Mandibular advancement for adult obstructive sleep apnea: A systematic review and meta-analysis

Outcomes of maxillomandibular advancement (MMA) by dentofacial class: A systematic review and meta-analysis

The aim of this paper was to systematically review and compare the Apnoea-Hypopnoea Index (AHI), Lowest O2 Saturation (LSAT), Oxygen Desaturation Index (ODI), Epworth Sleep Scale (ESS), and Body Mass Index (BMI) between dentofacial (skeletal) classes I, II, and III before and after maxillomandibular advancement (MMA) for Obstructive Sleep Apnoea (OSA). The PubMed, Scopus, and CINAHL databases were searched from inception to 23 November 2022. Two reviewers screened for articles that reported occlusion/malocclusion class type as I, II, or III, and reported preoperative and postoperative AHI, LSAT, ODI, ESS, and/or BMI. Two reviewers independently screened title/abstracts and subsequently, full-text articles that met eligibility criteria. Preoperative ESS and ODI were significantly higher in Class II (13.77, 95% CI, 11.38% to 16.17% and 47.49, 95% CI, 33.04% to 61.95%) than in Class III (12.47, 95% CI, 9.95% to 14.99% and 32.47, 95% CI, -10.37% to 75.30%) (p < 0.0001). Postoperatively, class I showed the greatest percentage reduction of AHI, with a reduction of 89.61% (95% CI, 84.47% to 94.75%) compared with class II and III (p < 0.0001). Additionally, amongst all malocclusion classes and operative status, meta-regression showed positive correlations between ESS and AHI (r = 0.94, p < 0.001) and ESS and ODI (r = 0.90, p < 0.001). Class I subjects with no dentofacial discrepancy had the greatest improvement in AHI compared with Class II and III. Class II subjects may express more severe ODI and ESS preoperatively compared with Class III subjects. Additionally, subjective outcomes (ESS) may be a predictor for objective outcomes (AHI and ODI) for patients undergoing MMA.

Monitoring of Home Respiratory Polygraphy During Mandibular Distraction Osteogenesis Succeeded by LeFort I Osteotomy in Adult Patients With Obstructive Sleep Apnea

BACKGROUND

Bilateral internal ramus distraction (BIRD) is now part of select protocols for treating obstructive sleep apnea (OSA). Introducing a home monitoring protocol offers a valuable alternative to overnight laboratory polysomnography (PSG).

PURPOSE

The purpose of this study was to evaluate and compare OSA parameters obtained via home respiratory polygraphy (HRP) and hospital PSG in a cohort of patients undergoing mandibular distraction for OSA management.

STUDY DESIGN, SETTING, SAMPLE

Hospital Universitario La Princesa (Madrid) researchers conducted a prospective cohort study with patients diagnosed with moderate (apnea-hypopnea index (AHI) = 15 to 30) to severe (AHI>30) OSA undergoing BIRD followed by LeFort maxillary osteotomy. Exclusion criteria were as follows: severe systemic diseases, central apneas, smoking, poor dental hygiene, or prior OSA interventions.

PREDICTOR VARIABLE

The predictor variable was PSG and HRP techniques.

MAIN OUTCOME VARIABLES

The main outcome variable comprises a collection of OSA parameters, including the AHI, oxygen desaturation index (ODI), and time spent below 90% oxygen saturation (T90). These data were measured both before and after distraction, as well as after 6 mm, 9 mm, and 12 mm of mandibular distraction.

COVARIATES

The covariates were age, sex, cardiovascular risk parameters, and the Epworth sleepiness scale.

ANALYSES

Pearson's correlation analyzed AHI, ODI, and T90 values from PSG and HRP. Wilcoxon Signed Rank-Sum Test compared 2 distraction stages, and the Friedman Test evaluated 3 stages (P < .05). Multiple regression analysis assessed if covariates were independent risk factors for postoperative persistent OSA.

RESULTS

The study included 32 patients (25% with moderate and 75% with severe OSA). Final AHI was 10.9 ± 8.9 (events/hour) with HRP, compared to 15.2 ± 13.4 with PSG (r = 0.7, P < .05). ODI was 9.0 ± 8.1 (des/h) with HRP and 8.7 ± 9.5 with PSG (r = 0.85, P < .05). T90 was 1.6 ± 2.2 with HRP and 1.3 ± 3.0 with PSG (r = 0.6, P < .05). Based on HRP data, AHI improved from D1 (34.0 ± 19.5) to D2 (20.8 ± 14.1) and D3 (12.5 ± 10.4) (P < .05). ODI decreased from D1 (26.1 ± 19.0) to D2 (16.0 ± 12.6) and D3 (9.4 ± 8.8) (P < .05). T90 reduced from D1 (8.2 ± 12.6) to D2 (4.1 ± 5.2) and D3 (1.9 ± 2.8) (P < .05). Multiple regression analysis of comorbidities produced nonsignificant results.

CONCLUSION AND RELEVANCE

Monitoring BIRD through HRP has demonstrated efficacy in yielding results that align with PSG.

Evaluation of risk factors for sleep-disordered breathing in dogs

BACKGROUND

Brachycephalic dogs display sleep-disordered breathing (SDB). The risk factors for SDB remain unknown.

OBJECTIVES

To identify risk factors for SDB. We hypothesized that brachycephaly, increasing severity of brachycephalic obstructive airway syndrome (BOAS), excess weight, and aging predispose to SDB.

ANIMALS

Sixty-three privately owned pet dogs were prospectively recruited: 28 brachycephalic and 35 normocephalic (mesaticephalic or dolicocephalic) dogs.

METHODS

Prospective observational cross-sectional study with convenience sampling. Recording with the neckband was done over 1 night at each dog's home. The primary outcome measure was the obstructive respiratory event index (OREI). Body condition score (BCS) was assessed, and BOAS severity was graded for brachycephalic dogs.

RESULTS

Brachycephaly was a significant risk factor for high OREI value (ratio of the geometric means 5.6, 95% confidence interval [CI] 3.2-9.9; P < .001) but aging was not (1.1, 95% CI 1.0-1.2; P = .2). Excess weight, defined as a BCS of over 5/9, (3.5, 95% CI 1.8-6.7; P < .001) was a significant risk factor. In brachycephalic dogs, BOAS-positive class (moderate or severe BOAS signs) was a significant risk factor (2.5, 95% CI 1.1-5.6; P = .03).

CONCLUSIONS AND CLINICAL IMPORTANCE

Brachycephaly decreases welfare in a multitude of ways, including disrupting sleep. Brachycephaly, increasing severity of BOAS and excess weight are risk factors for obstructive SDB.

Pharmacological interventions for the treatment of obstructive sleep apnea syndrome

Obstructive Sleep Apnea Syndrome (OSAS) affects 13-33% of males and 6-9% of females globally and poses significant treatment challenges, including poor adherence to Continuous Positive Airway Pressure (CPAP) and residual excessive sleepiness (RES). This review aims to elucidate the emerging interest in pharmacological treatments for OSAS, focusing on recent advancements in this area. A thorough analysis of extensive clinical trials involving various drugs, including selective dopamine reuptake inhibitors, selective norepinephrine inhibitors, combined antimuscarinic agents, and orexin agonists, was conducted. These trials focused on ameliorating respiratory metrics and enhancing sleep quality in individuals affected by OSAS. The studied pharmacological agents showed potential in improving primary outcomes, notably the apnea-hypopnea index (AHI) and the Epworth sleepiness scale (ESS). These improvements suggest enhanced sleep quality and symptom management in OSAS patients. With a deeper understanding of OSAS, pharmacological interventions are emerging as a promising direction for its effective management. This review provides a comprehensive overview of the current state of drug research in OSAS, highlighting the potential of these treatments in addressing the disorder's complex challenges.

Maxillomandibular Advancement for Obstructive Sleep Apnea Syndrome: Long-Term Results of Respiratory Function and Reverse Face-Lift

PURPOSE

Scientific literature considers maxillomandibular advancement (MMA) as the most effective surgical treatment for the management of adult obstructive sleep apnea syndrome (OSAS). Maxillomandibular advancement enlarges the pharyngeal space by expanding the skeletal framework. Moreover, it projects the soft tissue of the cheeks, the mouth, and the nose in the aging face, which is characterized by multiple signs affecting the middle third and the lower third. The potential of orthognathic surgery (double jaw surgical advancement) of expanding the skeletal foundation to increase the facial drape support and to rejuvenate the face by a "reverse face-lift" is now recognized. The aim of this study was to review the surgical outcomes after MMA in terms of respiratory function and assessment of facial esthetics.

METHODS

We retrospectively reviewed the charts of all patients affected by OSAS who underwent maxillomandibular advancement between January 2010 and December 2015 in 2 tertiary hospitals (IRCCS Policlinico San Martino of Genoa and IRCCS Policlinico Ca' Granda of Milan). During the postoperative follow-up examination, all patients underwent polysomnographic examination and esthetic assessment to evaluate the respiratory function and facial rejuvenation after double jaw surgical advancement.

RESULTS

The final study sample included 25 patients (5 females, 20 males). The overall success rate of the surgical treatment (apnea/hypopnea index, AHI <20) was 79%; the overall rate of surgical cure (AHI <5) was 47%. Twenty-three patients (92%) showed a degree of rejuvenation after MMA.

CONCLUSIONS

Maxillomandibular advancement is currently the most effective surgical treatment for the management of OSAS in adult patients who are not responders to medical treatment. "Reverse face-lift" is the consequence of the double jaw surgical advancement.

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.

Palatal Coupling Maneuvers Do Not Predict Hypoglossal Nerve Stimulator Treatment Efficacy

OBJECTIVE(S)

Maneuvers during drug-induced sleep endoscopy (DISE), for patients with obstructive sleep apnea (OSA), have been used as predictors for success with oral appliances. Hypoglossal nerve stimulation (HGNS) promotes opening at the velum through palatoglossus coupling. In this study, we evaluate maneuvers during DISE as predictors for HGNS treatment efficacy.

METHODS

We evaluated patients undergoing HGNS between November, 2014 and February, 2021. We assessed maneuvers including jaw thrust and chin lift during preoperative DISE. The impact of tongue base and palatal opening during these maneuvers were rated from 1 to 4 (1: no improvement, 2: mild improvement, 3: moderate improvement, 4: significant improvement). Patients were grouped by a score of 1-2 (weak response) or 3-4 (strong response). Apnea hypopnea index (AHI) change was calculated from the difference between preoperative and postoperative sleep study.

RESULTS

One hundred and seventy one patients were included. With jaw thrust, there was no significant difference in AHI change between patients with weak or strong response at the palate (n = 68 vs. 94, 9.5 vs. 13.6, p = 0.21) or tongue base (n = 24 vs. 138, 16.6 vs. 11.3, p = 0.24). On chin lift, there was no significant difference at the palate (n = 82 vs. 18, 13.9 vs. 11.4, p = 0.63) or tongue base (n = 92 vs. 72, 10.8 vs. 14.6, p = 0.24). On multiple linear regression analysis, lower body mass index, higher preoperative AHI, and higher preoperative oxygen nadir were associated with a larger AHI change.

CONCLUSION

Palatal coupling maneuvers during DISE are not predictive of AHI change with HGNS. Findings using these maneuvers should not preclude HGNS candidacy.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:431-436, 2023.

Central and mixed sleep apnea related to patients treated with maxillomandibular advancement for obstructive sleep apnea: A retrospective cohort study

The aim of this study was to evaluate the clinical efficacy of maxillomandibular advancement (MMA) for obstructive sleep apnea (OSA) patients with a percentage of central and mixed apnea index in the total apnea-hypopnea index (CMAI%) ≧25%. Patients treated with MMA for OSA were retrospectively evaluated for baseline and postoperative patient data and polysomnographic results. The pre- and postoperative obstructive, central and mixed apnea parameters were compared. Of the included 78 patients, 21 patients (27%) presented with CMAI% ≧25% (median CMAI%, 49.1%; 35.9-63.8) prior to MMA. In 67% of these cases, MMA resulted in CMAI% <25 (median CMAI%, 6.1%; 2.1-8.9) and significantly improved the apnea-hypopnea index (AHI) (p < 0.001), the lowest oxyhemoglobin saturation (p < 0.001), central and mixed apnea index (p < 0.001), percentage of central and mixed apneas of total AHI (p = 0.004), central apnea index (p < 0.001), and mixed apnea index (p < 0.001). CMAI% ≧25% emerged in 25% of patients after MMA (median CMAI%, 49.1%; 35.9-63.8). Within the undeniable limitations of the study, it seems that the presence of CMAI% ≧25% should not be regarded as a contraindication for MMA in OSA patients.

Effectiveness of Surgical Mandibular Advancement in Improving Airway Dimensions in Nongrowing Skeletal Class II Patients With Obstructive Sleep Apnea—A CBCT Study

Background:

Skeletal nongrowing class II patients with retrognathic mandible are often at risk of developing obstructive sleep apnea (OSA). This skeletal discrepancy, when severe enough, is often addressed by surgical mandibular advancement which not only achieves aesthetics, structural balance, and functional efficiency but also improves the airway function.

Objective:

The aim of the study was to evaluate the effectiveness of surgical mandibular advancement on airway dimensions, in nongrowing skeletal class II patients with mandibular retrognathism associated with OSA.

Materials and Methods:

The sample consisted of 8 patients with skeletal class II due to retrognathic mandible associated with OSA. Screening was done with functional outcomes of sleep questionnaire (FOSQ) score and confirmed with polysomnography. Pretreatment and posttreatment airway dimensions/volume were assessed and calculated on cone beam computed tomography (CBCT). Three months post surgery, oxygen saturation was recorded.

Results:

A statistically significant improvement in mean oxygen saturation level was observed from 87.62 ± 7.70 to 97.75 ± 0.46 and mean increase in airway volume was from 48.60 ± 7.17 to 69.48 ± 26.22. The smallest cross section increased from 137 ± 74.37 to 253.75 ± 76.67. Anteroposterior dimensions increased significantly from 6.17 ± 1.78 to 9.33 ± 2.07 and transversed from 24.56 ± 6.41 to 30.14 ± 3.35. FOSQ score improved from 9.37 ± 2.61 to 15.25 ± 0.88.

Conclusion:

Surgical mandibular advancement is an effective treatment option in improving airway dimensions in nongrowing skeletal class II patients with mandibular retrognathism associated with OSA.

Efficiency of maxillomandibular advancement for the treatment of obstructive apnea syndrome: a comprehensive overview of systematic reviews

OBJECTIVES

To evaluate the efficiency of maxillomandibular advancement using aggregated individual patient data from multiple studies.

MATERIALS AND METHODS

This overview was structured according to the PICO strategy. It adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses checklist and was recorded on the international prospective register of systematic reviews (PROSPERO-CRD42020206135). Searches were conducted in the PubMed/MEDLINE, Scopus, Embase, Web of Science, LILACS, and Cochrane databases for studies published until January 1, 2021. Data from the included studies were collected by one author, while another reviewed the compilation.

RESULTS

Twelve systematic reviews were included. The outcome measures studied were the apnea-hypopnea index, respiratory disturbance index, mean oxygen saturation, lowest oxygen saturation, sleepiness data, posterior air space, sella-nasion point A angle, sella-nasion point B angle, surgical success, and surgical cure in patients who underwent surgery. The AMSTAR scale presented moderate evaluations, with grades varying between 6 and 10 points. The Glenny scale revealed that the study selection did not include all languages. Only three reviews identified quality assessments conducted by at least two reviewers and only five related possible searches for unpublished data.

CONCLUSIONS

Bimaxillary advancement surgery improved respiratory indicators, sleepiness data, and increased upper airway size. However, it is necessary to standardize the surgical criteria to establish measurable efficiency of the procedure.

CLINICAL RELEVANCE

This overview makes a critical analysis of the results of the selected systematic reviews with the aim of presenting the most clinically relevant data on the maxillomandibular advancement for treating obstructive apnea syndrome, with a focus on improving respiratory, anatomical, and quality of life indices. There are no overviews that approach this theme from a well-structured perspective.

Efficacy and safety of Chinese medicine for obstructive sleep apnea: A protocol for systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is significant public concern. Clinical practice indicates that Chinese medicine has certain therapeutic advantages, while there is a lack of evidence-based medicine support. The aim of this study is to synthesize related data to explore efficacy and safety of Chinese medicine for OSA.

METHODS

Data in PubMed, Embase, Web of Science, CNKI, WanFang, VIP databases were comprehensively searched. All the randomized controlled trials (RCTs) in OSA children were identified, in which the effects of Chinese medicine on a range of outcomes were compared. The search had a deadline of January 1, 2020. Two investigators independently conducted data extraction and assessed the literature quality of the included studies. The Revman5.3 software was used for meta-analysis of the included literature.

RESULTS

The efficacy and safety of Chinese medicine for OSA were evaluated in terms of apnea hypopnea index (AHI, the average and lowest blood oxygen, the Epworth Sleep Scale [ESS], and adverse effects).

CONCLUSIONS

This study provides reliable evidence-based support for the clinical application of Chinese medicine for OSA.

PROSPERO REGISTRATION NUMBER

CRD42020154864.

Evaluation of Hyoid Position and Retroglossal Airway After Mandibular Alveolar Archwise Distraction Osteogenesis

The interaction between form and function in the craniofacial region is a well-accepted fact in orthodontics. The aim of the present study is to objectively evaluate if mandibular sagittal symphyseal distraction causes an increase in the retroglossal airway size and hyoid position in a retrospective clinical study. The pretreatment (T0) and 3 months post-distraction (T1) cone-beam computed tomography images of 12 patients (mean age 17.1 years) were retrieved. The retroglossal airway volume and hyoid-mandibular plane distance, hyoid-C3 distance, sella-nasion-B point angle angle, lower incisor to mandibular plane, and Mandibular plane angles were measured using 3D medical imaging software. The average amount of distraction at the superior border of the bony transport segment was 6.2 mm and 4.4 mm at the inferior border. The changes in retroglossal airway volume (2943.2 mm), incisor to mandibular plane (6.5°), and mandibular plane (2.1°) were significant. The changes in hyoid-mandibular plane distance and hyoid-C3 distances were not significant. However, a downward repositioning in Hyoid position was observed along with the mandibular clockwise rotation. This study showed that symphyseal dentoalveolar distraction osteogenesis, as a complementary to orthodontic therapy, can affect the form and size of the pharynx. Therefore, the airway size should be one of the diagnostic and decisive factors for an ideal treatment planning.

Stability of fixation methods in large mandibular advancements after sagittal split ramus osteotomy: an in vitro biomechanical study

Sagittal split ramus osteotomy (SSRO) with large mandibular advancements is a common surgical procedure and could be indicated for patients with sleep apnoea. As a large variety of fixation methods is used for the stabilisation of SSRO, a biomechanical test model was used to analyse which fixation technique was most stable. For this in vitro study, 80 polyurethane hemimandibles with a prefabricated SSRO were used as substrates. Loads in Newtons were recorded at displacements of the mandibular incisive edge at 1mm, 3mm and 5mm. The samples were divided into two groups: mandibular advancements of 10mm and 15mm. In both groups, four fixation techniques were used: (A) one four-hole miniplate; (B) two four-hole miniplates; (C) one four-hole miniplate plus one bicortical screw; and (D) three bicortical screws in an inverted-L arrangement. In group 1, three bicortical screws resulted in the best stability, and in group 2, two miniplates resulted in the best stability. The use of two miniplates did not show significant differences between both groups. Other fixation methods showed more stability with 10mm advancements. This study therefore suggests that in SSRO with advancements exceeding 10mm, the use of two miniplates is the optimal means of providing rigid fixation.

Clinical, esthetic, and quality of life outcomes after telegnathic surgery in Caucasian OSAS patients

OBJECTIVE

To carry out both an objective and subjective assessment of the facial esthetics, clinical outcome, and quality of life evaluation in 25 OSAS patients treated with telegnathic surgery.

METHODS

Patients were analyzed using AHI, Legan and Burstone and airway cephalometric analysis for the objective study together with youthful and esthetic perception and SF-36 health surveys for the subjective part.

RESULTS

Facial convexity, nasolabial and lower face-throat angle, upper lip protrusion, and vertical height-depth ratio improved the facial and neck esthetics, while the maxillary and mandibular prognathism increased. Eighty-eight percent considered an esthetic change on their facial profile and 52% a more youthful profile. FS-36 survey (pre- 48.86 and post-surgery 71.74) and AHI (pre- 41.32 and post-surgery 7.80) scores improved significantly.

DISCUSSION

Results after telegnathic surgery were both esthetically and clinically satisfactory. The FS-36 survey should be considered for monitoring treatment in OSAS patients.

Thirty-five alternatives to positive airway pressure therapy for obstructive sleep apnea: an overview of meta-analyses

INTRODUCTION

Positive airway pressure (PAP) devices are generally considered to be the first-line treatment of choice for most adults with obstructive sleep apnea (OSA). However, there are several alternatives. It is important for patients and their sleep providers to be aware of the most up-to-date information regarding the current international literature. Areas covered: The objective is to provide an overview of the meta-analyses evaluating non-PAP treatments for OSA. Four authors searched four databases, including PubMed/MEDLINE through 30 November 2017, for meta-analyses evaluating non-PAP therapies as treatment for OSA. Thirty-five non-PAP treatments were identified and were categorized based on the following anatomical subsites: (1) nose, (2) palate and oropharynx, (3) tongue, (4) skeletal surgery and jaw repositioning, and (5) other surgical and medical interventions. Treatments identified included surgeries, drugs, behavior modifications, nonsurgical weight loss, medical devices, body positioning, and oxygen treatment. Expert commentary: The 35 treatments described vary in their effectiveness in treating OSA in adults. In general, isolated nasal treatments are the least effective, whereas treatments that bypass the upper airway, significantly open the upper airway, and/or address multiple levels of the upper airway are more effective in improving apnea-hypopnea index and lowest oxygen saturation.

Challenges and perspectives in obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is a major challenge for physicians and healthcare systems throughout the world. The high prevalence and the impact on daily life of OSA oblige clinicians to offer effective and acceptable treatment options. However, recent evidence has raised questions about the benefits of positive airway pressure therapy in ameliorating comorbidities.

An international expert group considered the current state of knowledge based on the most relevant publications in the previous 5 years, discussed the current challenges in the field, and proposed topics for future research on epidemiology, phenotyping, underlying mechanisms, prognostic implications and optimal treatment of patients with OSA.

The group concluded that a revision to the diagnostic criteria for OSA is required to include factors that reflect different clinical and pathophysiological phenotypes and relevant comorbidities (e.g.nondipping nocturnal blood pressure). Furthermore, current severity thresholds require revision to reflect factors such as the disparity in the apnoea–hypopnoea index (AHI) between polysomnography and sleep studies that do not include sleep stage measurements, in addition to the poor correlation between AHI and daytime symptoms such as sleepiness. Management decisions should be linked to the underlying phenotype and consider outcomes beyond AHI.

Obstructive sleep apnea: current perspectives

The prevalence of obstructive sleep apnea (OSA) continues to rise. So too do the health, safety, and economic consequences. On an individual level, the causes and consequences of OSA can vary substantially between patients. In recent years, four key contributors to OSA pathogenesis or "phenotypes" have been characterized. These include a narrow, crowded, or collapsible upper airway "anatomical compromise" and "non-anatomical" contributors such as ineffective pharyngeal dilator muscle function during sleep, a low threshold for arousal to airway narrowing during sleep, and unstable control of breathing (high loop gain). Each of these phenotypes is a target for therapy. This review summarizes the latest knowledge on the different contributors to OSA with a focus on measurement techniques including emerging clinical tools designed to facilitate translation of new cause-driven targeted approaches to treat OSA. The potential for some of the specific pathophysiological causes of OSA to drive some of the key symptoms and consequences of OSA is also highlighted.