Biomechanics of the upper airway: Changing concepts in the pathogenesis of obstructive sleep apnea

Gender differences in the upper airway, craniofacial morphological and polysomnographic parameters in patients with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) is a common sleep disorder characterized by repetitive episodes of upper airway collapse during sleep associated with arousals with or without oxygen desaturation.

OBJECTIVE

This study aims to assess and analyse the morphological and neurological factors associated with obstructive sleep apnoea using polysomnography study data and two-dimensional cephalometric analysis of airway and skeletal parameters and their correlation in the patients with varying severities of obstructive sleep apnoea.

METHODS

This study included 892 patients who underwent a complete work up, including a thorough history, clinical examination, standard polysomnography study and 2D cephalometric analysis to diagnose obstructive sleep apnoea. This study divided the participants into two groups based on the AHI score from the PSG study: AHI < 15 and AHI > 15 groups. The groups were further divided into male and female groups to study the prevalence of OSA. The analysis involved 13 cephalometric parameters: Seven linear and six angular measurements. The airway parameters measured in this study were minimum posterior airway space (PAS_min), hyoid bone to the mandibular plane (H_MNP) and soft palate length (SPL). All the subjects in this study underwent a standard overnight polysomnography study at the sleep centre in Samsung Medical Center.

RESULTS

A total of 892 adult participants (M: F = 727:165, mean age: 50.6 ± 13.2 years and age range: 18-85 years). AHI >15 group was significantly older with higher BMI, NC and WC compared to the AHI < 15 groups in both male and female groups. There was statistical significance observed in N1, N3, AI, ODI, lowest saturation (%) and apnoea max length between the groups (p < .001). The arousal index (AI), especially the respiratory arousal index was considerably higher in the male group. There were significantly higher values in all the PSG parameters in the male group. In the airway parameters, hyoid bone position and soft palate length showed significant differences (p < .001), whereas the PAS did not show any differences (p = .225) between the AHI <15 and AHI >15 groups. The overall skeletal cephalometric parameters showed no significant differences between the groups, whereas the gonial angle and AB to mandibular plane angle showed significant differences in the female group (p = .028, p = .041 respectively).

CONCLUSION

The partial correlation of cephalometric parameters with AHI showed a stronger correlation between the H_MNP and AHI in both men and women. The position of the hyoid bone and the soft palate length influences the progression of OSA, especially in male patients. This study found no direct association between the minimum PAS and varying severities of OSA in men and women. We speculate that more than the craniofacial morphological factors such as the sagittal and vertical position of the maxilla and the mandible, the position of the hyoid bone might be more responsible for the severity of OSA.

Anthropometric 3D evaluation of the face in patients with sleep related breathing disorders

PURPOSE

To evaluate craniofacial measurements on 3D-stereophotogrammetry and see if particular measurements are more typical in obstructive sleep apnea (OSA) and have a correlation with its severity.

METHODS

Subjects included were adults undergoing a diagnostic polysomnography. Age, BMI, neck, abdominal and hip circumference (cm) were recorded. 3D-stereophotogrammetry was performed and landmarks were placed on the 3D-image. Different linear, angular and volume measurements were performed to gauge facial and neck anatomy. The relationship between these measurements and the severity of OSA, based on the obstructive apnea/hypopnea index (OAHI, events/h), was assessed by multiple linear regression, and adjusted for BMI and sex.

RESULTS

Of 91 subjects included (61 male), mean age was 46 ± 12 years, BMI 30.1 ± 6.5 kg/m2, OAHI 19.3 ± 18.8/h. BMI was higher (p = 0.0145) in females (32.9 ± 7.7) than in males (28.6 ± 5.3). This was also true for hip circumference (118 ± 15 vs 107 ± 10, p = 0.0006), while the neck circumference was higher (p < 0.0001) in males (41 ± 4 vs 37 ± 4). The following parameters could predict the logOAHI (r2-adjusted = 0.51): sex (p < 0.0001), BMI (p = 0.0116), neck-depth/mandibular-length (p = 0.0002), mandibular-width angle (p = 0.0118), neck-depth euclidean distance/surface distance (E/S) (p = 0.0001) and the interaction terms between sex and neck-depth/mandibular-length (p = 0.0034), sex and neck-depth E/S (p = 0.0276) and BMI and neck-depth E/S (p = 0.0118). The interaction between sex and neck-depth/mandibular-length showed a steeper linear course in females. This is also true for the interaction term BMI with neck-depth E/S in patients with a higher BMI. With a same neck-depth ratio, the OAHI is larger in men.

CONCLUSION

Measurements involving the width of the face and addressing the soft tissue in the upper neck were found to have a significant relation with OSA severity. We found remarkable differences between non-obese/obese subjects and between males and females.

Current Trends in Orthognathic Surgery

Orthognathic surgery has evolved significantly over the past century. Osteotomies of the midface and mandible are contemporaneously used to perform independent or coordinated movements to address functional and aesthetic problems. Specific advances in the past twenty years include increasing fidelity with computer-assisted planning, the use of patient-specific fixation, expanding indications for management of upper airway obstruction, and shifts in orthodontic-surgical paradigms. This review article serves to highlight the contemporary practice of orthognathic surgery.

Upper Airway Characteristics and Morphological Changes by Different MADs in OSA Adult Subjects Assessed by CBCT 3D Imaging

This study aimed to analyse the effectiveness of four different designs of the Mandibular Advancement Device (MAD) and the morphological changes on upper airway characteristics of Obstructive Sleep Apnea (OSA) patients inducted by each of them, detected by Cone Beam Computer Tomography (CBCT) 3D imaging. Twenty-two patients were recruited after an OSA diagnosis with PSG. Four different customised and titratable MADs were used and an initial CBCT scan was obtained for each patient. Six months after the end of the MAD titration phase, all the subjects performed a second PSG with the MAD in situ; the second PSG showed an Apnoea-Hypopnoea Index (AHI) of <5 or a decrease of 50% in AHI when compared with the initial AHI. Moreover, a second CBCT scan with the MAD in situ was performed. DICOM files were imported into the airway analysis software programme and the pharyngeal area around the oropharynx was highlighted. The area and volume of the oropharynx with and without the device was evaluated. A considerable improvement of the airway was observed (+33.76%), and a significant difference in the enlargement ratio between the posterior soft palate (+32.41%) and the posterior tongue (+36.96%) region was also found. The greatest increase in airway volume was achieved in patients treated with the MAD Forward and TAP (+42.77% and +41.63%, respectively). MAD therapy is effective to treat moderate to severe OSA with an increased upper airway volume. The design of the MAD can influence the effectiveness of the treatment.

The effect of surgical weight loss on upper airway fat in obstructive sleep apnoea

PURPOSE

Obesity is a reversible risk factor for obstructive sleep apnoea (OSA). Weight loss can potentially improve OSA by reducing fat around and within tissues surrounding the upper airway, but imaging studies are limited. Our aim was to study the effects of large amounts of weight loss on the upper airway and volume and fat content of multiple surrounding soft tissues.

METHODS

Participants undergoing bariatric surgery were recruited. Magnetic resonance imaging (MRI) was performed at baseline and six-months after surgery. Volumetric analysis of the airway space, tongue, pharyngeal lateral walls, and soft palate were performed as well as calculation of intra-tissue fat content from Dixon imaging sequences.

RESULTS

Among 18 participants (89% women), the group experienced 27.4 ± 4.7% reduction in body weight. Velopharyngeal airway volume increased (large effect; Cohen's d [95% CI], 0.8 [0.1, 1.4]) and tongue (large effect; Cohen's d [95% CI], - 1.4 [- 2.1, - 0.7]) and pharyngeal lateral wall (Cohen's d [95% CI], - 0.7 [- 1.2, - 0.1]) volumes decreased. Intra-tissue fat decreased following weight loss in the tongue, tongue base, lateral walls, and soft palate. There was a greater effect of weight loss on intra-tissue fat than parapharyngeal fat pad volume (medium effect; Cohen's d [95% CI], - 0.5 [- 1.2, 0.1], p = 0.083).

CONCLUSION

The study showed an increase in velopharyngeal volume, reduction in tongue volume, and reduced intra-tissue fat in multiple upper airway soft tissues following weight loss in OSA. Further studies are needed to assess the effect of these anatomical changes on upper airway function and its relationship to OSA improvement.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Predictors of uvulopalatopharyngoplasty outcomes in patients with supine predominant positional obstructive sleep apnea: a prospective observational study

BACKGROUND

It is uncertain which factors substantially influence outcomes after uvulopalatopharyngoplasty (UPPP) in patients with supine predominant obstructive sleep apnea (POSA).

OBJECTIVE

To explore the predictors of UPPP outcomes in POSA patients.

METHODS

A total of 108 patient(52 positional patients (POSA) and 56 nonpositional patients(NPP)), who underwent the revised uvulopalatopharyngoplasty (H-UPPP), were retrospectively studied. The pre-operative information of these patients, including polysomnography (PSG), and upper airway CT, were collected for analysis.

RESULTS

No difference was found in surgical success rates between POSA and NPP undergoing H-UPPP. In POSA patients, there were statistically significant differences between responders and nonresponders in body mass index (BMI), preoperative supine AHI, time of SaO2 < 90% (TS90) (all p < .05), minimal anteroposterior airway (mAP) (p = .016), minimal lateral airway (mLAT) (p = .002), minimal cross-sectional airway area (mCSA) (p < .001) at the velopharynx. mLAT (p = .014) and mCSA (p = .002) at the glossopharynx. The independent associated factors for surgical success were lower BMI (p < .001), narrowerm LAT (p = .002) and mAP (p < .001) at velopharynx, and wider mCSA (p < .001) at glossopharynx in POSA.

CONCLUSION

POSA patients with lower BMI, narrower mLAT and mAP at velopharynx, wider mCSA at glossopharynx were more likely to achieve a positive outcome with H-UPPP.

Defining Age-related OSA Features in Robin Sequence Using Polysomnographic-based Analyses of Respiratory Arousal Responses and Gas-exchange Parameters

INTRODUCTION

Robin sequence (RS) is a leading cause of obstructive sleep apnea (OSA) in newborns. Most studies have focused on understanding anatomic factors leading to OSA and changes in apnea-hypopnea index (AHI) on polysomnography (PSG) beyond the neonatal period. This study aims to define age-related OSA features between patients with RS, without RS and healthy controls using PSG-based analyses of respiratory arousal responses and gas-exchange parameters.

DESIGN

Retrospective comparison of PSG features in a total of 48 children encompassing three groups: (a) infants with RS (n = 24, <1-year old), (b) non-RS older children (1-2 years old) with severe OSA (obstructive AHI (OAHI) of ≥10 events; n = 12), and (c) control infants and children (0-2 years old) without sleep apnea (OAHI ≤1.5/h, n = 12). We examined OSA sleep-stage specific and position-specific indexes, and the relationship between OSA severity and respiratory arousal indexes (OAHI/respiratory arousal indexes).

RESULTS

OSA sleep-stage specific indexes (rapid eye movement [REM] vs non-REM[NREM]) as well as position-specific indexes (supine vs nonsupine) were similar in individuals with and without RS. Relative to the non-RS groups, infants with RS have more sustained hypoxemia (time with SpO₂ < 90%) and reduced arousal responses to OSA demonstrated by higher OAHI/respiratory arousal indexes. OAHI/respiratory arousal indexes significantly correlated with the severity of hypoxemia in infants with RS.

CONCLUSION

Infants with RS and OSA show reduced arousal responses to apneic events, which correlates with higher hypoxemia severity. OAHI/respiratory arousal indexes in RS may identify high-risk individuals with upper airway obstruction and reduced arousal protective responses.

Comparison of airway changes after maxillomandibular advancement with or without genial tubercle advancement in obstructive sleep apnea using cone-beam computed tomography

INTRODUCTION

This study compared the airway changes of patients with obstructive sleep apnea (OSA) after maxillomandibular advancement (MMA) with or without genial tubercle advancement (GTA) using cone-beam computed tomography.

METHODS

The authors retrospectively studied 26 patients with moderate to severe OSA who underwent MMA with or without GTA. Airway changes were determined from preoperative and postoperative 3-dimensional reconstructed cone-beam computed tomography images. The Wilcoxon signed rank test, Mann-Whitney U tests, and Spearman correlation coefficients were used in data analysis.

RESULTS

Airway was changed in all dimensions significantly after MMA with or without GTA. There was no significant difference in horizontal surgical changes between MMA and MMA with the GTA group. The mean increase in total airway volume was 66.8% for MMA alone and 74.7% for MMA with GTA (P = 0.39). Patients who underwent MMA had a larger percentage change of segmented upper airway volume than patients with MMA and GTA (106.6% vs 85.3%; P = 0.65). The group with MMA and GTA had a greater percentage change of segmented lower airway volume than the MMA alone group (80.1% vs 56.3%; P = 0.42).

CONCLUSIONS

Differences in airway changes between MMA alone and MMA with GTA were not statistically significant. Performing the GTA concomitantly with MMA may not cause greater improvement in the pharyngeal airway in patients with OSA compared with MMA alone.

OSAS Severity and Occlusal Parameters: A Prospective Study among Adult Subjects with Comorbidities

Introduction: OSAS is an emerging public health problem. Early diagnosis in adults with comorbidities is the gold standard to avoid complications caused by a late diagnosis. The aim of the study, part of the SLeeP@SA project, was to identify within a population with dysmetabolic comorbidities the association of occlusal clinical signs, defined by orthodontic parameters, and of the anthropometric phenotype, with the severity of OSAS. Materials and Methods: A dedicated questionnaire containing questions regarding the presence of deep bite, augmented overjet, partial edentulism, and bruxism was completed by clinic staff. OSAS was evaluated using an unattended home PSG device, which recorded the AHI value. BMI and neck circumference were also measured. The Kolmogorov-Smirnov test was performed to evaluate the association of the AHI with occlusal clinical signs. The significance was set at p ≤ 0.05. The association of AHI with BMI and neck circumference was evaluated with the Pearson correlation coefficient. Results: In total, 199 subjects were evaluated. No statistically significant association between occlusal parameters and AHI was found, while the AHI showed a positive correlation with BMI and neck circumference. The neck circumference seemed to be a better clinical predictor for OSAS severity than BMI, especially for females. Conclusions: These results highlight how the orthodontic clinical data alone are not sufficient to establish an association between occlusal anomalies and OSAS severity, but further investigation involving a specialist orthodontic diagnosis is necessary.

Restricted upper airway dimensions in patients with dentofacial deformity from juvenile idiopathic arthritis

BACKGROUND

This retrospective, cross-sectional study aimed to assess the pharyngeal airway dimensions of patients with juvenile idiopathic arthritis (JIA) and moderate/severe JIA-related dentofacial deformity (mandibular retrognathia/micrognathia), and compare the results with JIA patients with a normal mandibular appearance and a group of non-JIA patients.

METHODS

Seventy-eight patients were retrospectively included in a 1:1:1 manner as specified below. All patients had previously been treated at the Section of Orthodontics, Aarhus University, Denmark. All had a pretreatment cone beam computed tomography (CBCT). Group 1 (JIA+); 26 JIA patients with severe arthritis-related dentofacial deformity and mandibular retrognathia/micrognathia. Group 2 (JIA-); 26 JIA patients with normal mandibular morphology/position. Group 3 (Controls); 26 non-JIA subjects. Dentofacial morphology and upper airway dimensions, excluding the nasal cavity, were assessed in a validated three-dimensional (3D) fashion. Assessment of dentofacial deformity comprised six morphometric measures. Assessment of airway dimensions comprised nine measures.

RESULTS

Five morphometric measures of dentofacial deformity were significantly deviating in the JIA+ group compared with the JIA- and control groups: Posterior mandibular height, anterior facial height, mandibular inclination, mandibular occlusal inclination, and mandibular sagittal position. Five of the airway measurements showed significant inter-group differences: JIA+ had a significantly smaller nasopharyngeal airway dimension (ad2-PNS), a smaller velopharyngeal volume, a smaller minimal cross-sectional area and a smaller minimal hydraulic diameter than JIA- and controls. No significant differences in upper airway dimensions were seen between JIA- and controls.

CONCLUSION

JIA patients with severe arthritis-related dentofacial deformity and mandibular micrognathia had significantly restricted upper airway dimensions compared with JIA patients without dentofacial deformity and controls. The restrictions of upper airway dimension seen in the JIA+ group herein were previously associated with sleep-disordered breathing in the non-JIA background population. Further studies are needed to elucidate the role of dentofacial deformity and restricted airways in the development of sleep-disordered breathing in JIA.

Impact of Hyoid Position, Mandible Body Length and Anthropometric Measurements on Sleep Indices in Patients with Snoring in North Indian Population

Introduction

In Indian population, the estimated prevalence of OSA is 7.5% to 13.5%. Craniofacial anatomical variations and obesity are the major risk factors for OSA. Among the craniofacial anatomy, the neck circumference and abnormal craniofacial morphology play an important role in the pathogenesis of OSA. Obesity is the major risk factor for which waist and hip circumference and BMI are considered.

Aim

The aim of this paper was to evaluate the impact of hyoid position, mandible body length (MBL) and anthropometric measurements on sleep indices in patients with snoring in North Indian population.

Methods

In this cross-sectional study, we analyzed the position of the hyoid, mandible body length and anthropometric measurements, of 104 patients attending ENT OPD with the complaint of snoring and excessive daytime sleepiness. All subjects underwent a full overnight polysomnography. The position of the hyoid, MBL and the anthropometric measurements were compared with the sleep architecture of the subjects, and a p value < 0.05 was considered significant.

Results

A strong positive correlation is seen between the position of the hyoid, MBL and anthropometric measurements on the sleep indices in this study. Pearson 2-tailed correlation was evaluated, and upon analysis, it was found that at significance level of 0.01, obesity (BMI) is strongly correlated with overall AHI with correlation coefficient of 0.926, whereas AHI in supine position was having coefficient of 0.837 and AHI on right side and left side was almost same 0.597 and 0.575, respectively. Similarly WC is strongly correlated with AHI and RDI, having coefficient of 0.930 with both. NC and HC also showed strong positive correlation with overall AHI and RDI having correlation coefficient of 0.893, 0.926 with AHI and 0.893, 0.926 with RDI, respectively. The MBL also showed a strong positive correlation with AHI and RDI with correlation coefficient of 0.994 in both. The position of the hyoid also showed a strong positive correlation with AHI and RDI.

Conclusion

Results indicated that significant positive correlation was found between position of the hyoid, MBL and anthropometric measurements on the sleep indices in patients with snoring in North Indian population.

Surgical correction of nasal obstruction in obstructive sleep apnea improves CPAP outcomes and compliance

BACKGROUND

Although continuous positive airway pressure (CPAP) therapy curtails most of the negative impacts of obstructive sleep apnea (OSA), its efficacy is limited by its low long-term adherence. Nasal obstruction contributes to OSA pathophysiology and necessitates high CPAP titration pressures which reduce CPAP compliance.

AIM

This study aims at elucidating the outcomes of surgical correction of nasal obstruction in patients intolerant to CPAP therapy.

METHODS

Forty-nine patients with severe OSA intolerant to CPAP secondary to surgically correctable nasal obstruction were operated upon. Patients were evaluated preoperatively and at least 3 months after the surgical intervention. Subjective assessment entailed the Nasal Obstruction Symptom Evaluation score (NOSE) and the Epworth Sleepiness Scale (ESS). Objectively the patients were assessed by acoustic rhinometry and standard polysomnography.

RESULTS

Nasal surgical intervention resulted in an a statistically significant decrease in the mean NOSE score, ESS and optimal CPAP titration pressure. In addition, the minimal cross-sectional area (MCA1&2) increased significantly postoperatively. There was a positive correlation between the improvement in NOSE score as well as the MCA1& 2 and the postoperative decrease in CPAP titration pressure. Surgical correction of nasal obstruction improved CPAP outcomes and compliance in all patients.

CONCLUSIONS

Nasal surgery in OSA objectively assessed by acoustic rhinometry improved nasal obstruction with a resultant decrease in the CPAP pressure requirements. Given that lower CPAP pressures improve adherence to CPAP therapy, surgical alleviation of nasal obstruction should be considered a crucial intervention in the management armamentarium of OSA.

Obstructive Sleep Apnoea in pycnodysostosis; a three-dimensional upper airway analysis

AIM

To assess the upper airway (UA) morphology in patients with pycnodysostosis with a 3D analysis, compare results with normative data and investigate correlation of the total volume (TV) to other UA morphology variables.

MATERIALS AND METHODS

Cone beam computed tomography (CBCT) images of eight Danish patients with pycnodysostosis (4 males, 4 females with a mean age of 31.8 years, SD:16.3 years), were analysed using Mimics® (Materialise®, Belgium) and compared with a sex- and age-matched control group (6 males, 8 females with a mean age of 33.6 years, SD:18.6 years).

RESULTS

The distance from the tip of the epiglottis (E) to the Frankfurt horizontal plane (Fp) was significantly shorter in the pycnodysostosis group (p < 0.042). Regarding the cross-sectional measurements, at the "maximum constriction" (p < 0.005), the "upper airway limit" (p < 0.001) and the "lower airway limit" (p < 0.035) cross-sections were significantly smaller in the pycnodysostosis group. The volumes "nasopharynx" (p < 0.002) and "total airway" (TV) (p < 0.01) were also significantly smaller.

CONCLUSION

Patients with pycnodysostosis have a reduced total airway as well as nasopharyngeal volume compared with matched controls. Additionally, they have a reduced cross-sectional area in the upper and lower borders of the UA, and the area of maximum constriction is also reduced. These factors might explain the high prevalence of obstructive sleep apnoea in pycnodysostosis. TV is positively correlated to total length and cross-sections at all levels including the maximum constriction area as well as the anteroposterior dimension at the upper and lower airway borders.

Counterclockwise Rotational Orthognathic Surgery for the Obstructive Sleep Apnea in Class II Dentofacial Deformity: Polysomnography and 3D Computed Tomographic Analysis

ABSTRACT

Traditionally, maxillomandibular advancement is an orthognathic surgical procedure that has been used to manage obstructive sleep apnea in patients not able or willing to maintain adherence to continuous positive airway pressure therapy or for patient who are not able to adhere to treatment. However, maxillomandibular advancement often leads to unsatisfactory cosmetic results.This prospective study investigated functional and esthetic outcomes using polysomnography and 3-dimensional computed tomography, after counterclockwise rotational orthognathic surgery. We enrolled 17 patients with obstructive sleep apnea, who underwent orthognathic surgery at single institution between March 2013 and December 2018.After 12 months, the patients' mean self-rated score for facial appearance, using a 10-step visual analog scale, was 7.36. The preoperative apnea-hypopnea index and respiratory disturbance index were 34.70 and 37.45, respectively; postoperative indices were 11.60 and to 12.69, respectively (P = 0.003, 0.003). The mean posterior pharyngeal airway space increased from 5357.88 mm3 preoperatively to 8481.94 mm3 after 6 postoperative months.Counterclockwise rotational orthognathic surgery for the correction of obstructive sleep apnea turned out to be the ideal solution not only in the correction of the sleep apnea, but also in the facial esthetics.

Cone-beam computed tomography assessment of upper airway dimensions in patients at risk of obstructive sleep apnea identified using STOP-Bang scores

Purpose

The aim of this study was to identify correlations between the STOP-Bang score and upper airway dimensions using cone-beam computed tomography (CBCT) scans.

Materials and Methods

This study included 101 subjects (46 men, 55 women) from dental patients who received CBCT scans from 2014 to 2020. The patients were divided into those with a low obstructive sleep apnoea (OSA) risk (STOP-Bang score<3) and those with an intermediate to high OSA risk (STOP-Bang score≥3), and their upper airway dimensions were then analysed on CBCT scans. Comparisons between the low-risk and intermediate/high-risk groups were conducted using the t-test and the Mann-Whitney test. Correlations between the total STOP-Bang score and upper airway dimension parameters were established using Spearman correlation coefficients. P values≤0.05 were considered to indicate statistical significance.

Results

Intermediate/high-risk subjects were predominantly male and over 50 years of age, with a higher body mass index. They had significantly longer upper airways, smaller average airway volumes, and smaller widths and antero-posterior dimensions of the narrowest upper airway segment. The total upper airway length was positively correlated with the STOP-Bang score (r_s= 0.278). The average volume (r_s= −0.203) and width of the narrowest upper airway segment (r_s= −0.305) were both negatively correlated with STOP-Bang scores.

Conclusion

Subjects with higher STOP-Bang scores had upper airways that were longer, narrower, and smaller in terms of average volume. CBCT scans taken for dental patients as part of investigative procedures could be correlated with STOP-Bang scores to screen for patients at risk of OSA.

A Modified Cosmetic Genioplasty Can Affect Airway Space Positively in Skeletal Class II Patients: Studying Alterations of Hyoid Bone Position and Posterior Airway Space

BACKGROUND

Improving the posterior airway space is one of the most important functions of genioplasty. Studies have shown that the posterior airway space (PAS) can play an important role in the evaluation of obstructive sleep apnea syndrome (OSAS). The purpose of this study is to evaluate the airway safety of our modified technology by observing the impact on PAS in skeletal Class II patients without OSAS.

METHODS

We have modified a cosmetic genioplasty, which can guarantee the continuity of the lower edge of the bilateral mandible by rotating the chin segment clockwise. Fourteen patients submitted to our modified cosmetic genioplasty alone were included in the study. The facial convexity angle and the ratio of the face were measured by analyzing photographs. The position of the hyoid bone and the width of the PAS were measured by analyzing lateral cephalograms. The volume and the cross-sectional area (CSA) of the PAS were measured using 3D reconstruction. The Wilcoxon signed-rank test and paired samples t test were used to assess the significance of differences of the data (p < 0.05).

RESULTS

Soft tissue measurements were statistically different (p = 0.001) and achieved satisfactory results. The position of the hyoid bone moved up (L_X: p = 0.004; L_ML: p = 0.056) and forward (L_Y: p = 0.001; L_CV3: p = 0.016). The increase in the CSA had statistical significance (p < 0.005). There were significant statistical differences in the total airway volume and hypopharynx (p = 0.001), except in the oropharynx (p = 0.096).

CONCLUSIONS

Our modified genioplasty not only achieved better cosmetic results by ensuring the continuity of the lower edge of the bilateral mandible but also exerted a significant positive impact on the posterior airway space for patients with skeletal class II, thus helping reduce the prevalence of OSAS. We hence suggest performing this modified cosmetic genioplasty on the skeletal class II patients with/without OSAS if necessary.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Correlation study of increase of pharyngeal airway space after mandibular advancement, taking natural head position into consideration

The increase in the pharyngeal airway space after mandibular advancement has not been well explained, and in this study we aimed to show whether there is a correlation in the increase of pharyngeal airway space as a consequence of the mandibular advancement or of the relative change between the mandibular position and the natural head position (NHP). Fifteen patients who had bilateral sagittal split osteotomy for mandibular advancement with or without genioplasty were studied retrospectively. The primary variables of mandibular position, NHP, and pharyngeal airway space were measured in three dimensions using preoperative and postoperative cone-beam computed tomographic datasets and were compared using the paired t test. The secondary variable of pharyngeal airway space was defined as the square root of the mean cross-sectional area (CSA^1/2) of the pharyngeal airway space. Pearson's correlation coefficient was used to find out whether there was a correlation between the change in CSA^1/2 and the change in mandibular position, or the relative change between the mandibular position and the NHP. Volumes and minimal cross-sectional areas were increased in the pharyngeal airway space, and lengths of airways decreased. Correlation existed only between the increase in CSA^1/2 and the relative change between the mandibular position and NHP. The increase in pharyngeal airway space after mandibular advancement correlated with the relative changes between the mandibular position and the NHP.

High-Resolution Pulse Oximetry and Titration of a Mandibular Advancement Device for Obstructive Sleep Apnea

Background: To determine whether utilizing high-resolution pulse oximetry is a viable method for evaluating the successful titration of oral appliances for the treatment of obstructive sleep apnea (OSA) patients.

Methods: Of 136 consecutive potentially eligible OSA patients, 133 were fitted with mandibular advancement devices (MADs), and 101 completed all phases of treatment. The vertical and horizontal dimensions of the appliances were adjusted based on three-nights with a high-resolution pulse oximeter during sleep and associated software after each adjustment.

Results: Significant improvements in OSA severity were apparent in patients at all disease severity levels. High-resolution pulse oximetry provided reliable guidance in the titration process of mandibular advancement therapy. In 67 subjects (66.3%), a respiratory event index of <5 events/hour was achieved.

Conclusions: OSA can be effectively treated with a MAD at any severity level, and high-resolution pulse oximetry provides critical information to guide oral appliance titration.

Establishing a Patent Nasal Passage in Obstructive Sleep Apnea

The role of the nose in the pathophysiology and treatment of sleep-disordered breathing (SDB) has not been fully understood and might have been underestimated. In the Staring resistor model, the nose is regarded as a passive and noncollapsible tube, but recent studies have shown that the nose might participate more in the pathophysiology of SDB as anatomic, neuromuscular, and respiratory factors than previously reported, which might imply the nose is an active noncollapsible tube. The roles of nasal treatments for OSA are not only the reduction of AHI, but also the improvement of subjective symptoms, sleep quality, and CPAP adherence.

Principles of Urgent Management of Acute Airway Obstruction

Recognizing and acting early on airway compromise reduces morbidity and mortality in patients with airway obstruction. Causes include foreign bodies, toxic/hot fumes, difficult intubation, laryngeal spasm, and tumors. Before definitive control of the airway is possible, provide 100% oxygen with a tightly fitting mask to optimize body oxygen stores. Pulse oximetry is a poor indicator of airway compromise; a decreasing arterial hemoglobin oxygen saturation is a late sign of impending hypoxemia. Basic airway maneuvers improve the patency of an obstructed airway. Getting help from an anesthetist early is a priority.

Three-dimensional morphological evaluation of the hard palate in Korean adults with mild-to-moderate obstructive sleep apnea

Objective

The purpose of this study was to evaluate differences in three-dimensional (3D) morphology of the hard palate between Korean adults with and without mild-to-moderate obstructive sleep apnea (OSA) using cone-beam computed tomographic (CBCT) data.

Methods

The protocol for the two-dimensional (2D) and 3D mathematical modeling was established by analyzing CBCT images of 30 adults with OSA and 30 matched controls without OSA, using MIMICS software. The linear and angular measurements were also determined using this software. The measurements were repeated for 30 palates, by the same operator, to assess reliability.

Results

The palates of OSA patients were higher in the posterior part and narrower in the anterior-superior part than those of the control group (p < 0.05). The nasal cavities of patients with OSA were narrower (p < 0.05) than those of controls. The increasing angle of the first molar palatal root is a compensation of the upper dental arch to improve occlusion. However, for most palatal measurements, there were no significant differences between the OSA and control groups (p > 0.05). The results of 2D and 3D mathematical models were consistent for linear and angular measurements, indicating that 2D and 3D mathematical modeling of the palate is a reliable methodology.

Conclusions

OSA is a multifactorial disease; the palates of adults with mild-to-moderate OSA do not have specific morphological features distinct from those of healthy controls.

Three-dimensional photography for the evaluation of facial profiles in obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Craniofacial structure is an important determinant of obstructive sleep apnoea (OSA) syndrome risk. Three-dimensional stereo-photogrammetry (3dMD) is a novel technique which allows quantification of the craniofacial profile. This study compares the facial images of OSA patients captured by 3dMD to three-dimensional computed tomography (3-D CT) and two-dimensional (2-D) digital photogrammetry. Measurements were correlated with indices of OSA severity.

METHODS

Thirty-eight patients diagnosed with OSA were included, and digital photogrammetry, 3dMD and 3-D CT were performed. Distances, areas, angles and volumes from the images captured by three methods were analysed.

RESULTS

Almost all measurements captured by 3dMD showed strong agreement with 3-D CT measurements. Results from 2-D digital photogrammetry showed poor agreement with 3-D CT. Mandibular width, neck perimeter size and maxillary volume measurements correlated well with the severity of OSA using all three imaging methods. Mandibular length, facial width, binocular width, neck width, cranial base triangle area, cranial base area 1 and middle cranial fossa volume correlated well with OSA severity using 3dMD and 3-D CT, but not with 2-D digital photogrammetry.

CONCLUSION

3dMD provided accurate craniofacial measurements of OSA patients, which were highly concordant with those obtained by CT, while avoiding the radiation associated with CT.

Pre-optimization of spinal surgery patients: Development of a neurosurgical enhanced recovery after surgery (ERAS) protocol

OBJECTIVE

Despite surgical, technological, medical, and anesthetic improvements, patient outcomes following elective neurosurgical procedures can be associated with high morbidity. Enhanced recovery after surgery (ERAS) protocols are multimodal care pathways designed to optimize patient outcomes by addressing pre-, peri-, and post-operative factors. Despite significant data suggesting improved patient outcomes with the adoption of these pathways, development and implementation has been limited in the neurosurgical population.

METHODS/RESULTS

This study protocol was designed to establish the feasibility of a randomized controlled trial to assess the efficacy of implementation of an ERAS protocol on the improvement of clinical and patient reported outcomes and patient satisfaction scores in an elective inpatient spine surgery population. Neurosurgical patients undergoing spinal surgery will be recruited and randomly allocated to one of two treatment arms: ERAS protocol (experimental group) or hospital standard (control group). The experimental group will undergo interventions at the pre-, peri-, and post-operative time points, which are exclusive to this group as compared to the hospital standard group.

CONCLUSIONS

The present proposal aims to provide supporting data for the application of these specific ERAS components in the spine surgery population and provide rationale/justification of this type of care pathway. This study will help inform the design of a future multi-institutional, randomized controlled trial.

RESULTS

of this study will guide further efforts to limit post-operative morbidity in patients undergoing elective spinal surgery and to highlight the impact of ERAS care pathways in improving patient reported outcomes and satisfaction.

A new simple three-dimensional method to characterize upper airway in orthognathic surgery patient

OBJECTIVES

To develop and validate a new reproducible 3D upper airway analysis based on skeletal structures not involved in the modification, which occur during orthognathic surgery.

METHODS

From retrospective cohort of orthognathic surgically treated patients, pre- and postsurgical CBCT-scans of 10 post-pubertal patients were randomly selected. Two operators identified the landmarks, calculated the airway volumes, cross sections and linear measurements on the 10 scans twice at two different time intervals. Statistical analysis included test for normal distribution, technical error measurements, and intra- and inter-observers reliability.

RESULTS

Intra- and inter-observer reliability was excellent for volumes and cross sections. The entire data sets exhibited normal distribution. Technical error of measurements showed an error in the range of 1.6 to 10.2% for volume, 1.6 to 12.2% for cross-sectional measurements, and 0.3 to 2.5% for linear measurements. No systematic errors were detected.

CONCLUSIONS

This new proposed definition of upper airway boundaries was shown to be technical feasible and tested to be reliable in measuring upper airway in patients undergoing orthognathic surgery.

Upper Airway Changes After Mandibular Setback and/or Advancement Genioplasty in Obese Patients

PURPOSE

Orthognathic surgeries, such as bilateral sagittal split ramus osteotomy (BSSO) and genioplasty, can influence the pharyngeal airway space (PAS) and this has been supported by previous studies. The purpose of this study was to assess changes of the PAS in patients with a high body mass index (BMI) likely to have narrow airways before and after setback BSSO with or without advancement genioplasty surgery by 3-dimensional computed tomography.

MATERIALS AND METHODS

Thirty-five adults with a BMI of at least 24.0 kg/m² were treated from 2010 to 2016. Samples were grouped mandibular setback (group A; n = 11), advancement genioplasty (group B; n = 12), and mandibular setback plus advancement genioplasty (group C; n = 12). Computed tomograms were obtained 1 week preoperatively (T0), 1 week postoperatively (T1), and at least 1 year postoperatively (T2). The area of the posterior nasal spine and posterior plane (PPA), the soft palate plane (SPA), the plane of the most posterior point of the tongue base (PTA), the plane of the root of the epiglottis (EA), and the volumes of the palatopharyngeal part (VP), oropharyngeal part (VO), glossopharyngeal part (VG), and laryngeal part (VL) were measured and compared within groups using analysis of variance. The P value was set at .05.

RESULTS

In group A, all results showed statistically significant differences (P < .05) from T0 to T2 except for VO, VG, VL, SPA, PTA, and EA. In group B, VO, VG, VL, SPA, PTA, and EA showed statistically significant increases (P < .05) from T0 to T2. The hyoid at T2 showed significant advancement compared with T0 (P < .05). In group C, there were statistically significant decreases (P < .05) from T0 to T1 for VG, VL, PTA, and EA.

CONCLUSION

In adults with a high BMI, mandibular setback BSSO could decrease the PAS, whereas advancement genioplasty could enlarge the PAS, after surgery. Therefore, undergoing advancement genioplasty concurrently with mandibular setback BSSO could help in lessening the negative effects of a PAS decrease.

Computational fluid dynamics study of the pharyngeal airway space before and after mandibular setback surgery in patients with mandibular prognathism

The purpose of this study was to investigate the relationship between the pressure drop in the pharyngeal airway space (ΔP_PAS) and the minimum cross-sectional area (minCSA) of the pharyngeal airway before and after mandibular setback surgery using computational fluid dynamics, in order to prevent iatrogenic obstructive sleep apnoea. Eleven patients with mandibular prognathism underwent bilateral sagittal split osteotomy for mandibular setback. Three-dimensional models of the upper airway were reconstructed from preoperative and postoperative computed tomography images, and simulations were performed using computational fluid dynamics. ΔP_PAS and the minCSA of the pharyngeal airway were calculated, and the relationship between them was evaluated by non-linear regression analysis. In all cases, the minCSA was found at the level of the velopharynx. After surgery, ΔP_PAS increased significantly and the minCSA decreased significantly. The non-linear regression equation expressing the relationship between these variables was ΔP_PAS=3.73×minCSA^-2.06. When the minCSA was <1cm², ΔP_PAS increased greatly. The results of this study suggest that surgeons should consider bimaxillary orthognathic surgery rather than mandibular setback surgery to prevent the development of iatrogenic obstructive sleep apnoea when correcting a skeletal class III malocclusion.

Nasal Surgery for Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea is a common condition, primarily caused by narrowing of the nasal and pharyngeal airway. Treatment with continuous positive airway pressure (CPAP) is considered the first line of therapy, but long-term compliance is only about 40%, often because of nasal obstruction. Any nasal obstruction can worsen CPAP compliance. Treatment of the nasal obstruction with topical nasal steroid sprays or nasal dilators has been shown to improve sleep disordered breathing. Surgical treatment of nasal obstruction, has been shown to improve sleep disordered breathing, as well as CPAP requirement and compliance with CPAP.

Cone-beam CT analysis of patients with obstructive sleep apnea compared to normal controls

Purpose

To evaluate the upper airway dimensions of obstructive sleep apnea (OSA) and control subjects using a cone-beam computed tomography (CBCT) unit commonly applied in clinical practice in order to assess airway dimensions in the same fashion as that routinely employed in a clinical setting.

Materials and Methods

This was a retrospective analysis utilizing existing CBCT scans to evaluate the dimensions of the upper airway in OSA and control subjects. The CBCT data of sixteen OSA and sixteen control subjects were compared. The average area, average volume, total volume, and total length of the upper airway were computed. Width and anterior-posterior (AP) measurements were obtained on the smallest axial slice.

Results

OSA subjects had a significantly smaller average airway area, average airway volume, total airway volume, and mean airway width. OSA subjects had a significantly larger airway length measurement. The mean A-P distance was not significantly different between groups.

Conclusion

OSA subjects have a smaller upper airway compared to controls with the exception of airway length. The lack of a significant difference in the mean A-P distance may indicate that patient position during imaging (upright vs. supine) can affect this measurement. Comparison of this study with a future prospective study design will allow for validation of these results.

Inferior Turbinate Size and CPAP Titration Based Treatment Pressures: No Association Found among Patients Who Have Not Had Nasal Surgery

Objective. To evaluate the effect of turbinate sizes on the titrated continuous positive airway pressure (CPAP) therapeutic treatment pressures for patients with obstructive sleep apnea (OSA) who have not had nasal surgery. Study Design. Retrospective case series. Methods. A chart review was performed for 250 consecutive patients. Results. 45 patients met inclusion criteria. The mean ± standard deviation (M ± SD) for age was 54.6 ± 22.4 years and for body mass index was 28.5 ± 5.9 kg/m(2). The Spearman's rank correlation coefficient (r s ) between CPAP therapeutic treatment pressures and several variables were calculated and were weakly correlated (age r s = 0.29, nasal obstruction r s = -0.30), moderately correlated (body mass index r s = 0.42 and lowest oxygen saturation r s = -0.47), or strongly correlated (apnea-hypopnea index r s = 0.60 and oxygen desaturation index (r s = 0.62)). No statistical significance was found with one-way analysis of variance (ANOVA) between CPAP therapeutic treatment pressures and inferior turbinate size (right turbinates p value = 0.2012, left turbinate p value = 0.3064), nasal septal deviation (p value = 0.4979), or mask type (p value = 0.5136). Conclusion. In this study, CPAP titration based therapeutic treatment pressures were not found to be associated with inferior turbinate sizes; however, the CPAP therapeutic treatment pressures were strongly correlated with apnea-hypopnea index and oxygen desaturation index.

[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.

Retrospective study of changes in pharyngeal airway space and position of hyoid bone after mandibular setback surgery by cephalometric analysis

Background

The posterior movement of mandible was known as the main cause of the changes in the pharyngeal airway space (PAS) and the postoperative obstructive sleep apnea (OSA). The purpose of this study was to know the changes of PAS and position of hyoid bone.

Methods

Lateral cephalographies of 13 patients who had undergone sagittal split ramus osteotomy (SSRO) setback surgery were taken preoperatively (T1), postoperatively within 2 months (T2), and follow-up after 6 months or more (T3). On the basis of F-H plane, diameters of nasopharynx, oropharynx, and hypopharynx were measured. The movements of the soft palate, tongue, and hyoid bone were also measured.

Results

The amount of mandible setback was 7.5 ± 3.8 mm. In the measurements of PAS, there was a statistically significant decrease of 2.8 ± 2.5 mm in nasopharynx (P < 0.01), and 1.7 ± 2.4 mm in oropharynx (P < 0.01) were observed after surgery. The hypopharynx decreased 1.0 ± 2.1 mm after surgery and continuously decreased 1.0 ± 2.8 mm at follow-up. The changes in hyoid bone position showed the posterior movement only after surgery and posteroinferior movement at follow-up.

Conclusions

The PAS such as nasopharynx, oropharynx, and hypopharynx showed relatively high correlation with the amount of mandibular setback. The change of resistance in upper airway may be important for the prevention of OSA after mandibular setback surgery.

Is Le Fort I Osteotomy Associated With Maxillary Sinusitis?

PURPOSE

The purpose of the present study was to investigate the association between Le Fort I osteotomy and the anatomic, radiologic, and symptomatic modifications of the maxillary sinus.

MATERIALS AND METHODS

Subjects who had undergone Le Fort I osteotomy from January 2008 to December 2013 were enrolled in a retrospective cohort study. The eligibility criteria were the availability of a cone beam computed tomography (CBCT) scan taken before and 12 to 24 months after the procedure. The exclusion criteria were the unavailability of CBCT scans, the use of tobacco, and previous orthognathic procedures. The primary predictor variable was time (pre-vs postoperative). The primary outcome variables were the sinus volume, mucosal thickening, iatrogenic alterations in the sinus anatomy, and rhinosinusitis symptoms, evaluated using the Sino-Nasal Outcome 20-item Test (SNOT-20). Descriptive statistics were computed for each variable, and paired analyses were used to compare the pre- and postoperative values.

RESULTS

The data from 64 subjects (mean age 27; 59.4% were female; median follow-up 32.4 months, range 13 to 66 months) were studied. Postoperatively, 1.6% of the sample (0% preoperatively) had moderate-to-severe and 15.6% (3.1% preoperatively) had mild-to-moderate sinusitis symptoms. The rest of the sample presented with mild to no symptoms. The increase in the SNOT scores after surgery was statistically significant (P = .016). Radiologic evidence of postoperative inflammatory processes affecting the paranasal sinuses was found in 27.3% of the sinuses (9.4% preoperatively). The postoperative Lund-Mackay scores were significantly greater (P = .0005). A 19% decrease was found in the mean postoperative sinus volume, with a 37% incidence of iatrogenic injury.

CONCLUSIONS

The study results indicate that Le Fort I osteotomies can have an important impact on sinus health. The postoperative radiologic evidence of maxillary sinus inflammatory processes and the incidence of rhinosinusitis symptoms and iatrogenic damage in these patients have led us to conclude that CBCT scans and the SNOT-20 questionnaire should be used routinely during postoperative monitoring. Larger long-term studies are warranted to clarify the postoperative outcomes and complications.

The effect of nasal surgery on continuous positive airway pressure device use and therapeutic treatment pressures: a systematic review and meta-analysis

BACKGROUND

The relationship between nasal surgery and its effect on continuous positive airway pressure (CPAP) device therapeutic treatment pressures and CPAP device use has not been previously systematically examined.

STUDY OBJECTIVES

To conduct a systematic review and meta-analysis evaluating the effect of isolated nasal surgery on therapeutic CPAP device pressures and use in adults with obstructive sleep apnea (OSA).

METHODS

MEDLINE, Scopus, Web of Science, and The Cochrane Library were searched through July 15, 2014. The MOOSE consensus statement and PRISMA statement were followed.

RESULTS

Eighteen studies (279 patients) reported CPAP data after isolated nasal surgery. Seven studies (82 patients) reported preoperative and postoperative mean therapeutic CPAP device pressures and standard deviations (SD), which reduced from 11.6 ± 2.2 to 9.5 ± 2.0 centimeters of water pressure (cwp) after nasal surgery. Pooled random effects analysis demonstrated a statistically significant pressure reduction, with a mean difference (MD) of -2.66 cwp (95% confidence interval (CI), -3.65 to -1.67); P < 0.00001. Eleven studies (153 patients) reported subjective, self-reported data for CPAP use; and a subgroup analysis demonstrated that 89.1% (57 of 64 patients) who were not using CPAP prior to nasal surgery subsequently accepted, adhered to, or tolerated it after nasal surgery. Objective, device meter-based hours of use increased in 33 patients from 3.0 ± 3.1 to 5.5 ± 2.0 h in the short term (<6 mo of follow-up).

CONCLUSION

Isolated nasal surgery in patients with OSA and nasal obstruction reduces therapeutic CPAP device pressures and the currently published literature's objective and subjective data consistently suggest that it also increases CPAP use in select patients.

Upper airway imaging in sleep-disordered breathing

Our understanding of sleep-disordered breathing has evolved considerably over the past three decades, and clinical techniques of evaluation have progressed tremendously. Myriad imaging techniques are now available for the physician to approach the dynamic features resulting in turbulent airflow, upper airway narrowing or collapse at different levels. Controversy exists in the choice of investigations, probably because the best evaluation should be a combination of different techniques. Physical, radiographic, endoscopic and acoustic evaluations could be integrated to understand the degree and the levels of airway reduction and/or obstruction in a given patient. This review focuses on cost-effective and easily implemented techniques in daily practice, allowing quality assessment of the dynamic anatomy of sleep-disordered breathing: cephalometry, (sleep-)endoscopy and acoustic reflectometry of the upper airway.

Velopharyngeal anatomy in patients with obstructive sleep apnea versus normal subjects

PURPOSE

Obesity can cause disturbed breathing and is one of the most significant risk factors for obstructive sleep apnea (OSA). However, the anatomic basis of OSA and, specifically, the anatomic mechanisms leading from obesity to OSA are still unclear. We examined the anatomic features of the velopharynx in patients with OSA versus those without in correlation with the body mass index (BMI), age, history of snoring, and OSA severity and re-evaluated the contribution of adding a frontal view to the cephalometric analysis of patients with OSA.

MATERIALS AND METHODS

Lateral and frontal cephalometric measurements were taken to assess the velopharyngeal anatomic features of 306 men with various degrees of OSA and 64 men without OSA and without a history of snoring. The demographic, polysomnographic, and cephalometric features were compared.

RESULTS

The patients with OSA had an increased pharyngeal length, thicker velum, a thicker posterior pharyngeal wall, a reduced pharyngeal width, and a consequent narrowing of the pharyngeal lumen. As the BMI increased, the OSA severity increased. Also, in parallel, the velum and posterior pharyngeal wall thickness increased and the pharyngeal width decreased. Three types of velopharyngeal narrowing, with an increased occurrence in severe degrees of OSA, were identified: bottle shape, hourglass shape, and tube shape. These aerodynamically unfavorable changes might cause increased upper airway resistance, explaining the development of both OSA and hypoventilation syndrome in obese patients.

CONCLUSIONS

Velopharyngeal thickening and lumen narrowing were shown to be features of obese men with OSA. However, these features developed only above a threshold BMI value. The combination of frontal and lateral cephalometry is important for comprehensive evaluation of patients with OSA.

Sleep apnea and cervical spine pathology

PURPOSE

Sleep apnea is a multi-factorial disease with a variety of identified causes. With its close proximity to the upper airway, the cervical spine and its associated pathologies can produce sleep apnea symptoms in select populations. The aim of this article was to summarize the literature discussing how cervical spine pathologies may cause sleep apnea.

METHODS

A search of the PubMed database for English-language literature concerning the cervical spine and its relationship with sleep apnea was conducted. Seventeen published papers were selected and reviewed.

RESULTS

Single-lesion pathologies of the cervical spine causing sleep apnea include osteochondromas, osteophytes, and other rare pathologies. Multifocal lesions include rheumatoid arthritis of the cervical spine and endogenous cervical fusions. Furthermore, occipital-cervical misalignment pre- and post-cervical fusion surgery may predispose patients to sleep apnea.

CONCLUSIONS

Pathologies of the cervical spine present significant additional etiologies for producing obstructive sleep apnea in select patient populations. Knowledge of these entities and their pathophysiologic mechanisms is informative for the clinician in diagnosing and managing sleep apnea in certain populations.

How does obstructive sleep apnoea evolve in syndromic craniosynostosis? A prospective cohort study

OBJECTIVE

To describe the course of obstructive sleep apnoea syndrome (OSAS) in children with syndromic craniosynostosis.

DESIGN

Prospective cohort study.

SETTING

Dutch Craniofacial Centre from January 2007 to January 2012.

PATIENTS

A total of 97 children with syndromic craniosynostosis underwent level III sleep study. Patients generally undergo cranial vault remodelling during their first year of life, but OSAS treatment only on indication.

MAIN OUTCOME MEASURES

Obstructive apnoea-hypopnoea index, the central apnoea index and haemoglobin oxygenation-desaturation index derived from consecutive sleep studies.

RESULTS

The overall prevalence of OSAS in syndromic craniosynostosis was 68% as defined by level III sleep study. Twenty-three patients were treated for OSAS. Longitudinal profiles were computed for 80 untreated patients using 241 sleep studies. A mixed effects model showed higher values for the patients with midface hypoplasia as compared to those without midface hypoplasia (Omnibus likelihood ratio test=7.9). In paired measurements, the obstructive apnoea-hypopnoea index (Z=-3.4) significantly decreased over time, especially in the first years of life (Z=-3.3), but not in patients with midface hypoplasia (Z=-1.5). No patient developed severe OSAS during follow-up if it was not yet diagnosed during the first sleep study.

CONCLUSIONS

OSAS is highly prevalent in syndromic craniosynostosis. There is some natural improvement, mainly during the first 3 years of life and least in children with Apert or Crouzon/Pfeiffer syndrome. In the absence of other co-morbid risk factors, it is highly unlikely that if severe OSAS is not present early in life it will develop during childhood. Ongoing clinical surveillance is of great importance and continuous monitoring for the development of other co-morbid risk factors for OSAS should be warranted.

Central and peripheral factors contributing to obstructive sleep apneas

Apnea, the cessation of breathing, is a common physiological and pathophysiological phenomenon. Among the different forms of apnea, obstructive sleep apnea (OSA) is clinically the most prominent manifestation. OSA is characterized by repetitive airway occlusions that are typically associated with peripheral airway obstructions. However, it would be an oversimplification to conclude that OSA is caused by peripheral obstructions. OSA is the result of a dynamic interplay between chemo- and mechanosensory reflexes, neuromodulation, behavioral state and the differential activation of the central respiratory network and its motor outputs. This interplay has numerous neuronal and cardiovascular consequences that are initially adaptive but in the long-term become major contributors to morbidity and mortality. Not only OSA, but also central apneas (CA) have multiple, and partly overlapping mechanisms. In OSA and CA the underlying mechanisms are neither "exclusively peripheral" nor "exclusively central" in origin. This review discusses the complex interplay of peripheral and central nervous components that characterizes the cessation of breathing.

Upper Airway Anatomical Changes after Velopharyngeal Surgery in Obstructive Sleep Apnea Patients with Small Tonsils

Objective

To evaluate the relationships between anatomical changes and treatment outcomes after velopharyngeal surgery in obstructive sleep apnea (OSA) patients with small tonsils (grade 0-2 on the Brodsky scale).

Study Design

Case series with planned data collection.

Setting

University medical center.

Subjects and Methods

Thirty-six OSA patients with small tonsils underwent velopharyngeal surgery including revised uvulopalatopharyngoplasty with uvula preservation and transpalatal advancement pharyngoplasty. Pre- and postoperative upper airway 3-dimensional computed tomography and polysomnography findings were obtained for comparison and analysis.

Results

The overall apnea hypopnea index (AHI) decreased from 56.8 (interquartile range, 37.5-70.1) preoperatively to 16.1 (10.8-33.5) postoperatively ( P < .001). The change in minimal cross-sectional area of the velopharynx (VmCSA) was independently associated with the change in AHI ( P = .001, R2 = 0.271). Preoperative VmCSA was the only preoperative anatomical variable that was an independent predictor of change in VmCSA ( P = .009, R2 = 0.184). Postoperative VmCSA was independently associated with postoperative AHI ( P < .001, R2 = 0.341).

Conclusion

In patients with small tonsils, an adequate increase in VmCSA is associated with a successful outcome after surgery. Patients with a relatively small preoperative VmCSA are more likely to have favorable anatomical changes after surgery.