Clinical diversity in acute necrotizing encephalopathy

Acute necrotizing encephalopathy is a novel disease entity, proposed by Mizuguchi et al in 1995, that shows a characteristic selective and symmetric involvement of the thalamus, brain stem, and cerebellum. It usually leaves sequelae. The etiology of acute necrotizing encephalopathy is unknown. We describe here six patients aged 6 months to 5 years (four boys and two girls). Four cases were typical, and the patients' cranial computed tomographic scans and magnetic resonance imaging showed irreversible symmetric involvement of the thalamus, brain stem, and cerebellum. Three of the patients died, and one was left with severe sequelae. In the other two patients, who had selective reversible thalamic involvement, the disease was mild; one also showed transient unilateral thalamic involvement. These patients recovered completely. We consider the illness in these two patients to fit the criteria of the mild form of acute necrotizing encephalopathy. We believe that acute necrotizing encephalopathy has some clinical diversity, as is seen in other neurologic disorders, and that a mild form could exist.