An epidemiological study of nonsyndromal craniosynostoses.

Objective: To compare our data with recent studies that have suggested a change in the distribution of the forms of nonsyndromal synostosis in the clinical population, we conducted a retrospective analysis of the diagnoses of children with isolated synostosis examined at a large craniofacial center between 1987 and 2009. This also included the range of nonsyndromal multisuture synostoses. Design: A retrospective chart review of all preoperative patients with nonsyndromal synostosis seen between 1987 and 2009 was performed. Only patients with a radiologically confirmed craniosynostosis were included. Data on patients' sex and laterality in unilateral synostoses were collected. Two temporally distinct subgroups (1996-2000 and 2005-2009) were defined to evaluate changes in the distribution of the most common forms of isolated craniosynostosis using the Fisher exact test. Results: A total of 690 patients met the inclusion criteria. The largest group of patients had sagittal synostosis, with metopic synostosis as the second most common diagnosis, representing one-fourth of the patients, followed closely by unilateral coronal synostosis. All other synostoses encompassed one-eighth of the group. Patients with sagittal or metopic synostosis were overwhelmingly male, whereas those with unilateral coronal synostosis were predominantly female. Patients with unilateral synostoses were affected primarily at the right suture. Conclusions: Data from our patients indicate a much higher incidence of metopic synostosis than has been reported in the traditional clinical literature but is consistent with recent published data. The causes of this are unclear at this point, but the Fisher exact test excludes an increase in the frequency of metopic synostosis. Improved clinical diagnosis or ascertainment bias remains a possibility. Further research is needed to elucidate the answer to this question. Our data also indicate the occurrence of a small number of rare multisuture synostoses of unknown origin.