‘Extremely severe’ brain damage found in babies with Zika-linked defect

Brazil - The BMJ 2015
A map showing cities and States in Brazil with cases of microcephaly up to February 13, 2016. – Photo: The BMJ 2015

For the first time, radiological findings of babies born in Brazil with microcephaly, presumably caused by Zika virus infection, show “extremely severe” brain damage with a range of abnormalities.  Doctors have tried to distinguish the abnormalities in babies with microcephaly from the patterns seen with other congenital infections for the first time.

The results are published today (April 14) in the journal The BMJ.

“This study shows the largest and most detailed case series of neuroimaging findings in children with microcephaly and presumed Zika virus related infection to date,” writes Maria de Fatima Vasco Aragao the lead author of the paper from Mauricio de Nassau University, Recife, Brazil.  The malformations were symmetrical in 75 per cent of the babies studies.

“It is important to understand that the disease is not microcephaly, but a new congenital infection presumed to be related to Zika virus (that is, Zika virus congenital syndrome), which can include microcephaly and other malformations,” the authors write.

As on February 13, 2016, Brazil notified 5,280 cases of microcephaly but only 1,345 have been investigated and classified.  According to the Brazilian government, only 508 cases have been diagnosed as microcephaly.

The researchers studied 23 babies with typical microcephaly and born in the Brazilian state of Pernambuco between July and December 2015 to mothers who had a rash during pregnancy, consistent with a Zika virus infection.  Of the 23 babies studied, 15 underwent CT, one baby underwent MRI and seven underwent CT and MRI.

Brain calcification was the most commonly seen abnormality. All the 22 babies that underwent CT scan had calcification — a condition in which calcium builds up in the brain. The hypothesis is that the Zika virus destroys brain cells, and forms lesions similar to “scars” on which calcium is deposited.

Twenty-one of 23 babies had malformations of cortical development, and 20 babies had decreased brain volume due to underdevelopment or incomplete development of the brain.  And 19 babies had ventriculomegaly — abnormal enlargement (more than 10 millimetres in size) of brain cavities due to the presence of too much cebebrospinal fluid.

MRI studies carried out on eight babies also showed calcification, malformations of cortical development and ventriculomegal. Six of the eight babies studied using MRI had moderate to severe brain decrease in brain volume.

The babies also had underdevelopment of the cerebellum, which plays an important role in motor control, and the brainstem which connects the cerebrum with the spinal cord and communicates messages from the brain to the rest of the body.

Delayed myelination — process of a myeline sheath forming around nerve fibers that enables transmission of impulses — was also observed.

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