Definition of Synostosis (Craniosynostosis)
Craniosynostosis (kray-nee-o-sin-os-TOE-sis) is a birth defect in which one or more of the joints between the bones of your baby’s skull close prematurely, before your baby’s brain is fully formed. When your baby has craniosynostosis, his or her brain can’t grow in its natural shape and the head is misshapen.
Craniosynostosis can affect one or more of the joints in your baby’s skull. In some cases, craniosynostosis is associated with an underlying brain abnormality that prevents the brain from growing properly.
Treating craniosynostosis usually involves surgery to separate the fused bones. If there’s no underlying brain abnormality, the surgery allows your baby’s brain adequate space to grow and develop.
Symptoms of Synostosis (Craniosynostosis)
Your baby’s skull has seven bones. Normally, these bones don’t fuse until around age 2, giving your baby’s brain time to grow. Joints called cranial sutures, made of strong, fibrous tissue, hold these bones together. In the front of your baby’s skull, the sutures intersect in the large soft spot (fontanel) on the top of your baby’s head. Normally, the sutures remain flexible until the bones fuse.
Signs of craniosynostosis include:
- A misshapen skull, with the shape depending on which of the cranial sutures are affected
- An abnormal feeling or disappearing “soft spot” (fontanel) on your baby’s skull
- Slow or no growth of the head as your baby grows
- Development of a raised, hard ridge along affected sutures
- Increased pressure within the skull (intracranial pressure)
The signs of craniosynostosis may not be noticeable at birth, but they become apparent during the first few months of your baby’s life.
Craniosynostosis types and characteristics
There are many different types of craniosynostosis. The term given to each type depends on what sutures are affected. Some of the most common types of craniosynostosis are:
- Sagittal synostosis (scaphocephaly). Premature fusion of the suture at the top of the head (sagittal suture) forces the head to grow long and narrow, rather than wide. Scaphocephaly is the most common type of craniosynostosis.
- Coronal synostosis (anterior plagiocephaly). Premature fusion of a coronal suture — one of the structures that run from each ear to the sagittal suture on top of the head — may force your baby’s forehead to flatten on the affected side. It may also raise the eye socket and cause a deviated nose and slanted skull.
- Bicoronal synostosis (brachycephaly). When both of the coronal sutures fuse prematurely, your baby may have a flat, elevated forehead and brow.
Rare types and characteristics
Two less common types of craniosynostosis are:
- Metopic synostosis (trigonocephaly). The metopic suture runs from your baby’s nose to the sagittal suture. Premature fusion gives the scalp a triangular appearance.
- Lambdoid synostosis (posterior plagiocephaly). This rare form of craniosynostosis involves the lambdoid suture, which runs across the skull near the back of the head. It may cause flattening of your baby’s head on the affected side.
Misshapen head may not mean craniosynostosis
A misshapen head doesn’t always indicate craniosynostosis. For example, if the back of your baby’s head appears flattened, it could be the result of birth trauma or your baby’s spending too much time on his or her back. This condition is sometimes treated with a custom-fit helmet that helps mold your baby’s head back into a normal position.
When to see a doctor
Contact your pediatrician if you think your baby’s head isn’t growing as it should or if it has an unusual shape.
Craniosynostosis is often classified as nonsyndromic or syndromic. Nonsyndromic craniosynostosis is the most common type of craniosynostosis, and its cause is unknown.
However, syndromic craniosynostosis is a complication caused by certain genetic syndromes, such as Apert syndrome, Pfeiffer syndrome and Crouzon syndrome, which can affect your baby’s skull development. [1,p41;3,p3] Besides craniosynostosis, other conditions also may accompany such syndromes — including hand and foot deformities, dental abnormalities, and heart problems.
Complications of Synostosis (Craniosynostosis)
Babies with craniosynostosis, particularly those with an underlying syndrome, may develop increased pressure inside the skull (intracranial pressure). Their skulls don’t expand enough to make room for their growing brains.
If untreated, increased intracranial pressure can cause:
- Brain damage
- Death, in rare instances
In addition, facial deformities that affect the middle of your child’s face may cause:
- Upper airway obstructions, compromising your baby’s ability to breathe
- Permanent head deformity
- Problems with speech and language development
- Poor self-esteem
Preparing for your appointment
In some cases, your baby’s doctor may suspect craniosynostosis at a routine well-child visit due to the disappearance of your baby’s soft spots or because your baby’s head isn’t growing as it should. In other cases, you may make an appointment because you suspect your child has craniosynostosis.
What you can do
If you have time to prepare before your baby’s appointment, it’s a good idea to:
- Write down any signs you’ve noticed, such as raised ridges or the absence of soft spots on your baby’s head.
- Write down questions to ask your doctor.
Your time with your doctor may be limited, so preparing a list of questions can help you make the most of your time together. For craniosynostosis, some basic questions to ask your doctor include:
- What’s the most likely cause of my baby’s symptoms?
- Are there other possible causes?
- What kinds of tests does my baby need? Do these tests require any special preparation?
- Is this condition temporary or long lasting?
- What treatments are available, and which do you recommend?
- What are the risks involved with surgery?
- Who will perform the surgery if it’s needed?
- Are there alternatives to surgery?
- What happens if we choose not to have the surgery right now?
- Will the abnormal shape of the skull affect the functioning of my baby’s brain?
- Are there brochures or other printed material that I can take with me? What websites do you recommend?
- What is the likelihood of future children having the same condition?
What to expect from your doctor
Your doctor is likely to have questions for you, as well. Being ready to answer them may reserve time to go over points you want to spend more time on. Your doctor may ask:
- When did you first notice the changes in your baby’s head?
- How much time does your baby spend on his or her back?
- In what position does your baby sleep?
- Has your baby had any seizures?
- Is your baby’s development on schedule?
- Were there any complications in your pregnancy?
- Do you have a family history of craniosynostosis or of genetic conditions, such as Apert syndrome and Crouzon syndrome?
Tests and diagnosis
Diagnosis of craniosynostosis may include:
- A physical exam. Your doctor will feel your baby’s head for abnormalities such as suture ridges and look for facial deformities.
Imaging studies. A computerized tomography (CT) scan of your baby’s skull will show whether any sutures have fused. Fused sutures are identifiable by their absence, because they’re invisible once fused, and by the ridging of the suture line.
X-rays also may be used to measure precise dimensions of your baby’s skull, using a technique called cephalometry.
Genetic testing. If your doctor suspects your baby’s misshapen skull is caused by an underlying hereditary syndrome, genetic testing may help identify the syndrome.
Genetic tests usually require a blood sample. Depending on what type of abnormality is suspected, your doctor may take a sample of your baby’s hair, skin or other tissue, such as cells from the inside of the cheek. The sample is sent to a lab for analysis.
Treatments and drugs
Mild cases of craniosynostosis — those that involve only one suture and no underlying syndrome — may require no treatment. Skull abnormalities may become less obvious as your baby grows and develops hair. Or your doctor might recommend a specially molded helmet to help reshape your baby’s head and allow room for your baby’s brain growth.
For most babies, however, surgery is the primary treatment for craniosynostosis. The type and timing of surgery depend on the type of craniosynostosis and whether there’s an underlying syndrome that needs treatment.
The purpose of surgery is to relieve pressure on the brain, create room for the brain to grow normally and improve your child’s appearance. A team that includes a specialist in surgery of the head and face (craniofacial surgeon) and a specialist in brain surgery (neurosurgeon) often performs the procedure.
Traditional surgery. The surgeon makes an incision in your baby’s scalp and cranial bones, then reshapes the affected portion of the skull. Sometimes plates and screws, often made of material that is absorbed over time, are used to hold the bones in place. Surgery, which is performed during general anesthesia, usually takes hours.
After surgery, your baby remains in the hospital for at least three days. Some children may require a second surgery later because the craniosynostosis recurs. Also, children with facial deformities often require future surgeries to reshape their faces.
- Endoscopic surgery. This less invasive form of surgery isn’t an option for everyone. But in certain cases, the surgeon may use a lighted tube (endoscope) inserted through one or two small scalp incisions over the affected suture. The surgeon then opens the suture to enable your baby’s brain to grow normally. Endoscopic surgery usually takes about an hour, causes less swelling and blood loss, and shortens the hospital stay, often to one day after surgery.
If your baby has an underlying syndrome, your doctor may recommend regular follow-up visits after surgery to monitor head growth and check for increased intracranial pressure. Head growth will be routinely monitored at well-child visits.
Coping and support
Having a baby with craniosynostosis can cause anxiety and be emotionally draining. Talking to people who are dealing with similar challenges can provide you with information and emotional support.
Ask your doctor about support groups in your community. If a group isn’t for you, perhaps your doctor can put you in touch with a family who has dealt with craniosynostosis. Or you may be able to find group or individual support online.