Transient splenial lesion of the corpus callosum associated with antiepileptic drugs: evaluation by diffusion-weighted MR imaging.

Transient focal lesions in the splenium of the corpus callosum have been reported in epileptic patients receiving antiepileptic drugs. The characteristic imaging features included an oval high signal lesion on T2-weighted images in the central part of the splenium, no enhancement on post-contrast MR images, and complete reversibility without specific treatment. We report identical MR imaging findings in a depressive patient who had received antiepileptic drugs. In addition, diffusion-weighted MR imaging findings are described in our case, which is the first report on this unique lesion associated with antiepileptic drugs. Although this lesion has been assumed to be vasogenic edema in the previous reports, diffusion-weighted MR imaging showed markedly restricted diffusion of the lesion in the present case, suggesting that cytotoxic edema was the main pathophysiological abnormality.