A Guide for Parents and Professionals
Craniosynostosis is a condition in which one or more of a baby’s skull sutures close too early, affecting skull growth and head shape. It occurs in about 1 in every 2,000–2,500 births in the United States. While each type involves a different suture, understanding how common each type is can help families better understand their child’s diagnosis.
Below are the estimated frequencies of the major forms of nonsyndromic craniosynostosis (cases not linked to an underlying genetic syndrome). These percentages come from large population studies and may vary slightly across regions.
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Sagittal Craniosynostosis (Scaphocephaly)
Frequency: ~40–55% of all cases
Sagittal craniosynostosis is the most common type. The sagittal suture runs from front to back along the top of the skull. When it closes early:
The head becomes long and narrow (scaphocephaly)
It occurs more often in boys than girls
Most cases are isolated and not part of a syndrome
This form’s high frequency makes it the most recognized and commonly treated type.
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Unilateral Coronal Craniosynostosis (Anterior Plagiocephaly)
Frequency: ~20–25% of cases
Unilateral coronal synostosis affects one of the coronal sutures, which run ear-to-ear at the top of the head. When one side fuses early:
The forehead and eyebrow on that side flatten
The eye on the affected side may appear more open
It occurs more often in girls
It is the most common cause of true anterior plagiocephaly
This type is frequently confused with positional plagiocephaly, so accurate diagnosis—sometimes including CT imaging—is important.
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Metopic Craniosynostosis (Trigonocephaly)
Frequency: ~20–25% of cases
The metopic suture runs from the top of the head down the middle of the forehead toward the nose. When it fuses prematurely:
The forehead forms a triangular shape
The eyes may appear closer together (hypotelorism)
Metopic fusion can be tricky to diagnose because the metopic suture normally closes earlier than other sutures. Only the cases that cause head-shape changes are considered metopic craniosynostosis.
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Bicoronal Craniosynostosis (Brachycephaly / Turribrachycephaly)
Frequency: ~10% of cases
Bicoronal synostosis involves the fusion of both coronal sutures. It produces:
A short, wide head shape (brachycephaly)
A tall skull (turribrachycephaly)
More likelihood of being associated with a syndrome such as Crouzon, Apert, Muenke, or Pfeiffer
Because this type restricts forward skull growth on both sides, it may influence orbital development and forehead contour more significantly.
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Lambdoid Craniosynostosis (Posterior Plagiocephaly)
**Frequency: < 3% of cases (extremely rare)
Lambdoid craniosynostosis affects the back suture of the skull. It is so rare that many pediatric neurosurgeons may only see a few true cases in an entire career.
Features include:
Flattening low and behind the ear
The ear shifts downward and backward (a key clue compared to positional plagiocephaly)
Often unilateral, very rarely bilateral
Because it is often misdiagnosed as positional flattening, a specialist’s evaluation is critical.
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Summary Table of Craniosynostosis Types and Frequencies
Type of Craniosynostosis Approx. Percentage of Cases Notes
Sagittal 40–55% Most common; long narrow head
Unilateral Coronal 20–25% More common in girls; causes anterior plagiocephaly
Metopic 20–25% Triangular forehead; can be over-diagnosed
Bicoronal ~10% Often syndromic; short, wide head shape
Lambdoid < 3% Rarest type; true posterior plagiocephaly
