The Temporal Region in Unilateral Coronal Craniosynostosis: A Volumetric Study of Short- and Long-Term Changes after Fronto-orbital Advancement

Background: The temporal region is significantly affected by both restricted and compensatory growth in unilateral coronal craniosynostosis. Recurrent deformity in this region after fronto-orbital advancement often requires a revision operation in adolescence. The authors performed a three-dimensional analysis of the temporal region in patients with unilateral coronal craniosynostosis to define the baseline deformity and the immediate and long-term changes after fronto-orbital advancement. Methods: A retrospective analysis of patients with nonsyndromic unilateral coronal craniosynostosis who underwent reconstruction with fronto-orbital advancement or revision cranioplasty after fronto-orbital advancement between 2005 and 2010 was performed. Volumetric and craniometric computed tomographic data were obtained from the bilateral temporal regions and analyzed using the appropriate statistical tests. Results: Fifteen patients immediately before and after fronto-orbital advancement and 14 precranioplasty patients were included. In all groups, the supraorbits on the synostotic sides were significantly constricted in the transverse dimension. The temporal fossa volume on the synostotic side was displaced and significantly smaller than the nonsynostotic side in all groups. The temporalis muscle of the synostotic side was smaller but disproportionately large for the temporal fossa. Conclusions: In unilateral coronal craniosynostosis, there is a baseline and persistent deficiency in the transverse dimension of the supraorbit on the synostotic side. The temporalis muscle is smaller on the synostotic side but is disproportionately large for the temporal fossa of the affected side, which is inferolaterally displaced and smaller because of compensatory growth. These subtle abnormalities in the relationships between the bony dimensions and soft tissues appear to contribute to the temporal hollow deformity often observed after fronto-orbital advancement.