MRI of encephalitis in children: comparison of CT and MRI in the acute stage with long-term follow-up.

We examined 14 children aged 28 days to 12.7 years with encephalitis by CT or MRI. Of the patients examined by CT 58% had a normal first scan, whereas all MRI investigations demonstrated abnormalities. The clinical features correlated with several MRI investigations. On MRI herpes (HSV) encephalitis started in the medial temporal lobe and encephalomalacia developed within a few weeks. All patients had a follow-up examination 0.5 to 6.5 years after the acute phase. MRI revealed abnormalities in 13 of the 14 children; one boy, with lesions in only the white matter, had a normal follow-up MRI. Even with immediate, optimal therapy the children demonstrated severe parenchymal abnormalities. Signal abnormalities seen in the acute phase of the disease were likely to persist. In children with HSV encephalitis atypical lesions in different areas were seen.