Clinical Analysis of MOG Antibody‐Associated Disease Overlapped With Anti‐NMDA Receptor Encephalitis: A Long‐Term Retrospective Study

To summarise the clinical characteristics, radiological features, treatments and prognosis of patients with myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) overlapped with NMDA receptor (NMDAR) encephalitis. We retrospectively analysed patients who exhibited dual positivity for MOG antibodies and NMDAR antibodies in serum/CSF from Jan 2018 to Jun 2023. Ten patients with MOGAD and NMDAR encephalitis were enrolled. The median age of initial attacks was 23 (range: 10-43) years old. Common symptoms were cortical encephalopathies (8/10), focal neurological deficits (4/10), as well as other presentations including headache, fever, optic neuritis and transverse myelitis. CSF pleocytosis was general (9/10, median 63.9 cells/μl). Lesions on brain MRI included brainstem (37.5%), cerebral cortex (33.3%), basal ganglia (25.0%) and hippocampus (20.8%). The average follow-up duration was 25.4 months. 10/10 patients developed more than one relapse attacks, with MOG positivity before (10%), simultaneous (40%) or after anti-NMDAR encephalitis (50%). Most patients (7/10) had good response to first-line therapy but experienced next relapse with an average interval of 6.7 (range: 2-14) months. We conducted initial analysis of lymphocyte subsets in these patients, which revealed that CD3+ and CD4 + T cells increased after immunosuppressants medication (p < 0.01 and p < 0.05, respectively). We concluded that MOGAD overlapping with NMDAR encephalitis presents a distinct clinical phenotype which differs from either MOGAD or NMDAR encephalitis. Brainstem in combination with cortical lesions might be warning signs for this overlapping syndrome. Due to the high recurrent rates, we recommend early diagnosis and timely treatment with efficient immunosuppressants at onset.