Acute Flaccid Myelitis

Source: MedlinePlus Health Topics, U.S. National Library of Medicine

Last synced 8/9/2026Status: primary verified

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 it is different from polio . AFM is not caused by polioviruses. What causes acute flaccid myelitis (AFM)? AFM can be caused by several different viruses. Researchers think that enteroviruses have been causing the recent increases in the number of children with AFM. AFM can also be caused by other viruses, including flaviviruses, herpesviruses, and adenoviruses. 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 more likely to develop acute flaccid myelitis (AFM)? Anyone can get AFM, but most cases (more than 90%) 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 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, 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. To find out if you have AFM, your doctor may use: A neurologic exam , including looking at where there is weakness, poor muscle tone, and decreased reflexes An MRI to look at the spin

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This information is for general education and is not medical advice. Always talk to a licensed U.S. clinician about your situation, medications, or treatment decisions.