Acute flaccid myelitis

Acute flaccid myelitis (AFM) is a rare disease that affects the spinal cord, the part of the nervous system that carries messages to and from the brain. Symptoms of AFM include sudden (acute) weakness in the arm(s) or leg(s), along with loss of muscle tone and decreased or absent reflexes. Some people with AFM report pain. In some cases, AFM can affect the nerves controlling the head and neck, causing facial weakness, drooping of the eyelids, and difficulty swallowing, speaking, or moving the eyes. The most serious complication of AFM is respiratory failure if the muscles involved with breathing become weakened. Most cases of AFM have been in children, but it can develop in adults.

Many times symptoms of AFM develop after a viral infection, such as poliovirus, West Nile virus, and adenovirus. In some cases no clear possible cause is found. In addition, even when associated with a viral infection, it is not known how the infection triggers AFM, and it is not clear why some people develop AFM after an infection and others do not.

AFM can be difficult to diagnose because the symptoms are similar to other neurological diseases, such as Guillain-Barre syndrome (GBS), acute disseminated encephalomyelitis (ADEM), and transverse myelitis. Diagnosis may include a physical exam, an MRI of the spine, testing of the cerebral spinal fluid (CSF), and tests checking nerve speed (nerve conduction velocity; NCV) and the response of muscles to the messages from the nerves (electromyography; EMG).

To prevent infections by AFM-related viruses , specialists recommend staying up-to-date with polio vaccines and to minimize exposure to mosquitoes. There is no specific treatment for AFM. Treatments that have been tried include immunoglobulin, corticosteroids, plasma exchange, and antiviral therapy, but there is no clear evidence that any of these treatments affect recovery. Other treatment is supportive and depends on the symptoms. Physical therapy and occupation therapy are especially important during recovery. The extent of recovery varies. Although some people may make a full recovery, most have continued muscle weakness even after a year. Long term outcomes are not known.

For more detailed information about acute flaccid myelitis, you may visit the Centers for Disease Control and Prevention (CDC) webpage.