Craniosynostosis is a rare skull problem that causes a baby to be born with, or develop, an abnormally shaped head.
The irregular skull shape in craniosynostosis can cause persistent headaches, learning difficulties, eye problems and other symptoms. Most symptoms develop in later childhood.
The symptoms of craniosynostosis usually result from increased pressure within the skull, which is called intracranial pressure (ICP).
Different types of craniosynostosis can be described based on the areas of the skull affected and the resulting changes in shape.
How is craniosynostosis diagnosed?
Craniosynostosis can usually be diagnosed by a paediatrician (specialist in treating children) after a visual examination of your baby's head.
Any severe distortions of the skull or face will be apparent, and the existence of ridges over fused sutures or misalignment of the ears also provide evidence of craniosynostosis.
An X-ray or CT scan of the skull may be taken to confirm a diagnosis. CT scans are usually only required to plan some types of surgery or if the diagnosis is in doubt.
If your child has other birth defects that suggest craniosynostosis may be part of a wider syndrome, a sample of their blood, hair or saliva may be taken and tested for any genetic mutations.
What causes craniosynostosis?
Craniosynostosis is the result of the premature fusion of different sections of the skull. This means the skull is unable to grow in affected areas.
When one area of the skull is prevented from growing, other areas may "overgrow" to compensate and limit the pressure developing around the brain. A lack of growth in some areas and compensatory growth in other areas will result in an altered head shape.
Craniosynostosis is usually classfied as either:
nonsyndromic – there are no other birth defects and the cause is unknown
syndromic – craniosynostosis is the result of one of several rare syndromes
A syndrome is a range of symptoms related to a common cause, which is usually – but not always – genetic.
How common is craniosynostosis?
Craniosynostosis is rare, affecting an estimated 1 in every 1,800 to 3,000 children. Three out of every four cases affect boys.
Nonsyndromic craniosynostosis is the most common form of the condition, accounting for 80-95% of all cases.
There are more than 150 different syndromes that can cause syndromic craniosynostosis, all of which are very rare. These include:
Apert syndrome – which affects 1 in every 100,000 children and disrupts the normal growth of bone before birth, resulting in deformities of the head, hands, feet and face
Crouzon syndrome – which affects 1 in every 60,000 children and disrupts the normal growth of bone in both the skull and the face, often resulting in severe facial disfigurement
Pfeiffer syndrome – which affects 1 in every 100,000 children and disrupts bone growth, resulting in deformities of the head and face; it also causes big toes, wide thumbs, and webbed hands and feet
Saethre-Chotzen – a genetic condition that affects around in 1 every 50,000 births and can cause a wide range of disfigurements, including facial defects
The main treatment for craniosynostosis is surgery. This can either be carried out during the first year of your baby's life, or delayed until later childhood.
The timing of the surgery is decided by doctors, in consultation with you.
Most children with craniosynostosis recover well after surgery and the appearance of their skull improves significantly.
However, around 1 in 15 children may have further problems with their skull's development as they get older, which will require further surgery to correct.
Craniosynostosis is a rare type of birth defect that affects the shape of a baby's skull
The human skull
Many people think of the human skull as a single section of bone similar to the shell of an egg. However, the skull is more like a football – it consists of a number of plates of bone that fit together to create a sphere.
In between the plates of bone are strong elastic tissues called sutures. The sutures give the bone plates flexibility so the skull is able to grow along with the brain. This is important because the human brain grows rapidly following birth, literally doubling in size during the first three years of life, and the skull must grow to accommodate this growth.
After the skull and brain have grown to their full adult size, the sutures fuse together to create a single structure of bone. However, in cases of craniosynostosis, one or more sutures fuse together before birth or shortly afterwards.
Symptoms of craniosynostosis
Craniosynostosis causes an irregular skull shape. The baby's skull shape is determined by the type of craniosynostosis they have.
A baby's skull consists of seven plates of bone connected by strong elastic tissues called sutures. The sutures give the bone plates flexibility so the skull can grow along with the brain.
Other signs of craniosynostosis can include:
a hard ridge developing along the sutures
the soft spot (fontanelle) on your baby's head disappearing or feeling different
your baby's head not growing in proportion with the rest of their body
an increase in pressure within the baby's skull or raised intracranial pressure (ICP)
In some cases, craniosynostosis may not be noticeable until a few months after birth.
Intracranial pressure (ICP)
Raised intracranial pressure (ICP) is a symptom that may occur in all types of craniosynostosis. ICP increases when pressure builds up inside your child's skull because of its irregular shape.
When only one suture is involved, raised ICP occurs in less than 15% of children. However, in syndromic craniosynostosis where multiple sutures are involved, raised ICP is more common and may occur in up to 60% of cases.
If your child has mild craniosynostosis, it may not be spotted until they begin to experience problems because of an increase in ICP. This usually occurs when a child is between four and eight years old.
The symptoms of ICP usually begin with:
a persistent headache – 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 will not be caused by raised ICP, but they do require further investigation.
Left untreated, other symptoms of raised ICP can include:
sluggishness and unresponsiveness
swollen eyes or difficulty following a moving object
Types of craniosynostosis
There are several types of craniosynostosis, depending on which sutures are affected. Different sutures being affected can lead to a different shaped skull.
These are described below.
Sagittal synostosis is the most common type of craniosynostosis, accounting for around half of all cases.
It 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 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 prominent forehead and brow.
Metopic synostosis is an uncommon type of craniosynostosis, occuring in 4-10% of cases. 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 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 is known as positional plagiocephaly.
Parents sometimes think their child has craniosynostosis when they in fact have positional plagiocephaly. This is also known as "flat head syndrome".
This is where the back or side of a baby's head becomes flattened, usually because they sleep on their back.
Positional plagiocephaly is quite a common condition and does not cause any health problems. Although an infant's head may become flattened during the first few months of life, the shape of their head often mostly corrects itself by their first birthday.
Your GP will be able to determine if your child has craniosynostosis or positional plagiocephaly.
Surgery is the main treatment for craniosynostosis, and when it's carried out depends on your child's condition and your personal preferences.
Sometimes the surgery is carried out later in childhood to reduce the likelihood of the operation needing to be repeated.
Earlier surgery may be recommended if there are problems inside the head or with the eyes and jaw, or for cosmetic reasons.
You should talk to your child's doctors to decide when the operation should be carried out.
There are four hospitals with specialist surgical units and teams with experience and expertise in carrying out this type of surgery. These are:
John Radcliffe Hospital in Oxford
Great Ormond Street Hospital in London
Birmingham Children's Hospital
Alder Hey Hospital in Liverpool
Surgery for craniosynostosis is usually carried out by a team of two surgeons who each have their own speciality. These are:
a neurosurgeon – a specialist in the nervous system and brain
a craniofacial surgeon – a specialist in surgery of the face, head and jaws
Open surgery for craniosynostosis is carried out under a general anaesthetic, which means your child will be asleep during the procedure and will not feel any pain.
The neurosurgeon will make an incision across the top of your child's scalp. This will leave a scar, but it will be hidden by their hair. The neurosurgeon will remove affected areas of skull.
The removed pieces of bone are reshaped by the craniofacial surgeon before being returned to a normal position in the skull. The incision will then be sealed using dissolvable stitches.
In some cases, endoscopic surgery may be an alternative surgical treatment.
This involves inserting a long, thin flexible tube with a light and a camera on the end (endoscope) into the scalp. The suture is then opened to allow the skull to continue growing normally.
Endoscopic surgery for craniosynostosis is usually only used in children younger than six months as the skull has not yet fully hardened.
The advantages of endoscopy surgery can include a shorter operation and quicker recovery.
After the operation
Extra precautions always have to be taken in cases where surgery is carried out on the skulls of very young children.
It is therefore likely your child would be transferred to a high dependency unit (HDU) for one or two days after the operation so their condition can be carefully monitored.
Most children are well enough to leave hospital around five days after having open surgery.
After surgery, most children will only experience mild pain, but it is common for them to develop significant swelling around their eyes. The swelling can often prevent them from opening their eyes.
Your child may find this annoying or distressing, but the swelling does not present a health risk and should go down after a few days.
It is likely your child will be asked to attend regular check-ups after having surgery so the future development of their skull can be monitored.
The check-ups will be quite frequent at first, such as every six weeks, before becoming less frequent as your child gets older. Most children will only require an annual check-up once they reach the age of six.
How to prepare for your child's hospital stay
A practical guide on how to prepare for your child going into hospital, including information on what to bring and the facilities available for both parents and children. Facilities may vary from one hospital to another, this video uses Royal Alexandra Children's Hospital in Brighton as an example.