Focal lesion in the splenium of the corpus callosum in epileptic patients:Antiepileptic drug toxicity?

BACKGROUND AND PURPOSE: Discrete focal lesions in the splenium of the corpu s callosum on MR images in epileptic patients have received little attentio n in the literature. Our purpose was to describe these lesions, which may b e related to the toxicity of antiepileptic drugs (AEDs), and to discuss the possible mechanisms of their development. METHODS: We examined six patients with epilepsy whose brain MR imaging find ings showed a discrete focal nonhemorrhagic lesion in the splenium of the c orpus callosum, The medical records and MR images were reviewed retrospecti vely with respect to the patients' clinical history, medication, and labora tory findings to determine the etiology of the lesion. RESULTS: In all six patients MR imaging showed a focal lesion in the spleni um of the corpus callosum, which was ovoid in shape and 15 to 19 mm in size . In the three patients who received contrast material, there was no enhanc ement of the lesion. Four of six patients had a history of medication with dilantin, in two of whom the level of serum dilantin was found to be elevat ed (22.3 mu g/mL and 70.4 mu g/mL, respectively). Vigabatrin was administer ed in three patients, one of whom took dilantin together with vigabatrin, I n two patients, the focal lesion in the corpus callosum disappeared on foll ow-up MR images after withdrawal of dilantin and/or vigabatrin, CONCLUSION: A discrete, focal, ovoid, nonhemorrhagic lesion in the splenium of the corpus callosum may be seen on brain MR images of patients with epi lepsy. The lesion is considered to be reversible demyelination related to A EDs toxicity.