Pharyngeal airway morphology in healthy individuals and in obstructive sleep apnea patients treated with maxillomandibular advancement: a comparative study

Cephalometric Screening Assessment for Superior Airway Space Narrowing-Added Value of Three-Dimensional Imaging

Background: Assessing the morphology of the superior airway space is a crucial diagnostic step in the treatment planning of patients with obstructive sleep apnea syndrome (OSAS) or prior to orthognathic surgery. The aim of this study is to evaluate the necessary scope of a two-dimensional cephalometric assessment and the necessity of three-dimensional imaging in the identification of superior airway space narrowing (SASN). Methods: The computed tomography studies of 100 non-obese, non-OSAS patients were evaluated and analyzed retrospectively. Multiplanar reconstructions were created and underwent cephalometric evaluation. The three-dimensional superior airway morphology was segmented and measured for the minimal cross-sectional area (Amin) and volume (V0). Patients were grouped according to Amin < 80 mm2 and V0 < 12 cm3. Cephalometric parameters (CPs) were analyzed according to Amin and V0 with an unpaired t-test, Pearson correlation, and ROC-curve analysis. Results: The CPs regarding sagittal airway space dimensions (IPAS, MPAS, SPAS) and mandibular body length (GoGn) show the strongest correlation to the three-dimensional minimal cross-sectional area (Amin). The ROC-curve analysis classifying for SASN led to an AUC of 0.86 for IPAS, 0.87 for MPAS, 0.88 for SPAS, and 0.63 for GoGn. Three-dimensional imaging may further improve the diagnostic accuracy in the identification of SASN for IPAS below 13.5 mm, MPAS below 10.2 mm, SPAS below 12.5 mm, and GoGn below 90.2 mm. Conclusions: Two-dimensional cephalometric sagittal airway space diameters and mandibular body length are useful initial screening parameters in the identification of superior airway space narrowing. Nevertheless, as the correlation of two-dimensional cephalometric parameters with three-dimensional upper airway space narrowing is varying and highly dependent on acquisition circumstances, indications for three-dimensional imaging, if possible, in the supine position to evaluate upper airway space morphology should be provided generously, especially in patients with low but normal airway space parameters in two-dimensional cephalometry.

Methodological parameters for upper airway assessment by cone-beam computed tomography in adults with obstructive sleep apnea: a systematic review of the literature and meta-analysis

BACKGROUND

A reliable method for analyzing the upper airway (UA) remains a challenge. This study aimed to report the methods for UA assessment using cone-beam computed tomography (CBCT) in adults with obstructive sleep apnea (OSA).

METHODS

We performed a systematic review (PROSPERO #CRD42021237490 and PRISMA checklist) that applied a search strategy to seven databases and grey literature.

RESULTS

In 29 studies with moderate-to-high risk of bias, investigators mostly reported the body position during CBCT (upright or supine) and hard tissue references, diverging in UA delimitation and terminologies. The meta-analysis showed two subgroups (upright and supine), and no statistical differences were identified (p = 0.18) considering the UA area. The volume in the OSA group was smaller than that in the control group (p < 0.003 and Cohen's d =  - 0.81) in the upright position. Patients with OSA showed smaller anteroposterior dimensions than the control group and were not affected by the position during image acquisition (p = 0.02; Cohen's d =  - 0.52). The lateral measurements were also lower in the OSA group (supine) (p = 0.002; Cohen's d =  - 0.6).

CONCLUSIONS

Patients with OSA showed smaller UA measurements in the upright (volume) and supine (lateral dimension) positions. The anteroposterior dimension was also reduced in patients with OSA compared to the control group, regardless of the position during CBCT acquisition.

A semi-automatic approach for longitudinal 3D upper airway analysis using voxel-based registration

OBJECTIVES

To propose and validate a reliable semi-automatic approach for three-dimensional (3D) analysis of the upper airway (UA) based on voxel-based registration (VBR).

METHODS

Post-operative cone beam computed tomography (CBCT) scans of 10 orthognathic surgery patients were superimposed to the pre-operative CBCT scans by VBR using the anterior cranial base as reference. Anatomic landmarks were used to automatically cut the UA and calculate volumes and cross-sectional areas (CSA). The 3D analysis was performed by two observers twice, at an interval of two weeks. Intraclass correlations and Bland-Altman plots were used to quantify the measurement error and reliability of the method. The relative Dahlberg error was calculated and compared with a similar method based on landmark re-identification and manual measurements.

RESULTS

Intraclass correlation coefficient (ICC) showed excellent intra- and inter-observer reliability (ICC ≥ 0.995). Bland-Altman plots showed good observer agreement, low bias and no systematic errors. The relative Dahlberg error ranged between 0.51 and 4.30% for volume and 0.24 and 2.90% for CSA. This was lower when compared with a similar, manual method. Voxel-based registration introduced 0.05-1.44% method error.

CONCLUSIONS

The proposed method was shown to have excellent reliability and high observer agreement. The method is feasible for longitudinal clinical trials on large cohorts due to being semi-automatic.

Three-dimensional pharyngeal airway space changes after bimaxillary advancement

INTRODUCTION

The probability of improvement in the upper airway space (UAS) with orthognathic surgery should be considered during the surgical-orthodontic treatment decision, providing not only an esthetic, but also a functional benefit for the patient.

OBJECTIVE

The purpose of this study was to evaluate the 3D changes in the upper airway space after maxillomandibular advancement surgery (MMA).

METHODS

A retrospective analysis of 56 patients, 21 male and 35 female, with a mean age of 35.8 ± 10.7 years, who underwent MMA was performed. Pre- and postoperative cone-beam computed tomography scans (CBCT) were obtained for each patient, and the changes in the UAS were compared using Dolphin Imaging 11.7 software. Two parameters of the pharyngeal airway space (PAS) were measured: airway volume (AV) and minimum axial area (MAA). Paired t-test was used to compare the data between T0 and T1, at 5% significance level.

RESULTS

There was a statistically significant increase in the UAS. Bimaxillary advancement surgery increased the AV and the MAA, on average, by 73.6 ± 74.75% and 113.5 ± 123.87%, respectively.

CONCLUSION

MMA surgery tends to cause significant increase in the UAS; however, this increase is largely variable.

Upper Airway Changes Following Different Orthognathic Surgeries, Evaluated by Cone Beam Computed Tomography: A Systematic Review and Meta-analysis

PURPOSE

This study sought to assess the upper airway changes following different orthognathic surgeries using cone-beam computed tomography.

METHODS

An electronic search of the literature was conducted in major electronic databases including Medline (PubMed), Web of Science, Scopus, and Open Grey for articles published up to January 20, 2018. Human studies that evaluated the changes in the volume and minimum cross-sectional area of the upper airway or its subdivisions in patients who had undergone orthognathic surgery by use of cone-beam computed tomography were included. Manual search of the bibliographies of the included articles was also conducted. The included studies underwent risk of bias assessment.

RESULTS

A total of 1330 articles were retrieved. After excluding the duplicates and irrelevant articles, 41 studies fulfilled the eligibility criteria for this systematic review; out of which, 30 entered the meta-analysis. The majority of studies had a medium risk of bias. Mandibular setback, and maxillary advancement + mandibular setback decreased the volume of the upper airway (-6042.87 mm3 and -1498.78 mm3, respectively) and all its subdivisions in long-term (>3 months), except for the nasopharynx, the volume of which increased following maxillary advancement + mandibular setback. Mandibular advancement and maxillomandibular advancement both increased the upper airway volume in long-term (7559.38 mm3 and 7967.06 mm3, respectively); however, only the changes after the former procedure were significant. The minimum cross-sectional area increased after maxillomandibular advancement (161.43 mm2), and decreased following maxillary advancement + mandibular setback (-23.79 mm2) in long-term.

CONCLUSION

There is moderate evidence to suggest that mandibular advancement is the only orthognathic movement that provides a statistically significant change in long-term upper airway volume.

The correlation of maxillomandibular advancement and airway volume change in obstructive sleep apnea using cone beam computed tomography

The purpose of this retrospective study was to evaluate the correlation of maxillomandibular advancement (MMA) and airway volume changes in patients with obstructive sleep apnea (OSA), and to determine the surgical skeletal movements necessary to achieve an increase in total airway volume (TAV) of ≥70%. Thirty patients with OSA treated by MMA were evaluated. Pre- and postoperative cone beam computed tomography images were used to determine the horizontal distance and angular changes in surgical parameters and linear, area, and volumetric airway parameters. Postoperatively, the horizontal distance of surgical parameters (A-point, UI, B-point, pogonion, and menton) and craniofacial angulation (SNA and SNB) increased significantly, similar to total surface area, TAV, and minimum cross-sectional area of the airway (p<0.0001). The total airway length decreased significantly (p<0.0001). The mean increase in TAV was 67.2%. There were positive correlations between linear surgical changes and the percentage change in TAV. All surgical parameters were predictive of a change in TAV ≥70%. The optimal surgical change was 6mm for A-point, 7.9mm for UI, 7.6mm for B-point, 11.2mm for pogonion, and 10mm for menton. In conclusion, maxillary advancement of less than 10mm was adequate in this study to obtain an increase in the TAV of at least 70%.

Is Maxillomandibular Advancement Associated With Comorbidity Reduction in Patients With Obstructive Sleep Apnea?

PURPOSE

This study investigated whether patients with documented obstructive sleep apnea (OSA) who have a decrease in apnea-hypopnea index (AHI) score and self-reported symptoms after maxillomandibular advancement (MMA) with genial tubercle advancement (GTA) also have a change in their medical comorbidity profile a minimum of 2 years postoperatively. Changes in the quantity of medical diagnoses, quantity of prescription medications, and average weight and body mass index (BMI) were assessed.

PATIENTS AND METHODS

This is a retrospective cohort study of patients with a diagnosis of OSA (AHI score >5 on polysomnogram [PSG]) treated at the Massachusetts General Hospital (Boston, MA) with MMA and GTA from 2001 through 2015. Patients were identified through the oral and maxillofacial surgery patient data registry. Inclusion criteria were the availability of complete clinical records and requisite follow-up time. The primary predictor variable was operative status (preoperative or postoperative). The primary outcome variables were comorbidities reported to be associated with OSA and identified in the authors' previous study (J Oral Maxillofac Surg 76:1999.e1, 2018). Two-tailed paired t tests were used for continuous variables and χ² or Fisher exact tests were used for categorical variables.

RESULTS

Forty-six patients (39 men, 7 women) met the inclusion criteria. Average weight (206.7 ± 42.4 lb preoperatively; 213.8 ± 41.7 lb postoperatively; P = .014) and average BMI (30.0 ± 5.7 kg/m² preoperatively; 30.9 ± 5.3 kg/m² postoperatively; P = .041) significantly increased in patients postoperatively. No meaningful changes in the number of medical diagnoses or number of prescription medications were noted. Stratification of patients by BMI showed significant increases in weight (188.6 ± 21.5 lb preoperatively; 200.1 ± 27.9 lb postoperatively; P = .0085) and BMI (27.1 ± 1.44 kg/m² preoperatively; 28.9 ± 3.52 kg/m² postoperatively; P = .013) only in "overweight" patients. No other parameters were found to be relevant.

CONCLUSIONS

Subjective improvement in OSA symptoms was reported by all patients and objective PSG improvement was reported for 71% of those evaluated. However, no relevant changes in comorbidity profile were found, suggesting that the medical conditions commonly observed with OSA are likely of multifocal etiology.

Impact of Bimaxillary Advancement Surgery on the Upper Airway and on Obstructive Sleep Apnea Syndrome: a Meta-Analysis

Upper airway changes following bimaxillary advancement surgery to treat obstructive sleep apnea syndrome remain controversial. The main objective of this systematic review and meta-analysis was to investigate the effects of bimaxillary advancement surgery on the upper airway (UA) of obstructive sleep apnea syndrome patients through examining changes three-dimensionally in vertical and supine position and through changes in oximetric variables (AHI, RDI, O2 Sat) and in the quality of life measured by the Epworth sleepiness scale (ESS). A thorough search of the PubMed, Scopus, Embase and Cochrane databases and a grey literature search (Opengrey) were conducted. No limit was placed on publication year or language. The inclusion criteria were: adult obstructive sleep apnea patients who had undergone bimaxillary advancement surgery, three-dimensional CBCT or CT and oximetric measurements and at least six weeks follow-up. Sample sizes of under 10 patients were excluded. Finally, 26 articles were included in the qualitative review and 23 in the meta-analysis. Bimaxillary advancement surgery has been shown to be beneficial in terms of increased upper airway size, improved oximetric indicators and the quality of life measured on the Epworth sleepiness scale.

Does the Medical Comorbidity Profile of Obstructive Sleep Apnea Patients Treated With Maxillomandibular Advancement Differ From That of Obstructive Sleep Apnea Patients Managed Nonsurgically?

PURPOSE

Obstructive sleep apnea (OSA) patients with retrognathia and measurable anatomic airway determinants may represent a subset of OSA patients and have distinct comorbidity profiles. Our aim was to compare the medical comorbidities of OSA patients managed surgically with maxillomandibular advancement with those of nonsurgical patients.

PATIENTS AND METHODS

In this cross-sectional retrospective study, patients for both cohorts were identified through the Massachusetts General Hospital oral and maxillofacial surgery data registry and the Massachusetts General Hospital Research Patient Data Registry. The inclusion criteria consisted of clinical records documenting body mass index (BMI), apnea-hypopnea index, respiratory disturbance index, and/or oxygen nadir. The primary predictor variable was the treatment modality chosen: surgical (maxillomandibular advancement) or nonsurgical. Demographic information and OSA parameters were evaluated. The primary outcome variable was the number of documented comorbidities in each group. Two-sample t tests were used for continuous variables, whereas χ² or Fisher exact tests were used for categorical variables.

RESULTS

The nonsurgical cohort consisted of 71 patients (67.6% men), and the surgical cohort consisted of 51 patients (84.3% men). Comparison of descriptive characteristics showed that the nonsurgical cohort had a higher average age (49 ± 9.4 years) than the surgical cohort (41 ± 10.7 years, P < .001). In addition, a higher average BMI was present in the nonsurgical group (42.3 ± 11.9 in nonsurgical group vs 29.7 ± 5.5 in surgical group, P < .001). Polysomnogram parameters were comparable with the exception of a higher Epworth Sleepiness Scale score in the surgical cohort (15.5 ± 5.30 in surgical group vs 9.90 ± 6.80 in nonsurgical group, P = .005). The nonsurgical cohort had a higher total number of comorbidities (7 ± 4 in nonsurgical group vs 4 ± 3 in surgical group, P < .001). Hypertension, cardiovascular disease, hyperlipidemia, pulmonary hypertension, obstructive pulmonary disease, and type 2 diabetes mellitus had higher prevalences within the nonsurgical group.

CONCLUSIONS

The results of this study suggest that nonsurgically managed OSA patients tend to have more complex medical comorbidity profiles than those managed surgically. Obesity (BMI >30) was more prevalent in the nonsurgical cohort, which may be contributory. The additive contribution of OSA needs to be further elucidated.

Mandibular positioning techniques to improve sleep quality in patients with obstructive sleep apnea: current perspectives

The purpose of this article is to review 1) mandibular advancement device (MAD) - indication, treatment success, and side effects; 2) maxillomandibular advancement (MMA) surgery of the jaws - indication, treatment success, and side effects; and 3) current perspectives. Both MAD and MMA are administered to increase the upper airway volume and reduce the collapsibility of the upper airway. MAD is noninvasive and is indicated as a first-stage treatment in adult patients with mild-to-moderate obstructive sleep apnea (OSA) and in patients with severe OSA unable to adhere to continuous positive airway pressure (CPAP). MAD remains inferior to CPAP in reducing the apnea-hypopnea index (AHI) with a treatment success ranging between 24% and 72%. However, patient compliance to MAD is greater, and with regard to subjective sleepiness and health outcomes, MAD and CPAP have been found to be similarly effective. Short-term side effects of MAD are minor and often transient. Long-term side effects primarily appear as changes in the dental occlusion related to decreases in overjet and overbite. MMA is efficacious but highly invasive and indicated as a second-stage treatment in patients with moderate-to-severe OSA, with prior failure to other treatment modalities or with craniofacial abnormalities. The surgical success and cure rates are found to be 86.0% and 43.2%, respectively. Side effects may appear as postsurgical complications such as temporary facial paresthesia and compromised facial esthetics. However, most patients report satisfaction with their postsurgical appearance. Both treatment modalities require experienced clinicians and multidisciplinary approaches in order to efficaciously treat OSA patients. Some researchers do propose possible predictors of treatment success, but clear patient selection criteria and clinical predictive values for treatment success are still needed in both treatment modalities.

Pharyngeal airspace of asthmatic individuals and those suffering from obstructive sleep apnea syndrome: Study by CBCT

PURPOSE

The objective of the present study was to comparatively evaluate the oropharyngeal space of patients with obstructive sleep apnea syndrome (OSA) and asthma by means of Cone Beam Computed Tomography (CBCT) images.

MATERIAL AND METHODS

The study included individuals with OSA and asthma (n=10), with OSA and without asthma (n=6), asthmatics without OSA (n=6) and healthy individuals (n=25). All patients were evaluated by a pneumologist and submitted to a nocturnal polysomnogram. Participants underwent CBCT examinations using an I-CAT^® device (Imaging Sciences International, Hatfield, PA, U.S.A.) and all images were exported to Dolphin Image 3D^® software. Cephalometric measurements were taken, as well as measurements of length (C), volume (VOL), sagittal area (SA) and minimum cross-sectional area (MCA); an evaluation was made of the format and contour of the upper airway in three dimensions, with p<0.05 considered significant.

RESULTS

In the results of the present study, a statistically significant difference was found between VOL, SA and MCA (p=0.011; p=0.009; p=0.010) with reduced elevated values among the OSA+Asthma, OSA, Asthma and Control groups. Significant differences were seen between the linear (AP), cross-sectional (TR) and mean transverse area (TA) measurements in the group of patients with OSA and asthma as compared to the control group. In the control group, the greatest narrowing of the airway was observed either in the retroglossal or retropalatal area, while more patients in the experimental groups showed narrowing in the retropalatal area.

CONCLUSION

The condition of OSA+asthma was associated with a substantial reduction in upper airway measurements in comparison to controls.

How does mandibular advancement with or without maxillary procedures affect pharyngeal airways? An overview of systematic reviews

BACKGROUND

Mandibular advancement surgery may positively affect pharyngeal airways and therefore potentially beneficial to obstructive sleep apnea (OSA).

OBJECTIVE

To collect evidence from published systematic reviews that have evaluated pharyngeal airway changes related to mandibular advancement with or without maxillary procedures.

METHODOLOGY

PubMed, EMBASE, Web of Science, and Cochrane Library were searched without limiting language or timeline. Eligible systematic reviews evaluating changes in pharyngeal airway dimensions and respiratory parameters after mandibular advancement with or without maxillary surgery were identified and included.

RESULTS

This overview has included eleven systematic reviews. Maxillomandibular advancement (MMA) increases linear, cross-sectional plane and volumetric measurements of pharyngeal airways significantly (p<0.0001), while reducing the apnea-hypopnea index (AHI) and the respiratory disturbance index (RDI) significantly (p<0.0001). Two systematic reviews included primary studies that have evaluated single-jaw mandibular advancement, but did not discuss their effect onto pharyngeal airways. Based on the included primary studies of those systematic reviews, single-jaw mandibular advancement was reported to significantly increase pharyngeal airway dimensions (p<0.05); however, conclusive long-term results were lacking.

CONCLUSION

MMA increases pharyngeal airway dimensions and is beneficial to patients suffering from OSA. However, more evidence is still needed to draw definite conclusion related to the effect of single-jaw mandibular advancement osteotomies on pharyngeal airways.