MOGAD-Like Encephalitic Syndromes Without MOG Antibodies in Children.

BACKGROUND AND

objectivesAlthough acute disseminated encephalomyelity (ADEM) can be myelin oligodendrocyte glycoprotein-IgG (MOG-IgG) positive or negative, it is unclear whether other MOG-antibody-associated disease (MOGAD)-like encephalitis syndromes occur without MOG-IgG. We aimed to define the frequency, clinico-radiologic features, outcomes, and antibody associations of such cases in children.

methodsProspective cohort study of children (<18 years) with encephalitis meeting clinico-radiologic MOGAD criteria, regardless of MOG-IgG status. Serum from all patients and CSF when available were tested by live cell-based assays (CBA-IIF, CBA-FACS) at 2 laboratories. Brain MRIs were centrally reviewed for MOGAD-like patterns (ADEM, cortical encephalitis, isolated/predominant central gray matter). Additional testing included CBAs for MOG-IgA, MOG-IgM, PLP1-IgG, glial fibrillary acidic protein-IgG, and AQP4-IgG, along with rat brain immunohistochemistry.

resultsAmong 160 patients with MOGAD-like encephalitis, 120 were MOG-IgG positive and 40 negative (20 ADEM, 11 cortical encephalitis, 9 isolated/predominant central gray matter encephalitis). Clinical-radiologic features were broadly comparable between groups, including lesion distribution, frequency of associated longitudinally extensive transverse myelitis, lesion resolution, and functional outcomes. Relapses were more frequent in MOG-IgG-positive patients (22, 18% vs 1, 3%; DISCUSSION: Children can develop the full spectrum of MOGAD-like encephalitis without MOG-IgG. Clinical features and immunotherapy response are similar to MOGAD, but relapses are uncommon.