Craniosynostosis is a birth defect in which one or more of the cranial sutures between the skull bones fuse prematurely. The brain is still continuing to grow but is restricted by the fused sutures. In a normal skull, the suture lines produce bone and allows the skull to expand in all directions as the brain grows. As the brain grows in a baby with craniosynostosis, the skull takes on an abnormal shape to accommodate the areas of the skull that are unable to move.
Sometimes the symptoms of craniosynostosis are noticeable at birth. If they are not evident at that time, they become noticeable during the first few months of life. Signs would include a misshapen skull, a hard ridge along the fused suture line, a disappearing fontanel (soft spot), and/or an abnormal head growth.
The diagnosis of craniosynostosis is rather straight forward. A medical practitioner will perform a physical examination of the baby's head and confirm diagnosis with imaging (usually an x-ray or CT scan) showing that the suture line has fused.
Types of Craniosynostosis
There are several types of craniosynostosis. If there are multiple sutures that have fused prematurely, the baby is given the diagnosis of complex craniosynostosis. If only one suture line is involved, the diagnosis is dependent on the suture line that is affected. The Mayo Clinic labels these as follows:
- Sagittal. Premature fusion of the sagittal suture that runs from the front to the back at the top of the skull forces the head to grow long and narrow. Sagittal craniosynostosis is the most common type.
- Coronal. Premature fusion of one of the coronal sutures (unicoronal) that run from each ear to the top of the skull may cause your baby's forehead to flatten on the affected side and bulge on the unaffected side. It also leads to turning of the nose and elevation of the eye socket on the affected side. When both of the coronal sutures fuse prematurely (bicoronal), it gives your baby's head a short and wide appearance, most commonly with the forehead tilted forward.
- Metopic. The metopic suture runs from the top of the bridge of the nose up through the midline of the forehead to the anterior fontanel or soft spot and the sagittal suture. Premature fusion gives the forehead a triangular appearance and widens the back part of the head.
- Lambdoid. This is a rare type of craniosynostosis that involves the lambdoid suture, which runs across the skull at the back of the head. It may cause one side of your baby's head to appear flat, one ear to be higher than the other ear and tilting of the top of the head to one side.
In most infants, the cause of craniosynostosis is not known and the infant is otherwise very healthy. In some cases, there are genetic conditions that infants develop craniosynostosis with. These include the following:
- Frontonasal dysplasia
Babies may receive genetic testing if the provider suspects that there could be a genetic component that caused the craniosynostosis to occur.
Less severe cases of craniosynostosis may simply require monitoring the growth of the baby's head but no other interventions. Treatment for more severe craniosynostosis usually requires surgical intervention. This will help to prevent the continued abnormal growth of the skull, reduce the possibility of pressure building on the brain, and improve the baby's head shape. The two most common types of surgeries that are performed to achieve these results are as follows:
Endoscopic: This type of surgery is usually a consideration only for babies less than six months of age. There are small incisions made on the baby's head in which a camera is inserted and the suture line is reopened by removing a portion of the skull bone. This usually involves a one night hospital stay. There are other types of interventions that must be done in order to help with reshaping the baby's skull. These either involve using spring assistance or using a molding helmet after surgery.
- Stainless steel cranial expander springs can be inserted after the portion of fused skull is removed. The amount of force that the spring applies is based off of the patient's age, the thickness of the skull, and the severity of the skull deformation. These typically stay in place for three months following surgery and then require an additional surgery for removal.
- Babies who have this intervention commonly have to wear a helmet to help with cranial remolding after surgery for 6-12 months. This surgery must be performed at a young age because the brain is rapidly growing in size in infants this age. The rapid brain growth and the helmet help to reshape the skull to more normal dimensions.
Open: Open surgery is usually the only option for babies greater than six months of age. This involves a larger incision that allows the surgeon to reshape the skull bones more easily. Like the endoscopic approach, a portion of the skull bone is removed. In addition to this, other bones in the skull are manipulated to bring the skull back to a normal shape. Surgeons sometimes use hardware to hold the skull bones in place. This surgery involves a longer hospital stay and oftentimes a blood transfusion during or after surgery. A helmet is not necessary after open surgery because the reshaping of the skull is done during the surgery.