Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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April 20, 2017
Fetal Zika Infection
- Background:
- Zika virus is an arbovirus transmitted by Aedes aegypti mosquitos.
- Mechanisms of infection:
- Direct delivery of the virus through the placenta; the cortical progenitor cells are the targets.
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Placenta mediates a response against the virus that probably changes the profile of inflammatory markers in the fetal tissues
- Pathophysiology:
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Zika virus induces cell death of human neural stem cells, causing apoptosis and autophagy, disrupts the formation of neurospheres, and reduces the growth of organoids.
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Destruction of brain parenchyma due to vasculopathy; Zika virus involves the carotid system and spares the vertebrobasilar circulation.
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Migrational abnormalities suggest that the infection occurs before 18 weeks.
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- Clinical Presentation:
- Maternal skin rash, fever, arthralgias, headache, and conjunctivitis
- There are some reports of fetal microcephaly and adult Guillain Barré syndrome.
- Key Diagnostic Features:
- Craniofacial disproportion with microcephaly
- Hypoplasia or agenesis of corpus callosum
- White matter thinning and enlargement of supratentorial subarachnoid space
- Ventriculomegaly
- Calcifications in the subcortical regions
- Lissencephaly
- Differential Diagnoses:
- Cytomegalovirus: Imaging findings show brain, basal ganglia, and periventricular calcifications, migrational abnormalities (polymicrogyria), white matter disease, echogenic streaks within the basal ganglia and thalami (lenticulostriate mineralizing vasculopathy), ventriculomegaly, and periventricular cysts. The periventricular and temporal pole cysts are more specific for CMV infection.
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Toxoplasmosis: Calcifications are seen in basal ganglia, periventricular regions, and cerebral parenchyma. Hydrocephalus is characterized by dilatation of lateral and third ventricles. Malformations of cortical development are less frequent.
- Treatment:
- Pregnant women with Zika virus infection should be followed with fetal ultrasound every 3–4 weeks.
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