Lessons From Zika and Other Virus Induced Skull Deformity

Objective: Viral infections during pregnancy can cause disturbance in normal craniofacial morphogenesis. While some pathogens such as cytomegalovirus and herpes simplex are familiar to us, others remain obscure. This review examines the arbovirus-induced cranial deformities and combines biomechanics with growth dynamics to gain a deeper appreciation of this complex morphogenetic process. Materials and Methods: Using Wolfram Alpha, we analyzed the impact of cell population changes. The growth dynamics of the brain, and thus the size of the calvarium, followed 2 potential logistic curves: compensated and uncompensated. To understand the potential mechanism of cell loss, we performed literature review on maternal immune activation and viral tropism for neurons and glial cells. Results: With arboviral infections such as Zika, uncompensated loss of cells during the critical phases of fetal brain development reduces the intracranial mass and therefore decreases the tensile stress across the cranial sutures. The deflationary effect produces microcephaly by subduction and reduced osteogenesis seen clinically in these infants. Conclusion: Many viral infections cause intense maternal immune activation, some have neurotropism and can result in cell loss within the developing cranium. Unable to overcome this loss, the cranium assumes a new, abnormal shape and volume. Secondary calvarial deformities is due to, and should not cause, changes in brain development.