Acute Stage Neuropathology of a Case of Infantile Acute Encephalopathy with Thalamic Involvement: Widespread Symmetrical Fresh Necrosis of the Brain

Abstract

The neuropathology of the acute stage of infantile acute encephalopathy characterized by symmetrical thalamic involvement is not yet known. We describe this disorder in detail for the case of a one‐year‐old Japanese boy who presented with high fever associated with convulsions and vomiting two days after common cold‐like symptoms, rapidly fell into coma and died 29 hours after the first occurrence of convulsions. Brain CT one day before death demonstrated widespread and symmetrical low density lesions in the thalami, the deep portion of the cerebral and cerebellar hemispheres, and the tegmentum of the brain stem. The unfixed brain was swollen but without uncal or tonsillar herniation. Sections of the formalin‐fixed brain showed symmetrical softening of the same regions as shown by brain CT as low density lesions. The essential histopathology of these areas was fresh necrosis with neither astrocytic proliferation nor microglial or inflammatory cell infiltration. This histopathological finding, combined with the peculiar distribution of the lesions which is irrelevant to the irrigation field of any major cerebral artery, raises the possibility of some metabolic disturbance as the cause of this condition.