Kraniosynostose

Craniosynostosis refers to the premature closure of the cranial sutures. The skull shape then undergoes characteristic changes depending on which suture(s) close early.

Epidemiology

There is a 3:1 male predominance with an overall incidence of 1 in 2000-2500. 8% of cases are syndromic or familial.

Pathology

Primary forms are either sporadic or familial. Secondary craniosynostosis occurs in relation to a variety of causes:

  • endocrine disorders
    • hyperthyroidism
    • hypophosphatemia 
    • vitamin D deficiency 
    • hypercalcemia
  • hematologic disorders causing bone marrow hyperplasia
    • sickle cell
    • thalassemia
  • inadequate brain growth
    • microcephaly
    • shunted hydrocephalus 
Ages of normal sutural/fontanelle closure
Types

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%)
Associations

Most occur as isolated anomalies but syndromic associations can be seen in a small proportion of cases (~10%):

Radiographic features

Restriction of skull growth is perpendicular to the affected suture line. Characteristic dysmorphic head shapes are associated with each type of craniosynostosis.

Ultrasound

Ultrasound may be useful in subtle cases. General features include:

  • sutures are normally hypoechoic
    • there may be a loss of normal decreased echogenicity in the region of the fusion
  • lack of suture patency
  • ridging of the sutures
CT

CT with 3D image reformations is the best modality used for evaluation of sutures .

Treatment and prognosis

Treatment is often with a cranioplasty. Abnormal intracranial pressure may affect neurocognition.

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