Monitoring CSF MOG Antibody in a Relapsing Case of MOGAD With Isolated CSF Positivity

ABSTRACT Myelin oligodendrocyte glycoprotein antibody‐associated disease presents with diverse clinical courses, and some patients experience frequent relapses. Although various immunotherapies have been employed, optimal long‐term management strategies remain unclear. We report the case of a 37‐year‐old woman diagnosed with myelin oligodendrocyte glycoprotein antibody‐associated disease. Myelin oligodendrocyte glycoprotein antibody was detected only in cerebrospinal fluid. The patient was primarily treated with steroids; however, she experienced recurrent encephalitis with multifocal brain lesions. A brain biopsy showed no evidence of neoplastic changes. High‐dose intravenous immunoglobulin maintenance therapy and azathioprine were initiated, resulting in clinical stabilization and conversion to cerebrospinal fluid myelin oligodendrocyte glycoprotein antibody negativity. Over 1.5 years of follow‐up, no relapse occurred and cerebrospinal myelin oligodendrocyte glycoprotein antibody negativity was retained. This case highlights the potential utility of monitoring cerebrospinal fluid myelin oligodendrocyte glycoprotein antibody as biomarkers for treatment response in myelin oligodendrocyte glycoprotein antibody‐associated disease, especially in seronegative cases.