What is acute flaccid myelitis (AFM)?

AFM is an uncommon disease that resembles polio. The disease is one of the nervous system. Muscle tone and responses become weak (flaccid). Although AFM is rare, it can be very serious, even to the point of making breathing difficult.

Before being described in 2014, AFM might have been diagnosed as a type of transverse myelitis. However, one difference between AFM and transverse myelitis has been found by magnetic resonance imaging (MRI) scans. The gray matter of the spinal cord is inflamed in people with AFM.

The number of cases of AFM has been rising. However, the Centers for Disease Control and Prevention predict that less than 1 person per 1 million people per year in the US will develop AFM. So far, most of the reported cases have involved people younger than age 18, but adults can get AFM.

What are the causes of acute flaccid myelitis (AFM)?

This disease, and diseases like it, may be caused by germs such as viruses, toxins or poisons in the environment, and possibly genetic issues. Some viruses that have been linked with AFM cases include the West Nile virus, poliovirus, and adenoviruses. Non-polio enteroviruses have also been linked to AFM and to diseases of the nervous system like AFM. Prior to the weakness setting in, the person with AFM often has symptoms of a cold-like illness, with fever and breathing issues.

What are the symptoms of acute flaccid myelitis (AFM)?

The onset of AFM is sudden (acute). Symptoms include:

  • Weakness in one or more limbs (arms, legs)
  • Flabby muscles affecting the face, head and neck, which might cause one side of the face to fall lower than the other
  • Unresponsive muscles and nerves in the mouth or throat that cause problems with swallowing or talking
  • Weakness in the eyes, so that you have drooping eyelids or problems moving your eyes.
  • Weakness in muscles and nerves in the respiratory system. You could have problems breathing, resulting in respiratory failure. At that point, a ventilator (a machine that breathes for you) is needed.
  • Pain in an arm or leg
  • Inability to urinate

With AFM, severe symptoms could result in partial paralysis or paralysis (inability to move the muscles). It is also possible that only one limb is affected severely. People with AFM generally do not have the spastic movements of someone with transverse myelitis.

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