THE ZIKA virus (ZIKV) infection in pregnant women has been implicated in the development of neurological abnormalities which lead to limb joint deformities in babies, according to Brazilian researchers.
Arthrogryposis multiplex congenita (AMC) is a birth defect of congenital joint contractures in two or more areas of the body. In a recent study, scientists found that AMC may arise from motor neuron impairment related to ZIKV. Dr Vanessa van der Linden, Paediatric Neurologist, Association for Assistance of Disabled Children, Recife, Brazil, and colleagues studied seven Brazilian children with AMC. Each child had also been diagnosed with congenital infections, which were presumed to be caused by ZIKV, as the infection occurred during the outbreak of the virus in Brazil. Each child underwent brain imaging, and high-definition imaging was collected of their joints and surrounding tissues.
The brain imaging revealed evidence of calcification in all of the children, which the researchers believed could be an indicator of ZIKV. This is because the destruction of nerve cells by the virus results in lesions that appear similar to calcium deposits. The high-definition imaging of the joints and surrounding tissues showed no evidence of joint abnormalities. This indicated that AMC among the children was the result of abnormalities in motor neurons, rather than in the joints.
“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 neurons leading to deformities as a result of fixed postures in utero,” the team explained. Although the authors of the study were unable to conclude that ZIKV infection during pregnancy is a definite cause of AMC, their findings are believed to show that the virus does have a role.
“Based on the neurophysiological observations, we suggest two possible mechanisms: tropism of neurons, with involvement of peripheral and central motor neurons, or a relation with vascular disorders,” explained the authours. “Congenital Zika syndrome should be added to the differential diagnosis of congenital infections and arthrogryposis.”