Learn about acute flaccid myelitis, a condition in children that is similar to polio

The Centers for Disease Control and Prevention (CDC) recently asked health departments and clinicians to watch for symptoms of acute flaccid myelitis in kids, especially through November. That’s when enteroviruses are most common. The rare neurological condition causes the muscles and reflexes in the body to become weak. About 90% of the cases in the U.S. have been in young children. “Acute flaccid myelitis is a rapid-onset flaccid myelitis,“ says Dr. Jan-Mendelt Tillema, a pediatric neurologist and researcher at Mayo Clinic. “It’s an acute weakness affecting mostly the legs but can also affect the arms as well as some of the cranial nerves.“ Those affected may have sudden loss of muscle tone, loss of reflexes, difficulty breathing, swallowing and other facial functions. “The majority of the symptoms are a weakness that really progresses over the course of a few hours to days, so the child will not be able to move most of the time the upper extremities or the lower extremities. And that can continue to worsen over a short time,“ Dr. Tillema says. “Similar to polio, imaging studies of children with acute flaccid myelitis show abnormalities in the spinal cord and brain that correspond to parts of the body showing weakness. That is why it is called ’poliolike,’“ says Dr. W. Charles Huskins, a pediatric infectious diseases physician at Mayo Clinic’s Children’s Center. “The location in the spinal cord where it is affected is typically in what we call the anterior horn cells, in the front part of the spinal cord, which is where the nerves to the muscles go. Those are the exact same locations that poliovirus attack also. The reason why it’s called poliolike is because it behaves like polio. And it has a very similar flaccid myelitis, which can be seen with both conditions. It’s basically a similar illness, just a different suspected virus,“ says Dr. Tillema. “The actual polio virus was not discovered in these early cases.“ Most children who developed acute flaccid myelitis had a mild respiratory illness or fever caused by a viral infection about one to four weeks prior to their neurological symptoms. “We are still learning more about acute flaccid myelitis and its causes,“ says Dr. Huskins. “Many cases show an association with enterovirus infection in the weeks prior to the onset of acute flaccid myelitis. There are many different enteroviruses that cause infection in humans, but one type of enterovirus — enterovirus D68 — appears to be more linked to cases of acute flaccid myelitis. Enteroviruses typically circulate in the late summer and early fall. That is likely the reason that cases of acute flaccid myelitis occur at that time.“ Learn more at Mayo Clinic News Network. ____________________________________________ For the safety of its patients, staff and visitors, Mayo Clinic has strict masking policies in place. Anyone shown without a mask was recorded prior to COVID-19 or recorded in an area not designated for patient care, where social distancing and other safety protocols were followed. FOR THE PUBLIC: More health and medical news on the Mayo Clinic News Network. FOR THE MEDIA ONLY: Register at to access clean and nat sound versions of this video on the Mayo Clinic News Network. Mayo Clinic Follow Mayo Clinic on Instagram: Like Mayo Clinic on Facebook: Follow Mayo Clinic on Twitter: