Craniosynostosis is the premature closure of the spaces between the bones that make up the skull.
In the growing child, the skull is made up of a number of bony plates. The bony plates are separated by sutures. As a baby reaches his or her first year of life, the bony plates of the skull become closer and eventually fuse together. The size and shape of the skull more or less reflect the size and shape of the brain. In a baby with craniosynostosis, one or more of the skull sutures stop growing before brain growth is complete. It can lead to constriction of the brain and deformity of the skull and facial structures.
Craniosynostosis occurs in about 1 in 2000 live births. It occurs more often with a twin pregnancy or if the shape of the uterus is abnormal and constrains the growth of the baby's head. Craniosynostosis is also seen more often: