Sarah B. Mulkey, the lead author of the study opined that combination of MRI and standard ultrasound (US) offers corresponding data needed for the evaluation of progressive changes in the brains of the Zika-affected fetus in pregnancy. Further, the study found that relying on ultrasound alone would have given one mother the false assurance that her fetus' brain was developing normally while the sharper MRI clearly pointed to brain abnormalities.
According to the recent report from the Centers for Disease Control and Prevention (CDC), 1,901 American women were exposed to Zika at some point during their pregnancies, but they gave birth to healthy off springs. In another 98 women, the babies were born with Zika-related defects, and eight more women had pregnancy losses with Zika-related congenital disabilities.
Children's National performed a longitudinal neuroimaging study, which involved 48 pregnant women who exposed to the Zika virus in the first or second trimester whose infection was detected by reverse transcription polymerase chain reaction or Immunoglobulin M testing. All of the women underwent at least one imaging session with initial MRI/US at 25.1 weeks gestational age. A total of 36 women underwent a second MRI/US imaging pair at roughly 31 weeks gestation.
Children's National radiologists read every image and 6% women were found with fetal abnormalities,
- One fetus found with heterotopias – clumps of grey matter in unusual locations, and abnormal cortical indent; a deformation at the outer layer of the cerebrum, while the US image showed the healthy brain development.
- Another fetus had a skull defect called parietal encephalocele and Chiari malformation Type II structural defect at cerebellum and the base of the skull. The same abnormalities were seen in US image.
- The third fetus found with a thin corpus callosum – a bundle of nerves, which connects the left and right cerebral hemispheres, defects in the brain stem, temporal cysts, subependymal heterotopias and general cerebral/cerebellar atrophy. While US imaging exhibited significant ventriculomegaly – fluid-filled structures in the brain that are too large, and a fetal head circumference that decreased drastically from the 32nd to 36th gestational week, a hallmark of microcephaly.
After the parturition, babies underwent US and MRI without sedation. One infant found with lenticulostriate vasculopathy – a brain lesion and nine infants with cysts in the choroid plexus -cells that produce cerebrospinal fluid, or germinal matrix – the source for neurons and glial cells that migrate during brain development.
Several factors could influence the brain development. Hence further studies are required to determine whether the brain cysts are due to Zika exposure in utero, or some other factors triggered those brain abnormalities, concluded Dr. Mulkey.