Upper airway assessment: radiographic and other imaging techniques

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.

Retrospective analysis of the upper airway anatomy and Sella turcica morphology across different skeletal malocclusions: a computerized technique

OBJECTIVE

This study aimed to investigate the normal volumetric space and variations in the measurements of different landmarks in adults with different skeletal relations of the maxilla and the mandible based on CBCT data. The study also analyses these landmarks to locate any correlations.

BACKGROUND

Numerous studies in orthodontics have found a relationship between orthodontic treatment and changes in the anatomy and function of the airway. Severe changes in airway morphology can cause breathing difficulties, lower quality of life, and even result in life-threatening conditions such as obstructive sleep apnoea. Consequently, orthodontic diagnosis and treatment planning require a thorough understanding of the airway space and its function.

METHODS

The present retrospective study was conducted using CBCT records of 120 adult patients, containing 40 samples of each skeletal class (20 males and 20 females). The boundaries were defined for the 3 major regions: the nasopharynx, the oropharynx, and the hypopharynx. Various measurements were recorded across these regions, as well as selective cephalometric landmarks. The obtained data was used to calculate average and standard deviation, while regression analysis was used to evaluate correlations and t-test was used to test statistical significance of gender differences.

RESULTS

The results demonstrate that skeletal Class III individuals exhibit a reduced airway volume in the nasopharynx compared to other groups, whereas skeletal Class II individuals displayed a diminished airway volume in the hypopharynx. A strong correlation was observed for Sella turcica parameters. There were no significant differences in skeletal parameters across genders. Nasopharynx cavity volume demonstrated significant differences between skeletal Class I-Class III as well as between skeletal Class II-Class III. Hypopharynx cavity volume also demonstrated significant differences between skeletal Class I-Class II and between skeletal Class II-Class III.

CONCLUSION

The major findings are the presence of a reduced nasopharyngeal volume in skeletal Class III malocclusions while skeletal Class II individuals displayed a diminished hypopharyngeal volume, making these critical areas to consider during the diagnostic and orthodontic treatment planning stages. This study also revealed a consistent correlation between Sella turcica parameters across various facial skeletal profiles, with skeletal Class II patients exhibiting a distinct pattern and skeletal Class I and Class III demonstrating an average relationship.

Assessment of Internal Nasal Dimensions of Individuals With Cleft Lip and Palate and Obstructive Sleep Apnea Syndrome by Computed Tomography

To evaluate nasal cavity (NC) dimensions of individuals with cleft lip and/or palate (CL/P), obstructive sleep apnea (OSA), and primary snoring, by tomographic image analysis, compared to individuals with OSA without CL/P (N-CL/P).

Cross-sectional and retrospective.

Tertiary referral center.

Patients were divided into 2 groups: (G1) CL/P + OSA or primary snoring, n = 11; (G2) N-CL/P + OSA, n = 13.

NC tomographic images were reconstructed using ITK-SNAP software, and measurements were obtained from these three-dimensional models using SpaceClaim software.

Total NC volumes, right and left NC volumes, and volumes of the nostril to the nasal valve (V1) and from the nasal valve to the superior limit of the nasopharynx (V2), cross-sectional areas, and perimeters.

NC volumes (total, right, and left sides), V1, and V2, though smaller in the CL/P + OSA, did not differ significantly from the N-CL/P + OSA. Cross-sectional areas and perimeters of the superior limit of the nasopharynx, in the CL/P + OSA, presented significantly higher values compared to the N-CL/P + OSA (P ≤ .05).

The internal nasal dimensions of patients with CL/P do not seem to be part of the etiopathogenesis, nor constitute a risk factor for OSA with greater severity, in this special group of patients.

Assessing the Accuracy of Lateral Cephalogram in Quantifying Three-Dimensional Pharyngeal Airway Morphology Compared to Cone-Beam Computed Tomography

BACKGROUND

When it comes to orthodontic diagnosis and treatment planning, the structures of the upper and lower airway space are crucial because of the role they play in craniofacial development.

AIM

The major objective of this study was to evaluate the accuracy of lateral cephalogram in the evaluation of upper and lower pharyngeal space by comparing it to clinical usage of cone-beam computed tomography (CBCT) in quantifying the 3D morphology of the pharyngeal airway.

METHODS AND MATERIALS

In total, 70 patients were included in the study. They had both a CBCT scan and a lateral cephalogram performed within a week of each other. Different cephalometric landmarks have been utilized to estimate linear and area dimensions for use in lateral cephalogram airway investigations. By superimposing the lateral cephalogram measurement of the vertical height of the pharyngeal airway over axial CBCT slices of 0.8 to 1 mm in thickness, airway volumes were calculated. For this study, we measured the pharyngeal airway space in each patient in two dimensions (2D) using the airway area from the lateral cephalogram and in three dimensions (3D) using the airway volume from the CBCT scan over the same region of interest, using a uniform scale and magnification throughout all split 3D volumes.

RESULTS

 The mean value of the area of pharyngeal space calculated by lateral cephalograph analysis (LCA) was 336.35 ± 86.49 mm2. The maximum value was 551.234 mm2. The minimum value was 206.32 mm2. The mean value of the volume of the same area calculated using CBCT was 3409.11 ± 1237.96 mm3. The maximum value was 5887.23 mm3. When the area calculated using LCA was compared with the volume calculated using CBCT, the correlation between them was significant statistically (r=0.831, p-value =0.000). The mean values of volume evaluated in 3D CBCT in males were 4198±1008 mm3 while for females it was 2980±1134.5 mm3. During the statistical analysis, these observations were found to have a positive correlation with increased volume of pharyngeal space in males as compared to that of females (p=0.006). The values of the area of pharyngeal space calculated using LCA in males was 370.1±60.9 mm2. while it was 301.9±88 mm2  in females.

CONCLUSION

The area estimated for the pharyngeal airway on LCA correlates strongly with the volume determined by a CBCT scan. Since we have considered pharyngeal space analysis using CBCT to be a reliable and standard methodology, therefore a positive correlation of area calculated using LCA with volume calculated using CBCT shows that the analysis made by LCA can be reliable.

Characteristics and Mechanism of Upper Airway Collapse Revealed by Dynamic MRI During Natural Sleep in Patients with Severe Obstructive Sleep Apnea

Purpose

Upper airway collapse during sleep in patients with obstructive sleep apnea (OSA) is a complex and dynamic phenomenon. By observing and analyzing the dynamic changes in the upper airway and its surrounding tissues during airway obstruction, we aim to reveal dynamic characteristics in different obstruction patterns, and the relationship between anatomical features during normal breathing and dynamic characteristics of airway obstruction.

Patients and Methods

Dynamic MRI was performed in 23 male patients (age range 26-63) with severe OSA diagnosed by overnight polysomnography, and obstruction events were identified from their images. Dynamic changes in parameters of the upper airway and surrounding tissues were measured to assess the key characteristics in different obstruction patterns.

Results

We categorized airway obstruction into four types based on the obstruction location and motion characteristics of tissues during collapse, and detailed the alterations in the airway and surrounding tissues under each obstruction pattern. In all 112 obstruction events extracted from the dynamic images of 23 patients, type A (retropalatal obstruction caused by the soft palate separated from the tongue), BI, BII (both retropalatal obstructions caused by the soft palate attached to the tongue, and C (retropalatal and retroglossal obstruction caused by the soft palate and the tongue), accounted for 28.6%, 44.6%, 12.5%, and 14.3% respectively. In severe OSA patients with tongue and palatal obstruction related to type B or C, the more posterior hyoid position, shorter distance between tongue and uvula, and wider retropalatal space, the larger the tongue displacement and deformation during collapse, and the greater the reduction in airway space.

Conclusion

There are multiple airway obstruction patterns, each with its own anatomical characteristics and behaviors during collapse. Hyoid position, tongue and uvula distance, and retropalatal space play an important role in airway collapse and should be paid more attention in the treatment of OSA.

Evaluation of pharyngeal airway space after orthodontic extraction treatment in class II malocclusion integrating with the subjective sleep quality assessment

Orthodontic treatment with premolar extractions is typically used to relieve dental crowding and retract anterior teeth for lip profile improvement. The aim of the study is to compare the changes in regional pharyngeal airway space (PAS) after orthodontic treatment with Class II malocclusion and to identify the correlations between questionnaire results and PAS dimensions after orthodontic treatment. In this retrospective cohort study, 79 consecutive patients were divided into normodivergent nonextraction, normodivergent extraction, and hyperdivergent extraction groups. Serial lateral cephalograms were used to evaluate the patients' PASs and hyoid bone positions. The Pittsburgh Sleep Quality Index and STOP-Bang questionnaire were used for sleep quality evaluation and obstructive sleep apnea (OSA) risk assessment, respectively, after treatment. The greatest airway reduction was observed in hyperdivergent extraction group. However, the changes in PAS and hyoid positions did not differ significantly among three groups. According to questionnaire results, all three groups had high sleep quality and low risk of OSA, with no significant intergroup differences. Moreover, pretreatment-to-posttreatment changes in PAS were not correlated with sleep quality or risk of OSA. Orthodontic retraction with premolar extractions nither exhibit significant reduction in airway dimensions nor increase their risk of OSA.

The prognostic role of ultrasound and magnetic resonance imaging in obstructive sleep apnoea based on lateral oropharyngeal wall obstruction

PURPOSE

This study examined the prognostic value of the lateral pharyngeal wall (LPW)-based obstruction and obstructive sleep apnoea (OSA) prediction using ultrasound (US) and MRI (magnetic resonance imaging).

METHODS

One hundred patients with and without OSA were enrolled, according to overnight polysomnography. The LPW thickness (LPWT) was measured using a Philips Ingenia 1.5 T MRI device, and US measurements were carried out at rest and during Müller's manoeuvre (MM) with a Samsung RS85 device. The obstruction was localised under drug-induced sleep endoscopy.

RESULTS

Significantly greater LPWT using MRI was observed in the OSA group compared to the control group, while US results showed a significant difference only in the case of LPWT during MM on the left side. Obese patients presented significantly higher LPWT values. A significant correlation between BMI and LPWT was observed. Men presented significantly higher LPWT MRI values and left-sided LPWT using US compared to women. LPWT and AHI parameters were significantly correlated. The severity of LPW obstruction correlated with LPWT, while the LPW collapse significantly correlated with AHI. The severity of LPW collapse differed depending on the AHI values. Using US LPWT values and anthropometric parameters, a 93% effectiveness in OSA prognostication and 89% in LPWT-based obstruction were detected. MRI detected OSA in 90% and LPW-based obstruction in 84%. US successfully detected LPW-based collapse severity in 67%.

CONCLUSION

US LPWT measurements were helpful in detecting OSA and LPWT-based obstruction. These examinations may be useful for surgical planning.

Relationship between hyoid bone and pharyngeal airway in different skeletal patterns

Background/purpose

The hyoid bone and its attached muscles play an important role in the maintenance of the pharyngeal airway space. The aim of the present study was to investigate the correlations between hyoid bone and pharyngeal airway spaces among three skeletal patterns.

Materials and methods

Cephalograms of 90 male and 90 female were divided into skeletal patterns: Class I, Class II, and Class III. The following pharyngeal airway spaces were measured: SP, soft palate related pharyngeal airway; BP, B point related pharyngeal airway; C2P, second cervical vertebra related pharyngeal airway; and LP, laryngopharyngeal airway. The paired t-test, one-way analysis of variance, and Pearson correlation analysis were used in the statistical analyses.

Results

SP was significantly longer in Class III (12.4 mm) than in Class I (10.7 mm) and Class II (9.5 mm), and BP was significantly greater in Class III (16.3 mm) than in Class II (12.4 mm). The hyoid bone had a significantly anterior location in Class III compared to Class II, whereas vertical positions of the hyoid bone showed no significant differences among the three skeletal patterns. Among female with a Class III skeletal pattern, the horizontal position of the hyoid bone had a positive moderate, significant correlation with the C2P, whereas among male, this was not observed.

Conclusion

The location of the maxilla (SNA) was not significantly correlated with the pharyngeal airway space. However, the more protruding the mandible (SNB) is, the more anterior the hyoid bone and the longer the pharyngeal airway will be.

Evaluation of pharyngeal airway volume for different dentofacial skeletal patterns using cone-beam computed tomography

Background/purpose

Understanding of the three-dimensional airway space in three skeletal patterns is important in orthodontic treatment. This study investigated differences between the volume of pharyngeal airway sections and the smallest cross-sectional area in three skeletal patterns by using cone-beam computed tomography (CBCT).

Materials and methods

The 90 patients were collected to measure total pharyngeal airway volume (TP), velopharyngeal airway volume (VP), glossopharyngeal airway volume (GP), oropharyngeal airway volume (OP), hypopharyngeal airway volume (HP), and the smallest cross-sectional areas (SCA) of the upper respiratory tract as well as other relevant anatomical structures. The mean values differences between classes were analyzed using ANOVA. Pearson's test was used to compare classes in terms of the correlations between different factors.

Results

Patients in skeletal classes I and III exhibited significantly higher SCA values (322.6 mm²and 344.5 mm² respectively) than those in skeletal class II (240.8 mm²). Subjects from skeletal classes I and III exhibited significantly higher values of VP, HP, and OP than those in skeletal class II. Skeletal classes I and III exhibited significantly higher TP values (31190.1 mm³ and 30696.2 mm³, respectively) than those in skeletal class II (22386.0 mm³). Non-significant relationships were discovered between pharyngeal airway and skeletal pattern. Conversely, significant relationships were found between TP and gender, ANB, SNB, hyoid and pogonion positions.

Conclusion

The skeletal class II has smaller airway volume than those in skeletal class I and III. The pharyngeal airway volumes could serve as a guide in differentiating the different skeletal classes in clinical settings.

Sagittal Measurement of Tongue Movement During Respiration: Comparison Between Ultrasonography and Magnetic Resonance Imaging

The tongue makes up the anterior pharyngeal wall and is critical for airway patency. Magnetic resonance imaging (MRI) is commonly used to study pharyngeal muscle function in pharyngeal disorders such as obstructive sleep apnoea. Tagged MRI and ultrasound studies have separately revealed ∼1 mm of anterior tongue movement during inspiration in healthy patients, but these modalities have not been directly compared. In the study described here, agreement between ultrasound and MRI in measuring regional tongue displacement in 21 healthy patients and 21 patients with obstructive sleep apnoea was evaluated. We found good consistency and agreement between the two techniques, with an intra-class correlation coefficient of 0.79 (95% confidence interval: 0.75-0.82) for anteroposterior tongue motion during inspiration. Ultrasound measurements of posterior tongue displacement were 0.24 ± 0.64 mm greater than MRI measurements (95% limits of agreement: 1.03 to -1.49). This may reflect the higher spatial and temporal resolution of the ultrasound technique. This study confirms that ultrasound is a suitable method for quantifying inspiratory tongue movement.

Sleep endoscopy findings in children with persistent obstructive sleep apnea after adenotonsillectomy

OBJECTIVES

Describe the patterns of obstruction in persistent pediatric OSA and their relationship with patient weight.

STUDY DESIGN

Retrospective review.

METHODS

All pediatric DISE procedures performed at a tertiary care hospital between October 2010 and October 2015 were reviewed. Patients had polysomnography after adenotonsillectomy that confirmed persistent obstructive sleep apnea (OSA). Variables included age, gender, co-morbidities, and AHI. DISE findings focused on inferior turbinates, adenoid, tongue base, epiglottis, aryepiglottic (AE) folds, arytenoids, lingual tonsil and their contributions to obstruction.

RESULTS

34 patients were included with mean age of 7.85 (2-16) years, mean BMI of 23.15 (13.6-44.8) and mean AHI of 6.34 (1.5-25.2) events per hour. Obstruction occurred at the level of the epiglottis in 97%, with retropositioning by tongue base (73.6%) or lingual tonsil enlargement (70.5%). Obstruction occurred at the inferior turbinates in 76.5%, the adenoid in 64.7% and the palate in 58.8%. Shortened AE folds were less often identified (15%). Multiple sites of partial or complete obstruction were found in 97% of patients. Overweight or obese patients had a mean of 3 sites of complete obstruction and 4.69 sites of partial or complete obstruction as compared to 2.33 and 4.52 in underweight or normal weight children. Overweight or obese children were more likely to have obstruction at the lingual tonsil or adenoid than normal/underweight children.

CONCLUSION

Multiple sites of obstruction in persistent pediatric OSA were found. Children with higher BMIs had slightly different findings, suggesting that attention to adenoid regrowth and lingual tonsil hypertrophy is important.

Are computed tomography 3D measurements of the upper airways in mouth-breathing children in agreement with the ENT clinical diagnosis of obstruction?

Introduction

Imaging studies have hystorically been used to support the clinical otorhinolaryngological evaluation of the upper respiratory tract for the diagnosis of obstructive causes of oral breathing.

Objective

The objective of this study was to compare 3D volumetric measurements of nasal cavity, nasopharynx and oropharynx of obstructed mouth-breathing children with measurements of non-obstructed mouth-breathing children.

Methods

This retrospective study included 25 mouth-breathing children aged 5–9 years evaluated by otorhinolaryngological clinical examination, flexible nasoendoscopy and full-head multi-slice computed tomography. Tomographic volumetric measurements and dichotomic otorhinolaryngological diagnosis (obstructed vs. non-obstructed) in three anatomical regions (the nasal cavity, nasopharynx and oropharynx) were compared and correlated. An independent sample t-test was used to assess the association between the 3D measurements of the upper airways and the otorhinolaryngological diagnosis of obstruction in the three anatomical regions. Inter- and intra-observer intraclass correlation coefficients were used to evaluate the reliability of the 3D measurements.

Results

The intra-class correlation coefficients ranged from 0.97 to 0.99. An association was found between turbinate hypertrophy and nasal cavity volume reduction (p < 0.05) and between adenoid hyperplasia and nasopharynx volume reduction (p < 0.001). No association was found between palatine tonsil hyperplasia and oropharynx volume reduction.

Conclusions

(1) The nasal cavity volume was reduced when hypertrophic turbinates were diagnosed; (2) the nasopharynx was reduced when adenoid hyperplasia was diagnosed; and (3) the oropharynx volume of mouth-breathing children with tonsil hyperplasia was similar to that of non-obstructed mouth-breathing children. The adoption of the actual anatomy of the various compartments of the upper airway is an improvement to the evaluation method.

Assessment of upper airways measurements in patients with mandibular skeletal Class II malocclusion

Objective:

Mandibular Class II malocclusions seem to interfere in upper airways measurements. The aim of this study was to assess the upper airways measurements of patients with skeletal Class II malocclusion in order to investigate the association between these measurements and the position and length of the mandible as well as mandibular growth trend, comparing the Class II group with a Class I one.

Methods:

A total of 80 lateral cephalograms from 80 individuals aged between 10 and 17 years old were assessed. Forty radiographs of Class I malocclusion individuals were matched by age with forty radiographs of individuals with mandibular Class II malocclusion. McNamara Jr., Ricketts, Downs and Jarabak's measurements were used for cephalometric evaluation. Data were submitted to descriptive and inferential statistical analysis by means of SPSS 20.0 statistical package. Student's t-test, Pearson correlation and intraclass correlation coefficient were used. A 95% confidence interval and 5% significance level were adopted to interpret the results.

Results:

There were differences between groups. Oropharynx and nasopharynx sizes as well as mandibular position and length were found to be reduced in Class II individuals. There was a statistically significant positive correlation between the size of the oropharynx and Xi-Pm, Co-Gn and SNB measurements. In addition, the size of the nasopharynx was found to be correlated with Xi-Pm, Co-Gn, facial depth, SNB, facial axis and FMA.

Conclusion:

Individuals with mandibular Class II malocclusion were shown to have upper airways measurements diminished. There was a correlation between mandibular length and position and the size of oropharynx and nasopharynx.

Tomographic Analysis of the Impact of Mandibular Advancement Surgery on Increased Airway Volume

PURPOSE

This study aimed to quantify, using cone-beam computed tomography (CBCT) in patients who underwent a mandibular advancement surgery associated with genioplasty, three-dimensional changes in airway space and to evaluate whether these changes differ between men and women.

MATERIALS AND METHODS

Preoperative and 8-month postoperative CBCT scans of 38 patients aged 18-45 years of either sex and any ethnicity who underwent mandibular advancement surgery associated with genioplasty were analyzed using the Xoran software (Xoran Technologies, Ann Arbor, MI, USA). The linear distances gonion-gnathion (Go-Gn) and condylion-menton (Co-Me) were obtained. Airway volume was measured using the Dolphin Imaging software, version 11.0. Then, data were tabulated and analyzed using Student's t-test.

RESULTS

Mean patient age was 30.3 years; 39.47% were men and 60.63% were women. The mean Go-Gn distance was 72.05 mm before surgery and 78.56 mm after surgery, with a mean gain of 6.51 mm. The mean Co-Me distance was 113.47 mm before surgery and 119.89 mm after surgery, with a mean increase of 6.42 mm. Both differences were statistically significant. The mean volume of airway space was 17,272.92 mm3 before surgery and 24,173.74 mm3 after surgery, with a statistically significant mean increase of 6900.82 mm3. There was no statistically significant difference in mean volumetric gain between men (7566.69 mm3) and women (7456.69 mm3).

CONCLUSION

Mandibular advancement surgery results in significant increase of airway space, and there is no difference in airway volume between men and women.

Submental Ultrasonographic Parameters among Patients with Obstructive Sleep Apnea

Objective

This study aimed to determine the value of submental ultrasonography (US) parameters for diagnostic workup among patients with obstructive sleep apnea (OSA) and to determine whether there is a correlation between US findings and the severity of OSA.

Study Design

Cross-sectional analysis.

Setting

Tertiary education hospital.

Subjects and Methods

The study included 147 patients with suspected OSA who underwent submental US to evaluate various parameters following overnight polysomnography. US findings were compared with the apnea-hypopnea index and other parameters.

Results

All US parameters, except for subcutaneous tissue thickness, were significantly different among patients with OSA. Of note, distance between lingual arteries (DLA), geniohyoid muscle thickness (GMT), and lateral parapharyngeal wall thickness (LPWT) were significantly greater in the patients with severe OSA than those with mild and moderate OSA ( P < .001). GMT had the strongest correlation with OSA ( r = 0.419, P < .001); LPWT and DLA also had high correlation coefficient values ( r = 0.343, P < .001, and r = 0.342, P < .001, respectively). Stepwise regression analysis showed that GMT (beta = 0.243, P = 0.004), LPWT (beta = 0.236, P = 0.004), and DLA (beta = 0.204, P = 0.008) were the most significant factors for predicting the severity of OSA according to the apnea-hypopnea index.

Conclusion

Submental US can be used to determine whether there is a correlation between US findings and severity of OSA. GMT could be considered a novel parameter for determining the severity of OSA.

Cephalometric Measurements With Multislice Computed Tomography in Patients With Obstructive Sleep Apnea Syndrome

INTRODUCTION

Obstructive sleep apnea syndrome (OSAS) is characterized by episodes of upper respiratory tract obstruction, decreased oxygen saturation, and sleep fragmentation during sleep, as well as excessive daytime somnolence. Cephalometric analysis offers distance, angle, area, and volume measurements between separate reference points belonging to bony and soft tissues on a film. Cephalometric measurements made with multislice computed tomography (CT) are quite helpful for standardization of measurements and obtaining highly reliable results. The aim of the current study was to make cephalometric measurements with multislice CT in OSAS patients and compare their results with those of a healthy control population. The authors also aimed to determine, which cephalometric parameters might be more valuable for diagnosis of OSAS.

MATERIALS AND METHOD

This study included 30 patients who were diagnosed with severe OSAS (apnea-hypopnea index >30) by an overnight polysomnography study, performed for suspected OSAS and 10 healthy controls without snoring or apnea who underwent three-dimensional head & neck multislice CT for any indication. All patients underwent a three-dimensional head & neck multislice CT to make cephalometric measurements and compare them across the groups.

RESULTS

ANS-PNS (anterior and posterior nasal spine), Go-Gn, and UP-PhW distances, as well as sella-nasion-A and sella-nasion-B angles, were significantly lower in the OSAS group compared with the controls (P < 0.05). Mandibulas plane -H, UD, TT-EA, ANS-B, PNS-TB, TT-TB, B-N, and PNS-PhW distances were significantly higher in the patient group compared with the controls (P < 0.05).

CONCLUSIONS

Our study reached the conclusion that some cephalometric measurements showed significant differences in patients with obstructive sleep apnea compared with the control group, and hence may lead to a susceptibility to having OSAS. Cephalometric measurements performed with multislice CT have come to the forefront as one of the most important tools for diagnosis of OSAS. An inferiorly located hyoid bone may be most commonly responsible for apnea episodes. It was also concluded that an inferiorly located hyoid bone might have been the result of maxillomandibular underdevelopment.

Computational fluid dynamics for the assessment of upper airway changes in skeletal Class III patients treated with mandibular setback surgery

OBJECTIVE

To analyze and compare pharyngeal airflow characteristics pre- and post-mandibular setback surgery in patients with Class III skeletal dysplasia using cone beam computed tomography (CBCT) and computational fluid dynamics (CFD).

MATERIALS AND METHODS

Records of 29 patients who had received orthodontic treatment along with mandibular setback surgery were obtained. CBCT scans were obtained at three time points: T1 (before surgery), T2 (average of 6 months after surgery), and T3 (average of 1 year after surgery). Digitized pharyngeal airway models were generated from these scans. CFD was used to simulate and characterize pharyngeal airflow.

RESULTS

Mean airway volume was significantly reduced from 35,490.324 mm³ at T1 to 24,387.369 mm³ at T2 and 25,069.459 mm³ at T3. Significant increase in mean negative pressure was noted from 3.110 Pa at T1 to 6.116 Pa at T2 and 6.295 Pa at T3. There was a statistically significant negative correlation between the change in airway volume and the change in pressure drop at both the T2 and T3 time points. There was a statistically significant negative correlation between the amount of mandibular setback and change in pressure drop at the T2 time point.

CONCLUSIONS

Following mandibular setback surgery, pharyngeal airway volume was decreased and relative mean negative pressure was increased, implying an increased effort required from a patient for maintaining constant pharyngeal airflow. Thus, high-risk patients undergoing a large amount of mandibular setback surgery should be evaluated for obstructive sleep apnea and the proposed treatment plan be revised based on the risk for potential airway compromise.

The Oropharyngeal Airway in Young Adults with Skeletal Class II and Class III Deformities: A 3-D Morphometric Analysis

Objectives

1) To determine the accuracy and reliability of an automated anthropometric measurement software for the oropharyngeal airway and 2) To compare the anthropometric dimensions of the oropharyngeal airway in skeletal class II and III deformity patients.

Methods

Cone-beam CT (CBCT) scans of 62 patients with skeletal class II or III deformities were used for this study. Volumetric, linear and surface area measurements retroglossal (RG) and retropalatal (RP) compartments of the oropharyngeal airway was measured with the 3dMDVultus software. Accuracy of automated anthropometric pharyngeal airway measurements was assessed using an airway phantom.

Results

The software was found to be reasonably accurate for measuring dimensions of air passages. The total oropharyngeal volume was significantly greater in the skeletal class III deformity group (16.7 ± 9.04 mm³) compared with class II subjects (11.87 ± 4.01 mm³). The average surface area of both the RG and RP compartments were significantly larger in the class III deformity group. The most constricted area in the RG and RP airway was significantly larger in individuals with skeletal class III deformity. The anterior-posterior (AP) length of this constriction was significantly greater in skeletal class III individuals in both compartments, whereas the width of the constriction was not significantly different between the two groups in both compartments. The RP compartment was larger but less uniform than the RG compartment in both skeletal deformities.

Conclusion

Significant differences were observed in morphological characteristics of the oropharyngeal airway in individuals with skeletal class II and III deformities. This information may be valuable for surgeons in orthognathic treatment planning, especially for mandibular setback surgery that might compromise the oropharyngeal patency.

[The syndrome of increased upper airways resistance: What are the clinical features and diagnostic procedures?]

The upper airway resistance syndrome "UARS" is a poorly defined entity, often described as a moderate variant of the obstructive sleep apnea syndrome. It is associated with respiratory effort-related arousal, absence of obstructive sleep apnea, and absence of significant desaturation. It is a relatively common condition that predominantly affects non-obese young adults, with no predominance in either sex. The degree of upper airway collapsibility during sleep of patients with UARS is intermediate between that of normal subjects and that of patients with mild-to-moderate sleep apnea syndrome. Craniofacial and palatal abnormalities are often noted. Patients frequently complain of a functional somatic syndrome, especially daytime sleepiness and chronic fatigue. Polysomnography with esophageal pressure measurements remains the gold standard diagnostic test. The absence of any neurological abnormality gives UARS a good prognosis and it is potentially reversible if treated early. However, some studies suggest that untreated UARS has an increased risk of arterial hypertension. It can also evolve into obstructive sleep apnea.

Analysis of Pharyngeal Airway Using Lateral Cephalogram vs CBCT Images: A Cross-sectional Retrospective Study

Background : As the basic biological relationship of form and function, changes in the normal pattern of nasopharyngeal space can profoundly affect the development of the craniofacial growth. The lateral cephalogram, part of the patient’s normal records for orthodontic treatment, may show some of these changes either at the initial examination or later during treatment. The validity of the information the lateral cephalogram may present, have been questioned previously. The aim of this study was to assess correlation between the area and the volume measurements of pharyngeal airway size in a lateral cephalogram and a 3-dimensional (3D) cone-beam computed tomography (CBCT) scan in adolescent subjects. Materials and Methods : CBCT scan and a lateral cephalogram of 35 subjects which were taken within 1 week were included in this study. Airway area of the region of interest from the lateral cephalogram and airway volume over the same of region of interest from the CBCT scan were assessed for all patients. The correlation between the area and the volume measurements were evaluated statistically by Pearson’s correlation coefficient test. Mann Whitney U Test was used for comparing the area and the volume measurements in different sex. Results : Strong correlation was found between lateral cephalogram and CBCT measurements of pharyngeal airway. (r=0.831). Conclusion : Pharyngeal airway area on a lateral cephalogram is correlated strongly with volumetric data on CBCT images. Henceforth the use of CBCT images for volume measurements in orthodontic patients can aid in the better evaluation of airways and acted as a diagnostic instrument in this area.

Assessment of Surgical Effects on Patients with Obstructive Sleep Apnea Syndrome Using Computational Fluid Dynamics Simulations

Obstructive sleep apnea syndrome is one of the most common sleep disorders. To treat patients with this health problem, it is important to detect the severity of this syndrome and occlusion sites in each patient. The goal of this study is to test the hypothesis that the cure of obstructive sleep apnea syndrome by maxillomandibular advancement surgery can be predicted by analyzing the effect of anatomical airway changes on the pressure effort required for normal breathing using a high-fidelity, 3-D numerical model. The employed numerical model consists of: 1) 3-D upper airway geometry construction from patient-specific computed tomographic scans using an image segmentation technique, 2) mixed-element mesh generation of the numerically constructed airway geometry for discretizing the domain of interest, and 3) computational fluid dynamics simulations for predicting the flow field within the airway and the degree of severity of breathing obstruction. In the present study, both laminar and turbulent flow simulations were performed to predict the flow field in the upper airway of the selected patients before and after maxillomandibular advancement surgery. Patients of different body mass indices were also studied to assess their effects. The numerical results were analyzed to evaluate the pressure gradient along the upper airway. The magnitude of the pressure gradient is regarded as the pressure effort required for breathing, and the extent of reduction of the pressure effort is taken to measure the success of the surgery. The description of the employed numerical model, numerical results from simulations of various patients, and suggestion for future work are detailed in this paper.

Computational fluid dynamic analysis of the posterior airway space after maxillomandibular advancement for obstructive sleep apnea syndrome

PURPOSE

This study evaluated the soft tissue change of the upper airway after maxillomandibular advancement (MMA) using computational fluid dynamics.

MATERIALS AND METHODS

Eight patients with obstructive sleep apnea syndrome who required MMA were recruited into this study. All participants underwent pre- and postoperative computed tomography and then MMA by a single oral and maxillofacial surgeon. Upper airway computed tomographic datasets for these 8 patients were created with high-fidelity 3-dimensional numerical models for computational fluid dynamics. The 3-dimensional models were simulated and analyzed to study how changes in airway anatomy affect the pressure effort required for normal breathing. Airway dimensions, skeletal changes, apnea-hypopnea index, and pressure effort of pre- and postoperative 3-dimensional models were compared and correlations were interpreted.

RESULTS

After MMA, laminar and turbulent air flows were significantly decreased at every level of the airway. The cross-sectional areas at the soft palate and tongue base were significantly increased.

CONCLUSIONS

This study showed that MMA increased airway dimensions by increasing the distance from the occipital base to the pogonion. An increase of this distance showed a significant correlation with an improvement in the apnea-hypopnea index and a decreased pressure effort of the upper airway. Decreasing the pressure effort will decrease the breathing workload. This improves the condition of obstructive sleep apnea syndrome.

Effect of large incisor retraction on upper airway morphology in adult bimaxillary protrusion patients

OBJECTIVE

To evaluate, using multislice computed tomography (MSCT), the morphologic changes in the upper airway after large incisor retraction in adult bimaxillary protrusion patients.

MATERIALS AND METHODS

Thirty adult patients with bimaxillary protrusion had four first premolars extracted, and then miniscrews were placed to provide anchorage. A CT scan was performed before incisor retraction and again posttreatment. Three-dimensional (3D) reconstruction of the pre- (T1) and post- (T2) CT data was used to assess for morphological changes of the upper airway. A paired t-test was used to compare changes from T1 to T2. The relationship among the three variables (upper incisor retraction amount, upper airway size, and hyoid position) was analyzed by Pearson correlation coefficient.

RESULTS

The amounts of upper incisor retraction at the incisal edge and apex were 7.64 ± 1.68 mm and 3.91 ± 2.10 mm, respectively. The hyoid was retracted 2.96 ± 0.54 mm and 9.87 ± 2.92 mm, respectively, in the horizontal and vertical directions. No significant difference was observed in the mean cross-sectional area of the nasopharynx (P > .05) between T1 and T2, while significant differences between T1 and T2 were found in the mean cross-sectional areas of the palatopharynx, glossopharynx, and hypopharynx (P < .05); these mean cross-sectional areas were decreased by 21.02% ± 7.89%, 25.18% ± 13.51%, and 38.19% ± 5.51%, respectively. The largest change in the cross-sectional area is always noted in the hypopharynx. There was a significant correlation among the retraction distance of the upper incisor at its edge, the retraction distance of the hyoid in the horizontal direction, and the decrease of the hypopharynx.

CONCLUSION

Large incisor retraction leads to narrowing of the upper airway in adult bimaxillary protrusion patients.

Thyroidectomy for goiter relieves obstructive sleep apnea: results of 8 cases

The author conducted a retrospective study of 8 adults with euthyroid goiter that had resulted in tracheal compression and led to moderate to severe obstructive sleep apnea (OSA). The purpose of the study was to evaluate the effects of thyroidectomy on the apnea-hypopnea index (AHI) in these patients and to determine if there is a relationship between tracheal compression and OSA. These patients had been treated by the author in a community hospital over a 4-year period. All 8 patients had reported compressive symptoms of orthopnea and dysphagia, and 3 of them also reported dyspnea. Computed tomography of the neck and chest had been used to confirm the extent of goiter and tracheal compression. OSA had been confirmed with preoperative polysomnography. At 90 days post-thyroidectomy, repeat polysomnography had been obtained. At follow-up, all 8 patients had reported symptomatic control of compressive symptoms, and 7 patients had demonstrated postoperative improvement in their AHI. Overall, the mean postoperative AHI had decreased from 52.1 to 36.6-a statistically significant reduction of 29.8% (p < 0.05). The results of this study suggest that thyroidectomy for tracheal compression secondary to goiter can significantly alleviate symptoms and improve AHI in those patients who experience OSA. Evaluation of all patients with OSA should include screening for goiter-induced tracheal compression.

Comparison of pharyngeal airway changes on plain radiography and cone-beam computed tomography after orthognathic surgery

PURPOSE

The purpose of the present prospective study was to develop a 3-dimensional analysis of the airway using cone-beam computed tomography (CBCT) and to determine whether changes in the airway before and after orthognathic surgery correlate on 2-dimensional lateral cephalogram and 3-dimensional CBCT images.

MATERIALS AND METHODS

Patients requiring orthognathic surgery during 2004 to 2005 were recruited for the present study. Lateral cephalograms and CBCT scans were obtained at 3 points: preoperatively, within 1 month postoperatively, and after 6 months postoperatively. The nasopharynx, oropharynx, and hypopharynx were segmented on both the radiograph and the CBCT scan for each patient in a repeatable manner at each point. For the lateral cephalogram, linear measurements in the middle of each of the 3 segments were obtained. For the CBCT, volumetric measurements of each of the 3 segments were obtained. The intrarater variability was assessed, and Pearson's correlation was used to compare the 2 imaging modalities.

RESULTS

A total of 20 patients scheduled for orthognathic surgery were recruited for the present study. Of the 20 patients, 13 were female and 7 were male. The mean age at surgery was 23.85 years (range 14 to 43). Of the 20 patients, 6 underwent maxillary advancement only, 8 underwent mandibular advancement with or without genioplasty, and 6 underwent 2-jaw surgery or mandibular setback. We examined the entire cohort without separation into procedure or examination point and found a weak, but statistically significant, correlation between the linear and volume measurements in the nasopharyngeal and oropharyngeal regions but not in the hypopharyngeal region (r = 0.43, P < .002; r = 0.49, P < .0002; r = 0.16, P = .26, respectively). The maxillary advancement group (n = 6) demonstrated a correlation between the linear and volume measurements in the nasopharyngeal region (r = 0.53, P = .03). The mandibular advancement with or without genioplasty group (n = 8) showed a correlation in the nasopharyngeal and oropharyngeal regions (r = 0.55, P < .02, and r = 0.46, P = .05, respectively). For the combination/setback procedures (n = 6), a correlation was found in the oropharyngeal region (r = 0.64, P < .01). All other comparisons between the linear and volume measurements did not correlate. Additionally, no correlations were found between the linear and volumetric change in airway size between 6 months postoperatively and preoperatively, except for the oropharyngeal region (r = 0.67, P < .01).

CONCLUSION

We present a method of measuring the airway that could be used for both 2-dimensional and 3-dimensional images. It includes segmentation of the pharyngeal airway into its nasopharyngeal, oropharyngeal, and hypopharyngeal components. Correlations were found between the linear and volumetric measurements of the segmented airway in patients who had undergone orthognathic surgery; however, the correlations were generally weak.

Anatomy and physiology of the upper airway

The nose is the major portal of air exchange between the internal and external environment. The nose participates in the vital functions of conditioning inspired air toward a temperature of 37°C and 100% relative humidity, providing local defense and filtering inhaled particulate matter and gases. It also functions in olfaction, which provides both a defense and pleasure for the individual. Understanding normal physiology provides the basis for recognizing abnormalities.

Avaliação do espaço aéreo faríngeo por meio da tomografia computadorizada de feixe cônico

INTRODUÇÃO: a avaliação do espaço aéreo superior faz parte da rotina na elaboração do diagnóstico e plano de tratamento ortodôntico. A radiografia cefalométrica em norma lateral tem sido usada rotineiramente na avaliação da permeabilidade do espaço aéreo, esbarrando na limitação de fornecer uma imagem bidimensional de uma estrutura tridimensional. A Tomografia Computadorizada de Feixe Cônico (TCFC) tem entrado na realidade ortodôntica trazendo um arsenal de informações concernentes ao espaço aéreo superior. Por fornecer uma imagem tridimensional, possibilita determinar de maneira precisa a área de maior estreitamento da faringe, que ofereceria maior resistência à passagem aérea. OBJETIVOS: o propósito deste artigo é esclarecer o ortodontista quanto aos recursos disponíveis na TCFC para o diagnóstico de possíveis barreiras físicas que possam diminuir a permeabilidade das vias aéreas superiores.

Comparison of airway space with conventional lateral headfilms and 3-dimensional reconstruction from cone-beam computed tomography

INTRODUCTION

Changes in the normal pattern of nasal respiration can profoundly affect the development of the craniofacial skeleton in both humans and experimental animals. The orthodontist is often the first clinician to notice that a child is breathing primarily through the mouth, either at the initial examination or later during treatment. The lateral headfilm, part of the patient's normal records, might show increased adenoid masses, suggesting that these could be part of the problem. Previous studies have, however, questioned the validity of the information from lateral headfilm.

METHODS

Our aim was to compare imaging information about nasopharyngeal airway size between a lateral cephalometric headfilm and a 3-dimensional cone-beam computed tomography scan in adolescent subjects. The nasopharyngeal airway area and volume were measured in 35 subjects (8 boys, 27 girls; average age, 14 years).

RESULTS

Volumetric measurement errors ranged from 0% to 5% compared with known physical airway phantoms used to calibrate. A moderately high (r = 0.75) correlation was found between airway area and volume; the larger the area, the larger the volume. However, there was considerable variability in the airway volumes of patients with relatively similar airways on the lateral headfilms. Nine of the 35 patients had over 25% of the potential nasopharyngeal airway volume occupied by inferior turbinate protuberances, leading to significant airway restriction in some patients.

CONCLUSIONS

The cone-beam 3-dimensional scan is a simple and effective method to accurately analyze the airway.

Diagnostic imaging and sleep medicine

Obstructive sleep apnea syndrome (OSAS) is a relatively common disorder characterized by recurrent episodes of upper airway collapse and obstruction during sleep. It results in apneic events (or in the case of partial obstruction, hypopneic events) that lead to loud snoring, hypoxia, and arousals that interrupt the normal sleep cycle. Typically, these nocturnal arousals cause patients to complain of excessive daytime sleepiness, which may interfere with routine daily activities. More importantly, when moderate to severe, OSAS can lead to a wide variety of medical complications, some of which can result in severe consequences or even death.

Combination of Bernouilli effect producing maneuver-induced pharyngeal narrowing rate with body mass index as predictive tool for obstructive sleep apnea syndrome

CONCLUSIONS

It is suggested that the combination of the pharyngeal narrowing rate during the Bernouilli effect producing maneuver (BEPM) with the body mass index (BMI) might be a promising predictive method for obstructive sleep apnea syndrome (OSAS).

OBJECTIVES

An attempt was made to clarify the possibility that the dynamic narrowing of the pharynx evaluated by nasopharyngoscopy with BEPM, a forced inspiration through the nose with the mouth closed, might be a reliable clinical daytime predictor for identifying patients at risk of developing OSAS.

SUBJECTS AND METHODS

Subjects were 57 patients complaining of snoring and sleepiness during daytime. Endoscopic images of the retropalatal pharynx were obtained and their area was measured by NIH imaging. The pharyngeal narrowing rate during quiet nasal breathing and that during BEPM were compared to assess pharyngeal dynamics. To increase the sensitivity of this method, BMI was added to the pharyngeal narrowing rate during BEPM.

RESULTS

The criterion of BEPM at a cut-off value of 50% with BMI at a cut-off value of 25 kg/m(2) achieved a sensitivity of 93%, while the specificity was 67% in differentiating simple snorers from OSAS patients (apnea index >5). In addition, the likelihood ratio of the method was found to be 2.81.

Role of dynamic MR imaging in obstructive sleep apnoea

The purpose of this study is to assess the role of dynamic MR imaging in the evaluation of obstructive sleep apnea. In this prospective study, MRI was performed in 22 patients (eighteen male and four female, ranging in age from 26 to 70 years) suspected of having obstructive sleep aponea (OSA). 18 of them had a polysomnography study prior to MRI evaluation, which confirmed the presence of OSA. Positive cases were classified according to anatomic location and cause of narrowing. Patients with isolated retropalatal narrowing on MRI were advised uvulopalatopharyngoplasty (UPPP). Two patients had normal findings on MRI, 8 patients had retropalatal narrowing, five had retroglossal narrowing and seven had narrowing at multiple levels. All twenty-patients had collapse of lateral pharyngeal wall. Four patient with isolated retropalatal narrowing, who underwent UPPP after MRI evaluation were found to be cured on 6 month postoperative follow up.Dynamic MR imaging can accurately diagnose the cause and level of upper airway narrowing in patients with OSA. It can characterize and anatomically classify the level of narrowing for planning reparative surgery.

Sonographic measurement of lateral parapharyngeal wall thickness in patients with obstructive sleep apnea

INTRODUCTION

Lateral parapharyngeal wall (LPW) thickness may be a predominant anatomic factor causing airway narrowing in apneic subjects. In this study, we explored sonographic measurement of the LPW thickness and compared the results with LPW thickness measured by magnetic resonance imaging (MRI). We also investigated the association between sonographic measurement of LPW thickness and apnea-hypopnea index (AHI).

METHOD

Seventy-six patients with suspected obstructive sleep apnea (OSA) underwent ultrasound examination of LPW thickness after overnight polysomnography. Fifteen out of 76 subjects also participated in correlation and reliability studies of sonographic and MRI measurements of LPW thickness.

RESULTS

There was good correlation between measurements of LPW thickness on ultrasound and MRI (r = 0.78, P = 0.001), although Bland-Altman analysis indicated overestimation of LPW thickness by ultrasound, when compared with the LPW as measured by MRI. The sonographic measurement of LPW thickness had high reproducibility, with intraclass correlation coefficients of 0.90 and 0.97 for intraoperator and interoperator reliability, respectively. Fifty-eight subjects with significant OSA (AHI > or = 10/h) had a higher body mass index, larger neck circumference, and greater LPW thickness measured by ultrasound than those (n = 18) with an AHI of less than 10 per hour. LPW thickness had a positive correlation with AHI on univariate analysis (r = 0.37, P = 0.001). On multivariate analysis, LPW thickness had a positive independent association with AHI after adjustment for age, sex, neck circumference, and body mass index. The positive association of LPW thickness with AHI remained significant in both univariate and multivariate analyses of men only (n = 62).

CONCLUSIONS

Sonographic measurement of LPW thickness is a novel and reliable technique and had good correlations with measurement by MRI and the severity of OSA. Ultrasound may provide an alternative imaging modality with easy accessibility and lower cost in OSA research.

Avaliação cefalométrica do espaço aéreo posterior em pacientes com oclusão Classe II submetidos à cirurgia ortognática

OBJETIVO: o avanço maxilomandibular é um método cirúrgico comumente usado no tratamento de pacientes acometidos pela Síndrome da Apnéia Obstrutiva do Sono (SAOS) e portadores de anormalidades anatômicas identificáveis neste complexo, que estreitam e/ou obstruem o espaço aéreo. O intuito deste estudo foi analisar variações cefalométricas do espaço aéreo faríngeo em indivíduos Classe II de Angle, após a cirurgia ortognática. METODOLOGIA: a amostra consistiu de telerradiografias laterais equivalentes aos períodos pré e pós-operatório de 30 indivíduos, divididos no grupo com avanço cirúrgico mandibular (n=15) e no grupo com avanço maxilomandibular (n=15). Os parâmetros cefalométricos usados permitiram avaliar o espaço aéreo posterior em 3 níveis: a hipofaringe (PFI-V), a orofaringe (PFM-PM, PFM-PO, PFM-U, PFM-Up) e a nasofaringe (PFM-PN, pm-PFS). A análise esquelética foi na base do crânio (N-S-Ba) e na mandíbula (Ar-Go-Me). A média das diferenças entre os valores pré e pós-operatórios das mensurações lineares (mm) e angulares (graus) foi avaliada pelo teste t pareado. RESULTADOS E CONCLUSÕES: estatisticamente, não houve redução do espaço aéreo faríngeo pós-avanço cirúrgico. O que se observou foi que apenas PFM-PO e PFS-pM se mantiveram constantes e na maioria restante os valores aumentaram.

Pharyngeal dimensions in healthy men and women

INTRODUCTION

Epidemiological studies reveal a high male prevalence of obstructive sleep apnea syndrome. A possible explanation for this male predominance is the existence of anatomical differences in the upper airway between men and women.

METHODS

The upper airways of 10 male and 10 female healthy volunteers were prospectively evaluated by magnetic resonance imaging. Anatomical pharyngeal and column cross-sectional linear measurements were made in sagittal T1 and axial T1 and T2 weighted fast spin-echo images.

RESULTS

Men had significantly greater mean sagittal pharyngeal structural dimensions compared to women for all structures with the exception of the craniocaudal length of the soft palate and the thickness of the submentonian fat. In contrast, cross-sectional linear dimensions were similar in men and women with the exception of the laterolateral tongue length, which was greater in men. All mean linear measurements of the pharyngeal air column were similar in men and women at all studied levels.

CONCLUSIONS

Men and women present pharyngeal air columns with similar dimensions, but in women this column is surrounded by smaller structures, which might imply a smaller effort to keep its patency. Our data suggest the existence of an anatomical protective factor in women against the upper airway collapse.

Endoscopic evaluation of dynamic narrowing of the pharynx by the Bernouilli effect producing maneuver in patients with obstructive sleep apnea syndrome

OBJECTIVE

To evaluate the dynamic narrowing of the retropalatal pharynx by the Bernouilli effect producing maneuver (BEPM) in patients with obstructive sleep apnea syndrome (OSAS) with computer-assisted analysis of nasopharyngoscopic images.

METHODS

Endoscopic images of the retropalatal pharynx were obtained and their area was measured by NIH imaging. Because changes in distance between the CCD camera of the nasopharyngoscope and the site of pharyngeal narrowing decreased the measurement reliability, the area of the retropalatal pharynx was divided by the square of the uvula's lateral side length for normalization. We calculated both normalized areas: the pharyngeal narrowing during quiet nasal breathing and that during BEPM, which is a forced inspiration through the nose with the mouth closed. The narrowing rate was then calculated as an index of the pharyngeal dynamics.

RESULTS

Nasopharyngoscopy combined with BEPM showed a medial motion of the lateral walls of the pharynx due to the Bernoulli effect, which is an increase in speed and a reduction in pressure of a moving gas passing through a tube constriction. There was a significant correlation between the narrowing rate of the retropalatal pharynx and the apnea index. The decrease in intraluminal pressure at the narrowing combined with the higher atmospheric pressure exercised on the lateral pharyngeal walls would induce the pharyngeal collapse. There was also a significant correlation between the normalized retropalatal are and the apnea index.

CONCLUSION

Nasopharyngoscopy with BEPM suggest that in addition to the static narrowing, the dynamic narrowing of the retropalatal pharynx contributes to the pathophysiology of OSAS. The correlation between the apnea index and both the normalized retropalatal area and the narrowing rate of the retropalatal pharynx due to the Bernoulli effect constitute a quantitative and predictive alternative to the evaluation and understanding of the upper airways changes in OSAS.

Assessment of lateral cephalometric diagnosis of adenoid hypertrophy and posterior upper airway obstruction: A systematic review

INTRODUCTION

Our objective was to evaluate the capability of lateral cephalograms in diagnosing hypertrophied adenoids and obstructed posterior nasopharyngeal airways.

METHODS

A systematic review of the literature by using several electronic databases (Cochrane Library, Medline, Medline in progress, PubMed, Web of Science, Embase, and Lilacs) was performed with the help of a senior health-sciences librarian. The electronic search was followed up with hand searches. After applying our inclusion-exclusion criteria, the search yielded 11 articles that were then scored based on their methodological validity.

RESULTS

Lateral cephalograms performed reasonably well in evaluating adenoid size; both quantitative measures of adenoid area and subjective grading of adenoid size on lateral cephalograms had reasonable correlations to actual adenoid size (range of r, 0.60 to 0.88). However, evidence suggested that cephalograms were less ideal for evaluating the size of the posterior nasopharyngeal airway. The diagnostic difference is likely because the adenoid is a simpler 3-dimensional structure than the nasopharynx; therefore, it loses less information when compressed into 2 dimensions by the radiograph.

CONCLUSIONS

Being used as a screening tool to determine the need for more rigorous ENT follow-up appears to be the greatest utility of lateral cephalograms. Because no consensus could be reached on what are the most useful landmarks, we recommend that clinicians look for multiple deviant measures of adenoid size rather than one definitive quantification.

Magnetic airway implants for the treatment of obstructive sleep apnea syndrome

OBJECTIVE

To evaluate repelling magnetic implants to treat obstructive sleep apnea (OSA) using a canine model.

STUDY DESIGN AND SETTING

Magnetic forces equivalent to effective CPAP were estimated with benchtop studies. An acute canine model was used to simulate pharyngeal collapse. Tolerance, safety, and stability of the implants were evaluated in a chronic series of 10 dogs observed over 6 months.

RESULTS

Equivalence to CPAP (10-12 cm H(2)O) was achieved with low-force (<10 g/cm length), light (approximately 2 gram) implants. Magnetic implants prevented airway collapse in the acute canine. Normal behavior, swallowing, and oral intake were noted in the chronic canine over 6 months. Implant extrusion was 10%. Histology showed fibrous encapsulation without chronic inflammation.

CONCLUSIONS

Repelling magnets successfully maintained a patent airway and were well tolerated in the canine.

SIGNIFICANCE

Repelling magnets could represent an implantable alternative to CPAP if human studies reveal similar findings.

Pharyngometric correlations with obstructive sleep apnea syndrome

OBJECTIVE

The primary objective of this study was to investigate the relationship between obstructive sleep apnea syndrome (OSAS) and pharyngometric dimensions as clinical predictors of OSAS.

MATERIAL AND METHODS

Pharyngometry included tonsil size, the breadth of the uvula (UB), the distance between the uvula and the posterior pharyngeal wall and open mouth standardized photographic measurement of the dimension of the free oropharynx (FOP). We also assessed modified Mallampati grade (MMP). In addition, clinical data on body weight, height, nasal obstruction and cardiovascular disease were included in our analysis.

RESULTS

A total of 96 consecutive patients of both sexes with sleep disorders were investigated with somnography. Of these, 35 were considered to have OSAS, with an apnea-hypopnea index (AHI) of > or = 10. Body mass index (BMI), FOP, UB, the use of cardiovascular medication and hypertension were significantly related to AHI, and tonsil size showed borderline significance. Regression models were used to determine an OSAS index using the parameters BMI and FOP. The index had a positive predictive value of 82% and a negative predictive value of 77%.

CONCLUSIONS

We showed that a photographic assessment of pharyngeal dimensions was significantly associated with OSAS. We also confirmed previous findings of associations between OSAS, BMI and cardiovascular morbidity.

Test-retest validity of acoustic pharyngometry measurements

BACKGROUND

Acoustic reflectometry is a relatively new technique that quantifies upper airway obstruction. The oropharyngeal airway is geometrically complex and variable; therefore establishing a standard operating protocol and understanding the possible sources of artifacts are of great importance in obtaining reliable results. This work aims at assessing the repeatability of pharyngeal cross-sectional area measurements obtained from normal and snoring individuals.

METHODS

Twenty adult normal volunteers (16 men and 4 women; mean age, 35.9 years) and 10 adult snorers (9 men and 1 woman; mean age, 36.4 years) were examined by acoustic reflectometry following the developed standard operating protocol.

RESULTS

Measurements of pharyngeal cross-sectional area are analyzed in 2 groups. In normal subjects where mean pharyngeal cross-sectional area in the first session was 3.187 cm(2), in the second session (same-day test-retest), the mean pharyngeal cross-sectional area was 3.239 cm(2), and in the third session 7 to 10 days later (day-to-day test-retest), it was 3.245 cm(2) (P > 0.4). In a second group of snoring patients where mean pharyngeal cross-sectional area in the first session was 2.244 cm(2), in the second session, mean pharyngeal cross-sectional area was 2.237 cm(2), and mean pharyngeal cross-sectional area in the third session (7 to 10 days later) was 2.238 cm(2) (P > 0.9).

CONCLUSIONS

These results show that repeatability of acoustic reflection results can be achieved following the standard operating protocol.

SIGNIFICANCE

The study results add to the reliability of this technique in assessing the pharyngeal airway in patients with snoring and obstructive sleep apnea.

Improvement of Facial Appearance and Nocturnal Breathing with Geniotomy (Sliding Genioplasty): Report of Two Cases

This article reports on two cases of nonobese female patients who presented in an orthodontic practice complaining of dental malocclusion and facial dysharmony. Because of the observed clinically and radiographically extreme mandibular retrognathia, they were referred for a sleep study and were found to have mild sleep apnea. Surgery in the form of advancement geniotomy was offered to relieve their retroglossal obstruction, improve their nocturnal sleep, and simultaneously address their facial esthetic concerns. Advancement geniotomy is useful for sleep apneic patients with exclusively retroglossal obstruction secondary to mandibular retrognathia.