Characteristics and predictors of disease course in children initially presenting with ADEM.

ADEM is an inflammatory disease, with new onset polyfocal neurologic symptoms, encephalopathy and multifocal demyelination, typically in childhood. Initial diagnosis of ADEM is challenging and up to 20 % of children with MS or NMOSD are initially diagnosed with ADEM. We describe characteristics of patients with monophasic ADEM vs. recurrent demyelinating syndromes at onset and identify features consistent with monophasic course. This is a multicenter observational study of children with demyelinating disease, followed at 12 regional pediatric MS centers. Descriptive statistics were used to report patient characteristics, clinical/imaging features and outcomes. Logistic regression was used to predict features associated with monophasic course. As of July 2019, 837 children with final diagnosis of ADEM (n = 79), MS (n = 646) or NMOSD (n = 112) were identified. The mean follow-up was 5·7 +/- 3·2 years. ADEM patients were youngest with mean age at first event 5·2 +/- 3·8 years (p < 0.001) and male predominant (66 %) (p < 0·001). After 2 years of follow-up, 83 % of patients initially diagnosed with monophasic ADEM retained this diagnosis. In multivariable analysis, older age (OR 1·16 [95 % CI 1·02 - 1·33] for 1-year increase, p = 0·02), presenting with optic neuritis (OR 8.18 [95 % CI 1.88 - 35.64], p = 0·005) and presence of gadolinium enhancement (OR 4.08 [95 % CI 1.38 - 12.08], p = 0·011) were associated with reclassification of ADEM to MS, NMOSD or DDNOS within 2 years. Children with monophasic ADEM vs. those reclassified as other demyelinating disorders are younger at onset, and less likely to have optic neuritis or gadolinium-enhancing lesions at onset.