Rapidly progressive acute necrotizing encephalopathy associated with influenza A in an elderly adult

BACKGROUND: Among the influenza‐associated encephalopathies, acute necrotizing encephalopathy (ANE) has a particularly poor prognosis. While it usually progresses within 48 h, we encountered a rapidly evolving case with the patient falling into coma from lucidity within 10 min. CASE PRESENTATION: A 71‐year‐old man was found unconscious after taking a 10‐min bath and brought to the emergency room. The head computed tomography (HCT) was normal, and he was diagnosed with heatstroke as a complication of influenza A. Despite effective therapy to correct his temperature, his consciousness did not improve, and within 24 h he progressed to multiple organ injury. Repeat HCT and subsequent magnetic resonance imaging revealed irreparably progressed ANE. CONCLUSION: To effectively treat ANE, early recognition and diagnosis are critical. Our case suggests that ANE should be considered and added to the differential diagnosis for adult patients with rapid cognitive deterioration.