Myelin Oligodendrocyte Glycoprotein (MOG) Antibody-Associated Disease Presenting as Acute Disseminated Encephalomyelitis Following COVID-19 mRNA Vaccination.

Acute disseminated encephalomyelitis (ADEM) is a rapidly progressive autoimmune demyelinating condition that primarily affects the central nervous system. The exact pathogenesis is not well understood, but current literature suggests roles for both environmental triggers and genetic predispositions. Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an increasingly recognized autoimmune demyelinating disorder that can present with an ADEM-like phenotype, particularly in adults. We report the case of a 53-year-old Asian-American female patient of Taiwanese ancestry with a past medical history of obstructive sleep apnea and no prior autoimmune disease or family history of demyelinating disorders who presented to the emergency room (ER) with left-sided numbness and weakness, ataxia, vertigo, and slurred speech in the context of a three-month long history of headaches that started one day after she received her first dose of Pfizer COVID-19 vaccine. Brain imaging studies showed findings most suggestive of ADEM. Initial pre-treatment cerebrospinal fluid (CSF) analysis showed markedly elevated protein (473 mg/dL, reference 15-45 mg/dL) with a normal glucose level and mild pleocytosis (6 WBC/µL). Extensive workup was negative for infectious, oncologic, and autoimmune etiologies including negative serum and CSF anti-MOG antibody testing during the acute presentation. The initial treatment of a five-day intravenous methylprednisolone course (250 mg every six hours, total 1,000 mg/day) did not result in significant clinical improvement. The patient was then started on plasma exchange therapy and successfully recovered by the end of the last session with objective improvement in ambulation, dysarthria, and limb strength. The patient tested positive for anti-myelin oligodendrocyte glycoprotein antibody in serum six months after hospital discharge at a titer of 1:32 by live cell-based assay. This case provides an example of a rare but serious event temporally associated with the SARS-CoV-19 mRNA vaccine and MOGAD presenting as ADEM in a previously healthy adult. The absolute risk of demyelinating events following COVID-19 vaccination is extremely low, and the benefit of vaccination vastly outweighs these rare risks.