Acute Flaccid Myelitis vs. Polio
Acute flaccid myelitis (AFM) is not always the same as polio despite their similarities, such as causing paralysis and typically affecting children.

No, acute flaccid myelitis (AFM) is not always the same as polio (also called poliomyelitis). Recent outbreaks (between 2014 and 2018) of AFM have led people to believe that polio is back. However, none of the AFM patients have tested positive for the poliovirus. This indicates that AFM is a different disease, meaning it may be caused by the poliovirus as well as non-polioviruses.

Polio was the cause of paralysis in many children and adults in the early 1950s. Since then, the virus was completely eradicated from the United States by 1979 through vaccination.

Polio and AFM do share similarities, such as causing paralysis and muscle weakness and typically occur in children. Poliovirus causes polio, whereas doctors do not know what exactly causes AFM. Many cases of AFM seem to emerge from infection with a virus (Enterovirus D68) that affects the respiratory system and results in symptoms of a cold. There is no research to back up how the virus triggers the infection in AFM.

AFM is a rare condition that affects fewer than one in a million children in the United States each year.

What are the symptoms of acute flaccid myelitis?

The initial symptoms of acute flaccid myelitis (AFM) are similar to the symptoms of a cold, which may include:

As the condition progresses, the symptoms progress to include:

  • Muscle weakness in the arms and legs
  • Facial weakness
  • Difficulty speaking, swallowing, or breathing (in severe cases)

Polio can also cause these symptoms in some severe cases. A complication of polio called paralytic polio can cause flaccid paralysis, in which the limbs become loose and weak. The condition can progress and lead to permanent muscle and limb weakness.

A few other similarities between polio and AFM include:

  • Breathing difficulties, requiring the use of external respiratory support (ventilator)
  • Some patients achieve their usual muscle functions faster, whereas others suffer from lifelong paralysis

How is acute flaccid myelitis diagnosed?

To diagnose acute flaccid myelitis (AFM), doctors will analyze the child’s signs and symptoms and their medical history. They will perform a neurological exam that will let them know about the functioning of the child’s muscles and nerves.

Confirming an AFM diagnosis may require tests such as:

  • Magnetic resonance imaging: Electromagnetic waves focused on the spinal region look for specific abnormalities that may indicate AFM.
  • A lumbar puncture (or a spinal tap): Removal of the cerebrospinal fluid (CSF) from the spinal cord with the help of a needle. CSF is then sent to the lab for analysis.
  • Nerve conduction studies or electromyography: The test looks for the transmission of electric signals from nerves to the muscles and the response of the muscles to these signals.

Other tests, such as blood and urine tests or testing the fluid from the nose or throat, may also be ordered to rule out other causes.

In comparison, to diagnose polio, doctors perform a physical exam, test the swab from the throat, and order stool tests.

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How is acute flaccid myelitis treated?

Supportive care

Acute flaccid myelitis (AFM) requires supportive care, especially for children who are facing breathing issues. These children need artificial breathing techniques, such as mechanical ventilation. Mechanical ventilation uses an external machine (ventilator) that does the work of the respiratory muscle (diaphragm) to allow the patient to breathe in.

Rehab program

Children who live with muscle weakness persisting for months or years can be enrolled in rehab programs, which help them strengthen their muscles and move their bodies.

Nerve transfer

Nerve transfer surgery has been successfully used in some patients. In this surgery, nerve tissue from a donor is transferred to the child affected with AFM.

Can acute flaccid myelitis be prevented?

While polio can be prevented by getting a polio vaccine, there is no way to prevent acute flaccid myelitis (AFM). However, people can help prevent the possible cause of AFM, Enterovirus D68, and other viruses by taking simple measures that include:

  • Make sure the child follows the rules of proper handwashing, such as using soap and water, especially after using the bathroom
  • Stay away from people who are sick
  • Do not share cups or eating utensils with people who are sick

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Medically Reviewed on 9/29/2021
References
Greenberg B. Acute Flaccid Myelitis. UpToDate. https://www.uptodate.com/contents/acute-flaccid-myelitis

Greb E. Consensus on Diagnosis, Management of Acute Flaccid Myelitis. Medscape. https://www.medscape.com/viewarticle/944568