Acute hemorrhagic leukoencephalitis (AHL)
is a very rare form of acute disseminated encephalomyelitis that usually results in death. It is characterized by a brief but intense attack of inflammation in the brain and spinal cord that damages the myelin -- the protective covering of the nerve fibers. It may also cause bleeding in the brain, leading to damage of the white matter. Symptoms usually come on quickly, beginning with symptoms such as fever, neck stiffness, fatigue, headache, nausea vomiting, seizures, and coma. AHL has a very poor prognosis, with rapid deterioration and death usually occurring within days to one week after onset of symptoms because of severe inflammation in the brain. Although the exact cause is unclear, AHL usually follows a viral infection, or less often, vaccination for measles, mumps, or rubella. Some researchers think that an infection or vaccination can initiate an autoimmune process in the body thus leading to AHL. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.