The skull is not a single bone like a crash helmet, but is made up of “plates” of bone that are joined together by seams (sutures) similar to what you might find in clothing.
The sutures are there to help with the moulding of the head during delivery, but they also have a role in the general shaping of the head as it grows. They are not in fact essential for head growth, the head will grow even when all the sutures have fused together, but if there is a problem with them, then the shape of the head can be affected.
Sutures normally fuse after all head growth has finished. However, they can sometimes fuse before birth and this is the condition known as craniosynostosis. It may affect a single suture or several. When it affects a single suture it is often referred to as ‘simple’ craniosynostosis. When it affects multiple sutures then it is often associated with a particular syndrome. In other words, the child may have other areas, particularly the facial bones and fingers affected as well.
Frequently Asked Questions
The premature closure of a single skull vault suture occurs weeks or months before a child is born. In most circumstances, the cause for it is unknown. It usually has no implications with regard to brain pressure/distortion and decisions concerning surgical treatment need to be made on cosmetic grounds. Without surgical intervention, the head shape is likely to remain much as it is, it will continue to grow but with similar proportions as now.
Sometimes, there is a slight tendency for the degree of asymmetry to become a little more pronounced over the years but there is no guarantee that this is going to happen. Surgical intervention carries an excellent chance of restoring a more normal contour to the head, although it is perhaps unrealistic to expect absolute perfection. However, it is usually possible to achieve a very marked improvement in head shape. Over the following years there is sometimes a slight tendency for the original head shape to reassert itself, but it is unusual for this to be to a degree that requires any further surgery.
The timing of the surgery varies depending upon which suture is involved. For children with sagittal synostosis, there is an operation that can be performed at around the age of 5 or 6 months. This involves the removal of the fused suture, combined with a manoeuvre designed to shorten the length of the head from front to back, while widening it from side to side. For children who, for some reason or another, are not operated upon at this early age, there are still procedures that can be carried out later but they involve a more extensive reconstruction of all or, at least, the front half of the head.
For children with premature fusion of either one coronal suture (which typically produces flattening of one side of the forehead and bulging of the other) or with metopic synostosis (which gives a triangular shape to the front of the head), surgery, in our experience, is best carried out when a child is 15 to 18 months old, or even older than this. This choice of the optimal age for surgery is different to what some craniofacial surgeons choose, but in our experience it means that there is less chance of the child’s head shape reverting to something like its original appearance over the years to come.
All of the operations involved in treating single suture synostosis are major and therefore have particular dangers. The dangers for any operation are usually related to some unexpected event such as bleeding, infection or an anaesthetic complication etc. With head operations, clearly if something unexpected occurs then the brain itself is going to be at risk. The brain is in fact contained within a thin leathery membrane and is not actually seen during these operations, but if something unexpected does occur then damage to it can result. The effects of this can be similar to a stroke or result in epilepsy or other signs of brain damage. Fortunately, our experience here is that the incidence of such adverse events is extremely low (well below 1% for surgery for the single suture synostoses). Most children are out of hospital within three to five days and no particular post-operative precautions are required at home. Children may have a degree of swelling of the forehead and eyelids following the surgery although we now use a particular technique during the surgery to try and keep this to a minimum.
Follow-up usually consists of a hospital clinic visit six to eight weeks after the operation and then further reviews at one year and at three years later. We like to undertake a long follow-up like this because of our interest in the continuing progress of children we have treated for craniosynostosis. Parents of children with craniosynostosis affecting a single skull vault suture often ask us if the condition will crop up again in subsequent pregnancies. Our Geneticists usually quote an incidence of approximately 2% for this, a figure that makes it still very unlikely although 1:50 is a higher incidence than for the general population.
Further information can be found in this publication;
The Clinical Management of Craniosynostosis
Edited by Hayward, Jones, Dunaway and Evans
MacKeith Press 2004
Distributed through Cambridge University Press