Acute necrotising encephalopathy of childhood: a new syndrome presenting with multifocal, symmetric brain lesions.

The clinicopathological features of a previously unrecognised type of acute encephalopathy prevalent among Japanese children is described by reviewing the records of 13 consecutive patients treated and 28 previously reported cases. The hallmark of this encephalopathy, proposed to be a novel entity termed acute necrotising encephalopathy of childhood, is multiple, necrotic brain lesions showing a symmetric distribution. The encephalopathy was noted in previously healthy children after respiratory tract infections, with presenting symptoms of coma, convulsions, vomiting, hyperpyrexia, and hepatomegaly. Laboratory examinations disclosed liver dysfunction, uraemia, and hypoproteinaemia. The histological appearance of the liver was variable and non-specific. Cerebrospinal fluid contained an increased amount of protein. Computed tomography and MRI showed the presence of symmetrically distributed brain lesions of the thalamus, cerebral white matter, brainstem, and cerebellum. Necropsy examination confirmed extensive fresh necrosis of these regions with evidence of local breakdown of the blood-brain barrier. Based on the characteristic combination of clinical and pathological findings, acute necrotising encephalopathy of childhood can be distinguished from previously known encephalopathies, including Reye's syndrome.