ABSTRACT
Acute disseminated encephalomyelitis (ADEM) is an acute inflammatory demyelinating disease of the brain and spinal cord characterized by widespread perivascular inflammation and demyelination and caused by an autoimmune attack on the brain, most commonly as a reaction to a viral infection. Microscopic pathology shows perivascular inflammation and patchy demyelination of the white matter tracts of the cerebral hemispheres, brainstem, spinal cord, and optic nerves. Significant axon destruction. ADEM is thought to be an autoimmune disease, partly because of the inability to isolate an infectious agent from the central nervous system, and because of experimental models of autoimmune diffuse white matter encephalomyelitis that can be induced in animals, or accidentally in humans, by injection of the myelin antigens with adjuvant. Acute necrotizing encephalopathy/acute hemorrhagic necrotizing encephalopathy is a devastating parainfectious encephalopathy originally described as a childhood illness, usually in the context of influenza, but later recognized in adults.
