Transient Elevation of Cerebrospinal Fluid Protein in a Patient of Mild Encephalitis with Reversible Lesion in the Splenium: A Case Report

Mild encephalitis with reversible lesion in the splenium (MERS) is a clinicoradiological syndrome presenting as a solitary lesion in the central portion of the splenium of the corpus callosum (SCC) with a radiological finding of restricted diffusion and low apparent diffusion coefficient (ADC) values. Complete resolution of the lesion on follow-up imaging and full clinical recovery are the hallmarks of this syndrome, even with only supportive therapy. MERS is usually associated with normal Cerebrospinal fluid (CSF) findings and an excellent prognosis, even without corticosteroid therapy. Magnetic resonance imaging (MRI) is the ideal modality for initial diagnosis and follow-up. Not many cases of this uncommon clinicoradiological syndrome with transient elevation of CSF proteins have been reported. In the subsequent sections, we present a case report of this unusual clinicoradiological entity with raised CSF protein. We also elaborate on possible differential diagnoses and the syndrome’s proposed pathophysiology.

Keywords
encephalitis; corpus callosum; reversible lesion; splenium; cerebrospinal fluid protein; diffusion magnetic resonance imaging