About Acute Flaccid Myelitis

What it is

Acute flaccid myelitis (AFM) is an uncommon but serious neurologic condition. It affects the nervous system, specifically the area of the spinal cord called gray matter, which causes the muscles and reflexes in the body to become weak.

Increases in AFM cases have occurred in 2014, 2016, and 2018 in the U.S.

Most AFM cases (more than 90%) have been in young children.

Symptoms

The most common symptoms of AFM are:

• Sudden onset of arm or leg weakness
• Loss of muscle tone
• Loss of reflexes

Causes

AFM can be caused by viruses, including enteroviruses. AFM can also be caused by other viruses, including flaviviruses (West Nile virus, Japanese encephalitis virus), herpesviruses, and adenoviruses.

Enteroviruses are common and usually cause mild illness. We are working to learn why a small number of people develop AFM after having a virus.

Prevention

Since we don't know what triggers AFM in a person, there is no specific action to take to prevent AFM. But you can take steps to prevent getting sick from a virus.

Testing and diagnosis

It is important that the tests to help with diagnosis are done as soon as possible after a patient develops symptoms.

Clinicians diagnose AFM by taking a thorough medical history, doing a physical exam, and performing an MRI to review pictures of the spinal cord.

Treatment and recovery

Currently, there is no specific treatment for AFM, but clinicians may recommend different interventions based on each patient.

There is no specific treatment for AFM, but a clinician who specializes in diseases like AFM may recommend certain interventions on a case-by-case basis. For example, clinicians may recommend physical or occupational therapy to help with arm or leg weakness caused by AFM. Physical rehabilitation might improve long-term outcomes if implemented during the initial phase of illness.

CDC is working closely with national experts to better understand how to treat AFM and will update our clinical guidance with new information when available. We are also working to understand the long-term outcomes of people with AFM.

For parents with children who have AFM

AFM can be devastating for patients and their families. CDC knows that families are facing uncertainties when it comes to their child’s recovery from AFM. We are keeping these children front and center as we work with our partners to better understand AFM, research why some people get this condition, and develop ways to treat and prevent it.