The sutures are bands of tissue that connect the bones of the skull. The sutures allow the skull to grow as the brain grows inside. They remain flexible for several years after birth and close and harden as the baby grows. After the sutures close, the skull cannot grow any more.
Craniosynostosis results when these sutures close too early, which restricts the ability of the brain and skull to grow to a normal shape and size. Craniosynostosis may occur spontaneously or may be caused by mutations in the baby's genes.
This defect occurs in 1 in every 2,500 babies. There are several types of craniosynostosis, depending on which suture is closed.
Craniosynostosis of the sagittal suture (the suture behind the baby's fontanelle or soft spot) is the most common. This type of craniosynostosis results in a narrow and long skull (dolichocephaly). About half of children who have this type of craniosynostosis develop learning disabilities.
Craniosynostosis of the coronal sutures (the sutures to the left and right of the soft spot) is the next most common. This type of craniosynostosis results in a short and broad skull if the sutures on both sides of the soft spot are closed (brachycephaly) or in a diagonal skull if the sutures on only one side of the soft spot are closed (plagiocephaly). Children who have this type of craniosynostosis often have other defects of the face and skull.
Doctors can identify craniosynostoses during a physical examination. Doctors may do genetic testing by analyzing a sample of the baby's blood to look for chromosome and gene abnormalities. This testing can help doctors determine whether a specific disorder is the cause and rule out other causes. Doctors may also do imaging tests of the skull and brain.
Craniosynostoses are usually corrected with surgery. However, a baby who has very mild craniosynostosis may not need surgery. Sometimes, a special helmet can be worn to help mold the baby’s skull into a more regular shape.