Craniosynostosis is a birth defect in which the bones in a baby’s skull join together too early. This happens before the baby’s brain is fully formed. As the baby’s brain grows, the skull can become more misshapen. The spaces between a typical baby’s skull bones are filled with flexible material and called sutures. These sutures allow the skull to grow as the baby’s brain grows. Around two years of age, a child’s skull bones begin to join together because the sutures become bone. When this occurs, the suture is said to “close.” In a baby with craniosynostosis, one or more of the sutures closes too early. This can limit or slow the growth of the baby’s brain.

When a suture closes and the skull bones join together too soon, the baby’s head will stop growing in only that part of the skull. In the other parts of the skull where the sutures have not joined together, the baby’s head will continue to grow. When that happens, the skull will have an abnormal shape, although the brain inside the skull has grown to its usual size. Sometimes, though, more than one suture closes too early. In these instances, the brain might not have enough room to grow to its usual size. This can lead to a build-up of pressure inside the skull.

How Many Babies are Born with Craniosynostosis?

Researchers estimate that about 1 in every 2,500 babies is born with craniosynostosis in the United States.

Craniosynostosis is the premature closure of one or more of the joints that connect the bones of a baby's skull (cranial sutures). Normally, the bones remain separate until about age 2, while the brain is growing. They then fuse together and stay connected throughout life. The closure is premature when it occurs before brain growth is complete.

Symptoms and severity vary depending on how many sutures close prematurely. For example, if only one closes prematurely (which is most common), brain growth may continue in other parts of the skull, leading only to an abnormally-shaped skull and no other health problems or complications. If multiple sutures close prematurely, brain growth can be restricted. This can lead to increased pressure in the skull, impaired brain development, seizures, blindness, and/or intellectual disability.

Craniosynostosis may occur as a single abnormality (isolated craniosynostosis) or it may occur as one feature of one of many syndromes. Most cases of isolated craniosynostosis occur randomly (sporadically) and have no known cause. In some cases, isolated craniosynostosis is due to a mutation in any of several genes, with autosomal dominant inheritance. When craniosynostosis is a feature of a larger syndrome (syndromic craniosynostosis), the cause and inheritance pattern depend on the syndrome the person has. However, most syndromic causes of craniosynostosis are autosomal dominant. Craniosynostosis can also be associated with a metabolic disease such as rickets, or hyperthyroidism.

Treatment for craniosynostosis depends on the severity in each child and may involve surgery in infancy to relieve pressure within the skull, allow for brain growth, and improve the appearance of the shape of the head. However, not all children with craniosynostosis will need surgery. The long-term outlook depends on how many sutures are involved and whether the child has a larger syndrome or other health problems. Children who have surgery and are otherwise healthy generally do not experience long-term complications, especially when only one suture is involved.

Craniosynostosis is a birth defect of the skull characterized by the premature closure of one or more of the fibrous joints between the bones of the skull (called the cranial sutures) before brain growth is complete. Closure of a single suture is most common. Normally the skull expands uniformly to accommodate the growth of the brain; premature closure of a single suture restricts the growth in that part of the skull and promotes growth in other parts of the skull where sutures remain open. This results in a misshapen skull but does not prevent the brain from expanding to a normal volume. However, when many sutures close prematurely, the skull cannot expand to accommodate the growing brain, which leads to increased pressure within the skull and impaired development of the brain. Craniosynostosis can be gene-linked or caused by metabolic diseases (such as rickets )or an overactive thyroid. Some cases are associated with other disorders such as microcephaly (abnormally small head) and hydrocephalus (excessive accumulation of cerebrospinal fluid in the brain). The first sign of craniosynostosis is an abnormally shaped skull. Other features can include signs of increased intracranial pressure, developmental delays, or impaired cognitive development, which are caused by constriction of the growing brain. Seizures and blindness may also occur.

Treatment for craniosynostosis generally consists of surgery to improve the symmetry and appearance of the head and to relieve pressure on the brain and the cranial nerves. For some children with less severe problems, cranial molds can reshape the skull to accommodate brain growth and improve the appearance of the head.

The prognosis for craniosynostosis varies depending on whether single or multiple cranial sutures are involved or other abnormalities are present. The prognosis is better for those with single suture involvement and no associated abnormalities.

The types of craniosynostosis depend on what sutures join together early.

• Sagittal synostosis – The sagittal suture runs along the top of the head, from the baby’s soft spot near the front of the head to the back of the head. When this suture closes too early, the baby’s head will grow long and narrow (scaphocephaly). It is the most common type of craniosynostosis.
• Coronal synostosis – The right and left coronal sutures run from each ear to the sagittal suture at the top of the head. When one of these sutures closes too early, the baby may have a flattened forehead on the side of the skull that closed early (anterior plagiocephaly). The baby’s eye socket on that side might also be raised up and his or her nose could be pulled toward that side. This is the second most common type of craniosynostosis.
  • Bicoronal synostosis – This type of craniosynostosis occurs when the coronal sutures on both sides of the baby’s head close too early. In this case, the baby’s head will grow broad and short (brachycephaly).
• Lambdoid synostosis – The lambdoid suture runs along the backside of the head. If this suture closes too early, the baby’s head may be flattened on the back side (posterior plagiocephaly). This is one of the rarest types of craniosynostosis.
• Metopic synostosis – The metopic suture runs from the baby’s nose to the sagittal suture at the top of the head. If this suture closes too early, the top of the baby’s head shape may look triangular, meaning narrow in the front and broad in the back (trigonocephaly). This is one of the rarest types of craniosynostosis.

The causes of craniosynostosis in most infants are unknown. Some babies have a craniosynostosis because of changes in their genes. In some cases, craniosynostosis occurs because of an abnormality in a single gene, which can cause a genetic syndrome. However, in most cases, craniosynostosis is thought to be caused by a combination of genes and other factors, such as things the mother comes in contact with in her environment, or what the mother eats or drinks, or certain medications she uses during pregnancy.

CDC, like the many families of children with birth defects, wants to find out what causes these conditions. Understanding the factors that are more common among babies with a birth defect will help us learn more about the causes. CDC funds the Centers for Birth Defects Research and Prevention, which collaborate on large studies such as the National Birth Defects Prevention Study (NBDPS; births 1997-2011), to understand the causes of and risks for birth defects, such as craniosynostosis.

Recently, CDC reported on important findings from research studies about some factors that increase the chance of having a baby with craniosynostosis:

• Maternal thyroid disease ― Women with thyroid disease or who are treated for thyroid disease while they are pregnant have a higher chance of having an infant with craniosynostosis, compared to women who don’t have thyroid disease.
• Certain medications ― Women who report using clomiphene citrate (a fertility medication) just before or early in pregnancy are more likely to have a baby with craniosynostosis, compared to women who didn’t take this medicine.

CDC continues to study birth defects, such as craniosynostosis, and how to prevent them. If you are pregnant or thinking about becoming pregnant, talk with your doctor about ways to increase your chances of having a healthy baby.

Craniosynostosis that involves only one suture and is an isolated abnormality typically is not inherited, occurring sporadically in people with no family history of craniosynostosis. More rarely, isolated craniosynostosis is caused by a mutation in any of several genes, with autosomal dominant inheritance.

In contrast, craniosynostosis that involves multiple sutures is more often one feature of a genetic syndrome with additional abnormalities that may affect multiple parts of the body. Most of the genetic syndromes that are associated with craniosynostosis also have autosomal dominant inheritance. However, they are often caused by a new (de novo) mutation in a person, rather than inherited from a parent with the syndrome. In either case, a person with an autosomal dominant syndrome has a 50% chance to pass the syndrome on to each of his/her children.

Craniosynostosis has been described in more than 150 different syndromes, but those most frequently associated with craniosynostosis include Apert syndrome, Crouzon syndrome, Pfeiffer syndrome, Carpenter syndrome (which is autosomal recessive), and Saethre-Chotzen syndrome.

Craniosynostosis usually is diagnosed soon after a baby is born. Sometimes, it is diagnosed later in life.

Usually, the first sign of craniosynostosis is an abnormally shaped skull. Other signs may include:

• No “soft spot” on the baby’s skull
• A raised firm edge where the sutures closed early
• Slow growth or no growth in the baby’s head size over time

Doctors can identify craniosynostosis during a physical exam. A doctor will feel the baby’s head for hard edges along the sutures and unusual soft spots. The doctor also will look for any problems with the shape of the baby’s face. If he or she suspects the baby might have craniosynostosis, the doctor usually requests one or more tests to help confirm the diagnosis. For example, a special x-ray test, such as a CT or CAT scan, can show the details of the skull and brain, whether certain sutures are closed, and how the brain is growing.

Many types of craniosynostosis require surgery. The surgical procedure is meant to relieve pressure on the brain, correct the craniosynostosis, and allow the brain to grow properly. When needed, a surgical procedure is usually performed during the first year of life. But, the timing of surgery depends on which sutures are closed and whether the baby has one of the genetic syndromes that can cause craniosynostosis.

Babies with very mild craniosynostosis might not need surgery. As the baby gets older and grows hair, the shape of the skull can become less noticeable. Sometimes, special medical helmets can be used to help mold the baby’s skull into a more regular shape.

Each baby born with craniosynostosis is different, and the condition can range from mild to severe. Most babies with craniosynostosis are otherwise healthy. Some children, however, have developmental delays or intellectual disabilities, because either the craniosynostosis has kept the baby’s brain from growing and working normally, or because the baby has a genetic syndrome that caused both craniosynostosis and problems with how the brain works. A baby with craniosynostosis will need to see a healthcare provider regularly to make sure that the brain and skull are developing properly. Babies with craniosynostosis can often benefit from early intervention services to help with any developmental delays or intellectual problems. Some children with craniosynostosis may have issues with self-esteem if they are concerned with visible differences between themselves and other children. Parent-to-parent support groups also can be useful for new families of babies with birth defects of the head and face, including craniosynostosis.

Many of the problems a baby can have depend on:

• Which sutures closed early
• When the sutures closed (was it before or after birth and at what age)
• Whether or not the brain has room to grow

Sometimes, if the condition is not treated, the build-up of pressure in the baby’s skull can lead to problems, such as blindness, seizures, or brain damage.

Craniosynostosis is a birth defect in which the bones in a baby’s skull join together too early. This happens before the baby’s brain is fully formed. As the baby’s brain grows, the skull can become more misshapen. To learn what it’s like to live with this condition or how families are affected, read this real story from people living with craniosynostosis.

Deborah's Story - In her own words

Connecting to care is vital for children with birth defects. This was especially true for Deborah, who has twin girls born with craniosynostosis. Read below to learn about their journey to get needed care, treatment, and services.

During my pregnancy with my twin girls, I had all of the prenatal testing and care, and I was prepared for two healthy babies. When the twins were born full-term, they went immediately to a neonatal intensive care unit (NICU) and stayed there for about two weeks. My family and I soon noticed that the appearance of their skulls seemed atypical. However, when we asked the doctors, quite often actually, we were told that there was no cause for concern.

When the twins came home, they seemed unresponsive and floppy. Their faces became more and more asymmetrical throughout their first two months. During this time, my family and I went to several pediatricians. We asked about their unresponsiveness and facial asymmetry. Again, were told that there was no cause for concern. Frantic, I got on the internet and started to look up these two symptoms and discovered something called craniosynostosis. Craniosynostosis is a birth defect in which the bones in a baby’s skull join together too early. This can limit or slow the growth of a baby’s brain. Right then, I felt in my gut that this was what was going on with my kids. I got on an online forum and started asking for advice. I posted pictures of the girls, and all of the forum members encouraged me to send the photos to various specialists across the country.

Fifteen minutes later, I got a response from a surgeon at the Mayo Clinic asking how soon we could be there. Fortunately, my parents were able to help me, and we got in a week later. When the doctor saw the girls, he immediately went into action. He scheduled one of the twins (the more affected one) for more scans of her skull and eventually, for two surgeries to release the sutures, the spaces between her skull bones that had already fused. He sent the other twin for cranio-banding, which is a helmet she had to wear to shape her head and reduce asymmetry. He also noted their floppiness and sent them to physical and occupational therapy, as well as genetics, neurology, and quite a few other appointments.

One of the appointments was with a licensed social worker. She was the integral point of access for our family. She told us about Medicaid, Social Security, and Early Intervention. She really got the ball rolling for us. Through several moves across multiple states, she has helped me access and navigate different programs in the different places we lived. Through those experiences, I began to explore what worked for us and what didn’t. From that point on, my girls were getting the services they needed. Even though there is no official reason or diagnosis that caused their sutures to fuse (and then restricted their brains from developing), our social worker and neurologist helped me access forms and waivers we needed to get them adequate medical equipment that they would need as they got older.

We are still learning as we go, but I am thankful for both the online forum and resources I found. I’m also extremely grateful for the social worker and her invaluable guidance on our journey!