Experts are investigating the links between Zika virus infection in the womb and joint deformities at birth.
Until recently there had been no confirmed associations between congenital viral infection in pregnancy and joint contractures, known as arthrogryposis.
But after the outbreak of microcephaly in Brazil associated with Zika virus, two reports appeared suggesting a link.
Now, Dr Vanessa van der Linden of the Brazil and Barao de Lucena Hospital, Recife, Brazil, and colleagues have investigated further. They set out to describe the clinical features of children with arthrogryposis, whose mothers had the Zika virus.
A sample of seven children had tests which confirmed arthrogryposis due to congenital infection in the arms and legs. All tested negative for the five other main infectious causes of microcephaly – toxoplasmosis, cytomegalovirus, rubella, syphilis, and HIV.
Brain scans showed malformations of cortical development and reduction in brain volume, among other abnormalities.
The researchers believe the children’s arthrogryposis "did not result from abnormalities of the joints themselves, but was likely to be of neurogenic origin".
Details appear in the BMJ today (10 August). "Zika syndrome should be added to the differential diagnosis of congenital infections and arthrogryposis," state the authors.
"The arthrogryposis was unrelated to the abnormalities of the joints themselves, but was possibly of neurogenic origin, with chronic involvement of central and peripheral motor neurones leading to deformities as a result of fixed postures in utero."
They add that, based on their neurophysiological observations, there are two possible mechanisms, "tropism of neurones, with involvement of peripheral and central motor neurones, or a relation with vascular disorders."
van der Linden, V. et al. Congenital Zika syndrome with arthrogryposis: retrospective case series study. BMJ 10 August 2016 doi: 10.1136/bmj.i3899 [abstract]
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