Acute flaccid myelitis (AFM): a condition affecting the nervous system characterized by sudden weakness in one or more limbs with loss of muscle tone and decreased or absent reflexes. Some patients with AFM also have weakness of facial muscles or problems with speech or swallowing. Acute flaccid myelitis is due to damage to nerves in the spinal cord and can result from different causes. Viral infections are one known cause of acute flaccid myelitis, including infections by poliovirus and other non-polio enteroviruses, flaviviruses (such as West Nile virus), and adenoviruses. Autoimmune reactions may also cause acute flaccid myelitis.
REFERENCE: Centers for Disease Control and Prevention. "Acute Flaccid Myelitis." Updated: Nov 01, 2016.