What is non-syndromic craniosynostosis
Craniosynostosis is a condition in which the sutures (growth seams) in an infant’s skull close too early, causing problems with normal brain and skull growth. Non-syndromic craniosynostosis is a non-inherited, isolated finding without related anomalies such as disorders of the limbs, ears or cardiovascular system. It typically involves the early closure of a single growth seam, or suture, in your child’s skull.
The specific diagnosis and appearance of a patient with non-syndromic craniosynostosis depends on which suture is affected. The most common forms of non-syndromic craniosynostosis affect the sagittal (most common), coronal, metopic and lambdoidal sutures. The shape of your child’s head depends on which suture is affected.
In sagittal synostosis (also known as scaphocephaly), the seam that runs from the front to the back of your child’s skull (the sagittal suture) fuses too early in prenatal development. Sagittal synostosis is the most common form of non-syndromic craniosynostosis.
Because of the early closure of the suture, your child’s head becomes long and narrow — growing forward and backward because it was restricted from growing on the sides. When looking at your child’s face, her forehead may appear larger and the sides of the skull appear narrow. When looking down at her skull from above, it will appear long and narrow.
Unicoronal synostosis is a premature fusion of one of the coronal sutures, the seams that run from the ear to the soft spot on your baby's head. Also referred to as anterior plagiocephaly or unilateral coronal synostosis, this is one of the most common forms of non-syndromic craniosynostosis.
In most cases, the cause of unicoronal synostosis is unknown, but there are often underlying genetic malformations associated with the condition (in upwards of 20 to 30 percent of cases).
When one of the sutures fuses early, it causes an asymmetrical forehead and brow. Unicoronal synostosis is characterized by a lack of forward growth on the affected side, resulting in flatness and retrusion. It is more frequently found on the left side of the head.
A common issue associated with this condition is the Harlequin deformity, where the eye socket on the affected side appears taller than the other eye, and the bridge of the nose is bent towards the affected side of the face. There is also typically a greater distance between the upper and lower eyelids on the affected side.
Bicoronal synostosis is a premature fusion of the coronal sutures, which run from ear-to-ear over the head and meet at the soft spot in the middle of your baby’s skull.
Bicoronal synostosis often results in brachycephaly, characterized by a disproportionately wide, flat head. The closure of the suture prevents normal forward growth of the skull, forcing the head to grow from side to side, resulting in a flat back of the head and often an extreme forehead incline.
Metopic synostosis (or trigonocephaly) is characterized by the early closure of the metopic suture during prenatal development. The metopic suture runs from the top of the head down the forehead to the nose.
Due to the early closure of this growth seam, your child’s forehead becomes triangular shaped when viewed from above, and her eyes may appear closer together. When looking at your child’s face, her forehead will appear to jut out in the middle.
Unlike other craniofacial abnormalities, metopic synostosis is generally an isolated condition. In rare cases, the presence of hypotelorism (close-set eyes) in trigonocephaly can be associated with other congenital anomalies.
Lambdoid synostosis, also known as posterior plagiocephaly, is the premature fusion of one of the lambdoid sutures, located on the back of the skull. Lambdoid synostosis is very rare and is the least common form of non-syndromic craniosynostosis.
It usually affects one side of the head, but in rare cases can involve both sutures.
Above, left: Due to growth restriction on the back right of head, compensatory growth of the brain and skull is directed to the infant’s left. Right: Asymmetric flattening of the back of the skull, as shown in the lower right of this infant’s head, is characteristic of unilateral lambdoid synostosis.
Early closure of a lambdoid suture causes a flattening of the back of the head on the side where the suture has fused. On the affected side, the ear is often displaced, moved toward the back of the head or set lower than the ear on the non-affected side. An atypical bulge in the mastoid region is also generally visible.
The following illustration depicts the typical characteristics of lambdoid synostosis. Note flatness on the back of one side of the head with a bossing on the opposite side. The ear on the flat side is also displaced posteriorly, one of the distinguishing features compared to positional plagiocephaly.
Complex multiple suture synostosis
Multiple suture synostosis is a more serious condition than any other form of single suture craniosynostosis because it involves the premature fusion of multiple sutures in your baby's cranium. The premature closure can cause multiple head deformities and indicate underlying brain abnormalities such as hydrocephalus and Arnold-Chiari malformation.
The cause of multiple suture synostosis may be sporadic or genetic, though it is more likely to be associated with a genetic syndrome such as Apert, Crouzon or Pfeiffer syndrome.
Clinicians who specialize in treating children with craniofacial anomalies are often able to diagnose non-syndromic craniosynostosis by examining the shape of your child’s head. A CT scan may be performed to confirm the diagnosis. The CT scan allows your child’s medical team to more closely evaluate atypical findings and rule out any associated anomalies, an important step in establishing the best treatment plan.
For example, an abnormal head shape isn’t always related to craniosynostosis. It is important to understand your child’s condition before determining what treatment is best.
Treatment of single suture or poly-suture non-syndromic craniosynostosis depends on the suture involved, the extent of the anomaly, and the age of your child.
Left untreated, 10 to 15 percent of patients with single suture synostosis will go on to develop elevated intracranial pressure that will require surgery. These craniofacial anomalies can also result in severe physical differences that patients find very difficult to live with. Surgery can help address these problems.
Surgical treatment of non-syndromic craniosynostosis
CHOP’s Craniofacial Program offers the full spectrum of treatment options for patients with non-syndromic craniosynostosis. Your child’s care will be managed by the nation’s top pediatric plastic and reconstructive surgeons working closely with pediatric neurosurgery specialists.
Depending on the age of your child, the type of suture involved, and the degree of deformity, a variety of interventions may be recommended. Learn more about the current surgical treatment approach for children with craniosynostosis »
Non-surgical treatment options
In mild cases of craniosynostosis, surgery may not be required.
For example, the metopic suture normally closes between 6 and 8 months of age. If it closes slightly early, it may cause a small ridge without any distinct changes in the shape of the skull. In these cases your child’s medical team may recommend conservative observation to monitor for any necessary treatment.
Watch this educational video to learn more about the treatment approaches available to children with different types of craniosynostosis.
Reviewed by Scott P. Bartlett, MD, Jesse A. Taylor, MD