Prenatal ultrasound diagnosis of fetal craniosynostosis

Craniosynostosis is defined as the premature closure of the calvarial sutures. The prevalence of this heterogeneous condition is 1 in 2000 and approximately 100 different forms have been described with an established genetic transmission in half of them. Prenatal diagnosis of craniosynostosis relies mainly on identification of associated anomalies and molecular analysis of fetal DNA, which is only feasible in some syndromic forms and in well-documented families. The objective of this study was to investigate the value of prenatal ultrasound examination of cranial sutures in fetuses at risk for craniosynostosis.

Forty fetuses at risk for craniosynostosis on the basis of either a family history (Group 1, n = 16) or skull deformity suspected on a first-level fetal ultrasound examination (Group 2, n = 24) were retrospectively investigated. Craniosynostosis was suspected on the basis of skull deformities when present, however the diagnosis was only made in cases where there was a loss of hypoechogenicity of the normal sutures. All infants had both clinical and radiological investigations performed postnatally.

In Group 1, serial ultrasound examination from 12 weeks' gestation onwards led to accurate prenatal diagnosis in all 16 cases. Dysmorphism and skull deformity preceded closure of the sutures by 4 to 16 weeks. In Group 2, prenatal diagnosis was correct in 23/24 cases. There were no false-negative results in either group.

This series questions further the uncertain genetic determinism of craniosynostosis and seems to rule out the hypothesis of a deformation sequence following primary closure of the cranial sutures. It also suggests that ultrasound examination is useful to demonstrate closure of the sutures in the third trimester of pregnancy in most affected cases.