Cytomegalovirus-Associated Mild Encephalopathy/Encephalitis With Reversible Splenial Lesion

Introduction: Mild encephalopathy with a reversible splenial lesion (MERS) is a clinical-radiologic syndrome presenting with a reversible lesion in the splenium of the corpus callosum. MERS is associated with many potential etiologies, including cytomegalovirus (CMV) infection in children. We report an adult patient with CMV-associated MERS. Case Report: A previously healthy 25-year-old man was admitted with a 4-day history of fever, headache, and vomiting. Brain magnetic resonance imaging demonstrated an isolated lesion of the splenium of the corpus callosum with hyperintensity on T2 and diffusion-weighted sequences and reduced values on apparent diffusion coefficient maps. High throughput gene detection for pathogens in cerebrospinal fluid revealed infection with CMV. The splenial lesion resolved 4 weeks after onset. Conclusion: This is the first report an adult patient with CMV-associated MERS. Recognition of this clinical-radiologic syndrome can guide diagnosis and management.