Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Acute Disseminated Encephalomyelitis ?
    ### Response:
    Acute disseminated encephalomyelitis (ADEM) is characterized by a brief but widespread attack of inflammation in the brain and spinal cord that damages myelin  the protective covering of nerve fibers. ADEM often follows viral or bacterial infections, or less often, vaccination for measles, mumps, or rubella.
    