CRANIOMAXILLOFACIAL DEFORMITIES/COSMETIC SURGERY The Spheno-Occipital Synchondrosis Fuses Prematurely in Patients With Crouzon Syndrome and Midface Hypoplasia Compared With Age- and Gender-Matched Controls Youssef Tahiri, MD, CM, MSc, FRCSC, * J. Thomas Paliga, BA,y Arastoo Vossough, MD,z Scott P. Bartlett, MD,x and Jesse A. Taylor, MDk Purpose: Premature closure of the spheno-occipital synchondrosis (SOS) has been associated with mid- face hypoplasia in animal models and patients with specific forms of syndromic craniosynostosis. The pre- sent study aimed to characterize SOS fusion in patients with Crouzon syndrome. Patients and Methods: A case-control study was performed in patients with Crouzon syndrome treated at the Children’s Hospital of Philadelphia from 1984 to 2012. The cases included patients with Crouzon syndrome and at least 1 high-quality computed tomography (CT) scan in which SOS patency could be as- sessed. Age- and gender-matched control CT scans were identified for comparison. The patient age at the CT scan was evaluated as the predictor, with SOS patency identified as the outcome variable. Three inde- pendent reviewers with high inter-rater reliability graded the SOS patency as open, partially fused, or completely fused. The Wilcoxon rank sum test was used to compare the Crouzon group and the controls. Results: During the study period, 30 patients were identified with Crouzon syndrome. A total of 24 patients, all with midface hypoplasia and with 112 cranial CT scans, met the inclusion criteria. Accordingly, 112 age- and gender-matched control CT scans were assessed. No patient in the control group had midface hypoplasia. Within the Crouzon group, the average age at complete closure (14.0  3.4 years) evident on the CT scan was significantly younger than that in the control group (16.6  2.2 years; P = .0152). The average age when the scans showed complete patency of the SOS in the Crouzon group (1.3  1.1 years) was significantly younger than that in the control group (3.2  2.3 years; P = .0001). Conclusions: The SOS closes significantly earlier in patients with Crouzon syndrome compared with age- and gender-matched controls. The strong statistical correlation supports premature closure of the SOS as a possible mechanistic contributor to midface hypoplasia. Ó 2014 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 72:1173-1179, 2014 Crouzon syndrome was initially reported in 1912 by the French neurosurgeon Dr Octave Crouzon. 1 The incidence has been estimated at 1 in 65,000 live births, and the inheritance is autosomal dominant, with an occurrence that is both sporadic and familial. 2 Prema- ture fusion of the cranial sutures and cranial base syn- chondroses in patients with Crouzon syndrome has been attributed to mutations in the fibroblast growth Received from Perelman School of Medicine at the University of Pennsylvania, Children’s Hospital of Philadelphia, Philadelphia, PA. *Craniofacial Fellow, Division of Plastic Surgery. yClinical Research Fellow, Division of Plastic Surgery. zAssociate Professor of Radiology, Department of Radiology. xProfessor of Surgery, Division of Plastic Surgery. kAssistant Professor of Surgery, Division of Plastic Surgery. The present study was funded by the Department of Surgery of the Children’s Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania. The data included in our report have been presented at the Inter- national Society of Craniofacial Surgery in September 2013. Address correspondence and reprint requests to Dr Taylor: Division of Plastic Surgery, Perelman School of Medicine at the University of Pennsylvania, Children’s Hospital of Philadelphia, Colket Translational Research Bldg, 3501 Civic Center Blvd, 9th Fl, Philadelphia, PA 19104; e-mail: Taylorj5@email.chop.edu Received October 2 2013 Accepted November 11 2013 Ó 2014 American Association of Oral and Maxillofacial Surgeons 0278-2391/13/01426-2$36.00/0 http://dx.doi.org/10.1016/j.joms.2013.11.015 1173