Neuroimaging important for evaluating Zika-exposed infants

MRI and CT scans of infants exposed to the Zika virus in the womb revealed a range of brain abnormalities, reported authors of a recent study published in JAMA Network Open. The findings place neuroimaging as an important step in evaluating such patients.

More than 100 infants with antenatal exposure to Zika virus underwent neuroimaging, and a majority of brain abnormalities were found among severely affected infants with congenital Zika virus (ZIKV). However, another 10% of infants without severe clinical findings also had abnormalities, according to Kara-Lee Pool, MD, with David Geffen School of Medicine at the University of California Los Angeles, and colleagues.

"There appears to be a spectrum of brain imaging abnormalities in ZIKV-exposed infants, including mild, nonspecific changes seen at cranial US [ultrasound], such as lenticulostriate vasculopathy and germinolytic cysts, to more significant brain abnormalities, such as subcortical calcifications, ventriculomegaly and, in its most severe form, thin cortical mantle and fetal brain disruption sequence," wrote Sarah B. Mulkey, MD, PhD, in an accompanying invited commentary. “Centered on the findings of Pool, et al, and others, early neuroimaging remains one of the most valuable investigations of the Zika-exposed infant.”

The infants in this study were born a few months after Brazil declared a national public health emergency due to Zika. Infants severely affected by ZIKV can exhibit a number of well-documented abnormalities, including microcephaly, neurologic impairment and other structural brain abnormalities, but there have been fewer studies performed to understand if neuroimaging can help in cases involving less serious exposure to Zika.

Pool and colleagues retrospectively reviewed neonatal CTs and MRIs of 110 infants—along with clinical outcome data—from a referral center in Rio de Janeiro, Brazil. Of that total, 81 had a CT, 45 had MRI and 16 had both imaging tests. Additionally, 62% of infants were classified into a severe group; 5% were considered mild or moderate; and 33% had no clinical findings.

Overall, 71 infants had abnormal findings with a majority (96%) classified as having severe ZIKV infection at birth. The most common abnormalities were structural, including brain calcifications, cortex malformations, ventriculomegaly, and reduced brain volumes. Infants exposed to ZIKV during the first trimester were 7.9 times more likely to show abnormal findings at neuroimaging.

“Neuroimaging of antenatally ZIKV-exposed infants is an important component in a comprehensive evaluation that may help identify and determine the extent of CNS involvement associated with in utero ZIKV infection,” Pool and colleagues concluded.