A case of Japanese encephalitis: CT and MRI findings in acute and convalescent stages.

We studied the CT and MR images of a patient with Japanese encephalitis. The first symptom was general malaise with high fever. The diagnosis of meningoencephalitis was made by spinal tap and clinical presentation. CT on the third day of illness showed no significant findings. MRI on the fifth day of illness demonstrated that the left thalamus and bilateral putamen were hyperintense on T2-weighted images. On CT one month later, the density in the thalamus and bilateral putamen was normal. MRI two month later showed high signal intensity only in the left thalamus. The patient recovered, but was judged to have dementia according to the simple dementia scale of Hasegawa. Flaccid paralysis was observed during the acute period.