Predicting the risk of reoperation in metopic synostosis: a quantitative CT scan analysis

Children with metopic synostosis have a well-described clinical picture of trigonocephaly, often with hypotelorbitism. The craniofacial disorder itself is well recognized; however, objective prognostic factors for predicting the risk of reoperation are not well known. In 39 children with metopic synostosis, measurements of the cranial length, cranial width, anterior intercoronal distance, anterior interorbital distance (intercanthal distance), lateral orbital distance, and interzygomatic buttress distance were taken from preoperative computed tomographic (CT) scans and were normalized relative to each child's age. To separate overall facial hypoplasia from regional hypoplasia, a ratio of intercanthal distance to interzygomatic buttress distance was determined. These prognostic factors were analyzed with respect to reoperation rate. A stepwise logistic regression analysis was used to determine the interrelationships between the prognostic factors. Twenty-eight percent of the children underwent reoperation (N=11, 1 total reoperation and 10 minor recontouring). All of the reoperations occurred in children with a decreased intercanthal distance (p=0.30). The ratio of intercanthal distance to midfacial width was related to reoperation rate, with those children who had a ratio < or =0.80 having a reoperation rate of 44% (8 of 18 total children with an intercanthal-to-zygomatic ratio < or =0.8, p=0.07). This relationship was significant in children younger than the age of 12 months (6 of 13 total children with an intercanthal-to-zygomatic ratio < or =0.8, 46% reoperation rate, p=0.006). This study suggests that preoperative CT measurements can be used as a means of risk stratification in outcome analyses of the surgical treatment of craniosynostosis. In children treated for metopic suture synostosis, a foreshortened intercanthal distance compared with the interzygomatic buttress distance was related to reoperation rate, especially in children younger than 12 months of age.