Impaired Brain Growth in Myelin Oligodendrocyte Glycoprotein Antibody–Associated Acute Disseminated Encephalomyelitis

BACKGROUND AND OBJECTIVES: Acute disseminated encephalomyelitis (ADEM) is the most common phenotype in pediatric myelin oligodendrocyte glycoprotein (MOG) antibody–associated disease. A previous study demonstrated impaired brain growth in ADEM. However, the effect of MOG antibodies on brain growth remains unknown. Here, we performed brain volume analyses in MOG-positive and MOG-negative ADEM at onset and over time. METHODS: In this observational cohort study, we included a total of 62 MRI scans from 24 patients with ADEM (54.2% female; median age 5 years), of which 16 (66.7%) were MOG positive. Patients were compared with healthy controls from the NIH pediatric MRI data repository and a matched local cohort. Mixed-effect models were applied to assess group differences and other relevant factors, including relapses. RESULTS: At baseline and before any steroid treatment, patients with ADEM, irrespective of MOG antibody status, showed reduced brain volume compared with matched controls (median [interquartile range] 1,741.9 cm3 [1,645.1–1,805.2] vs 1,810.4 cm(3) [1,786.5–1,836.2]). Longitudinal analysis revealed reduced brain growth for both MOG-positive and MOG-negative patients with ADEM. However, MOG-negative patients showed a stronger reduction (−138.3 cm(3) [95% CI −193.6 to −82.9]) than MOG-positive patients (−50.0 cm(3) [−126.5 to −5.2]), independent of age, sex, and treatment. Relapsing patients (all MOG positive) showed additional brain volume loss (−15.8 cm(3) [−68.9 to 37.3]). DISCUSSION: Patients with ADEM exhibit brain volume loss and failure of age-expected brain growth. Importantly, MOG-negative status was associated with a more pronounced brain volume loss compared with MOG-positive patients.