Acute Disseminated Encephalomyelitis

Filippi, Massimo; Rocca, Maria A.

Acute disseminated encephalomyelitis (ADEM) is an autoimmune demyelinating disease of central nervous system (CNS). ADEM is most commonly seen in children, although adults can also be affected. The disease typically starts with an abrupt onset within day to weeks after a viral infection or immunization. Presenting features include an acute encephalopathy with multifocal neurologic signs and fever. ADEM generally has a monophasic course, although recurrent ADEM has also been described and is defined as multiphasic ADEM. MRI shows widespread lesions located in both brain and spinal cord. An involvement of basal ganglia and thalami has also been described. Analysis of cerebrospinal fluid (CSF) may reveal mild lymphocytic pleocytosis and increased proteins, whereas oligoclonal bands are usually negative. In the absence of specific biologic markers, ADEM remains a diagnosis of exclusion and it is still based on clinical manifestations, imaging, and laboratory features. Therapy is based on steroid administration and the prognosis is usually favorable.