Abstract. Acute disseminated encephalomyelitis (ADEM) is a monophasic acute non-vasculitic inflammatory demyelinating disorder of the central nervous system characterized by diffuse neurologic signs and symptoms coupled with evidence of multifocal lesions of demyelination on neuroimaging. Despite the long-standing recognition of ADEM as a specific entity, no consensus definition of ADEM had been reached until recently. Historically, different definitions of ADEM have been used in published cases of pediatric and adult patients, which varied as to whether events required (1) monofocal or multifocal clinical features, (2) a change in mental status, and (3) a documentation of previous infection or immunization. The treatment has been given to the patient such as supportive therapy and high dose corticosteroids. Keywords: ADEM, neuroimaging, immunotherapy.