Your baby's skull consists of several bony plates that fuse during the first year or two, forming a protective enclosure for the brain. The joint is called a cranial suture.
Craniosynostosis, also called synostosis, is the premature joining of the plates. Closure of a single suture is most common. Synostosis is a rare condition. The cause is unknown, although it's sometimes related to inherited genetic syndromes. An abnormal-shaped skull occurs because the brain isn't able to grow in its natural shape. Instead, it compensates with growth in areas of the skull where the cranial sutures have not yet closed.
The first sign of craniosynostosis is an abnormal skull. The diagnosis is confirmed with a neurological exam and X-ray or a computerized tomography (CT) head scan.
A magnetic resonance image, an MRI, may also be used for further evaluation to ensure there are no other head abnormalities. Treatment is usually surgery during infancy to separate fused skull plates.