The skull of an infant or young child is made up of several bony plates that allow for growth of the skull. The borders where these plates intersect are called sutures or suture lines. The sutures between these bony plates normally close by the time the child is 2 or 3 years old.
Craniosynostosis is a condition where those sutures cause the baby to have an abnormally shaped head.
Symptoms of CraniosynostosisSymptoms depend on the type of craniosynostosis and may include:
- Head asymmetry
- Developmental delay: speech, motor, or delayed milestones
- headaches, pulling at hair, signs of increased intracranial pressure
Types of craniosynostosis
Sagittal synostosis is the most common form of synostosis accounting for about 50% of all cases with a prevalence of 1 in 2000 live births. Premature fusion of the sagittal suture restricts the transverse growth of the skull. This results in an increased anteroposterior skull length to accommodate the growing brain. Frontal bossing and an exaggerated occiput can be pronounced and results in the classic “boat skull” appearance.
The metopic suture is located at the front of the head and separates the frontal bones. It allows for transverse growth of the frontal bones and a widening of the anterior cranial fossa as the brain grows. This suture is the only one that naturally closes in childhood, between the ages of 0-2 years old. “Normal “closure of this suture typically results in the formation of a prominent midline ridge which is often felt along the middle of the forehead. “Premature” closure, however, causes more than a ridge. There is restriction of growth across the forehead leading to a triangular shape (trigonocephaly) and true narrowing of the orbits (hypotelorism). It is important to differentiate an isolated metopic ridge which does not require surgery, from true metopic synostosis, where surgery is recommended.
Premature fusion of a single coronal suture leads to a head shape called anterior plagiocephaly. This results in restricted anterior growth of the skull, involving the top of the skull as well as the cranial base. This causes deformities of the face, ear, nose and forehead. The affected forehead is flat with the contralateral side more forward. The affected side ear is also more forward. The face always has a characteristic “C-shaped” deformity or “facial twist”. This is characterized by the base of the nose drawn towards the affected side and the tip of the nose pointing away. The associated facial deformity is the key method of differentiating anterior plagiocephy from positional/deformational plagiocephaly, which is not the result of synostosis.
Lambdoid synostosis is the form of synostosis most commonly mistaken for posterior positional deformational plagiocephaly and must be closely evaluated. Unilateral lamdoid synostosis results in flattening of the back of the head on the affected side as well as compensatory growth of the mastoid process on the same side (ipsilateral mastoid bulge). This leads to a characteristic and unique “tilt” in the cranial base. This differentiates it from positional/deformational plagiocephaly. The ear on the affected side is often deviated back and toward the fused suture. This is one of the rarest types of craniosynostosis, accounting for only 2-4% of synostosis cases. Surgical management of lambdoid synostosis involves restructuring the posterior fossa to provide adequate space for normal brain development as well as restoring normal symmetry.
Fusion of both coronal sutures leads to a head shape called “bracycephaly.” This causes restriction of growth of the anterior fossa resulting in a shorter and wider than normal skull. Compensatory vertical growth also occurs, which is called turricephaly. Bicoronal synostosis is often seen in patients with associated syndromes such as Crouzon, Apert, Saethre-Chotzen, Muenke and Pfeiffer syndromes. These patients can also have additional sutures that are prematurely closed.
Signs and tests
The doctor will feel the infant's head and perform a physical exam.
The following tests may be done:
- Computed Tomography (CT) scan of the head
- Neuropsychologic testing
- Dilated fundoscopic exam
- MRI scan
Well-child visits are an important part of your child's health care. They allow your doctor or nurse to regularly check the growth of your infant's head over time. This will help identify any problems early.