Craniosynostosis is a rare type of birth defect that affects the shape of a baby's skull 

The human skull

Many people think of the human skull as a single section of bone similar to the shell of an egg. However, the skull is more like a football – it consists of a number of plates of bone that fit together to create a sphere.

In between the plates of bone are strong elastic tissues called sutures. The sutures give the bone plates flexibility so the skull is able to grow along with the brain. This is important because the human brain grows rapidly following birth, literally doubling in size during the first three years of life, and the skull must grow to accommodate this growth.

After the skull and brain have grown to their full adult size, the sutures fuse together to create a single structure of bone. However, in cases of craniosynostosis, one or more sutures fuse together before birth or shortly afterwards.

Craniosynostosis is a rare problem with the skull that causes a baby to be born with, or develop, an abnormally shaped head.

The irregular skull shape in craniosynostosis can cause persistent headaches, learning difficulties, eye problems and other symptoms. Most symptoms develop in later childhood.

The symptoms of craniosynostosis usually result from increased pressure within the skull, which is called intracranial pressure (ICP). 

Read more about the symptoms of craniosynostosis.

Craniosynostosis is usually diagnosed after a visual examination of your baby's head, although further tests may sometimes be necessary.

Read more about diagnosing craniosynostosis.

Why does it happen?

Craniosynostosis is the result of the premature fusion of different sections of the skull. This means the skull is unable to grow in affected areas.

When one area of the skull is prevented from growing, other areas may 'overgrow' to compensate and limit the pressure developing around the brain. A lack of growth in some areas and compensatory growth in other areas will result in an altered head shape.

In most cases of craniosyntosis, there are no other birth defects (known as nonsyndromic). When it develops with other birth defects, it is known as syndromic.

The causes of nonsyndromic craniosynostosis are unknown. There are theories about cell defects and the baby's position in the womb, but these have not been proven.

Syndromic craniosynostosis is the result of one of several possible syndromes. A syndrome is a range of symptoms related to a common cause, which is usually (but not always) genetic.

Some of the syndromes that can lead to craniosynostosis are listed below. 

Read more about the causes of craniosynostosis.

Different types of craniosynostosis can be described based on the areas of the skull affected and the resulting changes in shape (see symptoms of craniosynostosis for more information). 

How common is craniosynostosis?

Craniosynostosis is rare, affecting an estimated one in every 1,800 to 3,000 children. Three out of every four cases affect boys.

Nonsyndromic craniosynostosis is the most common form of the condition, accounting for 80-95% of all cases.

There are more than 150 different syndromes that can cause syndromic craniosynostosis, all of which are very rare. These include:

  • Apert syndrome, which affects one in every 100,000 children and disrupts the normal growth of bone before birth, resulting in deformities of the head, hands, feet and face
  • Crouzon syndrome, which affects one in every 60,000 children and disrupts the normal growth of bone in both the skull and the face, often resulting in severe facial disfigurement
  • Pfeiffer syndrome, which affects one in every 100,000 children and disrupts bone growth, resulting in deformities of the head and face – it also causes big toes, wide thumbs and webbed hands and feet
  • Saethre-Chotzen, a genetic condition that affects around in one every 50,000 births and can cause a wide range of disfigurements, including facial defects

Treating craniosynostosis

The main treatment for craniosynostosis is surgery.

This can either be carried out during the first year of your baby's life, or delayed until later childhood.

The timing of the surgery is decided by doctors, in consultation with you.

Most children with craniosynostosis recover well after surgery and the appearance of their skull improves significantly.

However, around one in 15 children may have further problems with their skull's development as they get older, which will require further surgery to correct.

Read more about treating craniosynostosis.

Page last reviewed: 22/08/2012

Next review due: 22/08/2014


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