Cases of craniosynostosis usually fall into well-demarcated categories: those related to a syndrome or identified by a combination of suture involvement and morphological appearance. Between 1976 and 1995, 53 (3.6%) of 1474 cases in the craniofacial databank were assessed and designated as nonsyndromic but unclassifiable. The records and radiological studies obtained in these patients were retrospectively analyzed and comparisons were made with patients classified in the databank as having simple craniosynostoses.
It proved possible to divide the formerly unclassifiable cases into two groups: those with “two-suture disease” (Group A) and a “complex” group (Group B) in which more than two sutures were affected. Group A consisted of 36 cases (68%) of patients presenting with clear evidence of simultaneous involvement of two sutures but with no progression over time to suggest a more diffuse pansynostosis. Suture involvement was as follows: 17 of 36 sagittal plus one coronal; seven of 36 sagittal plus metopic; six of 36 sagittal plus one lambdoid; and six of 36 metopic plus one coronal. The only significant difference between the Group A cases and the cases of simple craniosynostoses was in the percentage requiring a second operation (24% vs. 5%, p < 0.0001).
Group B consisted of 17 cases in which the patients presented at a slightly earlier age (mean 1 year) with severe morphological changes and multiple suture involvement. At the time of surgery, six of 17 patients showed large areas of lacunae within the cranial vault, making craniectomy the only option. In Group B, 10 of 17 patients displayed bilateral lambdoid plus sagittal suture involvement resulting in marked occipital recession posteriorly, whereas anteriorly in six of these 10 patients there was a massive frontal bone associated with posteriorly located coronal sutures. In contrast, there were also four patients in Group B with bilateral coronal plus metopic involvement resulting in a small frontal bone. There was a trend toward a lower intelligence quotient and a worse morphological outcome in the patients in Group B, but again the only result attaining statistical significance when compared to the databank was the rate of second operation (37.5 vs. 5%, p < 0.0001).
“Two-suture synostosis” is a relatively straightforward condition and is treatable with standard craniosynostosis techniques. However, possibly as a result of surgical compromise when two sutures are involved, the rate of reoperation is far higher than in simple suture cases. In contrast, patients in the “complex” group presenting with severe multisuture involvement require a more tailor-made approach to their management that often entails a second procedure.