Osseous anatomy of unilateral coronal synostosis

High resolution, thin slice computerized tomography (CT) scans with paraxial and three-dimensional surface reconstructions were utilized to document the endocranial, exocranial, and orbital anatomy of non-syndromal unicoronal synostosis (UCS). Eighteen patients with UCS were evaluated qualitatively and quantitatively. Of these, 10 were studied both preoperatively and 1 year postoperatively. The endocranial base in UCS is characterized by a 9 degree angulation toward the synostosis of the anterior cranial base with respect to the posterior cranial base. The exocranial base has a 7 degree angulation toward the synostosis between the midpalatal suture and the posterior cranial base. The locus of angulation appears to be posterior to the anterior clinoids endocranially, and between the maxillopalatopterygoid articulations and the mandibular condyle exocranially. The orbital rim height is greater ipsilateral to the synostosis than contralaterally. The analysis documents the normalizing effect of one of two different surgical procedures upon orbital height. Application of computer assisted medical imaging to the study of UCS has allowed in vivo quantitation of cranial base and orbital dysmorphology for both preoperative assessment and postoperative evaluation.