Reversible Cytotoxic Edema in the Splenium of the Corpus Callosum Related to Antiepileptic Treatment: Report of Two Cases and Literature Review

Purpose: Clinically silent lesions localized in the splenium of the corpus callosum (SCC) are a rare finding in the magnetic resonance imaging (MRI) of patients receiving antiepileptic drugs (AEDs). They are usually of benign character but may induce unnecessary complementary examinations if their nature is unrecognized. So far, 22 cases have been described in the literature, for which different etiologies have been proposed. We describe two further cases and discuss the probable lesion etiology. Methods: We report two cases including a 25‐year‐old male patient and a 12‐year‐old female patient with a transient SCC lesion discovered in the context of a presurgical epilepsy evaluation. Results: Comprehensive MRIs, including diffusion tensor imaging–based fiber tracking of the lesion, revealed a cytotoxic edema not disrupting neuronal fibers. Serum arginine vasopressin (AVP) measurements revealed an altered secretion during the acute phase in one patient. Conclusions: On the basis of our results, we hypothesize that the lesion consists of a cytotoxic edema, possibly induced by abrupt AED concentration changes and associated to alterations of AVP secretion.