Acute Flaccid Myelitis: Causes, Symptoms, and Treatment
Medically reviewed by Achuta Uppu, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Acute Flaccid Myelitis?
A neurologist (a doctor who treats brain and spinal cord problems) usually leads care for acute flaccid myelitis. Children often see a pediatric neurologist (a children's nerve doctor). Therapists may help with arm or leg weakness. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is acute flaccid myelitis?
Acute flaccid myelitis (AFM) is a rare but serious neurologic disease. Neurologic means it affects the nervous system, which includes the brain, spinal cord, and nerves. AFM affects an area of the spinal cord called gray matter. This can cause the muscles and reflexes in the body to become weak.
Some people call AFM a polio-like illness. But it is different from polio, and AFM is not caused by polioviruses. Most people with AFM had a mild respiratory illness or fever before they got AFM.
Symptoms
Symptoms start suddenly. Most people with AFM have:
- Arm or leg weakness.
- A loss of muscle tone, meaning floppy or limp muscles.
- A loss of reflexes.
Some people also have:
- Facial droop or weakness.
- Trouble moving the eyes or drooping eyelids.
- Trouble swallowing or slurred speech.
- Pain in the arms, legs, back, or neck.
- Numbness or tingling in the arms or legs, which is uncommon.
AFM can also weaken the muscles you need for breathing. This is called respiratory failure, when the muscles involved with breathing become weak and require machines to help patients breathe. It is one of the most severe symptoms of AFM. Serious neurologic complications such as body temperature changes and blood pressure instability could be life threatening.
Causes and who gets it
AFM can be caused by several different viruses. These include enteroviruses and other viruses, such as flaviviruses (a group that includes West Nile virus), herpesviruses, and adenoviruses. Enteroviruses are common and usually cause mild illness. Doctors are still learning why a small number of people develop AFM after having a virus.
Anyone can get AFM. But most cases, more than 90%, have been in young children.
How doctors diagnose it
AFM causes many of the same symptoms as other neurologic diseases, such as transverse myelitis and Guillain-Barre syndrome. Those are other neurologic diseases. This can make AFM hard to diagnose. Tests should be done as soon as possible after symptoms start. Doctors may use:
- A neurologic exam, looking at where there is weakness, poor muscle tone, and decreased reflexes.
- An MRI (a scan that takes pictures of the body) 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.
Treatment
There is no specific treatment for AFM. A neurologist may recommend treatments for specific symptoms. For example, physical therapy and occupational therapy may help with arm or leg weakness. Occupational therapy works on daily activities.
Physical rehabilitation might improve long-term outcomes if it is done during the first phase of the illness. Researchers do not know the long-term outcomes of people who get AFM.
When to see a doctor
Call 911 right away if you or your child suddenly has arm or leg weakness, floppy muscles, facial droop, trouble swallowing, slurred speech, or trouble breathing. AFM can weaken the muscles used for breathing.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Your doctor can check symptoms early and track recovery over time. The doctor can also refer you to a neurologist or a rehab team when needed.
Common questions
Is acute flaccid myelitis like polio?
Some people call AFM a polio-like illness, but it is different from polio. AFM is not caused by polioviruses.
Can acute flaccid myelitis be prevented?
There is no specific way to prevent AFM. But you can take steps to prevent getting sick from a virus. Wash your hands often with soap and water. Avoid close contact with people who are sick. Cover coughs and sneezes with a tissue or your upper shirt sleeve.
Who gets acute flaccid myelitis?
Anyone can get AFM. But most cases, more than 90%, have been in young children. Most people had a mild respiratory illness or fever before AFM started.
Do doctors know the long-term outlook?
Researchers do not know the long-term outcomes of people who get AFM. Health experts are still working to understand the long-term outcomes of people with AFM.
Sources
- MedlinePlus - Acute Flaccid Myelitis
- Centers for Disease Control and Prevention - About Acute Flaccid Myelitis
- Centers for Disease Control and Prevention - Signs and Symptoms of Acute Flaccid Myelitis
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
