Demyelination

Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease that affects all ages, except children less than 2 years. It occurs during the course of various infections, particularly the acute exanthematous diseases of childhood (measles, rubella, chickenpox, and smallpox immunization), other common viral infections (i.e., Epstein-Barr virus, adenovirus, cytomegalovirus, influenza, rhinoviruses, coronaviruses), and following vaccination against smallpox, measles, and rabies. The clinical features are the same regardless of the inciting event. The symptoms develop days to weeks after the onset of the predisposing cause. The symptoms and signs of acute disseminated encephalomyelitis are related to the portion of the central nervous system (CNS) that is most severely damaged. Death occurs in 20%–30%. There are neurological deficits in survivors.