What is Craniosynostosis?
The normal skull is composed of multiple plate-like bones that join one another at fibrous sutures. These sutures serve as joints to allow head molding during birth so the infant can pass through the birth canal. They also are an important site of new bone formation that allows head growth during the first years of life. Once growth is complete, these sutures fuse and the skull becomes one bone. Craniosynostosis occurs when one or more of these sutures fuse prematurely. Skull and brain growth are restricted as a result of this and an abnormal head shape results. Craniosynostosis is one of the most common craniofacial birth defects and occurs in approximately 1 in 2,000 births.
What Causes Craniosynostosis?
Craniosynostosis can affect each of the cranial sutures. Fusion of the different sutures causes the head to assume a corresponding shape. Most cases of craniosynostosis involve only one suture. Patients with single suture craniosynostosis commonly do not have other associated conditions. Researchers are discovering new genes that place patients at increased risk for craniosynostosis when combined with other factors in the environment. Patients with multi suture craniosynostosis are more likely to have a genetic syndrome and other associated findings and a known genetic cause. Our clinical geneticist will see your child and determine when genetic testing would be helpful for your family.
What are the Types of Craniosynostosis?
Sagittal synostosis (scaphocephaly) is the most common form of craniosynostosis, including 40-55% of patients. It affects males more often than females. The sagittal suture runs along the center of the skull from front to back. This pattern of suture fusion causes a long, narrow skull, a prominent forehead, narrow temples, and pointing of the back of the head.
Unilateral Coronal Craniosynostosis
Unilateral coronal craniosynostosis (frontal plagiocephaly) is the second most common form of craniosynostosis. This occurs slightly more commonly in girls and occurs in 20-25% of cases. The coronal suture runs across the skull from right to left. Fusion of one side causes the brow to be pulled back on the affected side. The forehead bulges on the opposite side, the ear may be displaced forward on the affected side and the nose and jaws may become tilted causing a twisted face.
Metopic craniosynostosis (trigonocephaly) results from fusion of the metopic suture, which is in the center of the forehead. This condition causes a narrow, pointed, triangular forehead with narrowing of the distance between the eyes. The metopic suture is the only cranial suture that fuses before adulthood. If a suture is closed in a child with a normal headshape, it is not concerning. Additionally, some children develop a ridge along the metopic suture that can be very noticeable and will improve with age. Your surgeon will be helpful in determining which condition your child has.
Lambdoid synostosis (posterior plagiocephaly) is the least common form of craniosynostosis, occurring in 1-2% of cases. Fusion of one lambdoid suture causes a tilt of the skull base, displacement of the ear, and a characteristic “wind-swept” shape of the skull.
What Other Conditions Look Like Craniosynostosis?
Deformational plagiocephaly results from an infant lying preferentially on one side of their head. This condition is very common and may be mistaken for craniosynostosis or vice versa. If the reason for your child’s abnormal head shape is uncertain, a physical examination by a plastic surgeon or neurosurgeon may be all that is needed to make the diagnosis. If there any question, X-rays or a CT scan may be needed to ensure craniosynostosis is not present. Deformational plagiocephaly can be treated successfully with repositioning exercises to strengthen the neck muscles and keep the child off of the flat side of their head. Physical therapy may be needed to treat a tight neck muscle called torticollis. Some parents elect to use a molding helmet to improve the shape of their child’s head. Our specialists can offer more information about this.
What are the Symptoms of Craniosynostosis?
The abnormal head shape and facial asymmetry associated with craniosynostosis may be the only symptoms that develop. These asymmetries may become more obvious when you view your child in a mirror. If you think your child’s head shape is abnormal, ask their pediatrician. Less commonly, patients develop increased intracranial pressure due to restriction of head growth. This can cause headaches, developmental delay, seizures, and vision loss. This is much more common in patients with premature fusion of multiple sutures. Signs and symptoms of increased intracranial pressure include:
- Vision changes
- A full or bulging fontanelle (soft spot)
- Increased sleepiness
- Noticeable scalp veins
- Increased irritability
- Poor feeding
- Increased head circumference
- Bulging eyes or inability to look upward
- Developmental delay
These symptoms are not specific signs of increased intracranial pressure and may be caused by many medical conditions. Your pediatrician should be contacted if you have any concerns.
How is Craniosynostosis Diagnosed?
The abnormal head shapes seen in patients with craniosynostosis are often very suggestive of the diagnosis. You surgeon or pediatrician may order X-rays of the skull or a CT scan to look at the cranial sutures and confirm the diagnosis. Older patients with elevated intracranial pressure may have changes in back of their eyes. For this reason, it may be recommended that your child see a pediatric ophthalmologist for an eye examination.
How is Craniosynostosis Treated?
Most patients with craniosynostosis are recommended to undergo surgery to enlarge the skull, to decrease the risk of developing elevated intracranial pressure, and to improve the shape of the head. There are two classes of operations available for this condition.
Minimally Invasive Suturectomy
Minimally invasive craniosynostosis surgery uses small incisions to remove the abnormal fused suture. This technique is only successful if the operation is performed early in life (usually before 5 months of age), and if the family correctly uses a molding helmet following the surgery. A molding helmet is prescribed that guides the future head growth after surgery. The helmet must be worn 23 hours a day for several months after surgery. Diminished use of the helmet will result in diminished results from the operation. Parents who are good candidates and are interested in this operation will be referred to our pediatric neurosurgeon who performs this operation.
Open Cranial Vault Remodeling
The traditional treatment for craniosynostosis is a cranial vault remodeling operation, which is performed by a pediatric plastic surgeon and pediatric neurosurgeon together. This operation requires a longer incision (which is hidden in the hairline), and a longer stay in the hospital. The abnormal bones of the skull are removed and reshaped during the operation so the improvement in the head shape is immediate. No helmet is required after surgery. Surgery is typically performed between 8-12 months of age when the skull is still thin and easy to reshape, but this operation can be safely done at any age.
How are Children Cared for Following Surgery to Correct Craniosynostosis?
Patients undergoing minimally invasive surgery for craniosynostosis typically remain in the hospital one night after the operation. They will be sent home with a prescription for pain medication. Arrangements will be made after surgery for a helmet to be fit for the child and they will need to wear this helmet 23 hours a day for several months after surgery. They will need an appointment with the orthotist to make adjustments to the helmet every 2-3 weeks, and likely will need a second helmet made as they grow.
Patients treated with an open cranial vault remodeling surgery will stay in the hospital 3-4 nights. They typically spend the first night after surgery in the ICU where pediatric intensive care specialists can monitor them. After surgery, they will likely have a drain to remove fluid from the site of their operation and this will be removed before they go home. Patients sometimes develop significant swelling after open craniosynostosis surgery that may cause their eyes to swell shut. This is more common with patients undergoing surgery for coronal and metopic craniosynostosis. This swelling is not harmful to the patients. The swelling is greatest 1-2 days after surgery and then will quickly improve. The patient’s energy level will also improve 3-5 days after surgery. Following open cranial vault remodeling, the segments of the skull are held together with plates and screws that will dissolve after 8-12 months. The bones will be healed 6 weeks after surgery but trauma to the head should be avoided. Parents sometimes notice small areas of swelling 8-12 months after surgery as the plates begin to dissolve.
Patients undergoing surgery for craniosynostosis are typically seen annually by their surgeons until they are done growing. Regular eye exams are needed to monitor for signs of intracranial pressure and to look for signs of eye muscle imbalance.