Transient blindness due to mild reversible encephalopathy in a 7-year-old boy.

Mild encephalopathy with a reversible splenial lesion (MERS) is a rare phenomenon, which shows transient lesion in corpus callosum and causes temporary encephalopathy features. A disturbance of consciousness and abnormal and delirious behavior are the most significant neurological symptoms. A seven-year-old child with a history of fever and cough was admitted to our hospital due to sudden bilateral blindness. His physical examination showed confusion, fever, and delirious behavior. No sign of meningeal irritation or focal neurological deficit was observed. The electroencephalogram showed diffuse slow waves representing mild encephalopathy. Brain MRI showed a signal alteration in the splenium of the corpus callosum, and magnetic resonance angiography (MRA) was normal. This finding was suggestive of a reversible cytotoxic lesion. Treatment with empiric antivirals was initiated, and the symptoms were completely resolved. In a few children, sudden blindness has been reported to be an initial symptom of MERS. There is currently no evidence of efficient treatment methods. However, to convince patients and their families about the good outcome of the disease, the diagnosis of MERS provides pediatricians with useful prognostic information.