Craniosynostosis

What is Craniosynostosis?

Craniosynostosis is a congenital medical condition (birth defect) in which the sutures (fibrous joints) between the bones of an infant's skull close (join or fuse) prematurely. The human skull is not a single, solid bone at birth; instead, it consists of several bones separated by sutures, allowing for the normal growth of the skull as the brain develops. When one or more of these sutures closes too early, it can restrict the growth of the skull in certain directions, leading to an abnormal head shape. The premature fusion of sutures can also affect the development of the brain and potentially cause increased pressure inside the skull, a condition known as intracranial pressure.

Types of Craniosynostosis

Craniosynostosis may be classified based on which sutures are affected, including:

• Sagittal synostosis: The sagittal suture runs from the front to the back of the skull. Premature fusion of this suture can result in a long, narrow head shape.
• Coronal synostosis: The coronal sutures are located on the sides of the skull, and premature fusion can lead to a shortening of the skull from ear to ear.
• Metopic synostosis: The metopic suture is at the top of the skull, and its premature closure can cause a triangular-shaped forehead.
• Lambdoid synostosis: The lambdoid suture is at the back of the skull. Premature fusion may result in flattening or asymmetry of the back of the head.

Causes of Craniosynostosis

The exact causes of craniosynostosis are not always clear, and it often occurs sporadically without a known cause. However, several factors have been associated with an increased risk of craniosynostosis, such as:

• Genetic Factors: Craniosynostosis can have a genetic component. Mutations in certain genes have been identified in some cases of craniosynostosis, and the condition may run in families. Syndromic craniosynostosis, which occurs as part of a broader genetic syndrome, is often associated with specific genetic mutations.
• Environmental Factors: While genetics plays a role, environmental factors may also contribute to the development of craniosynostosis. Some factors that have been suggested as potential contributors include maternal smoking during pregnancy, advanced paternal age, and certain medications taken during pregnancy.
• Syndromes: Craniosynostosis is sometimes associated with genetic syndromes, where it occurs along with other abnormalities. Examples include Apert syndrome, Crouzon syndrome, and Pfeiffer syndrome. These syndromes often involve mutations in specific genes that play a role in normal skull development.

Symptoms of Craniosynostosis

The symptoms of craniosynostosis can vary depending on which sutures are affected and how severely they are fused. In some cases, the condition may be evident at birth, while in others, it becomes more noticeable as the child grows. Common signs and symptoms of craniosynostosis include:

• Abnormal head shape
• Visible or palpable ridge on the skull
• Bulging or raised fontanelles (soft spots on a baby's skull)
• Developmental delays
• Hearing or vision problems
• Headache
• Nausea
• Vomiting
• Lethargy (very sleepy, difficult to wake)
• Increased irritability

Diagnosis of Craniosynostosis

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

Physicians can identify craniosynostosis during a physical exam. A physician will feel the baby’s head for hard edges along the sutures and unusual soft spots. The physician also will check for any issues with the shape of the baby’s face. If the physician suspects the baby might have craniosynostosis, he or she normally requests one or more tests to help confirm the diagnosis. For instance, 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. In some cases, if the physician suspects an underlying genetic syndrome, genetic testing may be ordered to help identify any genetic syndromes.

Treatment for Craniosynostosis

The primary treatment for craniosynostosis is surgical intervention to correct the premature fusion of sutures and allow for normal skull growth. The specific surgical approach depends on factors such as the type of craniosynostosis, the sutures involved, and the severity of the condition. Here are some common surgical procedures used to treat craniosynostosis:

• Suturectomy or Suture Release: This procedure involves surgically cutting and releasing the prematurely fused suture. It allows the skull bones to grow in a more typical fashion, correcting the abnormal head shape. The surgery is often performed in the first year of life to take advantage of the rapid skull growth during this period.
• Endoscopic Strip Craniectomy: In some cases, a less invasive approach known as endoscopic strip craniectomy may be used. This involves making small incisions and using an endoscope to remove a strip of bone along the fused suture. Endoscopic procedures may have a shorter recovery time and reduced scarring compared to traditional open surgery.
• Fronto-Orbital Advancement (FOA): FOA is a procedure used for cases of craniosynostosis affecting the coronal sutures. It involves reshaping the forehead and eye sockets to correct the abnormal skull growth. This surgery is often performed when both coronal sutures are prematurely fused.
• Posterior Vault Reconstruction: This procedure is used for cases involving the lambdoid sutures at the back of the skull. It may involve reshaping the back of the head to achieve a more normal appearance.
• Cranial Vault Remodeling: In cases where multiple sutures are affected or if the condition is associated with a syndromic form of craniosynostosis, a more extensive cranial vault remodeling surgery may be necessary.

The choice of surgical technique depends on the specific characteristics of the individual case. The goal of surgery is not only to correct the head shape but also to relieve any increased intracranial pressure and promote normal brain development.