Clinical presentation, MR imaging and outcome in children with myelin oligodendrocyte glycoprotein antibody-negative acute disseminated encephalomyelitis

Background: Acute disseminated encephalomyelitis (ADEM) without myelin oligodendrocyte glycoprotein (MOG) antibodies (abs) presents a diagnostic challenge. Objective: To investigate whether the diagnosis of MOG-negative (neg) ADEM was confirmed over time and to highlight the clinical and neuroradiological characteristics distinguishing monophasic MOG-neg ADEM from alternative diagnoses. Material and methods: Children diagnosed with a first clinical episode of MOG-neg ADEM and a dataset including clinical presentation, MRI, CSF studies and at least 3-month follow-up were included. Results: 47 children with MOG-neg ADEM were identified (m:f = 27:20 , median age 8.0 years. 38 (79.2 %) children maintained the initial diagnosis after a median follow-up of 34.2 months. In 9 (19.1 %) children an alternative diagnosis was assigned after a median follow-up of 4.2 months including multiple sclerosis (MS) n = 2; glioblastoma (GBM) n = 2; hemophagocytic lymphohistiocytosis (HLH) n = 2; CNS vasculitis n = 1; ADEM followed by optic neuritis (ADEMON) n = 2. Cerebral white matter lesions were identified in 84.2 % of MOG-neg ADEM children. Gadolinium enhancement was noted in 11.4 % of MOG-neg ADEM children. Of 38 MOG-neg ADEM children, 9 (23.7 %) had only one atypical MRI finding, whereas 23 (60.5 %) showed multiple atypical MRI features. All children with alternative diagnoses exhibited more than one atypical MRI feature. The outcome was favorable (mRS