Acute disseminated encephalomyelitis (ADEM) is a monophasic inflammatory disorder of the central nervous system (CNS). Unlike viral encephalitis, microorganisms do not invade the CNS. Instead, ADEM is a postinfectious disease mediated by auto-reactive cells or molecules. Clinical characteristics of ADEM are consistent with disseminated involvement of the CNS, including encephalopathy and pyramidal, cerebellar, and brainstem signs. Bilateral optic neuritis and transverse myelitis are particularly suggestive of demyelinating diseases such as ADEM. Unlike viral encephalitis, seizures rarely are a prominent symptom. The most useful diagnostic investigation is magnetic resonance neuroimaging that commonly shows multifocal lesions throughout the brain and spinal cord. As ADEM is an immune-mediated disorder, treatment includes immunomodulatory therapies (particularly steroids), although no clinical trials have been performed to define the most efficacious agent. In view of the treatment differences between ADEM and viral encephalitis, being familiar with ADEM is essential for pediatricians managing acute neurological disorders.
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