Acute Flaccid Myelitis

What is acute flaccid myelitis (AFM)?

Acute flaccid myelitis (AFM) is a neurologic disease. It is rare but serious. It affects an area of the spinal cord called gray matter. This can cause the muscles and reflexes in the body to become weak.

Because of these symptoms, some people call AFM a “polio-like” illness. But since 2014, people with AFM have been tested, and they did not have poliovirus.

What causes acute flaccid myelitis (AFM)?

Researchers think that viruses, including enteroviruses, likely play a role in causing AFM. Most people with AFM had a mild respiratory illness or fever (like you would get from a viral infection) before they got AFM.

Who is at risk for acute flaccid myelitis (AFM)?

Anyone can get AFM, but most cases (more than 90 percent) have been in young children.

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

Most people with AFM will suddenly have

Arm or leg weakness
A loss of muscle tone and reflexes

Some people also have other symptoms, including

Facial drooping/weakness
Trouble moving the eyes
Drooping eyelids
Trouble swallowing
Slurred speech
Pain in the arms, legs, back, or neck

Sometimes AFM can weaken the muscles that you need for breathing. This can lead to respiratory failure, which is very serious. If you get a respiratory failure, you may need to use a ventilator (breathing machine) to help you breathe.

If you or your child develops any of these symptoms, you should get medical care right away.

How is acute flaccid myelitis (AFM) diagnosed?

AFM causes many of the same symptoms as other neurologic diseases, such as transverse myelitis and Guillain-Barre syndrome. This can make it difficult to diagnose. The doctor may use many tools to make a diagnosis:

A neurologic exam, including looking at where there is weakness, poor muscle tone, and decreased reflexes
An MRI to look at the spinal cord and brain
Lab tests on the cerebrospinal fluid (the fluid around the brain and spinal cord)
Nerve conduction and electromyography (EMG) studies. These tests check nerve speed and the response of muscles to the messages from the nerves.

What are the treatments for acute flaccid myelitis (AFM)?

There is no specific treatment for AFM. A doctor who specializes in treating brain and spinal cord illnesses (neurologist) may recommend treatments for specific symptoms. For example, physical and/or occupational therapy may help with arm or leg weakness. Researchers do not know the long-term outcomes of people with AFM.