The puzzling picture of acute necrotizing encephalopathy after influenza A and B virus infection in young children.

Acute necrotizing encephalopathy is a complication of influenza A and B virus infection in young children, especially in Japan. The disease is characterized by high fever, convulsions and coma. A prominent feature of this central nervous system disease is bilateral thalamic necrosis, documented by magnetic resonance imaging. The pathogenesis of the virus-associated brain pathology has not yet been elucidated. There is considerable circumstantial evidence that influenza immunization may decrease the likelihood of children developing acute necrotizing encephalopathy.