Craniosynostosis is condition that affects the bones in your baby’s head and how the head is shaped. When a baby is born, the skull is made up of more than 6 separate bones. These separate bones allow the head to grow as the baby’s brain grows. The lines at which the bones come together are called sutures. In babies with craniosynostosis, some of the bones in the skull fuse together sooner than they are supposed to. This causes the baby’s head to be shaped differently from a typical baby.

In babies with craniosynostosis, the brain continues to grow, but because some of the bones have fused too soon, the skull grows “extra” where it is able to expand to make space for the growing brain. This leads to the abnormal head shape getting worse over time. If left untreated, craniosynostosis can lead to complications such as visual impairment, headaches, or delayed development.

Causes of craniosynostosis

The direct cause of craniosynostosis depends on the type. Some forms are inherited and in some cases the causes are unknown. In some cases families carry the genes for a specific syndrome that can affect the skull as well as other parts of the body, and in others synostosis can be related to genetic disorders such those affecting fibroblast growth factor (FGF). In many cases no specific cause is found.

How doctors diagnose craniosynostosis

In most cases, doctors can diagnose craniosynostosis with a physical exam, often at or shortly after birth. If the case is mild, for the first few months, providers may not be certain whether the head shape is just a normal variation or due to changes in the shape of the head from the birth process. Additional exams and, sometimes, scans can determine that the diagnosis is craniosynostosis. These include:

  • Physical exam: Doctors who specialize in synostosis can make the diagnosis based on characteristic features of the head and facial shape.
  • Imaging Studies: A three dimensional computerized tomography (CT) is sometimes helpful to identify which sutures have fused.
  • Genetic testing: This will be used if a doctor suspects an underlying genetic syndrome.

Types of craniosynostosis

There are different types of craniosynostosis, depending upon which of the sutures close too early. Craniosynostosis can be simple (one suture closes early) or complex (more than one suture closes early). Children born with craniosynostosis have a unique appearance. The exact shape of the skull is determined by which sutures close prematurely. As the sutures close, growth of the skull usually occurs in the opposite direction to make room for brain growth. With this information doctors can usually tell which suture or sutures are closed based on the shape of the head.

It is important to differentiate between positional skull deformation (also called “positional molding”) and craniosynostosis. Positional deformation is very common and occurs from babies reclining in one position for long periods of time, typically on their backs. It can result in the back of the head being flat or, if the baby prefers to turn the head to one side, being crooked in the back. Some babies also will develop asymmetry of the face or ears as well.  Positional molding is a non-surgical condition that can be corrected with less invasive procedures such as repositioning the baby, “tummy time,” stretching exercises, alternate seating, and sometimes helmets.  Positional molding usually improves by itself once babies are rolling and sitting. In contrast, true craniosynostosis gets worse over time and requires surgical intervention.  Your provider or specialist knows how to tell the difference between these conditions.

The different types of craniosynostosis include the following:

  • Sagittal synostosis, the most common type, happens when the suture along the top of the head fuses together. This causes the head to look narrower as well as longer from front to back.
  • Metopic synostosis happens when the suture in the center of the forehead fuses before birth. It causes a triangle-shaped forehead and narrow face. However, many babies with normally-shaped foreheads can develop a ridge (bump) on their heads after birth. This can be normal. The ridge smoothes out over time. If you are concerned, your baby’s care team can tell the difference.
  • Coronal synostosis is when one or both of the sutures on the side of the head fuse. It causes one side of the forehead and face to look different from the other. If it affects both sides of the head, the forehead can look tall and flat when looking at the baby from the side.
  • Lambdoid synostosis is very rare. It is when one or both of the sutures in the back fuse. This can cause the back of the head to have an abnormal shape. Sometimes, it can also make the back of your baby’s head look flat. Your doctor can tell if the flat spot is caused by lamdoid synostosis or by your baby laying on his/her back. An imaging study, like an X-ray, can also help tell the difference.

How doctors treat craniosynostosis

Most cases of craniosynostosis require a surgical procedure in order for normal cranial development to occur. The surgery will reduce and prevent pressure inside the head, fix facial and cranial deformations, and allow room for the brain to grow normally. The best time for surgical corrections depends on the specific problem and parent preference for the type of surgery. The exact type and timing of the surgery is determined by a variety of factors including whether there is a genetic syndrome or other associated problems and the specific type of craniosynostosis.

Treatment depends on:

  • The type of craniosynostosis your baby has
  • How late in development the doctor finds the craniosynostosis
  • How severely the sutures have affected your baby’s head shape and brain
  • Surgery is the most common treatment. Surgery helps prevent pressure on the brain. It also allows the brain to grow normally and fixes the head shape and any facial deformations (features on the face that have not grown properly because of the changes caused by the skull shape).

What is the outcome for my baby?

If your baby is treated early, he/she should grow and develop normally. If he/she is not treated early, it can affect how your baby’s brain and body grow and work.


This webpage is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.