Correct!
3. Heatstroke
This patient’s clinical presentation raises high concern for heatstroke. Heatstroke is a life-threatening condition that is defined as a core body temperature usually in excess of 40ºC (104ºF) with associated central nervous system dysfunction in the setting of a large environmental heat load that cannot be dissipated (1). This patient was found down outside and presented with severe hyperthermia (41°C) and acute encephalopathy. This case occurred in Tucson, Arizona during a summer day with a high temperature of 43.9°C on the day the patient presented. Severe hyperthermia can cause rhabdomyolysis leading to elevated CK and hyperkalemia as seen in this patient.
Malignant hyperthermia (MH) causes high fever and tachycardia along with muscle rigidity. MH typically occurs as a reaction to anesthetic medications (halothane and succinylcholine) but heat stress can cause MH-like syndrome with rigidity and rhabdomyolysis. Acute encephalitis could explain the patient’s encephalopathy, but the severe hyperthermia makes heatstroke more likely. Septic shock is also a possibility but would not explain the rhabdomyolysis. Delirium tremens can also present with fever and acute encephalopathy, especially in a patient with a history of alcohol abuse; however, blood pressure would be elevated rather than decreased as in this patient. Other differentials for this presentation include other drug intoxications (atropine, MDMA 3,4-methylenedioxymethamphetamine, cocaine), severe dehydration, lethal catatonia, serotonin syndrome, thyroid storm, neuroleptic malignant syndrome or pheochromocytoma multisystem crisis (1).
The patient was cooled with ice water and towels. His temperature improved to 38°C, heart rate decreased to the 130s, and blood pressure improved to 103/70. The patient’s urine drug screen came back positive for benzodiazepines and methamphetamine. Methamphetamine may have contributed to his hyperthermia. Acetaminophen, salicylate and ethanol levels were negative. Of note, aspirin and acetaminophen are ineffective in treating heatstroke since fever and hyperthermia increase core temperatures through different physiological pathways (1).
What type of heat-related illness(es) is this patient most likely suffering from? (Click on the correct answer to be directed to the third of six pages)