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Acute flaccid myelitis of unknown etiology linked to enterovirus D68
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Nearly 60 acute flaccid myelitis cases of undetermined etiology have been detected in California since June 2012 and may be associated with concurrent enterovirus D68, according to a recently published investigation.
The neurologic condition, which resulted in two deaths, primarily affects children and young adults and could contribute to worsened outcomes among patients who are immunocompromised, Keith Van Haren, MD, assistant professor of neurology at Stanford University Medical Center, and colleagues wrote.
Keith Van Haren
“With the elimination of wild poliovirus in populations throughout most of the world, the clinical syndrome of acute flaccid paralysis due to spinal motor neuron injury has largely disappeared from North America,” they wrote. “Despite occasional case reports, the absence of centralized public health surveillance for non-polio acute flaccid paralysis in the United States has precluded accurate incidence estimates, thereby limiting the ability to distinguish potential disease outbreaks from the natural fluctuation inherent in rare phenomena.”
Van Haren and colleagues examined cases involving patients admitted to California hospitals with acute onset of flaccid weakness in one or more limbs and evidence of spinal gray matter lesion from June 2012 through July 2015. Medical records from these patients were obtained and reviewed by a neurologist and infectious disease epidemiologist, and clinicians providing ongoing care were contacted for patient motor function assessments. Throat swabs, nasopharynx specimens, cerebrospinal fluid and serum samples were requested for all cases and tested for infectious agents at a state laboratory. With these data, researchers described clinical features and identified incidence trends of the unknown neurologic condition.
Van Haren and colleagues identified 59 cases reported within California during the study period. Median patient age was 9 years, and only nine patients were aged older than 21 years. The geographic distribution of cases was broad, with no identifiable spatial clustering. Ninety-two percent of patients experienced either respiratory or gastrointestinal symptoms, 80% reported recent fever, and 69% reported limb myalgia. Several patients also reported headache at onset (n = 49%), neck stiffness (34%) neurogenic bowel or bladder manifestations (51%) and focal paresthesia (36%). Neuroimaging of the spine detected T2 hyperintensity of spinal gray matter among 95% of patients, while 74% demonstrated high white blood cell counts within cerebrospinal fluid.
Patients were treated with IV steroids (n = 42), IV immunoglobulin (n = 43) and plasma exchange (n = 13). Motor recovery varied, but persisted among many patients. No neurological relapses were reported. Two patients, one aged 55 years and the other aged 73 years, had serious pre-existing conditions and died within 60 days of neurological symptom onset.
Of the 45 specimens tested, infectious agents were detected in 20. Of these, 15 were enterovirus positive, and nine were consistent with enterovirus D68. Although case incidence was significantly higher during the months of the U.S. enterovirus D68 outbreak (P < .001), no viruses of any kind were detected in cerebrospinal fluid.
Although the source of these cases remains unknown, Van Haren and colleagues wrote that infection should still be explored as a potential factor in the etiology and treatment of this emerging condition.
“Even when a specific infectious etiology is not identified, clinical suspicion of an infectious agent represents a crucial distinction in the early triage of clinical care and treatment decision, particularly when treatment strategies for similar clinical syndromes often call for immune modulation or suppression,” they wrote. “The deaths of two patients with pre-existing immunosuppression as well as the onset of paralysis in two children receiving oral steroids for asthma-like exacerbations suggest that immunosuppressive treatment regimens for patients with acute flaccid myelitis should be considered cautiously.” – by Dave Muoio
Disclosure: Van Haren reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.
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