S12-14 SESSION 12: FACIOCRANIOSYNOSTOSIS – PART II THE CLASSIFICATION OF APERT SYNDROME, BASED ON CRANIAL VAULT SUTURE SYNOSTOSIS ------DIFFERENT CRANIAL BASE ANGULATIONS AND AIRWAY COMPROMISE

Abstract

Introduction: Apert syndrome patients are different in clinical pathology, including obstructive sleep apnea, cleft palate and mental deficiency. These functional deficiencies may be due to anatomic deformities, which may be caused by different forms of associated suture fusion. Therefore, a classification system of Apert syndrome based on the type of craniosynostosis pattern might be helpful in determining treatment choices. Methods: CT scans of 31 unoperated Apert syndrome and 51 controls were included and subgrouped as: class I. Bilateral coronal synostosis; class II. Pansynostosis; class III. Perpendicular combination synostosis: a. unilateral coronal and metopic synostosis; b. sagittal with bilateral/unilateral lambdoid synostosis; c. others. Results: Class I, bilateral coronal synostosis is the most common (55%) subtype. The cranial base angulation of class I was normal, however, the cranial base angulation on the cranium side of the skull in class II (N-S-BA) increased 12.16 degrees (p=0.006), while the facial side cranial base angle (N-SO-BA) of class III-a decreased 4.31 degrees (p=0.035) over time. The external cranial base linear measurements of class I showed more evident reduction in anterior craniofacial structures than posterior, while other subtypes developed more severe shortening in the posterior aspects. Conclusion: Bicoronal synostosis is the most common subtype of Apert syndrome with the normalized cranial base angulation. Combined pansynostosis patients have flatter cranial base, while the combined unilateral coronal synostosis have a kyphotic cranial base. Class I have more significant nasopharyngeal airway compromise in a vertical direction, while class II and class III have more limited oropharyngeal space.