Characteristics and Predictors of Disease Course in Children Initially Presenting with Acute Disseminated Encephalomyelitis (ADEM)

Abstract

Background: Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disease of the central nervous system (CNS), characterized by new onset polyfocal neurologic symptoms with encephalopathy and multifocal demyelination, typically occurring in early childhood. The initial diagnosis of ADEM can be challenging, as up to 20% of children with multiple sclerosis (MS) or neuromyelitis optica spectrum disorder (NMOSD) are initially diagnosed with ADEM. Objective:To describe characteristics of patients with ADEM vs. recurrent demyelinating syndromes (MS, NMOSD, other) at the time of initial presentation and identify features at disease onset of presentations consistent with ADEM associated with monophasic demyelinating disease. Methods: This is a multicenter observational cohort study of children with a demyelinating disease diagnosis of ADEM, multiphasic ADEM, MS, and NMOSD who were followed at 12 regional pediatric MS referral centers in the US Network of Pediatric MS Centers. Descriptive statistics were used to report patient characteristics, clinical/imaging presenting features and subsequent outcomes. Logistic regression was used to predict features associated with a monophasic course. Results: As of July 2019, 872 pediatric patients with a final diagnosis of ADEM (n=89), MS (n= 664) or NMOSD (n=119) were identified. The mean +/- standard deviation follow-up for all patients was 5·7 +/- 3·1 years. ADEM patients were the youngest with mean age at first event 5·4 +/- 3·7 years (p < 0.001) and male predominance (62%) (p < 0·001). Severe clinical symptoms at onset were more frequent in ADEM (55% vs. 35% NMOSD and 15% MS, p < 0·001). After 2 years of follow-up, 78% (93/119) of patients initially diagnosed with ADEM retained this diagnosis (ADEM to ADEM), while 9·2% were later reclassified as MS, 3·3% as NMOSD and 7·5% as demyelinating disease not otherwise specified (DDNOS). In univariable logistic regression, younger age at first event was associated with retaining ADEM diagnosis, while presentation with optic neuritis and gadolinium enhancement on brain MRI were associated with ADEM reclassification to MS, NMOSD, or DDNOS at 2 years of follow-up. In multivariable analysis, older age at first event (OR 1·16 [95% CI 1·00 – 1·33] for 1-year increase, p = 0·04), presenting with optic neuritis (OR 15·31 [95% CI 3·27 – 71·66], p <0·001) and presence of gadolinium enhancement on brain MRI at onset (OR 6·80 [95% CI 2·03 – 22·78], p = 0·0019) were associated with reclassification of ADEM to MS, NMOSD or DDNOS within 2 years. Conclusion: Children who remain classified as ADEM vs. those who are reclassified as other demyelinating disorders are younger at onset, and less likely to have optic neuritis or gadolinium-enhancing lesions at disease onset. Funding: None to declare. Declaration of Interest: None to declare. Ethical Approval: The ethics committees of participating institutions approved this study. Parents and participants signed consent forms and assent forms when required by each center’s institutional review board prior to enrollment.