Clinical, Lab, and Radiological Evolution of an Adult Patient With Unilateral Cortical Lesion in Anti-Myelin Oligodendrocyte Glycoprotein (MOG)-Associated Encephalitis With Seizures and Anti-Glial Fibrillary Acidic Protein (GFAP) Positive Antibodies.

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease refers to a clinical and radiological spectrum of demyelinating disorders of the Central Nervous System. We report the case of a female adult patient presenting to our department with an episode of seizures and cognitive dysfunction, compatible with Gerstmann syndrome. Brain MRI revealed a high T2 and DWI signal unilateral cortical lesion at the inferior left parietal lobe and leptomeningeal contrast enhancement. Lumbar puncture showed pleocytosis of the lymphocytic type and elevated protein. Upon suspicion of autoimmune encephalitis, extensive laboratory testing was performed, and the patient's serum and cerebrospinal fluid (CSF) tested positive for anti-MOG, while anti-glial fibrillary acidic protein (GFAP) antibodies were detected in her serum. A diagnosis of FLAIR-hyperintense lesions in anti-MOG-associated encephalitis with seizures (FLAMES) was made, and the patient was treated with intravenous methylprednisolone for five days, leading to clinical remission within days. However, serum anti-MOG IgG titers were found to be higher on follow-up, and the patient experienced a relapse, thus treatment with azathioprine was initiated. We suggest that upon suspicion of autoimmune encephalitis, all patients should be tested for serum and CSF anti-MOG IgG antibodies. Furthermore, we consider that anti-MOG antibody titers and GFAP concentration could be used as possible biomarkers for the disease course and treatment strategy options.