Acute Disseminated Encephalomyelitis

Abstract

Acute disseminated encephalomyelitis (ADEM) is an immune-mediated demyelinating central nervous system (CNS) disorder with predilection to early childhood. ADEM is generally considered a monophasic disease. ADEM often occurs postinfectiously although a casual relationship has never been established. ADEM is clinically defined by acute polyfocal neurologic deficits including encephalopathy. MRI typically demonstrates reversible, ill-defined white matter lesions of the brain and often also the spinal cord, along with frequent involvement of thalamy and basal ganglia. CSF analysis may reveal a mild pleocytosis and elevated protein, but is generally negative for intrathecal oligoclonal immunoglobulin G synthesis. In the absence of a specific diagnostic test, ADEM is considered a diagnosis of exclusion. The role of biomarkers, including autoantibodies like antimyelinoligodendrocyte glycoprotein, in the pathogenesis and diagnosis of ADEM is currently under debate. Based on the presumed autoimmune etiology of ADEM, the current treatment approach consists of early immunotherapy. Outcome of ADEM in pediatric patients is generally favorable, but cognitive deficits have been reported even in the absence of other neurologic sequelae. This review summarizes the current knowledge on epidemiology, pathology, clinical presentation, neuroimaging features CFS findings, differential diagnosis, therapy, and outcome, with focus on recent advances and controversies.