Acute disseminated encephalomyelitis (ADEM) is a neurological condition characterized by a brief but intense attack of inflammation in the brain and spinal cord that damages myelin, the protective covering of nerve fibers. Acute disseminated encephalomyelitis usually occurs following a viral infection but may appear following vaccination, bacterial or parasitic infection, or even appear spontaneously. As it involves autoimmune demyelination, it is similar to multiple sclerosis.