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Acute disseminated encephalomyelitis in adults

Author
Amy T Waldman, MD
Section Editor
Francisco González-Scarano, MD
Deputy Editor
John F Dashe, MD, PhD

INTRODUCTION

Acute disseminated encephalomyelitis (ADEM), also known as postinfectious encephalomyelitis, is an autoimmune demyelinating disease of the central nervous system. Commonly triggered by viral infections and immunizations, ADEM is caused by an inflammatory reaction in the brain and spinal cord. Its onset is acute and often rapidly progressive. ADEM is typically monophasic, but some patients may either have recurrences, or are at risk for the development of multiple sclerosis.

This topic will review the pathogenesis, pathology, epidemiology, clinical features, diagnosis, and treatment of acute disseminated encephalomyelitis in adults. Clinical aspects of ADEM in children are discussed separately. (See "Acute disseminated encephalomyelitis in children: Pathogenesis, clinical features, and diagnosis" and "Acute disseminated encephalomyelitis in children: Treatment and prognosis".)

PATHOGENESIS

The pathogenesis of ADEM is reviewed here briefly and discussed in greater detail separately. (See "Acute disseminated encephalomyelitis in children: Pathogenesis, clinical features, and diagnosis", section on 'Pathogenesis'.)

Although the pathogenesis is incompletely understood, ADEM appears to be an autoimmune disorder of the central nervous system that is triggered by an environmental stimulus in genetically susceptible individuals. One proposed mechanism is that myelin autoantigens, such as myelin basic protein, proteolipid protein, and myelin oligodendrocyte protein, share antigenic determinants with those of an infecting pathogen. Antiviral antibodies or a cell-mediated response to the pathogen cross react with the myelin autoantigens, resulting in ADEM.

Alternatively, ADEM may be due to increased vascular permeability and congestion in the central nervous system, perhaps triggered by circulating immune complexes or other humoral factors that develop after the appearance of a foreign antigen introduced by infection or vaccination [1-4]. This process then leads to infiltration of the vessel walls by mononuclear cells, followed by perivenous edema and occasionally hemorrhages. Within days, microglia, lymphocytes, and phagocytes appear, ultimately causing demyelination and possible gliosis and necrosis. The extent of demyelination and subsequent glial and neuronal changes account for the variation in clinical features and disease prognosis.

                        

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Literature review current through: Nov 2016. | This topic last updated: Mon Jan 13 00:00:00 GMT+00:00 2014.
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