More frequent than 1 in 1000 births.

1. An abnormal head shape detracts from cosmetic appearance.
2. Depending on the type of synostosis, a loss of function is possible: mental deficiency and diminished performance in special fields, refraction anomalies, strabism, exophthalmus and loss of visual acuity, breathing with open mouth, sleep-apnea syndrome, malocclusion.
3. Corrective surgery is easier to perform in infants than later in life.

Unknown. Some types are hereditary.

Disturbance of the regulation of normal and age-dependent maturation of one or several sutures, leading to a premature closure and an abnormal structure. Fusion of the sagittal suture, bilateral and unilateral fusion of the coronal suture, fusion of the metopic suture, bilateral and unilateral fusion of the lambdoid suture, fusion of multiple sutures, and craniofacial dysostosis.

The growth of the skull is disturbed in the direction perpendicular to the involved suture, and increased in all other directions, which leads to a characteristic deformity.

It is important to look at the skull from all directions: From the front and the back, from both sides, and from the top. Due to the characteristic shape it is clinically possible to recognize the specific type of suture closure.
In addition, inspection and palpation of the suture sites are necessary: absent or present movements of the adjacent bones in young infants, visible and palpable bony ridge of a fused suture, palpable craniotabes and bony holes.
Measurement of head circumference (HC), largest frontooccipital length and biparietal breadth (see macrocrania). With the fusion of the sagittal suture the HC is relatively large, and relatively small with coronal suture fusion. Skull index: Breadth divided by length multiplied by 100. Normal values are 70 to 80. With fusion of the sagittal suture the values are lower, and higher with bilateral fusion of the coronal or lambdoid sutures.

With advancing age there is no spontaneous correction of the deformities. With growth there is often an increase in the deformity, but rarely an involvement of other sutures, and onset or worsening of functional damage.

Differential diagnosis includes: Birth molding, deformities due to tumor-like masses or tumors, plagiocephaly following congenital muscular torticollis, postural and positional molding.

Skull x-rays in two planes and CT: Confirmation of the fusion and quantification of the skull deformity and involvement of the skull base and facial bones, exclusion of combined malformations. In craniofacial dysostosis: CT with reconstruction. Opthalmological examinations, measurement of intracranial pressure during 24 to 48 hours, and genetic work-up and consulting.

Absolute indications for corrective surgery: Imminent (natural history) or present loss of function and/or increased intracranial pressure. Severe deformity.
Relative indication for corrective surgery: Single suture involvement. Surgery includes: Early decompression of the calvarium (multiple sutures involvement), vertex craniectomy (scaphocephaly) and osteotomy with transposition of the back of the head (fusion of the lambdoid sutures) within the first trimenon and frontoorbital advancement (fusion of the coronal suture(s) and the metopic suture) at 6 months of age.
Facial surgery is performed later.
Corrections with a special helmet in case of fusion of a suture are not indicated, but useful in severe positional molding.

Following one or several sessions there are good esthetic and functional results. There is only a positive influence on mental development in case of increased intracranial pressure.