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.
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