Acute Flaccid Myelitis: A reassuring primer for parents

The Pediatric Insider

© 2016 Roy Benaroch, MD

Nina wrote in: “Hi Dr. Roy. There has been a lot of discussion in the media lately around acute flaccid myelitis (AFM). This I am sure as it is for many parents is terrifying, especially when you are a card carrying vaccination parent (which doesn’t matter in this case from what I understand)! Any insight you can provide here would be so much appreciated.”

AFM has been in the news a lot lately, typically with breathless click-bait headlines.  The Washington Post, never stingy with words, came up with “A mysterious polio-like illness that paralyzes people may be surging this year.”  Huffpo’s headline was more direct: “A mysterious neurological condition is paralyzing children” The antivaccine sites (to which I will not provide links), predictably, blame it on vaccines, because they blame everything on vaccines. Which is ironic, because we’ve been able to prevent almost all historical cases of this condition with vaccination. It’s a funny world, sometimes.

Anyway: there’s no need to panic. While there’s more to learn about AFM, it’s not as mysterious as these headlines would lead you to believe – and it’s really rare.

 

What’s AFM, anyway?

AFM (Acute Flaccid Myelitis) is a disease of the nervous system. Inflammation causes damage to one section of the spinal cord, leading to weakness of one or more extremities. Sometimes, the weakness affects muscles in the head or neck. There’s typically no changes in sensation like numbness or tingling. The brain is not affected, so there aren’t symptoms like fuzzy thinking, seizures, or coma.

The words in the name AFM describe its key features: it’s Acute, meaning it starts suddenly; it’s Flaccid, meaning muscles are weak or floppy; and it’s a Myelitis, meaning there’s inflammation of the spinal cord.

 

What causes it?

Historically, almost all cases were caused by polio. 60 years ago, poliovirus infected about 60,000 children per year – thousands of whom became paralyzed. Polio has been entirely eradicated in the US and in most of the rest of the world. But until it’s 100% gone, we need to stay vigilant and keep vaccinating. We know that interruptions in vaccine programs have led to the return of polio to areas of Africa and Asia – and polio could come back here, too.

Though polio itself is not causing any of these AFM cases in the United States now, poliovirus has cousins – other viruses in the enterovirus family. One that seems to be associated with many cases of AFM is a relatively new enterovirus, called D68. Other new or “newish” viruses can cause AFM, too, like West Nile Virus. And some cases seem to be associated with other well-known or common viruses, like adenovirus.

 

That sounds kind of weaselly. How can one disease be caused by different viruses? And what’s with the “seems to” and “associated with” stuff? I just want a straight answer!

Medicine is messy sometimes, and often there are multiple causes for similar conditions. The common cold can be causes by dozens of different viruses (rhinovirus, coronavirus, human metapneumovirus, and many others), and pneumonia can be causes by a whole slew of viruses, bacteria, or even fungal infections. It would be simpler if we said that there was one cause of AFM, but it wouldn’t be true.

And those “seems to” kinds of phrases – that’s what happens when we’re accurate. Some cases of AFM will occur in children who have a definite viral diagnosis, but sometimes the tests are done too late to know for sure what the cause was. That doesn’t mean we’re completely in the dark, or that this is a huge mystery illness.

 

Who is catching this? How serious is it?

Children, mostly. So far in 2016, 89 people have been reported with AFM nationwide, mostly in the western states, and most cases have occurred in kids (average age, about 7.)

The best long term data we have on the outcome of AFM are from a case series from 2014. Though there we no deaths, many of the children did not have a return to normal muscle functioning. Supportive care has helped prevent complications, but so far no specific therapy has seemed to help these children recover.

 

What should parents do?

Don’t panic. Take a break from media and Facebook, and spend some time playing with your kids instead of reading about the Next Big Danger.

Though AFM remains rare, there are ways to prevent at least some cases. Make sure your child is fully vaccinated (that eliminates not only the risk of polio, but greatly reduces the risk of many other neurologic illnesses, including meningitis and encephalitis associated with influenza, mumps, and other causes). Try to avoid mosquito bites (which rarely can spread West Nile Virus and other causes of encephalitis). Wash hands, use hand sanitizer, try not to be around sick people, keep your children home when they’re sick, and get into the habit of not touching your face with your fingers. I know, that stuff sounds simple, but those are the best ways to keep your children healthy.

More about AFM from the CDC

keep calm

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