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Objective: The purpose of this study was to assess the relationship between cephalometric parameters and apnoea-hypopnoea index (AHI) controlling for the effect of gender, age, and body mass index (BMI) on a large sample of patients with obstructive sleep apnoea (OSA)., Methods: This retrospective cohort study was conducted on the lateral cephalograms of 253 Caucasian adult OSA patients. Cephalometric analyses were performed using 14 parameters for skeletal and soft tissue morphology, including antero-posterior and vertical jaw relationships, hyoid bone position, soft palate length and thickness, airway space, and tongue length and height. A hierarchical regression was run to examine the amount of variability in AHI that cephalometric variables explained after controlling for patients' general characteristics (gender, age, and BMI)., Results: After controlling for gender, age, and BMI, the increase in AHI variance accounted for by cephalometric parameters was equal to 0.103. Among the cephalometric variables, only MP-H and PNS-P were statistically significant (P < 0.05)., Limitations: Given the retrospective nature of the study, it is difficult to assess whether other confounding variables not considered in the present study could have influenced the relationship between cephalometric parameters and AHI., Conclusions: This study revealed the existence of a relationship between OSA severity and some cephalometric parameters. Indeed soft palate length and vertical position of the hyoid bone were significant predictors of AHI in adult Caucasian OSA patients., (© The Author(s) 2019. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Aim: The primary aim of this study was to assess the differences in the upper airway morphology between responders and non-responders to mandibular advancement splint (MAS) treatment in obstructive sleep apnoea (OSA) management. The secondary aim was to assess the correlation between the minimum cross-sectional area of the upper airway and the anatomical structures (i.e. mandibular external length, maxillary length, soft palate length, area of the tongue, maxillomandibular enclosure size, and anatomical balance ratio) surrounding the upper airway. The third aim was to assess the differences in the overall skeletal configuration between responders and non-responders to MAS treatment., Methods: Data from 64 patients (23 females and 41 males) diagnosed with OSA by polysomnography (PSG) at baseline and provided with an adjustable MAS were analysed. All patients had NewTom3G cone beam computed tomography (CBCT) scans, performed in the supine position, at baseline. After acclimatization to MAS, follow-up PSG tests were performed to assess the apnoea-hypopnea index (AHI) with the MAS in situ. Responders were defined by a post-treatment AHI less than 10/hour and at least 50 per cent reduction in AHI, and non-responders by a post-treatment AHI at least 10/hour or less than 50 per cent reduction in AHI. Several upper airway and anatomical variables surrounding the upper airway based on CBCT images were measured to determine the differences between responders and non-responders to MAS., Results: There were 36 responders (AHI = 24.8 ± 11.9 at baseline) and 28 non-responders (AHI = 31.2 ± 20.3 at baseline) to MAS. There were no significant differences in the upper airway morphology between responders and non-responders (P = 0.17-0.93) or in the anatomical structure surrounding the upper airway (P = 0.24-0.58)., Conclusion: Within the limitations of this study, it can be concluded that there are no significant differences in upper airway morphology and in anatomical structures surrounding the upper airway between responders and non-responders to MAS treatment. These findings suggest that the craniofacial anatomical structures analyzed in this study cannot explain the response to MAS treatment., (© The Author(s) 2019. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Aims: The aim of this work was to investigate the effects of commonly used orthodontic appliances on the magnetic resonance (MR) image quality of the craniofacial region, with special interest in the soft palate and velopharyngeal wall using real-time speech imaging sequences and anatomical imaging of the temporomandibular joints (TMJ) and pituitaries., Methods: Common orthodontic appliances were studied on 1.5 T scanner using standard spin and gradient echo sequences (based on the American Society for Testing and Materials standard test method) and sequences previously applied for high-resolution anatomical and dynamic real-time imaging during speech. Images were evaluated for the presence and size of artefacts., Results: Metallic orthodontic appliances had different effects on image quality. The most extensive individual effects were associated with the presence of stainless steel archwire, particularly if combined with stainless steel brackets and stainless steel molar bands. With those appliances, diagnostic quality of magnetic resonance imaging speech and palate images will be most likely severely degraded, or speech imaging and imaging of pituitaries and TMJ will be not possible. All non-metallic, non-metallic with Ni/Cr reinforcement or Ni/Ti alloys appliances were of little concern., Limitations: The results in the study are only valid at 1.5 T and for the sequences and devices used and cannot necessarily be extrapolated to all sequences and devices. Furthermore, both geometry and size of some appliances are subject dependent, and consequently, the effects on the image quality can vary between subjects. Therefore, the results presented in this article should be treated as a guide when assessing the risks of image quality degradation rather than an absolute evaluation of possible artefacts., Conclusions: Appliances manufactured from stainless steel cause extensive artefacts, which may render image non-diagnostic. The presence and type of orthodontic appliances should be always included in the patient's screening, so the risks of artefacts can be assessed prior to imaging. Although the risks to patients with fixed orthodontic appliances at 1.5 T MR scanners are low, their secure attachment should be confirmed prior to the examination., (© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Study Objectives: The objective of this study was to explore the mechanism of action of the oral pressure therapy (OPT) device, a new treatment for sleep apnea., Design: Case series., Setting: Academic medical center., Patients: Fifteen subjects with sleep apnea who had been successfully treated (responders) with the OPT device and 4 subjects who were not successfully treated (non-responders) with the OPT device., Interventions: All subjects underwent a MRI (without the device, with the device in place without vacuum and with the device in place with vacuum) to examine the biomechanical changes associated with the OPT device., Measurements and Results: Oral pressure therapy significantly (P = 0.002) increased the size of the retropalatal airway in both the lateral and anterior-posterior dimensions by moving the soft palate anteriorly and superiorly and the anterior-superior segment of the tongue forward, toward the teeth. The percentage and absolute increase in the cross-sectional area of the retropalatal region, the superior movement of the soft palate, and the anterior displacement of the tongue were significantly greater in the responders than in the non-responders. In responders, there were significant increases in the mean (P = 0.002), maximum (P = 0.0002), and minimum (P = 0.04) cross-sectional areas of the retropalatal region with the OPT device. However, in the retroglossal region, airway caliber decreased with the OPT device., Conclusions: In those who responded to oral pressure therapy, it increased airway caliber in the retropalatal region by moving the soft palate anteriorly and superiorly and the anterior-superior segment of the tongue forward., Citation: Schwab RJ, Kim C, Siegel L, Keenan BT, Black J, Farid-Moayer M, Podmore J, Vaska M. Examining the mechanism of action of a new device using oral pressure therapy for the treatment of obstructive sleep apnea.

Study Objectives: In patients with obstructive sleep apnea (OSA), the severity and frequency of respiratory events is increased in the supine body posture compared with the lateral recumbent posture. The mechanism responsible is not clear but may relate to the effect of posture on upper airway shape and size. This study compared the effect of body posture on upper airway shape and size in individuals with OSA with control subjects matched for age, BMI, and gender., Participants: 11 males with OSA and 11 age- and BMI-matched male control subjects., Results: Anatomical optical coherence tomography was used to scan the upper airway of all subjects while awake and breathing quietly, initially when supine, and then in the lateral recumbent posture. A standard head, neck, and tongue position was maintained during scanning. Airway cross-sectional area (CSA) and anteroposterior (A-P) and lateral diameters were obtained in the oropharyngeal and velopharyngeal regions in both postures. A-P to lateral diameter ratios provided an index of regional airway shape. In equivalent postures, the ratio of A-P to lateral diameter in the velopharynx was similar in OSA and control subjects. In both groups, this ratio was significantly less for the supine than for the lateral recumbent posture. CSA was smaller in OSA subjects than in controls but was unaffected by posture., Conclusions: The upper airway changes from a more transversely oriented elliptical shape when supine to a more circular shape when in the lateral recumbent posture but without altering CSA. Increased circularity decreases propensity to tube collapse and may account for the postural dependency of OSA.

Study Objective: To evaluate and compare outcomes of uvulopalatopharyngoplasty (UPPP) for obstructive sleep apnea/hypopnea syndrome (OSAHS) using anatomy- and severity-based staging systems., Design: Prospective design with a retrospective review., Setting: A tertiary-care, sleep disorder referral center., Patients: In total, 110 patients with OSAHS (105 men, 5 women; mean age, 43 years; apnea-hypopnea index, 44.4 +/- 28.8 events per hour; body mass index, 27.1 +/- 3.3 kg/m2)., Measurements: An anatomy-based staging system (stages I-IV) was used to classify patients with OSAHS by examining tongue-palate position, tonsil size, body mass index, and craniofacial deformities. Patients were also classified as having mild, moderate, moderate-severe, or severe OSAHS based on preoperative apnea-hypopnea index from polysomnography (a severity-based staging system). Surgical success was defined as a 50% or greater reduction in the apnea-hypopnea index and a postoperative apnea-hypopnea index of less than 20 events per hour., Intervention: UPPP was performed in all patients., Results: The overall success rate of UPPP was 78%. Success rates for mild (90%), moderate (73%), moderate-severe (81%), and severe (74%) diseases were similar (p = .10). Conversely, success rates for patients with anatomy-based stages I, II, III, and IV were 100%, 96%, 65%, and 20%, respectively; these rates were significantly different (p < .001). Changes in apnea-hypopnea index were significantly correlated with Friedman tongue position (FTP) (r = -0.33, p = .0004) and tonsil size (r = -0.37, p < .0001). The FTP (odds ratio = 0.43, SE = 0.13, p = .005, 95% confidence interval = 0.24-0.78) and tonsil size (odds ratio = 3.13, SE = 1.53, p = .02, 95% confidence interval = 1.20-8.17), but not the severity-based staging (odds ratio = 0.77, SE = 0.18, p = .283, 95% confidence interval = 0.49-1.23), were predictive of surgical success., Conclusion: The anatomy-based staging system predicted UPPP outcomes more effectively than did the severity-based staging. The anatomy-based staging system facilitates good case-selection information for counseling patients before UPPP surgery.

Study Objectives: To evaluate the morphological features of the mandible and the volume of the upper airway soft tissues in determining the anatomical risk factors for the upper airway in Japanese male patients with obstructive sleep apnea hypopnea syndrome (OSAHS)., Methods: Five morphological parameters of the mandible at the mandibular base plane and three volumetric parameters of the upper airway soft tissue were analyzed using three-dimensional (3D) magnetic resonance imaging software in 31 OSAHS and 20 controls., Results: There were no significant differences between the two groups in mandibular internal width (the distance between the internal right and left gonia [IRG and ILG]) and mandibular bony thickness. However, the patients with OSAHS had a significantly wider mandibular divergence (the angle between the spina mentalis (SM)- IRG line and SM- ILG line), a smaller mandibular internal length (the perpendicular distance from SM to the RG- LG line), and a smaller area than the normal subjects at the mandibular base plane. There were no significant differences in these morphological parameters for the mandible between obese and nonobese OSAHS patients. The volumes of the tongue, soft palate, and lateral pharyngeal walls were not significantly different between the OSAHS and the control groups., Conclusions: Japanese male OSAHS patients had specific anatomical features in the bottom part of the mandible; however, obesity seemed to be a less significant risk factor. Investigators and clinicians must realize that ethnicity may modify the effects of obesity and abnormal craniofacial anatomy as risk factors for the pathogenesis of OSAHS.

The obstructive sleep apnea syndrome (OSAS) occurs in patients of all ages, from the premature infant to the elderly. Much remains unknown about the pathophysiology of the syndrome. However, research suggests that OSAS in all age groups is due to a combination of both anatomic airway narrowing and abnormal upper airway neuromotor tone. The anatomic predisposing factors for OSAS differ over the lifespan. However, a smaller upper airway is noted in all age groups and probably predisposes to airway collapse during sleep. Despite the known anatomic factors, such as craniofacial anomalies, obesity, and adenotonsillar hypertrophy, that contribute to OSAS throughout life, a clear anatomic factor cannot always be identified. This suggests that alterations in upper airway neuromotor tone also play an important role in the etiology of OSAS. Infants and children are less likely than adults to arouse in response to upper airway obstruction and do not compensate for prolonged increases in inspiratory resistive load. The overall ventilatory drive is probably normal in patients of all ages with OSAS. However, upper airway neuromotor tone and reflexes during sleep vary with age and are increased in normal infants and children compared to adults, perhaps as a compensatory response for their relatively narrow airway. This compensatory response appears to be blunted in children with OSAS. Further research is needed to fully understand the complexities of upper airway structure and function during both normal development and disease.

Study Objectives: We utilized novel three-dimensional volumetric analysis techniques with magnetic resonance imaging (MRI) to study the upper airway and surrounding soft-tissue structures. These MRI techniques allowed us to objectively quantify the volume of the tongue, soft palate, parapharyngeal fat pads, and lateral pharyngeal walls., Design: We first validated our volumetric imaging techniques on a phantom and then demonstrated that our results were reliable and reproducible in normal subjects who did not lose weight. Finally, we studied 12 obese, nonapneic women during wakefulness before and after weight loss. We hypothesized that our novel magnetic-resonance computer-reconstruction techniques would allow us to detect small reductions in the volume of the tongue, soft palate, lateral pharyngeal walls, and parapharyngeal fat pads and increases in the volume of the upper airway with weight loss., Setting: University medical center., Participants: Normal controls and 12 obese nonapneic women., Interventions: Weight loss., Measurements and Results: Following a mean 17.1+/-8.62 kg (17.3%) reduction in weight, upper airway volume increased (p = 0.06) in both the retropalatal and retroglossal regions. This increase in upper airway volume was mediated by significant reductions in the volume of the lateral pharyngeal wall (p = 0.0001) and parapharyngeal fat pads (p = 0.001). However, the volume of the tongue (p = 0.35) and soft palate (p = 0.39) were not reduced significantly with weight loss., Conclusions: These data indicate that volumetric MRI is a powerful tool to study anatomic changes in the upper airway and surrounding soft-tissue structures and is sensitive enough to detect changes in these structures.

The pathogenesis of obstructive sleep apnea (OSA) remains unknown. However, we are beginning to understand the mechanisms leading to sleep apnea by evaluating the structure and function of the upper airway (UA) and the surrounding soft-tissue structures using sophisticated magnetic-resonance-imaging techniques. Knowledge of the morphology and mechanical behavior of the soft-tissue structures is essential for a complete understanding of the physiology of the UA. Although the tongue and soft palate have been considered the most important UA soft-tissue structures, our data have highlighted the importance of the lateral pharyngeal walls in the mediating UA caliber. We have demonstrated that: (1) during wakefulness, the predominant anatomic abnormality underlying UA narrowing in patients with OSA is thickening of the lateral pharyngeal walls; (2) during respiration, there are significant changes in lateral airway dimensions as well as in the thickness of the lateral walls; and (3) incremental levels of continuous positive airway pressure (CPAP) result in progressive thinning of the lateral pharyngeal walls. The dynamic biomechanical behavior of the lateral pharyngeal walls during wakefulness, sleep, and during apneas needs to be investigated.

To determine the structural basis for alterations in upper airway (UA) collapsibility, the pharyngeal critical pressure (Pcrit) was measured in an isolated feline upper airway preparation. The effect of airway elongation and dilation was explored by displacing the trachea caudally and the tongue anteriorly, respectively. With caudal-tracheal displacement, Pcrit fell progressively, a result that can be attributed to increased tension within the pharyngeal mucosa. In contrast, anterior-tongue displacement decreased Pcrit when the trachea had been caudally displaced but not with the trachea in the neutral position. These findings suggest that longitudinal tension within the airway mucosa modulates both Pcrit and the response in Pcrit to dilating forces. A mechanical model to account for these findings is discussed.

Velopharyngeal incompetence (VPI) is a recognized complication of uvulopalatopharyngoplasty (UPPP) for obstructive sleep apnea. A new uvulopalatal flap (UPF) technique that modifies the UPPP and reduces this risk is presented. The technique achieves the same anatomic results as the UPPP but is reversible. To evaluate clinical outcomes of this new procedure, selected variables were compared in patients who underwent UPPP and UPF procedures. Eighty patients were examined (59/80 UPF, 21/80 UPPP) in a prospective and consecutive manner. Subjects underwent polysomnography and extensive airway evaluations. The characteristics of all patients, at baseline, were evaluated. The study variables included age, sex, body mass index (BMI), palatal length (PNS P) in millimeters, respiratory disturbance index (RDI), lowest oxygen saturation during sleep and a subjective snoring scale. Sixty-seven of the 80 patients underwent simultaneous hypopharyngeal surgery. Data were analyzed with a SAS program. No statistical difference existed between groups. The postoperative character of the palate and the change in snoring scores were the same in all patients (p = 0.584). A positive correlation existed between improvement in the snoring score and the amount of tissue removed or repositioned in the patients treated with UPF (correlation coefficient = 0.370, p = 0.004). In contrast, there was a negative correlation in the UPPP group for the same parameters (correlation coefficient = -0.195, P = 0.409). This suggests there was a difference between these two groups despite the fact that the baseline and postoperative lengths, as well as tissue removed or repositioned, were equivalent. This further suggests that the UPF may reduce snoring to a greater extent than the UPPP. No significant complications were seen in either group. There was no evidence of VPI, even in the early postoperative period. The new reported procedure is reversible and conservative and reduces the risk of VPI. Snoring is improved, which is consistent with a decrease in airway resistance or obstruction.