Craniosynostosis

What is craniosynotosis?

Craniosynostosis is the term for a group of conditions in which a baby’s head develops abnormally because the seams between the bones close prematurely. This prevents the head from growing normally and may be associated with changes in the upper facial bones. Craniosynostosis can usually be recognized at birth, but for a very small number of children it does not become obvious until one year of age or older.

How does craniosynostosis occur?

Before birth and early in infancy, a child’s brain grows very rapidly, reaching 70 percent of its eventual adult size in the first year. To keep up with this growth, the head must expand rapidly while keeping the brain protected.

This expansion is possible because the head does not consist of a single bone; there are several bones separated by narrow openings, or seams. As the brain grows, these bones are pushed apart, and new bone forms in the seams (which are called sutures). The shape and location of these bones enables the head to expand in several directions — front-to-back as well as side-to-side.

As brain growth slows, the seams slowly close. The first to close is are the bones of the forehead, which occurs between ages one to two years. If any suture closes too early, however, problems can arise. The closing prevents that part of the head from expanding, so other areas have to compensate. The result is that portions of the head become distorted. In general, the more seams that fuse prematurely, the greater the degree of distortion.

Why did my child develop craniosynostosis?

The vast majority of children with craniosynostosis have no family history of the condition. The cause of the condition may be unknown. Abnormalities in the chromosomes (which carry the genetic code in cells) are present in some children with craniosynostosis.

Are there different varieties of craniosynostosis?

Yes. Several different types have been identified and named. Each is associated with a specific set of abnormalities in the bones of the head. In general, they are grouped into two broad categories:

1. Single-suture craniosynostosis, in which one bony seam closes prematurely

2. Multiple-suture craniosynostosis, which affects more than one bony seam

What problems can result from craniosynostosis?

The premature closing of the cranial bones can alter the normal proportions of a child’s head, often affecting the face. The head may become overly long or wide, or a combination of both. The condition can make a child’s face appear flat or concave (pushed-in), because the lower jaw grows normally while the upper jaw fails to grow forward at the normal rate. Sometimes the child’s eyes can bulge because the eye sockets are small and shallow (known as exorbitism).

But the problems associated with craniosynostosis can go beyond matters of appearance. A too-small head can place increased pressure on the brain, potentially leading to damage and cognitive problems. If the eyelids aren’t able to fully close, the corneas of the eye can become dry and damaged, resulting in reduced vision. In some rare cases, pressure inside the head can damage the optic nerve, causing impaired vision or blindness. Certain types of craniosynostosis can be associated with strabismus, a condition in which the eyes do not move in tandem. Hearing loss is another possibility, resulting from nerve damage or a build-up of fluid in the ear canal.

Depending on the specific condition, some children with craniosynostosis have breathing problems — a result of narrowed passages within the nose — or the palate may hang down too far in the back of the mouth, partially blocking the airway. Speech problems can develop from crowded teeth or a constricted airway.

What are the different types of single-suture craniosynostosis?

Scaphocephaly (“sagittal synostosis”). This results from a premature fusion of the bones along the middle seam at the very top of the head. Children with this condition tend to have a long head that is narrowed from side to side. The forehead and back of the head may be very prominent. This condition usually doesn’t cause increased pressure on the brain.

Trigonocephaly (“metopic synostosis”). This results from a premature fusion between the two bones of the forehead. Children with this condition tend to have a triangular or keel-shaped forehead. The distance between the eyes may be narrower than usual and the outer corners of the eyes may be angled upward.

Synostic frontal plagiocephaly (“unilateral coronal synostosis”). Premature closure of the spaces between bones on one side of the head that causes a child’s forehead to become flattened, an elevated and widened eye, tilting of the nose, and a slightly forward cheek on the same side.

Synostic posterior plagiocephaly (“lamboid synostosis”). This is caused by fusion of the bones on the side and the back of the head. It results in a flattened area on the side of the synostosis; the back of the head shifts to the unaffected side; and the area near the ear (mastoid process) may bulge. It is very rare and can be confused with deformational posterior plagiocephaly. [LINK]

How are these different varieties treated?

Scaphocephaly. An infant with this condition should be treated in the first few months of life. The neurosurgeon on your child’s care team performs a corrective procedure called a “strip craniectomy,” which involves removing a plate of bone at the top of the head. Children not treated in the first year of life may require a more complex operation involving the reshaping of the front and back of the head.

Trigonocephaly. Some minor forms of this condition can simply be monitored by your child’s doctor and will improve in time. Others can be treated by reshaping the central portion of the forehead. This operation is usually scheduled between eight and 10 months of age. If the diagnosis is determined earlier, the suture can be released and the head corrected with a molding helmet.

Synostic frontal plagiocephaly. Surgical correction for this condition is done around eight to 10 months of age. It involves repositioning of the forehead and the area above the eyes, as well as straightening the nose. Most children with single suture synostosis need only one operation. Earlier release of the suture and helmet molding is done in some centers.

What are the different types of multiple-suture craniosynostosis?

The forms of multiple-suture craniosynostosis are known as syndromes, and they usually are named after the physician who first described the condition.

Most arise in children who have no family history of the disorder. But once it occurs, there is a 50 percent chance that it will be passed on. Genetic testing can be done for Apert, Crouzon, Pfeiffer, and Saethre-Chotzen syndromes.

There are more than 70 types of multiple-suture craniosynostosis. The following are the most common.

Apert syndrome. This condition, which occurs in about 15 of one million babies, has a distinctive set of features. The child has distortions of the head and face: the head is usually too wide side-to-side and too narrow front-to-back. The eye sockets are somewhat widely spaced and the eyes protrude, with the eyelids tilted downward. The upper jaw is often underdeveloped, causing upper teeth to become crowded and out of alignment. Often there is also some degree of syndactyly, a webbing between the fingers, toes, or both. There may also be symphalangism, or fusion of the finger and toe joints. Children with Apert syndrome have a broad range of intelligence, from normal or above-normal intelligence, to some degree of mental retardation. A cleft palate occurs in about a third of children with this syndrome.

Crouzon syndrome. Occurring in about 15 in one million babies, this syndrome results from an underdevelopment of the bones in the middle third of the face and head. The child has a high, flat, prominent forehead and a head that is wider than usual; bulging eyes because of small eye sockets; strabismus, in which one eye tends to turn to the side or upwards rather than straight ahead; a smaller-than-normal upper jaw and protruding lower jaw; crowding of the teeth; a high, arched, narrow palate; and, in about half of children, hearing loss. There are no obvious abnormalities of the fingers or toes. Not all children with Crouzon syndrome have these problems to the same degree; some problems may be severe, while others are minor or virtually non-existent.

Pfeiffer syndrome. This type of craniosynostosis may be confused with Crouzon syndrome. A child with this syndrome has a head that is taller than normal and flat in the front and back; bulging eyes (which can be severe or minor); indented midface that causes the lower jaw to be unusually prominent; crowding of the teeth and a high, arched palate. Some children may have unusually broad thumbs and big toes. (This is sometimes used to distinguish the condition from Crouzon syndrome.) Some have partial syndactyly between the first and second toes and fingers. Children with this syndrome usually have normal intelligence.

Saethre-Chotzen syndrome. The features of this condition can be relatively minor – so minor, in many cases, that a doctor may miss the diagnosis. Because of this, it is not known how frequently the condition occurs. The major signs of the syndrome are: fusion of certain head bones that sometimes causes the head and face to be asymmetrical; low hairline with upturned hair follicles; ptosis (droopy eyelids); low-set ears and minor irregularities at the top of the ear and in the earfolds; a ‘beaked’ nose and a septum (the partition between the nostrils) that is deviated, or crooked; and short fingers (known as brachydactyly), with a partial fusion of the second and third fingers and/or toes. In rare cases, the midface may appear receded. Individuals with this condition usually do not have impaired intelligence.

Carpenter syndrome. In this very rare form of craniosynostosis (fewer than 40 cases have been reported to date), children develop an asymmetrical, tower-shaped head, a short neck, webbing between fingers and toes, and extra fingers. It is the only type of craniosynostosis where a pattern of inheritance can be traced in families as a recessive gene. The genetic cause is known for Apert, Crouzon, Pfeiffer, and Saethre-Chotzen syndromes. These are autosomal dominant syndromes meaning there is a 50% chance they can be passed on in a family.

How are children with multiple-suture craniosynostosis treated?

Because the problems associated with multiple-suture craniosynostosis are so variable, it is difficult to give specific answers to questions about treatment for these children. The members of your child’s care team will develop a treatment plan tailored to your child’s individual condition and needs.

Generally, the abnormal shape of the head is corrected during the first year. The surgeon also moves forward the forehead and bony rim over the eyes. This operation is called ‘fronto-orbital advancement.’ The next major operation is a midfacial (Le Fort III) advancement. The middle face, cheeks, nose, and upper jaw are brought forward to improve breathing and appearance. This procedure is usually done by gradual distraction of the bones (called “distraction osteogenesis”) using an external halo-like device. It is scheduled during mid to late childhood, depending on breathing problems, exposure of the eyes, or emotional/psychological issues. The later in childhood the operation is performed, the less likely it will have to be repeated. Adolescent patients often need further operations to correct dental occlusion and for final ‘touch-ups.’

The operations for syndactyly, or webbed fingers and toes, and symphalangism (fusion of finger and toe joints) associated with Apert syndrome and other conditions can begin during the first year. Often the little finger and thumb (and/or the so-called border digits of the foot) will be released early in infancy, but surgical treatment can be difficult because the webbing may consist not just of skin, but also of finger (and toe) bones and joints. The degree and location of syndactyly varies from child to child, but the fingers most commonly affected are the index, middle, and ring fingers. In some children, all the fingers are fused; in others, only one or two. The webbing can prevent children from moving individual fingers independently, making it difficult to perform common activities such as tying a shoe, buttoning a shirt, or using a zipper. A physical therapist can work with your child to get the most possible use of the hands and feet.