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Researchers look for more restrictive AFM diagnostic criteria to identify cases
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The CDC case definition of acute flaccid myelitis, or AFM, may be too broad and include children who have alternative diagnoses, according to research published in JAMA Pediatrics. Restricting the criteria used to diagnose the condition may allow physicians to better identify those with the condition, researchers said.
“A more precise definition of AFM is needed to facilitate the research that will help us understand causes, treatment and prevention of the disease,” Matthew J. Elrick, MD, PhD, from the department of neurology at Johns Hopkins University School of Medicine, told Infectious Diseases in Children. “The existing case definition performs well for its epidemiologic purpose of ascertaining all potential cases of AFM. However, we showed that this definition also captures patients with possible alternative diagnoses.”
Elrick and colleagues conducted a retrospective case analysis of 45 children aged younger than 18 years who were diagnosed with AFM between 2012 and 2015 using the CDC case definition. These children were separated into three groups: One group included children recruited from the United States and Canada with CDC-defined AFM, and two groups that included patients who had suspected AFM and were referred to the Johns Hopkins Transverse Myelitis Center for evaluation.
Three neurologists reviewed patient records and imaging data to determine whether definable alternative diagnoses could be made. All other patients were defined as having “restrictively defined AFM.”
Elrick said that identifying traits shared among children with restrictively defined AFM may be useful in determining inclusion criteria for future research studies.
The average age of the children was 6.1 years. Most were boys (60%) and white (82%). Three patients were Asian, and one was Hispanic.
Of the 45 cases, 11 were given alternate diagnoses, including transverse myelitis, other demyelinating syndromes, spinal cord stroke, Guillain-Barré syndrome, Chiari 1 myelopathy and meningitis. The remaining 34 patients were diagnosed with restrictively defined AFM. Infectious diseases were identified in all patients with restrictively defined AFM and in 63.6% of those with an alternate diagnosis.
The researchers noted that children with restrictively defined AFM were more likely to have asymmetry of weakness at onset, a preceding illness, symptoms that appeared over the course of hours to days rather than a quick onset, lower motor neuron signs, and findings that could be identified on magnetic resonance imaging.
Elrick said that studying past cases of AFM allows researchers and physicians to better understand the clinical characteristics of AFM and ultimately become better at diagnosing it. He added that previously published work has also shed light on the potential causes of AFM, including enterovirus-D68 and enterovirus-A71.
“This information forms a foundation for the field of AFM research,” Elrick said. “The next steps will be to gain a better understanding of disease pathogenesis, potential therapeutic targets, preventive strategies and optimal approaches to rehabilitation.” – by Katherine Bortz
Disclosure: Elrick reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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