Because this latest research, published in the British Medical Journal (BMJ) on Tuesday, was an observational study looking back at cases of arthrogryposis, it could not draw definitive conclusions on whether Zika is a direct cause.
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The Zika outbreak was first detected past year in Brazil, where it has been linked to more than 1,700 cases of microcephaly.
They point out that further research is needed with a larger number of cases to study the neurological abnormalities behind arthrogryposis, but suggest that children should receive orthopaedic follow-up.
The researchers focused on seven of the children, who were also born with arthrogryposis, a severe condition in which the muscles around the joints don’t develop properly, resulting in weak or stiff joints. Six of those evaluated had the joint deformity, called arthrogryposis, in both their arms and legs, and one had deformities only in the legs. But all of the babies had the pattern of abnormalities on their brain scans that would be expected with a congenital Zika syndrome, said lead researcher Dr. Vanessa van der Linden.
Microcephaly was common, but not present in all of the children with arthrogryposis involved in the study.
“In fact, researchers are now referring to the range of health problems linked to Zika virus infection in the womb as “congenital Zika syndrome”, although the researchersare still trying to figure out all of the health problems that this syndrome might involve”. All children tested negative for the five other main infectious causes of microcephaly – toxoplasmosis, cytomegalovirus, rubella, syphilis, and HIV.
All children showed signs of a build up of calcium in the brain – known as calcification.
All seven had calcium build-up in the brain, bolstering the theory that Zika destroys the brain cells of a fetus when a woman is infected during pregnancy. But the researchers suggest that condition might be related to the way motor neurons carry signals to the unborn baby’s muscles, or to problems with arteries and veins.
All the children underwent high definition scanning of the joints and surrounding tissues, but there was no evidence of joint abnormalities. The name of this condition literally means “crooked joints” in Greek.
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The researchers were led to believe the arthrogryposis did not come from the joints themselves but was more likely to be of “neurogenic origin”.
