A 14-month-old girl who presented with sudden onset of unreponsiveness following a fever for 2 days developed decerebrate posturing within 9 hours after admission to Children’s Memorial Hospital, Chicago, IL. She had no response to deep pain, her reflexes were exaggerated, and plantar responses were extensor. EEG showed slowing but no epileptiform discharges. Blood counts and chemistries were normal, except for elevated transaminases, with an aspartate aminotransferase level of 190 IU/L (normal, 22-59 IU/L). CSF analysis was normal. Initial head CT scan was normal, but 10 hours later, a second CT showed new bilateral thalamic hypodensities. MRI with MR angiography and venography, FLAIR imaging, and apparent diffusion coefficient (ADC) mapping confirmed thalamic and periventricular white matter involvement. Infectious, vascular, metabolic, and other etiologies were excluded. When discharged two weeks later to a rehabilitation facility with a diagnosis of acute necrotizing encephalopathy of childhood (ANEC), the child was blind, she responded only to noxious stimuli, and had diffuse spasticity. [1]

COMMENT. Rare in the United States, acute necrotizng encephalopathy (ANE) is reported principally in Japan. The above case in Chicago, extensively investigated by CT and MRI imaging, demonstrates the rapid evolution of thalamic involvement in ANE. Thirteen consecutive children treated and 28 cases of ANE seen at various institutions in Japan are reviewed by Mizuguchi M et al. (see Ped Neur Briefs July 1995) [2]. Onset is preceded by upper respiratory infection treated with antipyretics (aspirin in only 2 cases), and impaired consciousness, convulsions, and vomiting develop rapidly within 1 to 3 days. Hematemesis and diarrhea are common, and liver enlargement without jaundice is reported in all patients of this series. Decerebrate posturing occurs with coma, and the mortality is 28%. In survivors, slow recovery begins after 10 days, and spasticity, mental retardation, and seizures are common sequelae. Laboratory findings reveal liver dysfunction, uremia, and hypoproteinemia. Liver histology is nonspecific and unlike Reye’s syndrome. CSF protein is increased. CT and MRI show symmetric, multifocal areas of necrosis in the thalami, white matter, brainstem, and cerebellum. The etiology is undetermined, but recent viral infection with influenza, coxackie, and Rotavirus is detected in 20%.

The differential diagnosis, in addition to the acute toxic encephalopathy of Reye’s syndrome, includes Wernicke’s and Leigh’s encephalopathies, carbon monoxide poisoning, ADEM, and acute hemorrhagic leukoencephalitis. An infectious or toxic environmental factor appears most likely, (see Progress in Pediatric Neurology III, PNB Publishers, 1997;pp493-494 for abstract and commentary on ANE).