Citation, DOI & article data
Craniosynostosis (plural: craniosynostoses) refers to the premature closure of the cranial sutures. The skull shape then undergoes characteristic changes depending on which suture(s) close early.
There is a 3:1 male predominance with an overall incidence of 1 in 2000-2500. 8% of cases are syndromic or familial.
Most occur as isolated anomalies but syndromic associations can be seen in a small proportion of cases (~10%):
- acrocephalosyndactyly/acrocephalopolysyndactyly types
- choanal atresia
Primary forms are either sporadic or familial. Secondary craniosynostosis occurs in relation to a variety of causes:
- endocrine disorders
- hematologic disorders causing bone marrow hyperplasia
- inadequate brain growth
Ages of normal sutural/fontanelle closure 8
- metopic: 3-9 months
- anterior fontanelle: 18-24 months
- sphenosquamosal: 6-10 years
- sphenofrontal: approximately 15 years
- occipitomastoid: approximately 16 years
- sagittal: approximately 22 years
- coronal: approximately 24 years
- lambdoid: approximately 26 years
- squamosal: approximately 60 years
- brachycephaly: bicoronal and/or bilambdoid sutures
- scaphocephaly/dolichocephaly: sagittal suture
- plagiocephaly: unilateral coronal and lambdoid sutures
- trigonocephaly: metopic suture
- pachycephaly: lambdoid suture
- oxycephaly/turricephaly: sagittal, coronal and lambdoid sutures (tower like skull)
- cloverleaf skull/Kleeblattschädel: intrauterine sagittal, coronal, lambdoid sutures (most severe)
- harlequin eye: ipsilateral coronal suture
- progressive postnatal pansynostosis: a rare form of craniosynostosis which involves late (postnatal) fusion of all cranial sutures 9
The sagittal suture is most commonly involved (≈50%), where the lateral growth of the skull is arrested while anteroposterior growth continues, producing a narrowly elongated skull known as scaphocephaly (meaning boat-shaped) or dolichocephaly (from the ancient Greek for long, δολιχός: dolichos).
The next most common sutures in terms of involvement are:
- coronal (~20%)
- lambdoid (~5%)
- metopic (~5%)
Restriction of skull growth is perpendicular to the affected suture line. Characteristic dysmorphic head shapes are associated with each type of craniosynostosis.
Ultrasound can be used as a screening tool or in clinically-subtle cases and can reduce radiation exposure in infants to cases with inconclusive findings 11.
General features include:
- sutures are normally hypoechoic
- there may be a loss of normally decreased echogenicity in the region of the fusion
- lack of suture patency
- ridging of the sutures
Low-dose CT with 3D image reformations is the best modality for the evaluation of skull sutures 5.
Treatment and prognosis
Treatment is often with a cranioplasty. Abnormal intracranial pressure may affect neurocognition.
History and etymology
Craniosynostosis was first accurately characterized by Rudolph Virchow in 1851 10.
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