Mild encephalitis/encephalopathy with a reversible splenial lesion: evaluation by diffusion tensor imaging. Two case reports.

Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a clinico-radiological syndrome with a very particular clinical course. Three patients with MERS were evaluated by various sequences of magnetic resonance imaging with diffusion tensor imaging. Initial diffusion-weighted imaging showed reduction in the apparent diffusion coefficient values in the lesions, which completely resolved with the elimination of symptoms. However, diffusion anisotropy of the lesions showed no remarkable abnormalities in the early or delayed phases. These results may indicate that white matter architecture is preserved in both early and delayed phases in MERS.