Metopic Craniosynostosis (Trigonocephaly)

What is metopic craniosynostosis?

Metopic craniosynostosis is a birth defect that occurs when the two frontal bones in a fetus’ skull fuse too soon. This often occurs while a fetus is developing in the uterus, but can also occur shortly after birth. It results in a baby born with a triangle-shaped forehead called trigonocephaly.

The human skull is made up of several bones. The bones fit together with sutures in between them that act as growth plates. These sutures help the skull fit together with the growing brain. Sometimes, the bones and sutures fuse together before the brain finishes growing. This is known as craniosynostosis. Trigonocephaly results when the suture between the frontal bones of your baby’s skull (called the metopic suture), closes too early.

How common is metopic craniosynostosis?

Current studies suggest metopic craniosynostosis may be the second most common form of craniosynostosis. The exact rate of occurrence varies and ranges from 1 in 700 to 1 in 15,000 newborns in the United States.

What are the symptoms of metopic craniosynostosis?

Symptoms of metopic craniosynostosis can include:

• Bone growth abnormalities of your baby’s head and face.
• Pressure within your baby’s skull on their brain (intracranial pressure).
• Vision problems.

What does metopic craniosynostosis look like?

Metopic craniosynostosis affects how the features of your child’s face develop. This looks like the following:

• A narrow, bony, pointed forehead.
• Eyes close together.
• Raised or arched eyebrows.
• A wider back of the head.

What causes metopic craniosynostosis?

Early closing of the frontal bones in the skull before the brain finishes growing causes metopic craniosynostosis. This is known as premature fusion. Healthcare providers don’t know why this happens. Research suggests it could be the result of many factors, including:

• A genetic change (mutation of the FREM1 and SMAD6 genes).
• A side effect of a medication taken during pregnancy (valproic acid, clomiphene citrate).
• Thyroid disease that affects the birthing parent.
• The position of the fetus in the uterus.
• A symptom of an underlying genetic condition like Williams syndrome.

What are the risk factors for metopic craniosynostosis?

You may be more at risk of having a child with metopic craniosynostosis if you:

• Are expecting twins.
• Have an underlying health condition like thyroid disease or diabetes.
• Take certain medications to treat a condition like epilepsy.
• Use tobacco products.

To learn more about the risks of having a child with a birth defect, contact your healthcare provider and ask for preconception counseling. They can give you advice to lower your risk of having a child with a birth defect.

What are the complications of metopic craniosynostosis?

Metopic craniosynostosis complications may not show until your child grows and starts school. Common complications could include:

• Developmental delays (speech and language or motor skills).
• Problems with cognitive development.
• Behavioral changes (like irritability).
• Signs of high intracranial pressure, including headaches and vision issues.
• Slow head growth in comparison to the rest of their body.

How is metopic craniosynostosis diagnosed?

Sometimes, your healthcare provider may suspect metopic craniosynostosis during the second and third trimesters of pregnancy using a prenatal ultrasound, but usually, the diagnosis happens after your baby is born.

A diagnosis happens during a newborn physical exam. Your healthcare provider will look at your baby’s head starting from the top center (vertex) and look toward your baby’s face. The shape of your baby’s skull from this viewpoint (a bird’s eye view) can identify trigonocephaly if their head is triangular or cone-shaped instead of round.

Imaging tests, like an X-ray or computed tomography (CT) scan of your baby’s head, give your child’s care team more information about the shape of their skull bones. These tests help guide treatment for the condition.

What is the severity of metopic craniosynostosis?

Metopic craniosynostosis can vary in severity. The severity is specific to the angle of bone growth from the skull fusing together too soon. For example: Mild cases cause a small change to the forehead shape. Severe cases cause a steep slope that’s nearest to a triangular or cone shape. A moderate diagnosis is in between the two.

How is metopic craniosynostosis treated?

In mild cases of metopic craniosynostosis, or in cases where there’s just a metopic ridge without significant deformity, medical treatment isn’t necessary.

In cases where trigonocephaly is moderate or severe, treatment with surgery helps reshape your child’s head and gives their brain more space to grow. If necessary, surgery can relieve pressure on your child’s brain as well.

There are two types of surgery to treat metopic craniosynostosis:

• Endoscopic-assisted surgery: This type of surgery happens in younger infants, ideally before your child turns 4 months old but no later than 6 months. A surgeon will make a small incision in your child’s forehead nearest their hairline. They’ll use an endoscope to help remove a strip of bone over the metopic suture (the part of your baby’s skull that fused together too soon). An endoscope is a camera that helps your surgeon look and work inside your child’s skull without making a large incision (cut).
• Open surgery (cranial vault remodeling): This type of surgery usually happens between 6 and 12 months of age. Often, both a neurosurgeon and a plastic surgeon work together. A surgeon will make a larger incision (cut) within your child’s scalp (larger than an endoscopic incision). Then, they’ll remove abnormally shaped portions of the skull. Next, they’ll cut, modify and replace the skull bones to create an expected head shape. This also allows for more room for your child’s brain to grow.

Does my child need to wear a helmet after metopic craniosynostosis surgery?

After endoscopic surgery, your child will need to wear a helmet until they’re about 12 months old. The helmet helps your child’s skull grow into a round shape. After open surgery, your child usually doesn’t need a helmet but your surgeon will let you know what they recommend.

Are there side effects of the treatment?

Each type of surgery comes with possible risks and side effects, which could include:

• Blood loss.
• Infection.
• Brain bleed (hematoma).

Your child’s surgeon will go over these side effects before the procedure date. Open surgery has more risks than endoscopic surgery. It also has a longer operating time and healing time.

Your child may need blood transfusions after surgery if they had blood loss. This is most common during open surgery.

Additional surgeries to correct trigonocephaly aren’t common but may be necessary.

How long does it take to recover from surgery?

Your child may feel much better within a few weeks of surgery, but it could take between two to three months for your child to recover completely. The bone healing and regrowth may continue over the next year. Your child’s surgeon will explain their recovery and what to expect before the date of your child’s surgery.

Can metopic craniosynostosis be prevented?

There isn’t a way to prevent metopic craniosynostosis. You can reduce your risk by talking to a healthcare provider about ways you can prevent birth defects and stay healthy before and during pregnancy.

What can I expect if my child has metopic craniosynostosis?

Metopic craniosynostosis, while rare, can affect each child differently. Some children may have very small changes to the shape of their heads and don’t require treatment. Others might need surgery to reshape their head and additional care to treat complications like developmental delays.

Treatment with surgery is successful and side effects are usually minor. After endoscopic surgery, your child will stay overnight for close observation. They can often go home within one to two days of the procedure. For the open surgery, your child will spend 24 hours in intensive care so their healthcare providers can observe their progress around the clock. Then, a provider will move your child to another area of the hospital for a few days to a week to monitor their healing.

During their stay in the hospital, they’ll likely experience swelling of their head and face. This is normal, and their eyes may swell shut for two to three days before the swelling subsides.

Children who get endoscopic surgery may need to wear a helmet until they reach 12 months of age. This can be challenging for new parents, as their children will look different from others until their healing is complete. Many parents use stickers to decorate their child’s helmet to match their personality.

As your baby looks different, people may ask questions about them. You may not feel comfortable sharing the details of their diagnosis with others. Many families find comfort in speaking with a mental health professional to help them address any challenges that may arise.

When should my child see a healthcare provider?

Once your child heals completely, a craniofacial team (a group of specialty healthcare providers) will monitor them as they grow.

Visit a healthcare provider if your child misses developmental milestones for their age. This could include walking or saying their first words. While many children with metopic craniosynostosis have normal development, some children may experience developmental delays. They may need a little extra time to catch up to others at their age. A healthcare provider can help your child reach their goals.

Your surgeon will give you information on what to look out for after surgery, like infection. If anything seems off, contact their provider.

What questions should I ask my child’s healthcare provider?

• Does my child need surgery?
• What type of surgery do you recommend?
• Are there side effects to the treatment?
• When should I schedule follow-up appointments after surgery?
• What do I do if my child misses developmental milestones?