Three Dimensional Assessment of the Pharyngeal Airway in Individuals with Non-Syndromic Cleft Lip and Palate Tracy Cheung1, Snehlata Oberoi2* 1 University of California Los Angeles, Los Angeles, California, United States of America, 2 Division of Orthodontics, Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, California, United States of America Abstract Introduction: Children with cleft lip and palate (CLP) are known to have airway problems. Previous studies have shown that individuals with CLP have a 30% reduction in nasal airway size compared to non-cleft controls. No reports have been found on cross-sectional area and volume of the pharyngeal airway in clefts. Introduction of Cone-Beam CT (CBCT) and imaging software has facilitated generation of 3D images for assessment of the cross-sectional area and volume of the airway. Objective: To assess the pharyngeal airway in individuals with CLP using CBCT by measuring volume and smallest cross- sectional areas and compare with 19 age- and sex-matched non-cleft controls. Methods: Retrospective study of CBCT data of pre-adolescent individuals (N = 19, Mean age = 10.6, 7 females, 12 males, UCLP = 6, BCLP = 3) from the Center for Craniofacial Anomalies. Volumetric analysis was performed using image segmentation features in CB Works 3.0. Volume and smallest cross-sectional were studied in both groups. Seven measurements were repeated to verify reliability using Pearson correlation coefficient. Volume and cross-sectional area differences were analyzed using paired t-tests. Results: The method was found to be reliable. Individuals with CLP did not exhibit smaller total airway volume and cross sectional area than non-CLP controls. Conclusion: 3D imaging using CBCT and CB Works is reliable for assessing airway volume. Previous studies have shown that the nasal airway is restricted in individuals with CLP. In our study, we found that the pharyngeal airway is not compromised in these individuals. Citation: Cheung T, Oberoi S (2012) Three Dimensional Assessment of the Pharyngeal Airway in Individuals with Non-Syndromic Cleft Lip and Palate. PLoS ONE 7(8): e43405. doi:10.1371/journal.pone.0043405 Editor: Noam A. Cohen, Hospital of the University of Pennsylvania, United States of America Received March 21, 2012; Accepted July 20, 2012; Published August 29, 2012 Copyright: 2012 Cheung, Oberoi. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: No current external funding sources for this study. Competing Interests: The authors have declared that no competing interests exist. * E-mail: sneha.oberoi@ucsf.edu Introduction Birth defects affect approximately 3% of all births and contribute substantially to childhood morbidity in the United States [1]. Orofacial defects like cleft lip and/or palate (CLP) occur in an estimated 6,800 children annually, making it the most common birth defect in the United States [2]. Anatomical abnormalities associated with CLP increase the risk of airway complications [3]. CLP are frequently associated with nasal abnormalities such as septal deviation, nostril atresia, turbinate hypertrophy, maxillary constriction, vomerine spurs, and alar constriction [4,5,6,7,8]. These abnormalities are attributed in part to the congenital defect itself and partly to the surgeries done to repair the orofacial defect [9,10]. Collectively, the nasal abnormalities tend to reduce the dimensions of the nasal cavity and lower airway function [6,11]. Airway patency has been evaluated by two-dimensional (2D) radiographic imaging such as lateral and anterior-posterior cephalometric films and functional studies such as rhinomano- metry and plethysmography [12,13,14,15]. A rhinomanometry study showed that individuals with bilateral CLP had a 41% reduction in nasal airway compared to a 19% reduction in individuals with unilateral CLP [15]. Plethysmography showed that individuals with CLP had a 30% reduction in the nasal airway compared to non-cleft controls [12]. Lateral cephalometric films of children with CLP were compared with non-cleft controls and showed a reduction in the nasopharyngeal bony framework and pharyngeal airway [16]. Furthermore, a reduction in the upper airway in juveniles with CLP was found when compared to gender and age matched non-cleft controls and were found to persist through adolescence when lateral cephalometric films were compared [13]. Until recently, diagnostic imaging of the airway has been limited to 2D studies. Two-dimensional imaging using lateral head films is useful for analyzing airway size in the sagittal plane, but does not depict the three-dimensional anatomy. The physiologi- cally most relevant information is obtained from axial images which are perpendicular to the direction of airflow, but the axial plane is not visualized on lateral cephalograms [17]. In addition, lateral cephalometric films have many limitations, such as image enlargement and distortion, structure overlap, limited identifiable landmarks, and positioning problems that may adversely affect PLOS ONE | www.plosone.org 1 August 2012 | Volume 7 | Issue 8 | e43405