FROM MMWR
Infants born with laboratory-confirmed congenital Zika virus but who show no signs of microcephaly at birth may still experience a reduction in cranial size as they grow older, according to the Centers for Disease Control and Prevention’s latest Morbidity and Mortality Weekly Report .
“These findings demonstrate the importance of early neuroimaging for infants exposed to Zika virus prenatally and the need for comprehensive medical and developmental follow-up,” wrote Vanessa van der Linden, MD, of the Association for Assistance of Disabled Children in Recife, Brazil, and her coauthors.
Dr. van der Linden and her coinvestigators examined 13 infants, all of whom were born in Brazil between October 2015 and January 2016, who had confirmed brain abnormalities at birth despite having a normal head size. These abnormalities included ventriculomegaly, subcortical calcifications, cortical malformations, and decreased brain volume. Investigators defined microcephaly as being “head circumference (HC) [that’s] more than 2 [standard deviations] below the mean for gestational age and sex.”
Nine of the infants were male, four were female. Eleven of the infants were born within 37-41 weeks’ of gestation. The remaining two were born at 35-36 weeks’ of gestation, considered “preterm” by the investigators. All infants tested positive for Zika via immunoglobulin M testing of cerebrospinal fluid, serum, or both. Only six of the mothers reported having a rash while pregnant; four reported experiencing it during the first trimester, while the other two said it occurred in the second.
All 13 infants showed a decrease in HC to what was defined as microcephaly within 1 year of birth (October 2016). Neuroimaging showed that all but one had decreased brain volume, all had malformations of cortical development, four had cerebellum or brain-stem hypoplasia, ten had ventriculomegaly, and three had increased extra-axial CSF space.
“More than 60% of infants in this series had epilepsy (likely related to the cortical malformations), and all had significant motor disabilities consistent with mixed cerebral palsy,” the authors noted, adding that the “pathogenesis of postnatal microcephaly from congenital Zika virus infections is [still] not known.”
