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Five things you should know about acute flaccid myelitis (AFM)

What is acute flaccid myelitis, and what steps can you take to keep your family safe? Two University of Minnesota Masonic Children’s Hospital experts share helpful information.

Recent news reports of seven Minnesota children diagnosed with a rare, polio-like disorder called acute flaccid myelitis (AFM) have made state and national headlines.

What is AFM, who is at risk and what are the warning signs? To help Minnesota parents make sense of this rare but serious illness we spoke with two University of Minnesota Masonic Children's Hospital experts, including Pediatric Infectious Disease Physician Mark Schleiss, MD, and Pediatric Neurologist Hyoung Won Choi, MD, about AFM. Here’s what families should know.

The Minnesota Department of Health is currently investigating acute flaccid myelitis cases across the state. Visit their website for more information.

What is AFM? 

Acute flaccid myelitis, or AFM, is a condition that causes severe muscle weakness and loss of muscle tone in one or more parts of the body. This profound weakness is caused by inflammation of the spinal cord. AFM is believed to be caused by certain infections—most of them viral—that attack the spinal cord and damage it. Most of these viruses—known as enteroviruses—are common infections that everyone eventually acquires. No one knows why these viruses affect the spinal cord in only a tiny fraction of the population. Other germs, such as the bacterium that causes Lyme disease, can also cause AFM in some patients. AFM primarily affects children, but adult cases have also been reported.

“A common misconception about AFM is that it’s a muscle problem that causes a child to be unable to move an arm or a leg. But it’s not a disease within the arm muscles or leg muscles. The problem is in the spinal cord. AFM is an inflammatory condition of the grey matter in the spinal cord,” said Pediatric Infectious Disease Physician Mark Schleiss, MD.

The weakness that defines AFM can start anywhere in the body, including a child’s arms or legs, facial muscles and eye muscles. In severe cases, it can also affect the muscles that control swallowing or breathing. The weakness appears random and is often on one side of the body (for example, the right leg might be affected, but not the left leg).

Even though the viruses and germs that may cause it are extremely common, AFM is very rare, affecting less than one in a million people. The Centers for Disease Control and Prevention have identified a few hundred cases of AFM since they began tracking the condition in 2014.

What are the warning signs and long-term effects of AFM?

AFM tends to arrive suddenly. Often, the first symptom is sudden weakness in a muscle group, followed by the loss of muscle tone in one area of the body. Cases affecting a child’s facial muscles may be accompanied by facial drooping, challenges with swallowing or speaking and difficulty moving the eyes. A spinal MRI is needed to confirm an AFM diagnosis and is coupled with a full diagnostic workup, including a lumbar puncture (spinal tap) to eliminate other potential causes and attempt to identify the virus or germ responsible.

Once a virus or other germ damages the spinal cord’s cells, those cells cannot regenerate. There is no known cure for AFM. Children are typically treated with high-dose steroids, which appear to help reduce the inflammation associated with the infection that has produced AFM. However, there is hope. Many children can recover functional abilities and complete daily living activities with the help of physical therapy and occupational therapy, depending on the area affected by AFM. 

“Even though the spinal cord does not go back to normal, we have seen amazing things as children adapt and compensate,” Schleiss said.

Who is at risk? 

AFM can affect anyone, but the condition seems to be more common in children. “Although we have data on several similar conditions, such as poliomyelitis or transverse myelitis, we don’t yet have reliable long-term studies that indicate who might be at greater risk of developing AFM, or the individual chances of a full recovery,” said Pediatric Neurologist Hyoung Won Choi, MD.

What should a parent do if you suspect your child may have it? 

If your child suddenly becomes unable to move a part of his or her body—including an arm, a leg, the face, or the eyes—contact your child’s doctor right away or bring your child to the pediatric emergency department at University of Minnesota Masonic Children’s Hospital.
Children diagnosed with AFM will benefit from a multidisciplinary healthcare team to help regain as much function as possible.

What prevention steps can parents take, if any? 

The steps you can take to prevent AFM are the same steps you should take to prevent any other infection—frequent and careful hand washing. Good hand hygiene is the number-one way to avoid infections of all kinds. In order to reinforce good habits, parents may want to supervise their children as they wash their hands. Experts recommend washing with warm water and soap for 30 seconds.