Acute disseminated encephalomyelitis (ADEM) was originally described in the medical literature more than 200 years ago. However, consensus clinical diagnostic criteria are less than 15 years old. Accurate diagnostic testing for myelin oligodendrocyte glycoprotein (MOG) autoantibodies has only become clinically available in the last 3–5 years and has facilitated a rapidly evolving understanding of patients with recurrent demyelination following ADEM. The field is working to optimize treatment for these patients with hopes of prospective treatment studies in the not too distant future. New imaging data suggest that even monophasic demyelination may have long-term impacts that were previously unrecognized. Recent developments in the literature are described in order to guide practice for providers who treat both adults and children with monophasic and recurrent forms of ADEM with and without MOG antibodies.

The recent 2017 McDonald Criteria for MS provide a simplified means to confirm diagnosis at onset and over time, and have been shown to be equally applicable for POMS. MRI analyses demonstrate that brain volume is reduced at onset, and that both volumetric and tissue integrity measures decline over time, indicating that POMS shares the degenerative aspects that also characterize adult-onset disease. The presence of myelin oligodendrocyte glycoprotein (MOG) antibodies at onset is detected in more than 50% of children with acute disseminated encephalomyelitis. When persistent over time, they are associated with relapsing disease. The first randomized clinical trials of disease supports superiority of fingolimod over subcutaneous interferon beta 1a, and demonstrated a favorable safety profile. Finally, while Expanded Disability Status Scale (EDSS) scores remain low in the first 10 years post-onset, POMS is associated with high rates of patient-reported fatigue and reduced engagement in exercise and carries a risk for cognitive impairment. The past 15 years have borne witness to a marked expansion in recognition and research in POMS. There are now more specific diagnostic criteria, antibodies to CNS proteins appear to define diagnostically distinct disorders, clinical trials have successfully launched and one has completed, and we are gaining increasing appreciation of the impact of MS and related disorders on the lived experience of children and adolescents.

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