Ingrid Hein

December 01, 2016

CHICAGO — Zika infection can have devastating effects on the central nervous system beyond microcephaly, and can cause a wide range of brain abnormalities, including paralysis and death in adults, according to two new studies from Brazil.

The two radiologic studies revealed insights into the diagnosis and evaluation of the infection.

"All radiologists have to know about these typical symptoms because sometimes you don't see the symptoms of Zika virus in the pregnant mother," said Bianca Guedes Ribeiro, MD, from the Clínica de Diagnóstico por Imagem in Rio de Janeiro.

"If the microcephaly and calcifications don't show until the third trimester, it's late," she told Medscape Medical News.

Microcephaly is a nonspecific term used to describe a small head circumference, and can be caused by maternal exposure to HIV, alcohol, radiation, or TORCH pathogens (Toxoplasma gondii, other, rubella virus, cytomegalovirus, and herpes simplex virus). It is therefore important that radiologists know what to look for when it comes to Zika.

Dr Guedes Ribeiro presented results from one of the studies here at the Radiological Society of North America 2016 Annual Meeting.

She and her colleagues looked at pre- and postnatal images of the central nervous system in pregnant women exposed to the Zika virus. In their perinatal MRI and CT scans, they saw brain abnormalities presenting as multiple calcifications, both cortically and subcortically, and microcephaly. They diagnosed pachygyria, corpus callosum dysgenesis, and small anterior fontanel with premature closure of cranial sutures in their cohort.

During her presentation, Dr Guedes Ribeiro described one case in which a 27-year-old pregnant woman presented with fever, a telltale sign of Zika, and a rash at 12 weeks of gestation. In that case, the fetus did not show microcephaly or calcifications until 32 weeks. "In a case like this, the mother might only know she got the infection at the final ultrasound scanning," Dr Guedes Ribeiro explained.

When you see these findings, think about Zika.

Now that Zika is showing up in many other countries around the world, radiologists in the United States should consider the Zika virus when they see these typical central nervous system findings, as they do now in Brazil, even when a pregnant woman has no clinical history of Zika, said Dr Guedes Ribeiro. "When you see these findings, think about Zika," she advised.

"It's important to look deep inside the brain because you will get the detailed information about brain malformations that you can't get with clinical observations," said Fernanda Tovar-Moll, MD, PhD, from the D'Or Institute for Research and Education in Rio de Janeiro.

Dr Tovar-Moll was involved in a recent study that showed that a number of brain abnormalities, beyond microcephaly, can affect fetuses exposed to intrauterine Zika virus infection (Radiology. 2016;281:203-218). Radiologists need to be aware of these abnormalities so they can guide diagnoses and appropriate counseling for patients and their caregivers, the researchers explain.

All the babies she and her colleagues examined showed calcifications in the brain, "particularly between the grey and white matter junction," Dr Tovar-Moll told Medscape Medical News. "This is not the same or common in any other congenital infection."

In 10% of cases, Dr Tovar-Moll and her colleagues found that the baby's head was a normal size at birth. However, she reported, "the brain inside was very abnormal. The MRI and ultrasound showed that they already had severe malformations — even more severe than those with a smaller head size at birth."

It is incredibly important to look inside the brain because microcephaly is just one of the clinical signs for diagnosis, she added.

Paralysis in Some Adults

Dr Emerson de Melo Casagrande

"Zika also causes neurologic damage that leads to paralysis in adults," said Emerson de Melo Casagrande, MD, from the Federal Fluminense University in Niterói, Brazil.

"There are adults affected — who aren't in the focus of the media — who were healthy people but aren't now. Some of them will never recover," he reported.

Dr de Melo Casagrande presented results from a study that looked at adults, pregnant women, and newborns. He explained that the study got its start when the hospital began sending patients to radiology to rule out common diseases because serologic testing for Zika was not available.

Cross section of an adult's head in which change related to Bickerstaff encephalitis is evident in the midbrain. This central structure is the location of cross neurons that control the movements of the limbs and other organs, such as the eyes, and that control the patient's consciousness. Changes to this area cause paralysis and coma. This change does not enhance with contrast agent (gadolinium) because the pathophysiology is different than that seen in Guillain-Barré syndrome.

The researchers were surprised by the effect the virus could have in adults. Of the 16 adults with acute neurologic syndromes sent to their lab, many presented with evidence of Guillain-Barré syndrome, its Miller Fisher variant, and Bickerstaff encephalitis. All three of the patients who presented with encephalomyelitis are now paralyzed.

"They were healthy and now they can't move their arms or legs — that's from Zika," Dr de Melo Casagrande explained. Some patients recovered from the infection and others have sequelae in the face — they can work "and they have a life — but three people remain in the hospital."

They don't have the virus anymore, he pointed out, but it is still destroying their body as an autoimmune disease triggered by the infection. A previous infection could have had something to do with the strong reaction.

"We don't know what makes it more severe in those patients, but we know we need to move the Zika conversation away from microcephaly alone," said Dr de Melo Casagrande.

The problem in Brazil right now is that many hospitals cannot diagnose Zika because testing is not available. "They have a fast test for dengue because people can die from dengue," he explained. "But if it's not dengue, then you have to go home."

Dr de Melo Casagrande said that his team expects to continue to use radiology to exclude other infections. All people should be wary of Zika, not just pregnant women. "It can be devastating for anyone," he warned.

Dr Guedes Ribeiro, Dr Tovar-Moll, and Dr de Melo Casagrande have disclosed no relevant financial relationships.

Radiological Society of North America (RSNA) 2016 Annual Meeting: Abstracts PD232-SD-WEA3 and NR394-SD-WEB2. Presented November 30, 2016.


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