What is craniosynostosis and what causes it?

  • Craniosynostosis is a medical term that means the skull bones fuse too early as the baby grows.  Because the brain continues to grow as the baby grows, the skull must also expand with the brain growth.  When the skull fuses too early, this compresses the brain growth and also creates an abnormally shaped skull/head.
  • The skull is abnormally shaped because the fusion of skull bones causes an asymmetrical growth of the skull pieces.
  • Because the premature fusion of the skull does not allow the skull to grow with the brain, it can cause developmental delays and problems with brain development.
  • Early detection of craniosynostosis is important and usually requires surgical intervention.

What types of craniosynostosis are there?

Deformational (or Positional) Plagiocephaly:

  • Deformational Plagiocephaly is NOT a form of craniosynostosis but can look similar to it and can be confused with unilateral coronal synostosis (which is sometimes called plagiocephaly).
  • It is important for a baby with deformational plagiocephaly to be evaluated to make sure they do not have craniosynostosis.
  • Deformational plagiocephaly can be exacerbated by babies sleeping on their backs (which is encouraged to prevent risk of SIDS) and over time creates a flat spot on the back of the skull. The skull can also be misshaped in utero by compression of the mother’s pelvis.
  • It does not cause developmental delays or problems with the brain.
  • Often times the abnormal head shape resolves over time as babies become more mobile and spend less time lying on their backs.
  • This does not require surgical treatment.
  • Torticollis is often associated with this and may cause the baby to tilt his/her head or have limited neck motion.

Unilateral Coronal Synostosis (also called Plagiocephaly):

  • Involves fusion of either the right or left side of the coronal suture. Normally, the coronal suture extends from ear to ear over the top of the head.
  • This causes a child with to look as if the forehead and brow are pushed backward. The eye on the affected side also has a different shape, giving a “harlequin” eye appearance. 


  • Involves an early fusion of both coronal sutures, which are sutures that run over the top of the skull from ear to ear.  This creates a foreshortened anterior-posterior skull length and a widened appearance with a flattened back of skull.


  • A fusion of the metopic suture. This suture runs from the top of the head, down the middle of the forehead, toward the nose.
  • Early closure of this suture may result in a prominent ridge running down the forehead. Sometimes the forehead looks quite pointed. It resembles the bow of a boat. Frequently, the eyes are closer together.


  • An early closure or fusion of the sagittal suture. This suture runs from front to back, down the middle of the top of the head. This fusion causes a long, narrow skull.
  • The skull is long from front to back and narrow from ear to ear.
  • This is the most common form of craniosynostosis

Crouzon and Apert Syndromes:

  • These include craniosynostosis as part of the syndrome.
  • Involves fusion of both sides of the coronal suture (brachycephaly). This suture runs from ear to ear, over the top of the head. This fusion prevents the entire forehead from growing in a forward direction.
  • This results in the brain pushing the top of the skull higher. It then leads to a flattened, tall forehead. The bones protecting the eye are also kept from growing forward. This makes the eyes look very large and bulging.

What are treatments for craniosynostosis?

  • In most cases, surgery is the primary treatment. The purpose of the surgery is to release the premature fusion and allow the skull to grow with the brain.  The surgery also attempts to restore normal head shape.
  • In mild cases, where brain development is not affected, surgery may not be needed.
  • Often a CT scan is used to help with diagnosis and surgical planning.
  • One of the greatest concerns is increased intracranial pressure. As the brain is growing, it needs to be able to push the skull bones apart, giving it more room to grow. If there is a fusion of a suture, as in craniosynostosis, growth is restricted, and the brain is squeezed. As the brain grows larger, the skull cannot expand. This may lead to a buildup of pressure inside the skull. This increased pressure may cause a delay in development or a permanently damaged brain.

What is the prognosis for craniosynostosis patients?

  • When detected early, the prognosis is good.
  • Syndromic craniosynostosis is associated with poorer outcomes
  • If the brain is being compressed and the skull fusion is released surgically in a timely manner, this can have excellent prognosis in both brain development and skull shape.