermia can progress quickly.