Craniosynostosis

Craniosynostosis (CS) is the premature fusion of one or more cranial sutures. It is caused by a mutation in genes that code for fibroblast growth factor. Most affected infants are asymptomatic; CS is usually recognized based on an abnormal head shape in the first year of life. The shape of the skull is determined by which suture is prematurely fused, of which the sagittal suture (scaphocephaly) is the most commonly affected. When multiple sutures are involved, CS may cause hydrocephalus and/or cerebral constriction. Diagnosis is clinical, with skull x-ray and CT scan helping to assess the extent of fusion. Surgery is recommended in all infants for cosmetic reasons and to treat/prevent intracranial complications.

• Incidence: 1/2500 births
• Potential risk factors
  • Hereditary (positive family history)
  • Advanced maternal age
  • Nicotine use during pregnancy
  • Use of clomiphene citrate (used for infertility treatment)

References:^[1][2][3]

Epidemiological data refers to the US, unless otherwise specified.

• Mutation in genes which encode for the fibroblast growth factor (FGF), FGF receptor, and/or transforming growth factor beta (TGF-β)
• Altered FGF, FGF receptor, or TGF-β signaling between the dura mater and mesenchyma of the suture → premature fusion of the skull suture(s)

References:^[3][4][5]

• The skull is composed of 5 separate bones: 2 frontal bones, 2 parietal bones, and the occipital bone
• In a newborn, these bones are separated by patent sutures and fontanelles.
• Function of patent sutures and fontanelles
  • Allow compression and/or overlapping of the skull bones during childbirth
  • Allow for growth of the brain
• Premature closure of one or more sutures → craniosynostosis
• See the article on skull.

References:^[3][6]

• Usually asymptomatic
• Recognized as an abnormal head shape within the first year of life

References:^{[1][7][8][9][10][11]}

• Mainly a clinical diagnosis
• Skull x-ray (AP and lateral views): bony suture bridges or lack of suture clarity
• Cranial CT (with 3D reconstruction)
  • To assess extent of CS
  • To identify hydrocephalus
  • Helps plan surgical reconstruction

References:^[1][9]

The following conditions show patency of sutures similar to craniosynostosis on skull x-ray or ultrasound:

• Positional plagiocephaly
• Infant torticollis

References:^[10]

The differential diagnoses listed here are not exhaustive.

• Surgery: indicated in all patients either to minimize cerebral constriction or for cosmetic reasons
  • Strip craniectomy or cranial vault remodeling
  • Timing: controversial; mostly recommended at 3–9 months of age

References:^[2][3]