Craniosynostosis

What is craniosynostosis?

Craniosynostosis is a rare condition where one or more of the joints between the bones in a baby's skull, called sutures, fuse together too early. This stops the skull growing normally in that direction, which can change the shape of your baby's head and, in some cases, put pressure on their growing brain.

Symptoms of craniosynostosis

The main sign of craniosynostosis is an unusually shaped head, which often becomes more noticeable as your baby grows. Depending on which suture is affected, this can look like:

• a long, narrow head, sometimes described as egg or boat-shaped
• a pointy or triangular-looking forehead
• one side of the head flattened, or bulging out
• an uneven or asymmetrical face.

You may also notice:

• the soft spot on top of your baby's head (the fontanelle) disappearing before they turn 1, or bulging
• a small, hard ridge you can feel along the fused suture, instead of the usual softness.

If the condition is mild, it may not be noticeable until your child is a bit older. Rarely, craniosynostosis can also cause learning difficulties, sight or hearing loss, breathing problems, such as not being able to breathe easily through the mouth, dental problems like missing or crowded teeth, or, if pressure builds up inside the skull, seizures.

Causes and who is at risk

Researchers aren't sure of the exact cause of craniosynostosis. Most babies with the condition have just one affected suture and are otherwise healthy, sometimes called single-suture craniosynostosis, and this often happens due to a random gene change rather than something inherited.

Possible contributing factors include:

• external pressure on the baby's head before birth
• growth abnormalities in the membranes around the skull
• an underlying genetic condition.

If more than one suture is affected, craniosynostosis is more likely to be part of a genetic condition, such as Apert, Crouzon, Pfeiffer, Saethre-Chotzen or Carpenter syndrome. These conditions can also affect other parts of the body.

Certain factors may slightly increase the risk of having a baby with craniosynostosis, including the mother being treated for thyroid disease during pregnancy, using certain fertility or anti-seizure medicines around the time of conception, or smoking during pregnancy. Boys are somewhat more likely to be affected than girls and having an older father (over 40) has also been linked to a higher risk. Craniosynostosis affects around 1 in every 2,500 babies.

Are there different types of craniosynostosis?

Yes, types are named after which suture is affected:

• Saggital craniosynostosis: affects the suture running front to back along the top of the head, causing a long, narrow head shape, sometimes called scaphocephaly. This is the most common type, making up around half to two-thirds of cases, and can also cause a delay in speech
• Coronal craniosynostosis: affects one of the sutures running from ear to ear over the top of the head. If it affects one side (unicoronal), the forehead looks flattened on that side; if it affects both sides (bicoronal), the whole forehead and head look broader and flatter
• Metopic craniosynostosis: affects the suture running from the top of the nose to the forehead, causing a pointy or triangular-looking forehead, with a narrow ridge down the midline
• Lambdoid craniosynostosis: affects the suture at the back of the head, causing flattening on one side. This is the rarest type
• Syndromic (complex) craniosynostosis: affects more than one suture at once, and is caused by an underlying genetic condition, such as Apert, Crouzon, Pfeiffer or Saethre-Chotzen syndrome. This can also affect other parts of the body, alongside the head.

How is craniosynostosis diagnosed?

Craniosynostosis is usually first noticed because of your baby's head shape, either at birth, during the newborn check, or at a routine well-baby visit as they grow. Occasionally, it's spotted on a routine ultrasound scan during pregnancy.

To diagnose it, a doctor will:

• examine your baby's head and face, feeling for soft spots and any hard ridges along the sutures
• measure your baby's head circumference to check it's a typical size for their age.

If craniosynostosis is suspected, you'll usually be referred to a specialist centre for further tests, such as an X-ray or a CT scan, to confirm the diagnosis and work out which suture, or sutures, are affected. Your baby may also be offered genetic testing, particularly if more than one suture is affected, to check whether an underlying genetic condition is involved.

How is craniosynostosis treated?

Non-surgical treatment

Not every baby with craniosynostosis needs surgery. In mild cases, your care team may simply monitor your baby with regular check-ups. For mild head-shape changes, a specially designed helmet can be used on its own, or after a minimally invasive procedure, to gently reshape the skull as your baby grows. Depending on your child's symptoms, they may also need:

• regular hearing and eye tests, and glasses if needed
• speech and language therapy
• specialist dental treatment

psychological support or counselling, particularly if facial asymmetry affects their self-esteem as they get older.

Surgical treatment

When surgery is needed, the approach depends on which suture is affected, your baby's age, and the severity of the condition. There are two broad types of surgery. Endoscopic strip craniectomy is a minimally invasive option, usually offered to babies younger than about 4 months. A surgeon makes two small cuts and uses a thin tool with a camera (an endoscope) to remove a strip of bone, including the fused suture. It takes around one to two hours, involves a shorter hospital stay of around two days, and causes less scarring and blood loss than open surgery. Afterwards, your baby wears a soft helmet, often for up to a year, to help guide their skull into shape as it grows. A related option, spring-assisted surgery, uses the same technique but adds small surgical springs to gradually widen the skull over time.

Open cranial vault reconstruction is a more involved operation, generally used for babies over about 4 months, since skull growth slows and helmets become less effective after this age, or for more complex cases. The surgeon makes a cut across the top of the head, removes and reshapes the affected skull bones, and fixes them back in place with plates, screws or dissolvable material. It takes longer, around three to five hours, usually involves a hospital stay of 3 to 5 days including at least one night in intensive care, and leaves a larger scar, though this is hidden by hair as it grows back. Your baby won't usually need a helmet afterwards.

For metopic or coronal craniosynostosis, a similar open operation called fronto-orbital advancement is often used instead, reshaping the forehead and the upper eye sockets to create more room for the brain and eyes. This is usually done between 9 and 15 months of age.

If more than one suture is affected, often as part of a genetic syndrome, your child may need a series of operations over time rather than a single surgery.

As with any operation, there are risks, including bleeding, infection, cerebrospinal fluid leaks, and rarely, the need for further surgery. These risks are higher with open surgery than with the endoscopic approach. Your child's surgical team will talk you through the specific risks and benefits for your baby's situation.

When should I see a doctor?

See your GP if you're concerned about your baby's head shape or size, or if they have symptoms of craniosynostosis alongside problems with their vision or hearing, speech delay, or difficulty breathing normally through their mouth, which can cause snoring or disturbed sleep. It's also worth raising any missed developmental milestones, such as not crawling, standing or saying first words as expected.

If your child has a seizure, or sudden difficulty breathing, call 999 or your local emergency services straightaway.