Craniosynostosis is a birth defect in which one or more of the fibrous joints between the bones of an infant's skull close prematurely, before the infant's brain is fully formed. As a result of craniosynostosis, your baby's brain can't grow in its natural shape and his or her head is misshapen.

Craniosynostosis can affect one or more of the joints in an infant's skull. In some cases, craniosynostosis may be associated with an underlying brain abnormality that prevents the brain from growing properly.

Treating craniosynostosis usually requires that your infant undergo surgery to separate the fused bones. If there's no underlying brain abnormality, the surgery allows the brain adequate space to grow and develop.