What are the signs and symptoms of nonexertional heat stroke (NEHS)?

Updated: Nov 06, 2018
  • Author: Robert S Helman, MD; Chief Editor: Joe Alcock, MD, MS  more...
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Answer

NEHS is characterized by hyperthermia, anhidrosis, and an altered sensorium, which develop suddenly after a period of prolonged elevations in ambient temperatures (ie, heat waves). Core body temperatures greater than 41°C are diagnostic, although heat stroke may occur with lower core body temperatures.

Numerous central nervous system (CNS) symptoms, ranging from minor irritability to delusions, irrational behavior, hallucinations, and coma have been described. Other possible CNS symptoms include seizures, cranial nerve abnormalities, cerebellar dysfunction, and opisthotonos.

Anhidrosis due to cessation of sweating is a late occurrence in heat stroke and may not be present when patients are examined.

Patients with NEHS initially may exhibit a hyperdynamic circulatory state, but, in severe cases, hypodynamic states may be noted.

Classic heat stroke most commonly occurs during episodes of prolonged elevations in ambient temperatures. It affects people who are unable to control their environment and water intake (eg, infants, elderly persons, individuals who are chronically ill), people with reduced cardiovascular reserve (eg, elderly persons, patients with chronic cardiovascular illnesses), and people with impaired sweating (eg, from skin disease or ingestion of anticholinergic or psychiatric drugs). In addition, infants have an immature thermoregulatory system, and elderly persons have impaired perception of changes in body and ambient temperatures and a decreased capacity to sweat.


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