The increase of metopic synostosis: a pan-European observation.

Metopic synostosis is thought to have an incidence of about 1 in 15,000 births. Traditionally, this makes it the third most frequent single-suture craniosynostosis, after scaphocephaly (1 in 4200-8500) and plagiocephaly (1 in 11,000). Our units have, independently from each other, noted a marked increase in the number of metopic synostosis over the recent years. This is a pan-European, retrospective epidemiological study on the number of cases with metopic synostosis born between January 1, 1997, and January 1, 2006. This number was compared to the prevalence of scaphocephaly, the most frequently seen craniosynostosis. In the 7 units, a total of 3240 craniosynostosis were seen from 1997 until 2006. Forty-one percent (n = 1344) of those were sagittal synostosis, and 23% (n = 756) were metopic synostosis. There was a significant increase of the absolute number as well as of the percentage of metopic synostosis over these years (regression analysis, P = 0.017, R2 = 0.578) as opposed to a nonsignificant increase in the percentage of sagittal synostosis (P > 0.05, R2 = 0.368). The most remarkable increase occurred around 2000-2001, with the average of metopics being 20.1% from 1997 to 2000 and 25.5% from 2001 to 2005 (independent t-test, P = 0.002). The sagittal synostosis showed a smaller and nonsignificant increase in the same years: from 39.9% in 1997-2000 leading up to 42.5% in 2001-2005 (independent t-test, P > 0.05). The number of metopic synostosis has significantly increased over the reviewed period in all of our units, both in absolute numbers as in comparison to the total number of craniosynostosis.