Imaging Shows Brain Changes Caused by Zika

Radiologic imaging has shown a pattern of changes to the brain in neonates with microcephaly and Zika virus infection, as well as brain changes in adults who were neurologically affected following Zika virus infection, according to three studies presented at RSNA 2016.

In the first study, researchers from Brazil studied CT findings of the central nervous system in 14 newborn babies (nine male, five female) with congenital Zika virus infection confirmed by tests in cerebral spinal fluid (CSF). Their gestational age ranged from 31 to 40 weeks, weight at birth from 810 to 3.840 grams and head circumference from 23 to 33 centimeters.

The researchers found that all patients had calcification in the CNS, punctiform in eight (57.1%) and coarsely in six (42.8%). Thirteen neonates (92.8%) showed calcification in the cortico-medullary junction, three (21.4%) in thalamus and one (7.1%) in midbrain.

Location of the cortico-medullary junction calcifications were:

• Frontal lobe: 92.8%

• Parietal lobes: 78.5%

• Occipital lobe: 35.7%

• Temporal lobes: 28.5%

Global hypogyration of the cerebral cortex was seen in 11 (78.5%) infants. In 13 (92.8%) neonates ventriculomegaly was present. Cerebellar hypoplasia was seen in four patients (28.5%). In addition, prominent occipital bone was identified in nine patients (64.2%), which can be associated with fetal brain disruption sequence, characterized by severe microcephaly, overlapping sutures, scalp rugae, and marked neurological impairment, reflecting important intrauterine brain damage.

"Our study proves that Zika virus infection can cause congenital brain damage in babies with and without microcephaly," author Natacha Calheiros de Lima Petribu, MD, from the Department of Radiology at Barão de Lucena Hospital, said in a release.

The second study was a prospective study of seven pregnant patients with Zika infection at different gestational ages. The women underwent ultrasound and fetal MRI. After birth, the newborns underwent transfontanellar US, CT, and MRI of the head, with posterior 3D reconstructions of the skull. The researchers compared the cases with and without CNS involvement in the patients with intrauterine Zika infection.

The results showed that four infants showed brain abnormalities with microcephaly. Multiple calcifications with cortical and mainly subcortical distribution were seen in all four cases. There was significant thinning of the brain parenchyma. Neuronal migration anomalies were reported in three cases. The cerebellum was affected only in one case. The researchers noted that the brain stem was not affected in any of the cases.

"The emergence of Zika virus in the Americas has coincided with increased reports of babies born with microcephaly," study author Heron Werner Jr., MD, PhD, from the Department of Radiology at Clínica de Diagnóstico por Imagem, said in the same release. "An early diagnosis may help in treating these babies after birth. Moreover, the knowledge of abnormalities present in the central nervous system may give hints about the pathophysiology of the disease."

The third study evaluated adults who developed acute neurological syndrome, newborns with vertical infection with neurological disorders, and pregnant woman who presented suggestive exanthematic fever syndrome by Zika infection.

Adult patients with exanthematic fever suggesting Zika underwent neural axis MRI. Newborns with microcephaly whose mothers had exanthematic fever underwent brain MRI, some also with US and CT, and histopathological study of the placenta. Fetal MRI was performed in pregnant women who had exanthematic fever. There is a limited ability for laboratory confirmation of Zika in the locations affected by the epidemic, so that exanthematic fever was considered as a marker for infection.

The results showed that most adult patients presented with symptoms of Guillain-Barré syndrome and variants and a few patients presented with encephalomyelitis. The most common finding was lumbar root enhancement followed by lumbar dorsal ganglia enhancement and facial nerve enhancement. Other findings included:

• Brain stem lesions with high T2/FLAIR signal

• Spinal cord lesions with high T2/FLAIR signal

• Trigeminal nerve enhancement

There was good correlation of symptoms and imaging findings.

MRI imaging of the newborns and fetuses showed anatomical changes in the brain parenchyma and orbital injuries.

The conclusions of the studies point to the utility of imaging to determine injuries to the brain caused by Zika infection.

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