[Mild Encephalopathy with Reversible Splenial Lesion(MERS)]

Mild encephalitis/encephalopathy with a reversible splenial lesion(MERS)is a clinically and radiologically benign condition that has been described within the past two decades. MRI findings include isolated symmetrical ovoid lesions of the splenium with a high-intensity signal on DWI and decreased apparent diffusion coefficient. These findings have been associated with viral infections, epilepsy, antiepileptic drug usage, and metabolic disturbances, among others. These conditions may present with severe clinical features, such as consciousness disturbance or cytokine storm; however, patients usually recover completely with optimal treatment. Some pathological conditions with splenic lesions, such as Marchiafava-Bignami disease, may be irreversible. Therefore, diseases with splenic lesions require careful attention.