Findings may suggest a cause: Hypothermia: Environmental exposure, near-drowning, sedative overdose, severe hypothyroidism, Wernicke encephalopathy, or, in older people, sepsis Hyperthermia: Heatstroke, infection, stimulant drug overdose, or neuroleptic malignant syndrome Fever, petechial or purpuric rash, hypotension, or severe extremity infections (eg, gangrene of one or more toes): Sepsis or central nervous system (CNS) infection Needle marks: Drug overdose (eg, of opioids or insulin) A bitten tongue: Seizure Breath odor: Alcohol, other drug intoxication, or diabetic ketoacidosis Hypotension or pulse abnormalities: Cardiac dysfunction with hypoperfusion Difficulty breathing: Acute respiratory dysfunction from bacterial or viral illness Neurologic examination The neurologic examination determines whether the brain stem is intact and where the lesion is located within the CNS.