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Measuring tape is a critical tool for following Zika virus-exposed children

Invited commentary by Children’s National prenatal-neonatal neurologist emphasizes importance of studying this population long term July 07, 2020
A simple measuring tape could be the key to identifying which children could develop neurological and developmental abnormalities from Zika virus exposure during gestation. This is according to an invited commentary published July 7 in JAMA Network Open and written by Sarah Mulkey, M.D., Ph.D., prenatal-neonatal neurologist in the Division of Prenatal Pediatrics at Children’s National Hospital.

Zika virus (ZIKV), first isolated in 1947 in the Ziika Forest in Uganda, made headlines in 2015-2016 for causing a widespread epidemic that spread through parts of North and South America, several islands in the Pacific and parts of Southeast Asia. Although previously linked with no or mild symptoms, researchers discovered during this epidemic that Zika can cross from a pregnant woman to her gestating fetus, leading to a syndrome marked by microcephaly (decreased brain growth), abnormal neurologic tone, vision and hearing abnormalities, and joint contractures.

“For the 90% to 95% of ZIKV-exposed infants who fortunately were not born with severe abnormalities at birth and were normocephalic, our hope was that these children would have normal neurodevelopmental outcomes,” Dr. Mulkey writes in the commentary. “Unfortunately, this has not been the case.”

Her commentary expands on a study in the same issue entitled “Association between exposure to antenatal Zika virus and anatomic and neurodevelopmental abnormalities in children” by Cranston et al. In this study, the researchers find that head circumference — a simple measure taken regularly at postnatal appointments in the U.S. — can provide insight into which children were most likely to develop neurologic abnormalities. Their findings show that 68% of those whose head circumference was in the “normal” range at birth developed neurologic problems. Those whose head circumference was at the upper end of this range were significantly less likely to have abnormalities than those at the lower end.

Just this single measurement offers considerable insight into the risk of developing neurologic problems after Zika exposure. However, notes Dr. Mulkey, head circumference growth trajectory is also key. Of the 162 infants whose heads were initially in the normocephalic range at birth, about 10.5% went on to develop microcephaly in the months after birth.  

“Because early head growth trajectory is associated with cognitive outcomes in early childhood,” Dr. Mulkey writes, “following the head circumference percentile over time can enable recognition of a child with increased risk for poor outcome who could benefit from early intervention therapies.”

This simple assessment could be significantly augmented with neuroimaging, she adds. The study by Cranston et al., as well as others in the field, have shown that brain imaging often reveals problems in ZIKV-exposed children, such as calcifications and cerebral atrophy, even in those with normal head circumferences. This imaging doesn’t necessarily need to take place at birth, Dr. Mulkey says. Postnatal development of microcephaly, failure to thrive or developmental delay can all be triggers for imaging later on.

Together, Dr. Mulkey says, the study by Cranston et al. and others that focus on ZIKV-exposed children support the need for following these patients long term. Children exposed to ZIKV in the epidemic nearly five years ago are now approaching school age, a time fraught with more complicated cognitive and social demands. Through her own research at Children’s National’s Congenital Zika Virus Program and collaboration with colleagues in Colombia, Dr. Mulkey is following multiple cohorts of ZIKV exposed children as they grow. She recently published a study on neurological abnormalities in one of these cohorts in JAMA Pediatrics in January 2020.

“It’s really important to follow these children as long as possible so we’ll really know the outcomes of this virus,” Dr. Mulkey says.

Media contact: Beth Riggs | 301-233-4038

About Children’s National Hospital

Children’s National Hospital, based in Washington, D.C., celebrates 150 years of pediatric care, research and commitment to community. Volunteers opened the hospital in 1870 with 12 beds for children displaced after the Civil War. Today, 150 years stronger, it is among the nation's top 10 children's hospitals. It is ranked No. 1 for newborn care for the fourth straight year and ranked in all specialties evaluated by U.S. News & World Report. Children’s National is transforming pediatric medicine for all children. In 2020, construction will be complete on the Children’s National Research & Innovation Campus, the first in the nation dedicated to pediatric research. Children's National has been designated twice as a Magnet® hospital, demonstrating the highest standards of nursing and patient care delivery. This pediatric academic health system offers expert care through a convenient, community-based primary care network and specialty outpatient centers in the D.C., metropolitan area, including the Maryland and Northern Virginia suburbs. Children’s National is home to the Children’s National Research Institute and Sheikh Zayed Institute for Pediatric Surgical Innovation and is the nation’s seventh-highest NIH-funded children’s hospital. It is recognized for its expertise and innovation in pediatric care and as a strong voice for children through advocacy at the local, regional and national levels. 

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