Post-infectious Encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disorder of the central nervous system characterized by encephalopathy and polyfocal CNS neurological deficits, with higher incidence in children. It can be triggered by an immunological stressor such as an infection. It is important to differentiate ADEM from acute infectious encephalomyelitis because the mainstay of therapy for ADEM is immunosuppression such as with corticosteroids. ADEM is typically a monophasic syndrome with favorable outcome. However, recently described variants with antibody or paraneoplastic-associated disease may portend a relapsing course or require tumor screening. Examples of these include autoimmune astrocytopathies such as myelin oligodendrocyte glycoprotein (MOG)-IgG-associated encephalomyelitis and aquaporin 4 (AQP4)-associated neuromyelitis optica spectrum disorders (NMOSD), as well as autoimmune encephalitides associated with antibodies against neuronal surface antigens such as N-Methyl-D-aspartate (NMDAR) receptor encephalitis. Additionally, it is critical to differentiate ADEM from a first attack of a chronic demyelinating disorder such as multiple sclerosis (MS).