What is craniosynostosis?

Craniosynostosis is a condition in which the fibrous connections, between the bones of the skull, called sutures, grow together (fuse) too early during a child’s development. It most commonly affects only one of the sutures, but it can also occur in more than one. This fusion can cause problems with brain and skull growth. In some cases, it can lead to developmental delays and cognitive problems, especially if more than one suture is involved. Some children with craniosynostosis can also develop high pressure inside the skull, called increased intracranial pressure.

Craniosynostosis is often noticeable at birth, but can also be diagnosed in older children. This condition sometimes runs in families, but most often it occurs randomly.


John Meara, MD, DMD, MBA, Plastic Surgeon-in-Chief and Mark Proctor, MD, Neurosurgeon-in-Chief

Types of craniosynostosis

There are four main types of craniosynostosis: 

  • Sagittal synostosis is the most common type. Babies with this form of craniosynostosis have closing of the bones that make up the top and sides of the head. This causes the head to look long and narrow.
  • Coronal synostosis causes fused bones along the suture that runs from the ear to the baby’s fontanelle or “soft spot.” If the fusion is on one side only, it’s a unilateral coronal synostosis; if it affects both sides, it’s a bilateral coronal synostosis. Unilateral coronal synostosis can make one side of the forehead look flattened while the other side appears to bulge. Bilateral coronal synostosis can make the head look short and wide.
  • Metopic synostosis involves the fusion of the suture that runs from the "soft spot" on top of the head down the forehead to the top of the nose.  Children with this type of craniosynostosis may have a prominent ridge along their foreheads, and their skulls may have a pointed, triangular appearance in front.
  • Lambdoid synostosis is the fusion of the suture in the lower back of the skull. This can cause one side of the back of the head to look flatter than the other side. The ear on that side of the head may also stick out farther than the other ear and be pulled slightly backward. This type of crainiosynostosis is extremely rare, and much more commonly flattening in the back of the head is related to a benign condition from the way the baby sleeps.

How we care for craniosynostosis

At Boston Children’s Hospital, our clinicians in Neurosurgery and Plastic Surgery have extensive experience diagnosing and treating craniosynostosis in infants and children of all ages.