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Column originally published Mar 14, 2006

Possible Craniosynostosis Require Further Investigation

Question: Our first grandson was born a month ago. Shortly afterwards, we noticed that he has an oddly-shaped head. It is very long from front to back, and there was a hard bony ridge in the middle of his skull extending from the front to the back. Our family doctor consulted a paediatrician. After examination and some X rays on his head, this doctor told us that his skull bones didn’t develop normally, and he may need an operation. We are now waiting to see a neurosurgeon. Can you please explain to us what can be happening in our grandson?


What you have described is likely an uncommon medical condition called craniosynostosis. It involves the skull bones in his head.

If you feel around your head, you will notice that your skull is a bony structure. The adult skull appears to be one solid piece of bone. However, in a developing fetus, the skull is actually made up of 5 pieces of bones: two in the front, two on the side, and one in the back. These bones are separated by a small space called suture lines.

The reason for having several skull bones is two folds. When a baby is born, the head has to pass through the mother’s birth canal. Having several skull bones with space in between allows for molding of the head and facilitates a child’s birth.

Another important reason is that new bone is being formed at the edge of the skull bones bordering the sutures. By adding new bone this way, it will actually expand the size of the skull, giving new space for the brain to grow. Much of the brain’s growth happens in the first year of life. Therefore, it is most important for the skull to grow quickly in order to provide the space for the brain to grow, and this is achieved by new bone formation around each skull bone.

As I mentioned earlier, there are several sutures that separate the skull bones. These sutures normally stay open for the first few years of a child’s life. However, about one in every 2000 babies are born with one or more of these sutures closing prematurely. When this happens, there is rapid overgrowth of bone at the edge of the skull bones involved, so much so that the skull bones may fuse together across the suture lines. When you feel around the head, you will notice a bony ridge over the suture line that is closing prematurely. This is called craniosynostosis (CS).

CS can happen to one or more suture lines. We don’t know why this happens most of the time, although abnormal genes account for a small percentage of affected children, and sometimes CS can happen in several family members. Occasionally, an overactive thyroid gland in a newborn baby is the cause of CS.

If CS affects only one suture line, the rest of the skull bones can compensate by producing more new bone along other suture lines so that the skull can continue to grow and accommodate the growing brain. The end result can be a somewhat lopsided skull, or a pointed forehead, or an elongated head from front to back. This is more of a cosmetic problem and does not affect the brain’s function or development.

However, if more than one suture line is involved, this can severely reduce the growth of the skull and, in turn, the space available for the growing brain. The end result is an increase in the pressure inside the skull. This is a very serious situation which can lead to permanent brain damage. Children with increased pressure in the skull will experience severe headache, and they are often very irritable and can have projectile vomiting.

The best way to diagnose CS is skull X ray and CT scan. X ray can reveal excessive bone formation along suture lines and fusion of the skull bones, while CT scan is more accurate in pinpointing the location and degree of bone fusion.

If premature bone fusion affects important sutures and is putting pressure on the underlying brain, surgical intervention will be necessary to separate the fused bones in order to allow enough space for the brain to grow. Sometimes surgery is necessary cosmetically if premature closing of suture affects multiple skull bones which can lead to severely deformed skull and facial structures.

Whether your grandson needs operation or not depends on the severity of his condition. This can only be determined after additional tests when he sees the neurosurgeon. You should watch for any excessive crying and vomiting to ensure that he has no increased pressure inside the skull.

Before I finish, I should point out a more common problem that can affect the shape of a baby’s head. This condition is called plagiocephaly, or ‘flat head.’ Most of the time, it is caused by the baby sleeping in one position over a period of weeks and months. Because a baby’s skull bones are softer than adults, the weight of the head over one constant area of the skull can cause flattening of the skull bone.

This is a benign problem and does not require excessive investigation or surgery. The best treatment is simply change the baby’s sleeping position. Plagiocephaly is becoming more common in the past 10 to 15 years because doctors are advising parents to place their infants on the back to sleep in order to reduce the chance of Sudden Infant Death Syndrome (SIDS).