Acute Disseminated Encephalomyelitis: an update

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Acute disseminated encephalomyelitis (ADEM) is a monophasic autoimmune
demyelinating disease of the central nervous system that typically
follows a febrile infection or a vaccination. Children are
predominantly affected. A plethora of viral and bacterial pathogens and
a number of vaccinations have been associated with ADEM. Experimental
animal studies indicate that both primary and secondary autoimmune
responses contribute to central nervous system inflammation and
subsequent demyelination. The clinical diagnosis of ADEM is strongly
suggested by a close temporal relationship between an infectious
incident or an immunization and the onset of leukoencephalopathic
neurological symptoms. Paraclinical tests may support the diagnosis.
Particularly helpful are acute signs of newly developed extensive,
multifocal, subcortical white matter abnormalities on magnetic
resonance images of the brain. The cerebrospinal fluid may disclose a
mild lymphocytic pleocytosis and elevated albumin levels. Oligoclonal
bands are not always present in ADEM and, if so, may be transient. The
major differential diagnosis of ADEM is multiple sclerosis. Treatment
options for ADEM consist of anti-inflammatory and immunosuppressive
agents. In general, the disease is self-limiting and the prognostic
outcome favorable. In the absence of widely accepted clinical or
paraclinical diagnostic guidelines, a number of recently conducted
observational case series have substantially broadened our
understanding about the clinical phenotype, diagnosis, and prognosis of
ADEM.