We’ve gotten an email or two telling us to look out for Acute Flaccid Myelitis (AFM). What is it? Why does it matter?
AFM causes flaccid weakness to one or more limbs rapidly in a polio-like neurologic fashion. There can also be cranial nerve involvement, including ophthalmoplegia and dysarthria. There were 80 cases in the past 11 months, 3 times more compared to last year, the largest spike being in September.
What population should I be thinking of? The median age was 4 years with 99% having a preceding viral illness, usually respiratory or GI with majority having a fever (sounds like so much of peds).
What limbs are affected? Upper limb only was seen in about 47% of cases, lower limb only in 8.8%, 2-3 limbs in 15%, and all 4 limbs in 28.8%.
Confirmed cases reveal spinal cord lesions in the gray matter and probable cases have pleocytosis (>5 WBC per mm3, usually lymphocyte predominant) in the CSF. Enterovirus and rhinovirus were the most commonly detected viruses, although direct causation has not been established.
What can we do to help these people? Supportive care. Steroids, IVIG, plasmapheresis, antivirals, and immune-modulators like interferon haven’t been shown to be effective although more research is needed. 20-35% will have respiratory failure and require mechanical ventilation. Most kids will have persistent motor deficits and muscle atrophy in the affected limb for >1 year.
Resources:
https://www.cdc.gov/mmwr/volumes/67/wr/mm6745e1.htm?s_cid=mm6745e1_w
https://www.uptodate.com/contents/polio-and-other-infectious-causes-of-acute-flaccid-paralysis?sectionName=ACUTE%20FLACCID%20MYELITIS&topicRef=8365&anchor=H32712333&source=see_link#H32712333
http://www.ajnr.org/content/36/2/245/F4
