Your baby's skull has seven bones. 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, giving your baby's brain time to grow until the bones fuse at about age 2.
The signs of craniosynostosis are usually noticeable at birth, but they'll become more apparent during the first few months of your baby's life. These can include:
- A misshapen skull, with the shape depending on which of the sutures are affected
- An abnormal feeling or disappearing fontanel on your baby's skull
- Development of a raised, hard ridge along affected sutures
- Slow or no growth of the head as your baby grows
Types of craniosynostosis
There are several types of craniosynostosis. Most involve the fusion of a single cranial suture. Complex craniosynostosis involves the fusion of multiple sutures. Most cases of complex craniosynostosis are linked to genetic syndromes and are called syndromic craniosynostosis.
The term given to each type of craniosynostosis depends on what sutures are affected. Types of craniosynostosis include:
- 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.
Other reasons for a misshapen head
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 your baby spending too much time on one side of his or her head. This can be treated with regular position changes, or if significant, with helmet therapy (cranial orthosis) to help reshape the head to a more normal appearance.
When to see a doctor
Your doctor will routinely monitor your child's head growth at well-child visits. Talk to your pediatrician if you have concerns about your baby's head growth or shape.
Often the cause of craniosynostosis in not known, but sometimes it's related to genetic disorders.
- Nonsyndromic craniosynostosis is the most common type of craniosynostosis, and its cause is unknown, although it's thought to be a combination of genes and environmental factors.
- Syndromic craniosynostosis is caused by certain genetic syndromes, such as Apert syndrome, Pfeiffer syndrome or Crouzon syndrome, which can affect your baby's skull development.
If untreated, craniosynostosis may cause, for example:
- Permanent head and facial deformity
- Poor self-esteem and social isolation
The risk of intracranial pressure from simple craniosynostosis is small, as long as the suture and head shape are fixed surgically. But babies with complex craniosynostosis, particularly those with an underlying syndrome, may develop increased pressure inside the skull if their skulls don't expand enough to make room for their growing brains. If untreated, increased intracranial pressure can cause:
- Developmental delays
- Cognitive impairment
- No energy or interest (lethargy)
- Eye movement disorders
- Death, in rare instances