What is "sclerosing leukoencephalitis"

n. a rare chronic progressive encephalitis caused by the measles virus and occurring primarily in children and young adults; death usually occurs within three years; characterized by primary measles infection before the age of two years [syn: subacute sclerosing panencephalitis, SSPE, inclusion body encephalitis, subacute inclusion body encephalitis, subacute sclerosing leukoencephalitis, Bosin's disease, Dawson's encephalitis, Van Bogaert encephalitis]