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KEY POINTS
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Key Points

  • Condition due to premature fusion of cranial sutures (sagittal, coronal, lambdoid, or metopic).

  • Incidence is 1 in 2000 livebirths. One of the most common human malformations.

  • Eighty to ninety percent of cases are isolated, 10%–20% are syndromic.

  • Women with fetuses suspected of having craniosynostosis should be referred for a detailed fetal anatomic survey. Sonographers should pay attention to the fetal hands, midface, heart, and central nervous system.

  • Differential diagnosis includes Muenke coronal craniosynostosis, Saethre–Chotzen syndrome, Apert syndrome, Crouzon syndrome, Pfeiffer syndrome, and many others.

  • DNA diagnosis is available to detect mutations in the causative genes associated with craniosynostosis, including FGFR1, FGFR2, FGFR3, TWIST, and MSX2.

  • Newborns are at risk for difficulties with breathing, feeding, and vision. Consultation with genetics and neurosurgery is indicated.

  • Long-term outcome and recurrence risk depend on identification of a genetic basis through DNA analysis.

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CONDITION
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The term craniosynostosis refers to the process of premature bony fusion of the cranial sutures. The term is frequently used interchangeably with the word craniostenosis, which technically refers to the aberrant skull shape that results from the process of craniosynostosis (Graham, 1981). The weight of the brain doubles during the first year of life, and enlargement of the skull vault is distributed among the main cranial sutures—sagittal, coronal, lambdoid, and metopic. Premature fusion of a suture leads to reduced growth in the direction perpendicular to the fused suture (Thompson et al., 1994). Compensatory growth occurs in the remaining normal sutures. Normally, the cranial sutures are open at birth and become interdigitated by 7.5 months of age. Cranial sutures do not fuse completely until the fourth decade of life (Graham, 1981).

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It is important to determine whether craniosynostosis is primary or secondary. In primary craniosynostosis, abnormal skull development is genetically determined and alteration in sutural growth is present from birth (Flores-Sarnat, 2002). In primary craniosynostosis, the head of the affected individual is frequently asymmetric. The brain grows at a normal rate but must adjust to the confined space. The brain continues to grow in areas where the sutures are open but not in areas where the sutures are closed (Lyons-Jones et al., 1980). Most children affected with primary craniosynostosis are normal neurologically and benefit from surgery. In secondary craniosynostosis, brain growth is impaired and most affected children are neurologically abnormal. In secondary craniosynostosis, a metabolic, storage, hematologic, or structural disorder results in microcephaly or otherwise abnormal brain growth (Table 10-1). In evaluating the fetus with craniosynostosis, it is important to determine whether the craniosynostosis is isolated (80–90% of cases) or syndromic (10–20% of cases). More than 150 syndromes have been described that include craniosynostosis as an associated feature (Lajeunie et al., 1995; Warren and Longaker, 2001).

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Table Graphic Jump Location
Table 10-1Classification of Craniosynostosis

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