CDC Reports on Neurologic Disease Clusters

Pauline Anderson

October 03, 2014

Neurologists and others across the country are concerned about a mysterious cluster of acute neurologic illness of unknown etiology occurring in children in Colorado. The illness is characterized by focal limb weakness and abnormalities of the spinal cord gray matter.

The medical community is also being alerted to cases of acute flaccid paralysis (AFP) with anterior myelitis that have occurred in California over a 2-year period.

Both clusters are described in separate reports published online October 3 in the Centers for Disease Control and Prevention (CDC)'s Morbidity and Mortality Weekly Report.

"These 2 clusters represent a good example of how clinicians and the public health community can work together to describe unusual clusters of illness and potentially new diseases," said Daniel Feikin, MD, chief, Epidemiology Branch, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, CDC, Atlanta, Georgia, in a telephone information conference.

Colorado Cases

In the pediatric cases in Colorado, the Department of Public Health and Environment notified the CDC on September 12 about a cluster of 9 children ranging in age from 1 to 18 years (median age, 8 years) who were evaluated at Children's Hospital Colorado in suburban Denver.

The children presented with extremity weakness, cranial nerve dysfunction (eg, diplopia, facial droop, dysphagia, or dysarthria), or both. The onset of neurologic illness occurred between August 8 and September 15, 2014.

Other than neck, back, or extremity pain in some children, all had normal sensation. None had changes in mental status.

All had a preceding febrile illness, most with upper respiratory tract symptoms, occurring a median of 7 days before onset of neurologic illness.

Seven of 8 patients with MRI of the spinal cord had nonenhancing lesions of the gray matter of the spinal cord, and 7 of 9 with MRI of the brain had nonenhancing brainstem lesions, most commonly the dorsal pons. Two of 5 with MRI of the lumbosacral region had gadolinium enhancement of the ventral nerve roots of the cauda equina.

Eight children were up to date on polio vaccination. Eight have not yet fully recovered neurologically.

Cerebrospinal fluid (CSF) analysis showed that 8 patients had evidence of an inflammatory or infectious process while CSF glucose and CSF protein were normal or mildly elevated.

Initial testing from 8 patients showed no evidence of West Nile virus antibodies, although further testing is pending. Of the 8, 4 had evidence of enterovirus D68 (EV-D68).

EV-D68

Dr Feikin pointed out that EV-D68 is one of over 100 different types of EVs. First identified in 1962 in California, EV-D68 tends to cause respiratory illness, and so is similar to a rhinovirus in its clinical presentation. It's known to cause infection in both children and adults, although children tend to have more severe disease.

An MMWR issue in early September of this year described clusters of respiratory illness due to EV-D68 in Kansas City, Missouri, and Chicago, Illinois, but since then, the enterovirus seems to have spread across much of the United States, said Dr Feikin.

"As of this morning, 538 cases have been confirmed in respiratory illness patients in 43 states, although many specimens are still pending testing," said Dr Feikin, adding that the median age of these cases is 6 years, but they range in age from newborns to age 92 years.

In Colorado, there is a clear increase in respiratory illness; of a sample of specimens sent for typing, about three quarters were positive for EV-D68. Detection of the enterovirus in those with neurologic illness might be coincidental, however, said Dr Feikin.

"We don't know if these neurologic cases are related to EV-D68," he said. "We don't think we can say they are at this point. We are really not sure what's causing this neurologic cluster."

The CDC is attempting to describe the epidemiology of the neurologic syndrome and its geographic distribution. Part of difficulty, said Dr Feikin, is that there's no baseline information on this syndrome. "We don't have required national reporting of acute paralysis or of enterovirus, so we don't have a good idea of baseline rates of this syndrome would be."

The Colorado Department of Public Health has issued an alert informing clinicians of the cluster and requesting them to report of similar cases. The CDC has issued a national Health Advisory, which provides guidance for identifying and reporting cases.

Clinicians should report to their local and state health departments any patients aged 21 years or younger with acute-onset focal limb weakness occurring on or after August 1, 2014, and MRI evidence of a spinal cord lesion largely restricted to gray matter.

Clinicians can find a case report form on the CDC website. They can email queries and questions to limbweakness@cdc.gov.

California AFP Cases

In the California clusters, a total of 23 cases of AFP with anterior myelitis (evidence of inflammation of the spinal cord involving the gray matter including anterior horn cell bodies) were identified (mean age, 10 years) from June 2012 to June 2014. No common cause was identified, although clinical laboratory findings supported a viral etiology. Two patients tested positive for EV-D68 from upper respiratory tract specimens.

Poliovirus was determined to be an unlikely etiology for any of the cases based on epidemiologic and limited laboratory investigation findings. Because AFP with anterior myelitis is the classic presentation of paralytic poliomyelitis, the California Department of Public Health attempted to rule out poliovirus infection. Of 14 patients with available information, 12 had previously received polio vaccine.

It's unclear whether the increase in EV-D68 cases is related to the cluster of AFP with anterior myelitis in California because the cases were collected only until June 2014 while the increased cases of EV-D68 were noticed after that time.

Some enteroviruses can cause an anterior myelitis, but so can other infectious causes, such as West Nile virus and St. Louis encephalitis, noted Dr Feikin.

Physicians treating patients with AFP of unknown etiology should work with their local and state health departments to rule out poliomyelitis early during the course of disease.

MMWR Morb Mortal Wkly Rep. Published online October 3, 2014. Abstract (Colorado) Abstract (California)

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