Craniosynostosis
Craniosynostosis is a birth defect in which the bones of a child's skull fuse together too early. This happens before the baby's brain is fully formed. As the child's brain grows, the skull may become more deformed. The spaces between the skull bones of a typical child are filled with flexible material and are called sutures. These sutures allow the skull to grow as the child's brain grows. Around the age of two, the bones in a child's skull begin to fuse together as the sutures become bones. When this happens, the seam is considered "closed". In a child with craniosynostosis, one or more sutures close too early. This can limit or slow down the growth of the baby's brain.
When the suture tightens and the bones of the skull come together too early, the child's head will stop growing only in this part of the skull. In other parts of the skull where the sutures have not fused, the baby's head will continue to grow. When this happens, the skull will have an abnormal shape, although the brain inside the skull has grown to its normal size. However, sometimes a few sutures close too soon. In these cases, the brain may not have enough room to grow to its normal size. This can lead to increased pressure inside the skull.
Types of craniosynostosis
Types of craniosynostosis depend on which sutures fuse early.
- Sagittal suture: The sagittal suture runs along the top of the head from the baby's soft spot near the front of the head to the back of the head. When this suture closes too early, the baby's head lengthens and contracts (scaphocephaly). This is the most common type of craniosynostosis.
- Coronal suture: The right and left coronal sutures run from each ear to the sagittal suture at the top of the head. When one of these sutures closes too early, the child may have a flattened forehead on the side of the skull that closed earlier (anterior plagiocephaly). The eye socket of the child on this side can also be raised, and his nose can be pulled to this side. This is the second most common type of craniosynostosis.
- Bicoronal suture: This type of craniosynostosis occurs when the coronal sutures on both sides of a child's head close too early. In this case, the baby's head will become wide and short (brachycephaly).
- Lambdoid suture: The lambdoid suture runs along the back of the head. If this suture closes too early, the baby's head may be flattened at the back (posterior plagiocephaly). This is one of the rarest types of craniosynostosis.
- Metopic suture: The metopic suture runs from the baby's nose to the sagittal suture at the top of the head. If this suture closes too soon, the top of the baby's head may become triangular, narrow in front and wide in the back (trigonocephaly). This is one of the rarest types of craniosynostosis.
Other problems
Many of the problems a child may have depend on:
- Which sutures closed early
- When the sutures closed (was it before or after birth and at what age)
- Whether or not the brain has room to grow
Sometimes, if left untreated, increased pressure in a child's skull can lead to problems such as blindness, seizures, or brain damage.
Causes and risk factors
The cause of craniosynostosis in most infants is unknown. Some children develop craniosynostosis due to changes in their genes. In some cases, craniosynostosis occurs due to an abnormality in one gene, which can cause a genetic syndrome. However, in most cases, craniosynostosis is thought to be caused by a combination of genes and other factors, such as things the mother comes into contact with in her environment, or what the mother eats or drinks, or certain medications she takes during pregnancy.
Diagnosis
Craniosynostosis is usually diagnosed shortly after the baby is born. Sometimes it is diagnosed at a later age.
Usually, the first sign of craniosynostosis is an abnormal skull shape. Other signs may include:
- No “soft spot” on the baby’s skull
- A raised firm edge where the sutures closed early
- Slow growth or no growth in the baby’s head size over time
Doctors may identify craniosynostosis during a physical exam. The doctor will feel the baby's head for hard edges along the seams and unusual soft spots. The doctor will also look for any problems related to the shape of the child's face. If he suspects that the child may have craniosynostosis, the doctor will usually order one or more tests to confirm the diagnosis. For example, a special x-ray test, such as a CT scan, can show details of the skull and brain, whether certain sutures close, and how the brain develops.
Treatment
Many types of craniosynostosis require surgery. The surgery aims to relieve pressure on the brain, correct craniosynostosis, and ensure proper brain development. If necessary, surgery is usually performed within the first year of life. But the timing of the operation depends on which sutures are closed and whether the child has any genetic syndromes that can cause craniosynostosis.
Infants with very mild craniosynostosis may not require surgery. As the child grows and the hair grows, the shape of the skull may become less noticeable. Sometimes special medical helmets can be used to help shape a child's skull into a more regular shape.
Every baby born with craniosynostosis is different and the condition can range from mild to severe. Otherwise, most children with craniosynostosis are healthy. However, some children have developmental delays or mental retardation, either due to craniosynostosis preventing the child's brain from growing and functioning normally, or due to a genetic syndrome that has caused both craniosynostosis and problems with brain function. A child with craniosynostosis needs regular visits to the doctor to make sure the brain and skull are developing properly.