MOG antibody-associated encephalitis in adult: clinical phenotypes and outcomes

Background We investigated the clinical characteristics and outcomes of myelin oligodendrocyte glycoprotein (MOG) antibody-associated autoimmune encephalitis (MOGAE) in adult patients. Methods From an institutional cohort, we analysed adult patients with MOGAE followed-up for more than 1 year. Disease severity was assessed using the modified Rankin scale (mRS) and Clinical Assessment Scale in Autoimmune Encephalitis scores. Immunotherapy profiles, outcomes and disease relapses were evaluated along with serial brain MRI data. Results A total of 40 patients were enrolled and categorised into cortical encephalitis (18 patients), limbic encephalitis (LE, 5 patients) and acute disseminated encephalomyelitis (ADEM, 17 patients). 80.0% of patients achieved good clinical outcomes (mRS 0‒2) and 40.0% relapsed. The LE subtype was associated with an older onset age (p=0.004) and poor clinical outcomes (p=0.014) than the other subtypes but with a low rate of relapse (0.0%). 21/25 (84.0%) relapse attacks were associated with an absence or short (≤6 months) immunotherapy maintenance. On MRI, the development of either diffuse cerebral or medial temporal atrophy within the first 6 month was correlated with poor outcomes. MOG-antibody (MOG-Ab) was copresent with anti-N-methyl-D-aspartate receptor (NMDAR)-antibody in 13 patients, in whom atypical clinical presentation (cortical encephalitis or ADEM, p < 0.001) and disease relapse (46.2% vs 0.0%, p < 0.001) were more frequent compared with conventional NMDAR encephalitis without MOG-Ab. Conclusions Outcomes are different according to the three phenotypes in MOGAE. Short immunotherapy maintenance is associated with relapse, and brain atrophy was associated with poor outcomes. Patients with dual antibodies of NMDAR and MOG have a high relapse rate.