Craniosynotosis Surgery

This is the commonest form of single suture synostoses and occurs in approximately 1 in 5,000 live births. The vast majority of cases are not genetic in origin and are most commonly caused by reduced space for the baby’s head in the uterus during pregnancy. A small number of cases may have a genetic cause. It is 4 times commoner in boys than girls, though no one really understands why. Sagittal synostosis leads to a head shape which is long and narrow (called scaphocephaly) with a tendency for the forehead to be prominent and bossed and the back of the head to be prominent and pointed. Surgery, is in the form of a Total Calvarial Remodelling procedure (TCR) which usually takes place when affected children are between 12-18 months of age (though the window of opportunity to undertake the surgery is quite wide). The aim of surgery is to stop the head shape from getting worse, make the head shape better by reshaping the whole of the top portion of the skull and finally to reduce the risk of a child with sagittal synostosis developing raised intracranial pressure from approximately 15% (in cases that do not have surgery) to less than 2% (in cases that have do have surgery) by creating more space around the brain.

This is the second commonest suture to fuse and occurs in approximately 1 in 10,000 live births. The vast majority of cases are not genetic in origin and are most commonly caused by reduced space for the baby’s head in the uterus during pregnancy. A small number of cases have a genetic cause. It is commoner in boys than girls, though no one really understands why. Metopic synostosis leads to a forehead which is triangular in shape (called trigonocephaly) with a tendency for the eyes to appear closer together than normal. Surgery, is in the form of a Frontoorbital Advancement and Remodelling procedure (FOAR) which usually takes place when affected children are between 12-18 months of age (though the widow of opportunity to undertake the surgery is quite wide). The aim of surgery is to stop the head shape from getting worse, make the head shape better by reshaping the forehead and finally to reduce the risk of a child with metopic synostosis developing raised intracranial pressure from approximately 15% (in cases that do not have surgery) to less than 2% (in cases that have do have surgery) by creating more space around the brain.

Unicoronal synostosis refers to fusion of one of the 2 coronal sutures. It is more likely to be genetic in origin than the other single suture synostoses though some cases may still be caused by reduced space for the baby’s head in the uterus during pregnancy. Syndromes potentially causing unicoronal synostosis include Saethre Chotzen syndrome, Muenke syndrome and TCF 12 related craniosynostosis.

Unicoronal synostosis leads to a forehead which is flatter on the affected side (called plagiocephaly) with the affected eyebrow looking more elevated and the eye looking more widely open than the opposite side. The shape of the skull from above looks like a trapezium and there is a shortened distance from the ear to the eye on the affected side compared with the unaffected side. There is some associated facial asymmetry with the nose and the chin being deviated to the opposite side.

Surgery for unicoronal synostosis is in the form of a Frontoorbital Advancement and Remodelling procedure (FOAR) which usually takes place when affected children are between 12-18 months of age (though the widow of opportunity to undertake the surgery is quite wide). The aim of surgery is to stop the head shape from getting worse, make the head shape better by reshaping the forehead and finally to reduce the risk of a child with unicoronal synostosis developing raised intracranial pressure from approximately 15% (in cases that do not have a genetic origin and do not have surgery) to less than 2% (in cases that have do have surgery). Children found to have a syndromic cause usually have a higher risk for developing raised intracranial pressure.

This is the rarest of the major sutures to fuse and occurs in approximately 1 in 300,000 live births. The majority of cases affect only one lambdoid suture (unilambdoid) and so is more likely to have a genetic cause (such as ERF related craniosynostosis) and are most commonly caused by reduced space for the baby’s head in the uterus during pregnancy. Occasionally this affects both lambdoid sutures and is associated with fusion of other calvarial sutures and so is more likely to have a genetic cause. Unilambdoid synostosis leads to a flatness of the skull on the affected side of the back of the head together with a windswept appearance of the skull when viewed from both the front and the back. Surgery is in the form of a posterior remodelling procedure which usually takes place when affected children are around 12-18 months of age (though the widow of opportunity to undertake the surgery is quite wide). The aim of surgery is to stop the head shape from getting worse, make the head shape better by reshaping the back of the skull (occiput) and finally to reduce the risk of a child with lambdoid synostosis developing raised intracranial pressure from approximately 15% (in cases that do not have surgery) to less than 2% (in cases that have do have surgery) by creating more space around the brain. Children found to have a syndromic cause usually have a higher risk for developing raised intracranial pressure.

Bicoronal synostosis refers to fusion of both coronal sutures and is much more likely to be genetic in origin than unicoronal synostosis or other single suture synostoses though some cases may still be caused by reduced space for the baby’s head in the uterus during pregnancy. The vast majority of syndromic craniosynostosis have bicoronal synsotosis. In bicoronal synostosis, the skull shape is very tall (called turricephaly) and broad and short from front to back with a flat forehead (called brachycephaly).

Surgery for bicoronal synostosis, can be either in one stage - in the form of a Frontoorbital Advancement and Remodelling procedure (FOAR) which usually takes place when affected children are around 12-18 months of age (though the widow of opportunity to undertake the surgery is quite wide), or else a 2 stage procedure with the first stage involving a Posterior Vault Distraction procedure (PVD) followed by an FOAR at least a year later. Either way, the aim of surgery is to stop the head shape from getting worse, make the head shape better and to reduce the risk of a child with bicoronal synostosis developing raised intracranial pressure. Of course depending on the syndromic cause, other surgical procedures may be required from childhood to maturity.

Apert syndrome is a rare genetic syndromic form of craniosynostosis and occurs in 1 in 65,000 live births leading to a combination of craniofacial and limb abnormalities. The craniofacial features include brachycephaly (caused by bicoronal synostosis), shallow eye sockets (this is called exorbitism) making the eyes appear bulging and poor midfacial growth leading to an underdeveloped upper jaw and potential breathing problems such as sleep apnoea. Some cases have associated cleft palate. The limb features include complex symmetrical syndactyly (fusion of the fingers and toes). This requires surgery from a specialist hand surgeon affiliated to and working closely with the craniofacial team.

Apert syndrome is caused by one of 2 genetic mutations in a gene called the fibroblast growth factor receptor type 2 gene (or FGFR2 gene for short) giving rise to 2 different forms of Apert syndrome – one which has more complex facial features and less severe limb features, and one which has more severe limb features and less severe facial features. These genetic changes can either develop spontaneously (from unaffected parents) or else be inherited from an affected parent, in which case there is a 50% chance of an affected parent passing on the affected gene to their children.

Individuals with Apert syndrome usually have learning difficulties and developmental delay, though there is a spectrum of severity.

Crouzon syndrome is a rare genetic syndromic form of craniosynostosis and occurs in 1 in 60,000 live births. The craniofacial features (which can range from mild to severe) include brachycephaly (caused by bicoronal synostosis), shallow eye sockets (this is called exorbitism), making the eye appear bulging and poor midfacial growth leading to an underdeveloped upper jaw and potential breathing problems such as sleep apnoea. Some cases have associated cleft palate. The limbs are essentially normal in Crouzon syndrome.

The majority of cases of Crouzon syndrome are caused by genetic mutations in a gene called the fibroblast growth factor receptor type 2 gene (or FGFR2 gene for short). Rarely a specific mutation in the fibroblast growth factor receptor type 3 gene (or FGFR3 gene for short) can cause a more severe form of Crouzon syndrome. These genetic changes can either develop spontaneously (from unaffected parents) or else be inherited from an affected parent, in which case there is a 50% chance of an affected parent passing on the affected gene to their children.

Individuals with Crouzon syndrome usually have normal intelligence.

Pfeiffer syndrome is a rare genetic syndromic form of craniosynostosis and occurs in 1 in 100,000 live births leading to a combination of craniofacial and limb abnormalities. The craniofacial features (which can range from mild to severe) include brachycephaly (caused by bicoronal synostosis), shallow eye sockets (this is called exorbitism), making the eye appear bulging and poor midfacial growth leading to an underdeveloped upper jaw and potential breathing problems such as sleep apnoea. Some cases have an associated cleft palate. In the severest form of Pfeiffer syndrome all the sutures (growth lines) of the skull and face can be prematurely fused leading to a cloverleaf appearance to the skull. The limb features typically include broad thumbs and big toes which are bent away from the rest of the hand and foot. Other limb features may also include short fingers and toes and webbing or fusion of the fingers and toes. Individuals with Pfeiffer syndrome often have learning difficulties and developmental delay, most commonly affecting speech and language.

The majority of cases of Pfeiffer syndrome are caused by genetic mutations in a gene called the fibroblast growth factor receptor type 2 gene (or FGFR2 gene for short). Rarely a specific mutation in the fibroblast growth factor receptor type 1 gene (or FGFR1 gene for short) gene can cause a milder form of Pfeiffer syndrome. These genetic changes can either develop spontaneously (from unaffected parents) or else be inherited from an affected parent, in which case there is a 50% chance of an affected parent passing on the affected gene to their children.

Individuals with Pfeiffer syndrome often have learning difficulties and developmental delay, most commonly affecting speech and language, though there is a spectrum of severity.

Saethre-Chotzen syndrome is a rare genetic syndromic and occurs in 1 in 50,000 live births leading to a combination of craniofacial and limb abnormalities. The craniofacial features include either plagiocephaly - an asymmetric forehead and skull being short from front to back on one side (caused by unicoronal synostosis) or brachycephaly – the skull being short from front to back on both sides (caused by bicoronal synostosis); shallow eye sockets (this is called exorbitism), making the eye appear bulging and poor midfacial growth leading to an underdeveloped upper jaw. There is also an association with drooping upper eyelids (called ptosis) and small low set ears.

Some cases have an associated cleft palate. The limb features may include some minor webbing of some of the fingers and toes which rarely require any surgery.

In most cases it is caused by a genetic mutation in a gene called the TWIST 1 gene in which case individuals have normal intelligence. In a smaller subset of cases, a complete deletion of the TWIST 1 gene along with neighbouring genes are the cause, and in these cases, the individual may have learning difficulties and developmental delay. This genetic change can either develop spontaneously (from unaffected parents) or else be inherited from an affected parent, in which case there is a 50% chance of an affected parent passing on the affected gene to their children.

Muenke syndrome is a rare genetic syndromic and occurs in 1 in 30,000 live births. The craniofacial features include either plagiocephaly - an asymmetric flat forehead and skull being short from front to back on one side (caused by unicoronal synostosis) or brachycephaly – the skull being short from front to back on both sides with a flat and wide forehead (caused by bicoronal synostosis); shallow eye sockets (this is called exorbitism), making the eye appear bulging and poor midfacial growth leading to an underdeveloped upper jaw. This syndrome is associated with a type of hearing loss called sensorineural hearing loss. The craniofacial features in females are often more severe than in males. The limb features are usually mild and often do not require any surgical intervention.

Muenke syndrome is caused by a specific genetic mutation in a gene called the fibroblast growth factor receptor type 3 gene (or FGFR3 gene for short). This affects how the bone cells in the body grow. This genetic change can either develop spontaneously (from unaffected parents) or else be inherited from an affected parent, in which case there is a 50% chance of an affected parent passing on the affected gene to their children.

TCF12 related craniosynostosis syndrome is a newly identified genetic craniosynostosis syndrome. The craniofacial features most commonly cause brachycephaly – the skull being short from front to back on both sides (caused by bicoronal synostosis) but can also cause plagiocephaly - an asymmetric forehead and skull being short from front to back on one side (caused by unicoronal synostosis); shallow eye sockets (this is called exorbitism), making the eye appear bulging and poor midfacial growth. Clinical features overlap with those of Saethre Chotzen syndrome.

It is caused by a genetic mutation in a gene called the TCF12 gene. This genetic change can either develop spontaneously (from unaffected parents) or else be inherited from an affected parent, in which case there is a 50% chance of an affected parent passing on the affected gene to their children.

A small number of children with TCF12 related craniosynostosis may have learning difficulties and developmental delay, though there is a spectrum of severity.

ERF related craniosynostosis syndrome is a newly identified genetic craniosynostosis syndrome accounting for around 2% of all syndromic cases of craniosynostosis. The craniofacial features include multiple suture synostosis with a combination of the sagittal and bilateral lambdoid sutures being the most predominantly affected and often occurring after birth with a delayed presentation and a delayed risk of developing raised intracranial pressure. Affected children may also have widely spaced eyes (hypertelorism), shallow eye sockets (exorbitism) and some underdevelopment of the midface. In addition affected children may exhibit a Chiari-1 malformation (this is where the lowest portion of the back of the brain gets trapped and pinched in the bony opening at the base of the skull).

It is caused by a genetic mutation in a gene called the ERF gene. This genetic change can either develop spontaneously (from unaffected parents) or else be inherited from an affected parent, in which case there is a 50% chance of an affected parent passing on the affected gene to their children.

Some children with ERF related craniosynostosis have behavioural problems, speech and language delay, learning difficulties and developmental delay, though there is a spectrum of severity.

Craniofrontonasal dysplasia is a rare genetic syndromic and occurs in 1 in 100,000 live births and affects girls more severely than boys. The craniofacial features include either plagiocephaly - an asymmetric flat forehead and skull being short from front to back on one side (caused by unicoronal synostosis) or brachycephaly – the skull being short from front to back on both sides with a flat and wide forehead (caused by bicoronal synostosis); shallow eye sockets (this is called exorbitism), making the eyes appear bulging. In addition the eye sockets in this condition are placed widely apart (called hypertelorism). There is often poor midfacial growth leading to an underdeveloped upper jaw. Girls tend to have frizzy hair, a groove in the middle of the nose while some cases have an associated cleft lip and palate. Additional features include sloping shoulders and some minor webbing of the fingers and toes which rarely require any surgery. Frequently longitudinal splits can be seen in the nails of the fingers and toes.

Craniofrontonasal dysplasia is caused by a genetic mutation in a gene called the EphrinB1 (EFNB1) gene on the X chromosome. This genetic change can either develop spontaneously (from unaffected parents) or else be inherited from an affected parent. Unlike most X-linked conditions girls are more severely affected while boys may not require any surgical intervention.

Individuals with Craniofrontonasal dysplasia may have some learning difficulties and developmental delay, though there is a spectrum of severity.