Types of craniosynostosis
There are four main types of craniosynostosis that may occur in isolation or together. They are:
- sagittal synostosis
- coronal craniosynostosis
- metopic synostosis
- lambdoid synostosis
The different types of craniosynostosis are outlined below.
Sagittal synostosis
Sagittal synostosis is the most common type of craniosynostosis, accounting for around half of all of cases. In occurs when the suture at the top of the skull (the sagittal suture) fuses. This leads to a lack of growth in width and compensatory growth in length, resulting in a long, narrow skull.
Coronal craniosynostosis
Coronal craniosynostosis is the second most common type of craniosynostosis after sagittal synostosis, accounting for around one in four cases.
In coronal craniosynostosis, the fusion occurs in one or both of the two sutures that run from the top of the ear to the top of the skull. These are known as the coronal sutures.
If only one coronal suture is fused, the infant will develop a flattened forehead on the affected side. They may also have a raised eye socket and a crooked nose. If both coronal sutures are fused, the infant will develop a flat and elevated (prominent) forehead and brow.
Metopic synostosis
Metopic synostosis is an uncommon type of craniosynostosis, occuring in between 4%–10% of cases of craniosynostosis. The fusion occurs in the metopic synostosis, which is the suture that runs from the nose to the top of the skull. Infants with metopic synostosis will develop a pointed scalp that looks triangular.
Lambdoid synostosis
Lambdoid synostosis is the rarest type of craniosynostosis and occurs in about 2%–4% of cases. Fusion occurs in the lambdoid suture, which runs along the back of the head. Infants with lambdoid synostosis will develop a flattened head at the back.
However, not all children with a flattened head at the back have Lambdoid synostosis. It is common and normal for babies to have some flatness at the back of their head as a result of lying on their backs for prolonged periods of time. This type of flattening is known as positional plagiocephaly and often resolves with further development. See the box to the left for more information about positional plagiocephaly.
Intracranial pressure (ICP)
If your child has mild craniosynostosis, it may not be spotted until they begin to experience problems due to an increase in intercranial pressure (ICP) in their skull. This usually occurs when a child is between four to eight years old.
The symptoms of ICP usually begin with:
- a persistent headache, which is usually worse in the morning and last thing at night
- vision problems, such as double vision, blurred vision or a "greying out" of vision
- an unexplained decline in the child’s academic abilities
If your child complains of any of the above symptoms, take them to see your GP as soon as possible. In most cases, these symptoms are unlikely to be caused by raised ICP but they do require further investigation.
Left untreated, other symptoms of raised ICP can include:
- vomiting
- irritability
- sluggishness and unresponsiveness
- swollen eyes, or the eyes find it difficult to follow a moving object
- hearing difficulties
- breathing difficulties
