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Craniosynostosis is the premature fusion of one or more cranial sutures, resulting in abnormal skull shape and potential intracranial hypertension due to restriction of normal brain growth. It may occur isolated (non-syndromic) or as part of a syndromic disorder.

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Embryology

The cranial sutures normally remain open during infancy to accommodate brain growth.
Premature suture fusion causes growth restriction perpendicular to the fused suture and compensatory overgrowth in other directions.
Primary craniosynostosis: intrinsic abnormality in suture biology.
Secondary craniosynostosis: due to external factors (e.g., shunted hydrocephalus, metabolic disorders).

Classification

By Number of Sutures Involved

Type	Description
Simple	One suture involved
Complex	Multiple sutures involved
Pansynostosis	All sutures involved → microcephaly

By Specific Suture Affected

Term	Suture	Skull Shape
Scaphocephaly	Sagittal (most common)	Long narrow skull
Anterior plagiocephaly	Coronal (unilateral)	Asymmetric flattening of forehead
Brachycephaly	Coronal (bilateral)	Short, wide head, frontal bossing
Trigonocephaly	Metopic	Triangular forehead, hypotelorism
Posterior plagiocephaly	Lambdoid (rare)	Posterior flattening, mastoid bulge

![Three-dimensional CT reconstructions show the types of alterations of head shape in children.

Márquez JC, Bustos CH, Wagner MW. Craniosynostosis: Understanding the Misshaped Head. Radiographics. 2021;41(2):E45-E46. doi:https://doi.org/10.1148/rg.2021200127](https://prod-files-secure.s3.us-west-2.amazonaws.com/2aa05644-4658-4c26-84d3-64c36b55fb6c/59135041-1a84-4f8b-b623-fefbecb83134/Craniosynostosis.webp)

Three-dimensional CT reconstructions show the types of alterations of head shape in children.

Márquez JC, Bustos CH, Wagner MW. Craniosynostosis: Understanding the Misshaped Head. Radiographics. 2021;41(2):E45-E46. doi:https://doi.org/10.1148/rg.2021200127

Syndromic Craniosynostosis

Occurs in 15–30% of cases and often involves multiple sutures. Associated with craniofacial anomalies and genetic mutations.

Syndrome	Gene	Features
‣	FGFR2	Brachycephaly, proptosis, maxillary hypoplasia
‣	FGFR2	Brachycephaly, syndactyly
‣	FGFR1/2	Broad thumbs/toes, cloverleaf skull
‣	TWIST1	Ptosis, low hairline, mild facial asymmetry
‣	FGFR3	Mild, often coronal synostosis

Clinical Features

Abnormal head shape depending on fused suture