What is craniosynostosis and how is it diagnosed?

What is craniosynostosisWhat is craniosynostosis and how is it diagnosed?

If your infant has a misshapen or flattened head, it is very important that you get an accurate diagnosis of the cause.  Although the majority of head flattening is caused by external pressure on an area of the baby’s head, it is possible that there could be a more serious cause, such as craniosynostosis.  This article explores what craniosynostosis is, and how it is diagnosed.  Craniosynostosis is a rare but serious condition.


Craniosynostosis is the premature closing of your baby’s skull fissures. As new parents, we worry so much about our children’s soft spots, but when they close early, significant problems can result. The complications of craniosynostosis can leave babies with oddly-shaped heads, and in severe cases can cause swelling in the cranial cavity, headaches, vomiting, increasing head circumference, poor feeding, irritability, developmental delays, structurally-related speech impediments, hearing problems, reduced vision, loss of vision, breathing difficulties, and even seizures.

There are two types of craniosynostosis; primary and secondary. Primary craniosynostosis occurs in 2-8% of cases, when a child’s bones fuse together prematurely. This can keep the brain from growing correctly. Secondary craniosynostosis is the result of the brain’s lack of growth (microcephaly), and is more common than primary craniosynostosis.

The particular bones that fuse together early in a baby’s brain can also affect the treatment and outcome of the condition. The most common type of craniosynostosis is saggital (50-58% of cases), the second most frequent is coronal (20-29% of cases), the third is metopic (4-10% of cases). The least common type of craniosynostosis is lambdoid, which affects 2-4% of cases.

Craniosynostosis varies in severity, as well as in cause. Simple craniosynostosis affects only one of the sutures in a baby’s skull. Complex craniosynostosis involves more than one skull fissure, and syndromic craniosynostosis is synostosis that occurs in conjunction with other skeletal deformities in the body.

If your child has just been diagnosed with craniosynostosis, please skip to the end of the book. Several resources and contact information for support groups has been provided in hyperlink format. You are not alone, and sometimes when things get rough, it’s good to talk to someone who has been in your position.

Saggital craniosynostosis

The appearance of saggital craniosynostosis – scaphocephalic craniosynostosis – is identical to that of positional scaphocephaly. Children with this condition develop an elongated and narrow skull.  This happens when the fissure that runs between the front and back of the head closes too early.

Coronal craniosynostosis

Coronal craniosynostosis occurs when one or both of the bony seams on the sides in the front of the skull close early.

Unilateral coronal craniosynostosis (Unicoronal craniosynostosis [one-sided]) can be confused with deformational plagiocephaly, a condition which does not require surgical correction, since the coronal suture isn’t fused. Both conditions can cause plagiocephaly, or ‘flat head,’ a condition which creates a flat spot on one side of the skull.

Brachycephalic craniosynostosis is another name for bilateral coronal craniosynostosis. Children with this condition can look like children with positional brachycephaly, but with craniosynostosis, the skull fissures have closed.

Metopic craniosynostosis

Trigonocephaly, or metopic craniosynostosis, is the result of the skull fissure in a baby’s forehead closing too soon. Children with trigonocephaly often have eyes that appear too narrow and angled upwards towards the outside. Their faces can take on a sharply triangular appearance, hence “trigono”- cephaly.

Lambdoid craniosynostosis

The least common type of simple craniosynostosis is lambdoid craniosynostosis. This condition occurs when one or both of the two rear side fissures of the skull fuse early. It is also described as posterior plagiocephalic craniosynostosis, and looks similar to posterior positional plagiocephaly.


Complex craniosynostosis which involves the early closure of three or more sutures is referred to as pansynostosis, which means “all one bone”. Babies with pansynostosis can look very different from one another. Some will have what is called clover-leaf skull, where the different bones of the skull bulge outward, and look like a clover-leaf. Others will looks microcephalic, with little to no head growth. Oftentimes, this condition is the result of dwarfism.


According to Medscape.com, 0.04-0.1% of babies in the United States are born with craniosynostosis.


There are many reasons that a child may be born with craniosynostosis. A baby’s poor position in the womb, specific medications taken by the mother during pregnancy (valporic acid or phenytoin), a pre-existing defect or malformation in the fissures themselves, metabolic disorders, neuromuscular conditions, sugar-processing disorders, and genetics have all been tied to craniosynostosis.

Craniosynostosis can appear as a symptom for other conditions, in which case it is referred to as syndromic craniosynostosis. If the craniosynostosis develops in an other-wise healthy child, it is considered nonsyndromic craniosynostosis. It is always important to rule out any potentially related conditions if your child has been diagnosed with craniosynostosis – some of the potentially related syndromes and disorders are dangerous if untreated. There over 150 conditions which are associated with craniosynostosis. The following is a list of some of the conditions which sometimes accompany craniosynostosis:

  • Apert’s syndrome
  • Cranio-fronto-nasal dysplasia
  • Crouzon’s disease
  • Hurler’s syndrome
  • Morquio’s syndrome
  • Muenke (P250) syndrome
  • Pfieffer’s syndrome
  • Saethre-Chotzen syndrome



An infant with craniosynostosis is usually diagnosed as a result of physical exam by the doctor, or a parent’s concern about their child’s unusual head shape. Because the severity of craniosynostosis can vary significantly, some children go undiagnosed for several years until further complications such as blurred vision or increasing pressure on the brain develop. Symptoms of true craniosynostosis (not positional cephalic disorders) include:

  • Absence of a soft spot (fontanel) at birth
  • Early disappearance of the baby’s soft spot
  • Seizures
  • Bulging eyes
  • Raised hard ridges on the skull
  • Unusual head shape
  • Decreased head circumference
  • Increased head circumference
  • Obvious scalp veins
  • Slow head growth
  • No head growth
  • Developmental delays
  • Increasing irritability
  • Projectile vomiting
  • High-pitched crying
  • Poor feeding habits

Craniosynostosis can be confused with cephalic disorders such as positional plagiocephaly or brachycephaly. As a result, it is important that your doctor use diagnostic imaging when deciding what type of craniosynostosis your baby has. For example, in the past children with positional scaphocephaly were frequently misdiagnosed as having closed saggital sutures – an indication of scaphocephalic craniosynostosis.  An accurate diagnosis of the cause of any flat spots on your baby’s head is critical.

For complete information on all causes of flat head syndrome including craniosynostosis, and how to prevent and treat these conditions, please see our ebook.




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