Pharyngeal Airway Dimensions and Head Posture in Obstructive Sleep Apnea Patients with and without Morphological Deviations in the Upper Cervical Spine

Prediction of Pharyngeal 3D Volume Using 2D Lateral Area Measurements During Swallowing

This study evaluated the validity of pharyngeal 2D area measurements acquired from the lateral view for predicting the actual 3D volume in healthy adults during swallowing. Seventy-five healthy adults (39 females, 36 males; mean age 51.3 years) were examined using 320-row area detector computed tomography (320-ADCT). All participants swallowed a 10 mL honey-thick barium bolus upon command while seated in a 45° semi-reclining position. Multi-planar reconstruction images and dynamic 3D-CT images were obtained using Aquilion ONE software. Pharyngeal 2D area and 3D volume measurements were taken before swallowing and at the frame depicting maximum pharyngeal constriction. Pharyngeal volume before swallowing (PVhold) was accurately predicted by 2D area (R2 = 0.816). Adding height and sex to the model increased R2 to 0.836. Regarding pharyngeal volume during maximum constriction (PVmax), 2D area also exhibited acceptable predictive power (R2 = 0.777). However, analysis of statistical residuals and outliers revealed a greater tendency for prediction errors when there is less complete constriction of the pharynx as well as asymmetry in bolus flow or movement. Findings highlight the importance of routinely incorporating anterior-posterior views during VFSS exams. Future work is needed to determine clinical utility of pharyngeal volume measurements derived from 320-ADCT.

Association between orthodontic treatment and upper airway changes in children assessed with cone-beam computed tomography (CBCT): A systematic review

BACKGROUND

Some orthodontic devices used in children share similar design principles to appliances used to treat obstructive sleep apnoea in adults. As well as treating malocclusion, orthodontic appliances used in children may therefore also have effects on the upper airway.

OBJECTIVE

A review of the literature to assess the effects of orthodontic treatment on the upper airway dimensions in children assessed on CBCT.

MATERIALS AND METHODS

Following registration of the protocol (PROSPERO CRD42023439056), a systematic electronic search of published studies was performed using several databases (PubMed; Scopus, Web of Science and Science Direct) in accordance with the PRISMA guidelines. Inclusion criteria were as follows: age under 18 years, orthodontic treatment with any appliance, a control group who received no treatment or a non-active alternative treatment and airway measurement using CBCT. RoB-2 and ROBINS-I tools were used to assess risk of bias and quality of the evidence.

RESULTS

In total, 341 studies were identified following the initial search. Title and abstract screening resulted in 45 studies for further full-text analysis. On completion of the screening process, a total of 23 studies met the inclusion criteria. Study interventions included functional appliances (10 studies), rapid maxillary expansion (RME) (9 studies), reverse-pull headgear (1 study) and 4 premolar dental extractions (3 studies). The included studies had moderate to high risk of bias, and the quality of evidence was low.

CONCLUSION

The scientific evidence shows that functional appliances are associated with significant improvements in both upper airway volume and constriction when used in children however, the effects on the nasal cavity are limited. RME was associated with a significant increase in nasal cavity and nasopharyngeal dimensions, but not the upper pharyngeal airway. Neither reverse-pull headgear nor dental extractions were associated with any change in airway dimensions; however, the evidence is limited. Functional appliances may reduce the severity of obstructive sleep apnoea (OSA) in children.

Does obstructive sleep apnea-induced intermittent hypoxia increase the incidence of solitary pulmonary nodules, thyroid nodules, and other disorders? A retrospective study based on 750 cardiovascular disease patients

BACKGROUND

Obstructive sleep apnea (OSA) has been shown to be an important risk factor for cardiovascular disease (CVD), and intermittent hypoxia is an important pathogenetic factor for it. In the clinic, it was found that most CVD patients combined with OSA were also combined with solitary pulmonary nodules (SPN) or thyroid nodules (TN). Are these disorders related to intermittent hypoxia? One study showed that intermittent hypoxia is a pathogenic factor for lung cancer in mice, but there have been no clinical reports. So we conducted a retrospective study to explore whether intermittent hypoxia caused by OSA increases the incidence of SPN, TN, and other disorders.

METHODS

We selected 750 patients with cardiovascular disease (CVD), who were divided into the control group and the OSA group according to the result of portable sleep monitoring. Retrospectively analyzed the comorbidities that patients with OSA are prone to and explored the correlation between OSA and those comorbidities.

RESULTS

The incidence of SPN, TN, cervical spondylosis, and carotid-artery plaques was higher in the OSA group than in the control group. These diseases are significantly associated with OSA (p < 0.05), and their incidence increased with an elevated apnea-hypopnea index. After excluding interference from age, gender, BMI, smoking history, history of lung disease, and history of tumors, OSA showed a significant correlation with SPN. After excluding age, gender, BMI, and thyroid disease, OSA was associated with TN. Patients with comorbidities have lower nocturnal oxygen saturation and more extended periods of apnea. Logistic multiple regression results revealed that male, advanced age, obesity, CS, and nasal septum deviation were independent risk factors for OSA.

CONCLUSIONS

Patients combined with OSA may further develop more comorbidities, such as SPN, TN, and carotid-artery plaques. It may be related to intermittent hypoxia caused by OSA.

Morphological and acoustic modeling of the vocal tract

In speech production, the anatomical morphology forms the substrate on which the speakers build their articulatory strategy to reach specific articulatory-acoustic goals. The aim of this study is to characterize morphological inter-speaker variability by building a shape model of the full vocal tract including hard and soft structures. Static magnetic resonance imaging data from 41 speakers articulating altogether 1947 phonemes were considered, and the midsagittal articulator contours were manually outlined. A phoneme-independent average-articulation representative of morphology was calculated as the speaker mean articulation. A principal component analysis-driven shape model was derived from average-articulations, leading to five morphological components, which explained 87% of the variance. Almost three-quarters of the variance was related to independent variations of the horizontal oral and vertical pharyngeal lengths, the latter capturing male-female differences. The three additional components captured shape variations related to head tilt and palate shape. Plane wave propagation acoustic simulations were run to characterize morphological components. A lengthening of 1 cm of the vocal tract in the vertical or horizontal directions led to a decrease in formant values of 7%-8%. Further analyses are required to analyze three-dimensional variability and to understand the morphological-acoustic relationships per phoneme. Average-articulations and model code are publicly available (https://github.com/tonioser/VTMorphologicalModel).

Effects of Rapid Maxillary Expansion on Upper Airway Volume in Growing Children: A Three-Dimensional Cone-Beam Computed Tomography Study

Background: Rapid maxillary expansion (RME) is a common orthodontic procedure that widens the maxillary arch to treat moderate to mild overcrowding and transverse skeletal and dental abnormalities. Orthodontic equipment applies lateral tension on posterior maxilla teeth or palate mucosa to the mid-palatal suture. The maxilla may grow transversely when force is applied at right angles to the mid-palatal suture, which is usually inactive in children and adolescents. This study used cone-beam computed tomography (CBCT) and an authorized upper respiratory airway volume measurement approach to compare RME cohort pharyngeal airway volume changes to healthy controls. Materials and Methods: This retrospective analysis included 52 RME patients and 52 healthy controls. The RME category's expansion regimen entailed twisting the screw of expansion on a tooth-attached Hyrax-type expansion equipment by 0.25 mm daily for at least 14 days. After six months, a few RME participants used fixed orthodontic gear. The comparison group used fixed orthodontic appliances for minor malocclusions without extractions (without RME). CBCT scans from 1021 orthodontic patients who visited a dental hospital between 2012 and 2022 were examined. The registry comprised only anonymized photographs. Volume, minimum cross-sectional area (MCA), molar width, and inter-molar width were measured before and after therapy. Results: The control group had 12227.12 mm³ at T0 and 15805.54 mm³ at T1. The control group's T0-T1 volume difference was statistically significant (p = 0.007). The RME group has 12884.84 mm³ at T0 and 17471.08 mm³ at T1. The RME group had a significant volume difference at T0 and T1 (p = 0.002). The volume RME effect was ±1011.92 and statistically insignificant. (p > 0.05). MCA in the control group was 126.04 mm² at T0 and 170.61 mm² at T1. MCA at T0 and T1 in the control group was statistically significant (p = 0.041). RME group MCA was 126.53 mm³ at T0 and 164.69 mm² at T1. The RME group had a significant volume difference at T0 and T1 (p = 0.002). The MCA, RME effect was 5.92 and statistically insignificant (p > 0.05). Both the control and RME groups had statistically significant volume and MCA differences at T0 and T1. However, the intergroup analysis showed no significant differences across the groups. Conclusion: Tooth-borne RME does not affect upper airway or MCA volume in children compared to controls. Upper airway changes were better with younger skeletal ages before treatment. The findings may aid RME for young children.

Reliability of Acoustic Pharyngometry and Rhinometry Examination in Children and Adolescents

OBJECTIVES

The aim of this cross-sectional study was to examine the method error and reliability of acoustic pharyngometry and rhinometry in children and adolescents and to describe the feasibility of these methods in a young population.

MATERIAL AND METHODS

The study sample included 35 healthy subjects in the age of 9 to 14 years. The subjects were randomly recruited for the present project in the period from June 2021 to February 2022. Repeated measurements of the upper airway dimensions in standing mirror position were performed by the use of Acoustic Pharyngometer and Rhinometer. Volume (cm³), calculated resistance (cm H₂O/L/min), mean area (cm²), minimum cross-sectional area (MCA, cm²) and distance to MCA (cm) were examined. Method errors and reliability coefficients were evaluated using Dahlberg's formula and the Houston reliability coefficient. The feasibility of the methods were analysed using paired t-test and estimated by difference in drop-out rates.

RESULTS

No systematic error exhibited in the repeated measurements except volume in the left nostril (P = 0.017). The method errors of the acoustic pharyngometry and rhinometry were betweeen 0.0002 to 0.069 and 0.001 to 0.082 respectively. The Houston reliability coefficient for both methods were between 0.952 to 0.999. The acoustic pharyngometry was significantly more feasible compared to rhinometry (P < 0.001).

CONCLUSIONS

The study shows that acoustic pharyngometry and rhinometry in the standing mirror position are reliable methods, with acoustic pharyngometry being even more feasible than rhinometry, which is why it is recommended to practice the methods with children and ensure reliability of results before registering measurements.

Craniofacial Morphology and Upper Airway Dimensions in Patients with Hypermobile Ehlers-Danlos Syndrome Compared to Healthy Controls

Objectives

The aims of the present case-control study were to compare craniofacial morphology, airway minimum cross-sectional area and airway volume between patients with hypermobile Ehlers-Danlos syndrome and healthy controls.

Material and Methods

The sample comprised 18 hypermobile Ehlers-Danlos syndrome (hEDS) patients (16 females, 2 males, mean age 34.1 [SD 10.35] years), clinically diagnosed and genetically tested in order to exclude other types of EDS, and 16 controls (14 females, 2 males, mean age 37.9 [SD 10.87] years) with neutral occlusion and normal craniofacial morphology. Craniofacial morphology was assessed on lateral cephalograms. Minimum cross-sectional area and upper airway volume were assessed on cone-beam computed tomography and analysed by standard and well-validated methods. Differences were tested by logistic regression analysis adjusted for age, gender and body mass index (BMI).

Results

No significant differences in craniofacial morphology were found between hEDS patients and controls. Airway minimum cross-sectional area (P = 0.019) and airway volume (P = 0.044) were significantly smaller in hEDS patients compared to controls. When adjusted for age, gender and BMI no significant differences were found. However, minimum cross-sectional area was almost significant (P = 0.077).

Conclusions

The craniofacial morphology and airway dimensions of hypermobile Ehlers-Danlos syndrome patients were comparable to controls, with a tendency towards a smaller minimum cross-sectional area in the hypermobile Ehlers-Danlos syndrome group. The results may prove valuable for understanding the effect of hypermobile Ehlers-Danlos syndrome on craniofacial morphology and the upper airways.

Fluoroscopic evaluation of laryngopharyngeal anatomic variations attributable to head posture in dogs

OBJECTIVE

To fluoroscopically evaluate the effects of head posture and sedation on the laryngopharyngeal anatomic structures in dogs.

ANIMALS

6 clinically normal Beagles (mean age, 6.2 years; mean weight, 10.4 kg).

PROCEDURES

Each dog was sedated and placed in right lateral recumbency, and fluoroscopic examinations were performed with flexed, neutral, and extended head postures (FHP, NHP, and EHP, respectively). During 3 respiratory cycles, the angle between the basisphenoid bone and nasopharyngeal dorsal border (ABN), thickness of the soft palate, diameter of the nasopharyngeal lumen (DNL), overlapping length between the epiglottis and soft palate, and distance between the epiglottis and tympanic bulla (DET) were measured and percentage difference in the DNL (PDNLD) during a respiratory cycle was calculated.

RESULTS

For the FHP, NHP, and EHP, median ABN was 91.50° (interquartile range [IQR], 86.75° to 95.00°), 125.00° (IQR, 124.50° to 125.50°), and 160.00° (IQR, 160.00° to 163.50°), respectively, with no significant differences between ABN and posture angle. For the FHP, median DNL and DET significantly decreased, compared with values for the NHP, and median thickness of the soft palette significantly increased. For the EHP, the minimal DNL and DET significantly increased, and the median overlapping length between the epiglottis and soft palate significantly decreased, compared with values for the NHP. The PDNLD significantly increased and decreased with FHP and EHP, respectively, compared with the PDNLD with NHP. Sedation did not affect upper airway structure changes.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that head posture significantly affected the laryngopharyngeal structures in dogs. Fluoroscopic examination of the upper respiratory tract of a dog should be performed with an NHP to minimize posture-induced changes in measurements.

The Reliability and Influence of Body Position on Acoustic Pharyngometry and Rhinometry Outcomes

OBJECTIVES

The aim of this cross sectional study was to analyze the method error and reliability in acoustic pharyngometry and rhinometry and to analyze the difference between standing and sitting position in acoustic pharyngometry and rhinometry.

MATERIAL AND METHODS

The sample comprised 38 healthy subjects (11 men and 27 women) as part of a control group in another study. The subjects underwent repeated measures of acoustic pharyngometry and rhinometry in standing and sitting position. Upper airway dimensions in terms of volume, minimum cross-sectional areas (MCA) and distances were evaluated using the Eccovision® Acoustic Pharyngometer and Rhinometer. Method error and reliability were analyzed using paired t-test, Dahlberg's formula and the Houston reliability coefficient, and differences between body positions were analyzed using paired t-test.

RESULTS

There was no systematic error in the repeated measures except for the distance to MCA in the left nostril in sitting position (P = 0.041). The method error for the pharyngometry ranged between 0.001 to 0.164 cm/cm2/cm3 and the reliabity was 0.99. The method error for rhinometry ranged between 0.001 to 0.37 cm/cm2/cm3 and the reliability between 0.99 to 1. Difference between standing and sitting position was found only in the pharyngeal airway in terms of volume (P = 0.025) and mean area (P = 0.009) with smaller airway in sitting position.

CONCLUSIONS

The results indicate that acoustic pharyngometry and rhinometry are reliable methods to perform repeated measures of the upper airway dimensions especially in the standing mirror position. It may be essential to perform the measures with the patient positioned in the same body position each time.

Evaluation of upper airway volume and craniofacial volumetric structures in obstructive sleep apnoea adults: A descriptive CBCT study

OBJECTIVE

The aim of this investigation was to assess, with a descriptive three-dimensional evaluation, the volume of upper airway (UAWV) and the volume of craniofacial structures in adult patients suffering from obstructive sleep apnoea (OSA) and compare them to the corresponding findings in adults with no sleep disorders.

MATERIALS AND METHODS

The sample consisted of 54 adult males, 27 suffering from OSA diagnosed by means of the Apnoea Hypopnea Index and 27 with no history of sleep disorders. All subjects had a cone beam computerized tomography scan performed with the same head position. UAWV was assessed with the Amira® software, and craniofacial volumes by means of a specially developed data-processing program, which allowed the construction of tetrahedrons using anatomical landmarks. Assessed volumes were naso-maxillary, cranium upper anterior, oral cavity, post-oral cavity, hyoid to mandible, and post-hyoid. SPSS (version 19.0) was used for the statistical analysis. The Levene's test for Equality of Variance, the t-test for Equality of Means and the Mann-Whitney test were used to evaluate the variables. The level of significance was set at P ≤ 0.05.

RESULTS

The mean value of UAWV was smaller in the OSA group. The post-hyoid volume, the calculated posterior volume, and the ratio of posterior to total volume showed differences between the groups.

CONCLUSIONS

Craniofacial structures did not show significant differences between the groups, but in the OSA group the posterior space released for upper airway was significantly bigger and UAWV was significantly smaller.

Effects of rapid maxillary expansion on upper airway volume: A three-dimensional cone-beam computed tomography study

OBJECTIVE

To compare changes in pharyngeal airway volume and minimal cross-sectional area (MCA) between patients undergoing rapid maxillary expansion (RME) and a matched control group and to identify markers for predicting airway changes using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Pre- and posttreatment CBCT scans were selected of children who had RME (14 girls and 12 boys; mean age, 12.4 years) along with scans of a control group (matched for chronological age, skeletal age, gender, mandibular inclination) who underwent orthodontic treatment for minor malocclusions without RME. Changes in airway volume and MCA were evaluated using a standardized, previously validated method and analyzed by a mixed-effects linear regression model.

RESULTS

Upper airway volume and MCA increased significantly over time for both the RME and matched control groups (P < .01 and P = .05, respectively). Although the RME group showed a greater increase when compared with the matched controls, this difference was not statistically significant. A reduced skeletal age before treatment was a significant marker for a positive effect on the upper airway volume and MCA changes (P < .01).

CONCLUSIONS

Tooth-borne RME is not associated with a significant change in upper airway volume or MCA in children when compared with controls. The younger the skeletal age before treatment, the more positive the effect on the upper airway changes. The results may prove valuable, especially in RME of young children.