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Early neuroimaging essential for Zika-exposed neonates


 

EXPERT ANALYSIS FROM TERATOLOGY SOCIETY 2017

 

– The experience gleaned at ground zero of the Brazilian Zika virus epidemic drives home a clinical imperative: every neonate whose pregnant mother has presumed or confirmed Zika infection needs to undergo prompt neuroimaging, even if head circumference at birth is normal, Vanessa van der Linden, MD, said at the annual meeting of the Teratology Society.

Dr. van der Linden, a pediatric neurologist at the Association for Assistance of Disabled Children in Recife, Brazil, has done pioneering work in characterizing the recently recognized congenital Zika syndrome. She was the lead author of the first report of infants who had laboratory evidence of congenital Zika infection and normal head circumference at birth but who developed poor head growth and microcephaly later in infancy.

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The report described 13 Brazilian infants with laboratory-confirmed congenital Zika infection and normal head size at birth. Of these, 11 were born at term, and the other 2 were born at 35 and 36 weeks gestation. Brain imaging with contrast-free CT and/or MRI performed as early as day 2 of life showed that all infants had abnormalities consistent with congenital Zika syndrome, including reduced brain volume, subcortical calcifications, ventriculomegaly, and cortical malformations. Head growth decelerated as early as 5 months, and 11 of the infants developed microcephaly.

Comprehensive multispecialty medical and developmental follow-up documented that 10 of 13 infants had dysphagia, 7 had epilepsy, 3 had chorioretinal abnormalities, all 13 had hypertonia, and 12 had pyramidal and extrapyramidal signs with dystonia (MMWR. 2016 Dec 2;65[47]:1343-8).

In another recent publication, Dr. van der Linden and her coinvestigators described classic congenital Zika syndrome with microcephaly at birth as simply the tip of the Zika virus iceberg. In their retrospective review of 77 infants exposed to Zika in utero, 9 had microcephaly at birth, 7 developed microcephaly postnatally, and 3 didn’t have microcephaly at all. Those with microcephaly at birth showed the traditional neuroimaging findings of congenital Zika syndrome, including reduced brain volume, ventriculomegaly, subcortical calcifications, corpus callosum abnormalities, and an enlarged extra-axial space.

Those who subsequently developed microcephaly later in infancy showed most of the same neuroimaging abnormalities. The three infants who remained normocephalic displayed calcifications in the cortico-subcortical junction, asymmetric frontal polymicrogyria, delayed myelination, and milder ventriculomegaly than in the other two groups (AJNR Am J Neuroradiol. 2017 Jul;38[7]:1427-34).

The rehabilitation center where Dr. van der Linden and her colleagues are currently following roughly 200 children with congenital Zika syndrome is in the state of Pernambuco, which was particularly hard hit by the Zika epidemic.

She reported having no relevant financial disclosures.
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