Acute flaccid myelitis (AFM) is a rare, polio-like condition that affects the spinal cord, causing muscle weakness and paralysis, typically in the arms and legs. It is most often seen in children. The majority of patients fully recover from the illness, but some have permanent impairment.

What Are AFM and Other Polio-Like Diseases?

While fewer than one in one million people develop AFM in the U.S. each year, the numbers have spiked each fall since 2014, causing concern among public health officials. Research is underway to try and understand the reason for the increase. Making that effort more challenging is the fact that there is currently no diagnostic test for the illness. Doctors make a diagnosis based on criteria from the Centers for Disease Control and Prevention (CDC), which includes performing an MRI to look for spinal cord lesions. Mild cases can be especially difficult to identify.

AFM Symptoms

Most people who develop AFM experience sudden weakness in the limbs and loss of muscle tone and reflexes. Some patients also have symptoms that include:

• Drooping of facial muscles or eyelids
• Difficulty moving their eyes
• Slurred speech
• Difficulty swallowing
• Respiratory failure
• Inability to urinate
• Pain in their arms or legs
• Numbness or tingling in their arms or legs

There is no treatment for AFM, but doctors can provide supportive care to address the symptoms. Respiratory issues are the most serious consequence of AFM, these may require prompt medical attention and ventilator treatment.

AFM Causes and Risk Factors

The exact cause of AFM is unknown. Experts believe that infections with certain viruses including the poliovirus (even though AFM is not polio), West Nile virus or enterovirus D68, which typically causes summer colds, may play a role in developing the condition. Patients tend to have a fever or respiratory illness before developing muscle weakness. Other possible causes, such as genetic disorders and environmental toxins, are being researched as well.

Who is most at risk of developing AFM? Scientists do not yet know. In many of the diagnosed cases, the patients are healthy children who developed a minor viral infection.

Preventing AFM

AFM itself is not contagious, but the viruses thought to be factors in developing the condition are contagious. Consequently, many of the recommended prevention measures involve hygiene. The CDC advises people to:

• Wash hands frequently and effectively
• Disinfect surfaces at home and work
• Cough or sneeze into the bend of their elbow
• Avoid sharing food and beverages
• Get recommended vaccinations

If you or a family member develops sudden limb weakness at any time, but especially following a viral infection, it is important to talk with your doctor right away.