Hypoxic-ischemic encephalopathy mimicking acute necrotizing encephalopathy

Abstract

Background: Acute necrotizing encephalopathy is a rare childhood syndrome associated with distinct and unifying neuroimaging features that are often used for the diagnosis of this entity.

Patient: We describe a previously healthy 9-month-old girl who presented with upper respiratory symptoms, suspected seizures, and positive nasopharyngeal rapid antigen test for influenza A virus. Magnetic resonance imaging revealed signal abnormality in both thalami, bilateral caudate nuclei, brainstem tegmentum, subcortical white matter, and cerebellar hemispheres, suggestive of acute necrotizing encephalopathy. She subsequently had a cardiac arrest, was placed on extracorporeal membrane oxygenation, and treated with methylprednisone, intravenous immunoglobulin, and plasmapheresis without apparent clinical response. On autopsy, neuropathology showed evidence of hypoxic-ischemic injury but lacked evidence of hemorrhagic necrosis, which is typically associated with acute necrotizing encephalopathy.

Conclusion: Combined clinical and neuroimaging features may be suggestive but not sufficient for the diagnosis of acute necrotizing encephalopathy.

Keywords: acute necrotizing encephalopathy; hypoxic-ischemic encephalopathy; influenza; pediatric.