## 4 Discussion
### Airway Parameters  
Previous studies have demonstrated that groups with different craniofacial growth patterns have shown differences in CBCT-derived airway parameters [53; 54; 55; 56; 57]. Interestingly, despite minimal cephalometric differences between our two groups, we did find statistically significant differences in nasopharyngeal airway volume (NAV), total upper airway volume (TUAV), and MCCA. In the JIA group, 16 of 32 patients (50%) had an MCA of less than 100 mm\({}^{2}\), while the control group had only 6 of 32 patients (18.75%) with an MCA less than 100 mm\({}^{2}\). The value of 100 mm\({}^{2}\) was chosen because it roughly represents the lowest quarter (25%) of the range of MCCA values that were found in both our JIA and control groups, as well as being easy to visually identify using Dolphin Imaging. In addition, the oropharyngeal airway volume (OAV) difference between the groups approached statistical significance (\(p=0.051\)). Another possible question that arose from this study was \"Could the posterior face height be a significant factor in airway volume and MCCA?\". However, this seems unlikely given the difference in posterior face height between the two groups was 4.33 mm, which represents about 5% of the average posterior face height of 71.06 mm in the JIA group. However, the 2D representation of the cephalogram does not take into account the 3D anatomical dentofacial deformity present in some JIA patients (Figure 3). Finally, evidence of sleep-disordered breathing (SDB) has been previously shown in JIA patients that have no evidence of cervical spine or TMJ arthritis [48]. At present, not enough information is available to investigate other reasons as to why airway parameters were different between the two groups. However, based on our data, it does appear that additional factors other than craniofacial morphology may contribute to the anatomic airway reduction in JIA patients. In the general pediatric population, other factors that could contribute to airway compromise include obesity, size of adenoids and tonsils, and presence of allergic rhinitis [42; 58; 59; 60; 61; 62; 63; 64; 65; 66]. Anatomic and structural features alone are certainly part of the overall pathogenesis of SDB and OSA [60]. However, the fact that patients with OSA do not have airway compromise when awake demonstrates that there is more to the picture than just anatomy, and in fact, upper airway neuromuscular tone plays a large role in normal respiratory patency and function [67]. Additionally, children have been shown to have a reduced tendency toward cortical arousals that would otherwise correct for obstructions that occur during sleep [67]. Nevertheless, correlations between CBCT-derived airway dimensions and AHI have been shown, demonstrating that airway anatomy is a definite factor in airway compromise during sleep and that CBCT should be viewed as a useful tool in evaluating the airway in pediatric patients [34; 35]. That being said, CBCT airway analysis certainly has its limitations. A CBCT image provides a representation of the airway at only one static time point of the respiratory cycle with the patient in an upright and awake posture. Additionally, there is evidence that successive CBCT images taken on the same patient only a few months apart are prone to considerable variations in airway volumes [68]. Visual inspection of the 3D airway morphology revealed an interesting finding that requires further investigation from a larger sample. Of the 32 patients with JIA, 21 demonstrated asymmetric deviations of the airway form when evaluated from the 3D frontal view of the airway volume. This represented 67% of the patients reviewed. It is not uncommon for a JIA patient population to also show facial asymmetries when evaluating skeletal and soft tissue forms, but to be able to visualize this in a 3D manner was revolutionary (Figure 4). Further work is required in evaluating for the presence of a correlation between the skeletal/facial and airway asymmetries.