Correlation of diffusion tensor tractography with obstructive sleep apnea severity.

INTRODUCTION: Using correlation tractography, this study aimed to find statistically significant correlations between white matter (WM) tracts in participants with obstructive sleep apnea (OSA) and OSA severity. We hypothesized that changes in certain WM tracts could be related to OSA severity. METHODS: We enrolled 40 participants with OSA who underwent diffusion tensor imaging (DTI) using a 3.0 Tesla MRI scanner. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), and quantitative anisotropy (QA)-values were used in the connectometry analysis. The apnea-hypopnea index (AHI) is a representative measure of the severity of OSA. Diffusion MRI connectometry that was used to derive correlational tractography revealed changes in the values of FA, MD, AD, RD, and QA when correlated with the AHI. A false-discovery rate threshold of 0.05 was used to select tracts to conduct multiple corrections. RESULTS: Connectometry analysis revealed that the AHI in participants with OSA was negatively correlated with FA values in WM tracts that included the cingulum, corpus callosum, cerebellum, inferior longitudinal fasciculus, fornices, thalamic radiations, inferior fronto-occipital fasciculus, superior and posterior corticostriatal tracts, medial lemnisci, and arcuate fasciculus. However, there were no statistically significant results in the WM tracts, in which FA values were positively correlated with the AHI. In addition, connectometry analysis did not reveal statistically significant results in WM tracts, in which MD, AD, RD, and QA values were positively or negatively correlated with the AHI. CONCLUSION: Several WM tract changes were correlated with OSA severity. However, WM changes in OSA likely involve tissue edema and not neuronal changes, such as axonal loss. Connectometry analyses are valuable tools for detecting WM changes in sleep disorders.

Clinical and radiographic periodontal status in hypertensive patients with or without obstructive sleep apnea 10 years after diagnosis and CPAP initiation.

OBJECTIVES: Through inflammation and hyposalivation, obstructive sleep apnea (OSA) is suggested to affect periodontal status over time. Our aim was to compare the clinical and radiographic periodontal status of hypertensive patients with or without long-term presence of OSA, treated or untreated with continuous positive airway pressure treatment (CPAP). MATERIALS AND METHODS: In 2007-2009, a screening for OSA was conducted among 394 hypertensive primary care patients. Polygraphy was used to create three groups: no OSA, non-CPAP, or adherent CPAP based on the apnea hypopnea index (AHI). After 10 years, a cross-sectional sleep and periodontal examination including a clinical and radiographic examination, a questionnaire, and a matrix metalloproteinase-8 (MMP-8) chair-side test was conducted. Based on levels of alveolar bone, bleeding on probing (BoP), and probing pocket depth (PPD), patients were categorized into four periodontal stages: periodontal health/gingivitis and three periodontal disease stages. Periodontal status and periodontal stages were compared between the OSA (n = 49), non-CPAP (n = 38), or adherent CPAP (n = 34) groups. RESULTS: The 121 patients (53% women) had a median age of 71 years. No differences were seen between the OSA groups regarding median number of teeth (p = .061), teeth/implants, (p = .107), plaque index (p = .245), BoP (p = .848), PPD ≥ 4 mm (p = .561), PPD ≥ 6 mm (p = .630), presence of MMP-8 (p = .693) except for bone loss (p = .011). Among patients with stage periodontal health/gingivitis a significant difference was seen, as 70% of those were categorized as no OSA, 20% as non-CPAP, and 10% as adherent CPAP (p = .029). Differences were not seen in periodontal disease stages. CONCLUSIONS: Hypertensive patients with obstructive sleep apnea (OSA) did not have an adverse clinical periodontal status compared to patients without OSA. However, when combining radiographic and clinical status into periodontal stages, patients without OSA more frequently exhibited periodontal health or gingivitis compared to patients without OSA, regardless of CPAP treatment.

Decreased structural pathways mediating functional connectivity in obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is a common sleep breathing disorder that is often accompanied by changes in structural connectivity (SC) and functional connectivity (FC). However, the current understanding of the interaction between SC and FC in OSA is still limited. METHODS: The aim of this study is to integrate complementary neuroimaging modalities into a unified framework using multi-layer network analysis methods and to reveal their complex interrelationships. We introduce a new graph metric called SC-FC bandwidth, which measures the throughput of SC mediating FC in a multi-layer network. The bandwidth differences between two groups are evaluated using the network-based statistics (NBS) method. Additionally, we traced and analyzed the SC pathways corresponding to the abnormal bandwidth. RESULTS: In both the healthy control and patients with OSA, the majority offunctionally synchronized nodes were connected via SC paths of length 2. With the NBS method, we observed significantly lower bandwidth between the right Posterior cingulate gyrus and right Cuneus, bilateral Middle frontal gyrus, bilateral Gyrus rectus in OSA patients. By tracing the high-proportion SC pathways, it was found that OSA patients typically exhibit a decrease in direct SC-FC, SC-FC triangles, and SC-FC quads intra- and inter-networks. CONCLUSION: Complex interrelationship changes have been observed between the SC and FC in patients with OSA, which might leads to abnormal information transmission and communication in the brain network.

Role of automated functional imaging and myocardial work in assessment of cardiac function in children with obstructive sleep apnea.

BACKGROUND: Early identification of abnormal left ventricular function in children with obstructive sleep apnea (OSA) is difficult using conventional echocardiographic indices and commonly used clinical markers of myocardial damage. We sought to investigate the value of automatic function imaging and myocardial work parameters in predicting early cardiac impairment in children having OSA with preserved left heart function and thereby identifying an optimal index for assessment. PATIENTS AND METHODS: Fifty-two children who presented with symptoms of nocturnal sleep snoring and open-mouth breathing and 34 healthy controls were enrolled in this study. Clinical characteristics and conventional echocardiographic data were collected, and image analysis was performed using two-dimensional speckle-tracking echocardiography to obtain left ventricular global longitudinal strain (GLS), post-systolic index, peak strain dispersion, global work index (GWI), global constructive work (GCW), global wasted work, and global work efficiency. RESULTS: Children with OSA had significantly lower GLS, GWI, and GCW than those without (P < 0.05). Additionally, GWI (ß = -32.87, 95% CI: -53.47 to -12.27), and GCW (ß = -35.09, 95% CI: -55.35 to -14.84) were found to correlate with the disease severity in the multiple linear regression mode, with worsening values observed as the severity of the disease increased. ROC curve analysis revealed that GCW was the best predictor of myocardial dysfunction, with an AUC of 0.809 (P < 0.001), and the best cutoff point for diagnosing myocardial damage in children with OSA was 1965.5 mmHg%, with a sensitivity of 92.5% and a specificity of 58.7%. CONCLUSIONS: GLS, GWI, and GCW were identified as predictors of myocardial dysfunction in children with OSA, with GCW being the best predictor.

The Epworth sleepiness scale may have more advantages than the multiple sleep latency test in assessing sleepiness in patients with obstructive sleep apnea.

This study aimed to analyze the brain function of severe obstructive sleep apnea patients with various sleepiness assessment methods and explore the brain imaging basis for the differences between these methods. This study included 30 severe obstructive sleep apnea patients and 19 healthy controls. Obstructive sleep apnea patients were divided into a subjective excessive daytime sleepiness group and a subjective non-excessive daytime sleepiness group according to the Epworth sleepiness scale. Moreover, they were divided into an objective excessive daytime sleepiness group and an objective non-excessive daytime sleepiness group according to the multiple sleep latency test. The fractional amplitude of low-frequency fluctuation was used to assess the features of brain function. Compared with healthy controls, participants in the subjective excessive daytime sleepiness group exhibited higher fractional amplitude of low-frequency fluctuation signals in the right thalamus, left cerebellar lobe 6, left putamen, and pallidum. Participants in the objective excessive daytime sleepiness group showed higher fractional amplitude of low-frequency fluctuation signals in the right thalamus and lower fractional amplitude of low-frequency fluctuation signals in the right superior frontal gyrus, the dorsolateral and superior frontal gyrus, and the medial orbital. We concluded that the thalamus may be involved in subjective and objective sleepiness regulation. Functional abnormalities in the putamen and pallidum may be involved in subjective sleepiness, whereas the frontal lobe may be involved in objective sleepiness.

The role of the tongue in post-stroke dysphagia and obstructive sleep apnea: Correlation with sonography measurement.

OBJECTIVE: Obstructive sleep apnea (OSA) is a common risk factor for stroke, and dysphagia and pneumonia are both well-known complications of stroke. The development of these conditions is related to the oropharyngeal structures. We investigated whether specific structural features of the tongue may lead to the development of these complications. METHODS: Patients with ischemic stroke who required admission and community-dwelling elderly controls were enrolled. The participants underwent tongue measurements by received hand-held ultrasound, and received questionnaires to evaluate sleep quality and daytime sleepiness. The patient group also underwent objective sleep measurement by actigraphy and the 3-Step Swallowing Test (3-SSS). Sleep parameters and outcomes were analyzed. RESULTS: Patient with ischemic stroke had significantly thicker tongue than controls (6.53 cm v. 6.05 cm, p = 0.002). Multiple logistic regression analysis revealed that the anatomical parameters of the tongue in patients with stroke were significantly correlated with parameters of OSA, and the thickness of the tongue was positively correlated with the development of OSA (p = 0.024) and pneumonia (p = 0.048). CONCLUSIONS: A thicker-than average tongue may be a risk factor for OSA and pneumonia in patient with stroke. Hand-held ultrasound can be used to identify these anatomical features. Further studies are warranted to clarify the role of the tongue in these post-stroke complications.

Evaluation of condylar and mandibular movements on the upper airway during the use of mandibular advancement device for obstructive sleep apnea treatment.

OBJECTIVES: To evaluate the temporomandibular joint (TMJ), condylar and mandibular movements in obstructive sleep apnea (OSA) patients treated with mandibular advancement device (MAD) and to identify the influence of these anatomic factors on upper airway (UA) volume and polysomnographic outcomes after treatment. MATERIALS AND METHODS: Twenty OSA patients were prospectively treated with MAD. Clinical examinations, cone-beam computed tomography, and polysomnography were performed before MAD treatment and after achieving therapeutic protrusion. Polysomnographic variables and three-dimensional measurements of the TMJ, mandible, and upper airway were statistically analyzed. RESULTS: Condylar rotation, anterior translation, and anterior mandibular displacement were directly correlated with total UA volume, while vertical mandibular translation was inversely correlated with the volume of the inferior oropharynx. MAD treatment resulted in an increase in the volume and area of the superior oropharynx. There was no statistically significant correlation between condylar rotation and translation and polysomnographic variables. With MAD, there was a significant increase in vertical dimension, changes in condylar position (rotation and translation), and mandibular displacement. The central and medial lengths of the articular eminence were inversely correlated with condylar rotation and translation, respectively. The lateral length of the eminence was directly correlated with condylar translation, and the lateral height was directly correlated with condylar rotation and translation. CONCLUSION: Condylar and mandibular movements influenced UA volume. The articular eminence played a role in the amount of condylar rotation and translation. CLINICAL RELEVANCE: Individualized anatomical evaluation of the TMJ proves to be important in the therapy of OSA with MAD.

Cerebellar volumes and the intrinsic cerebellar network in patients with obstructive sleep apnea.

PURPOSE: This research aimed to explore changes in both cerebellar volume and the intrinsic cerebellar network in patients with obstructive sleep apnea (OSA). METHODS: Newly diagnosed OSA patients and healthy controls were included in the study. All participants underwent three-dimensional T1-weighted imaging using a 3-T MRI scanner. Cerebellar volumes, both overall and subdivided, were quantified using the ACAPULCO program. The intrinsic cerebellar network was assessed using the BRAPH program, which applied graph theory to the cerebellar volume subdivision. Comparisons were drawn between the patients with OSA and healthy controls. RESULTS: The study revealed that the 26 patients with OSA exhibited a notably lower total cerebellar volume compared to the 28 healthy controls (8.330 vs. 9.068%, p < 0.001). The volume of the left lobule VIIB was reduced in patients with OSA compared to healthy controls (0.339 vs. 0.407%, p = 0.001). Among patients with OSA, there was a negative correlation between the volume of the left lobule X and apnea-hypopnea index during non-rapid eye movement sleep (r = - 0.536, p = 0.005). However, no significant differences were observed in the intrinsic cerebellar network between patients and healthy controls. CONCLUSION: This study established that patients with OSA exhibited decreased total cerebellar volumes and particularly reduced volumes in subdivisions such as the left lobule VIIB compared to healthy controls. These findings suggest potential involvement of the cerebellum in the underlying mechanisms of OSA.

Is there an OAHI or O2 nadir that predicts the need for preoperative echocardiogram prior to adenotonsillectomy for children with severe obstructive sleep apnea?

PURPOSE: To investigate threshold values for obstructive apnea-hypopnea index (OAHI) and nadir oxygen saturation (NspO2) in children with severe obstructive sleep apnea (OSA) to identify children most appropriate for preoperative echocardiography. METHODS: A multi-institutional retrospective chart review was performed on children who underwent echocardiography and polysomnogram within a year. Children with severe OSA as defined by OAHI > 10 or NspO2 < 80% were included. Receiver operator curves and Youden's J index were used to assess the discriminatory ability and threshold values of OAHI and NspO2 for right heart strain (RHS) on echocardiography. RESULTS: A total of 173 prepubertal (< 10 years) children and 71 postpubertal (≥ 10 years) children of age were included. RHS was seen in 9 (5%) prepubertal children and 4 (6%) postpubertal children. In prepubertal children, OAHI and NspO2 were poor predictors of RHS (area under the curve [AUC] 0.53 [95%CI 0.45-0.61], p = 0.748; AUC 0.56 [95%CI 0.48-0.64], p = 0.609). In postpubertal children, threshold values of 55 events/hour and 69% were strong predictors for RHS (AUC 0.88 [95%CI 0.78-0.95], p < 0.001; AUC 0.92 [95%CI 0.83-0.97], p < 0.001). CONCLUSION: In children with severe OSA, evidence of RHS is low. Postpubertal children with OAHI > 55 and NspO2 < 69% appear most appropriate for echocardiography. Clinicians should weigh the risks and benefits of preoperative echocardiography for each child with these threshold values in mind.

Comparative study of anatomical features of primary and accessory maxillary ostia between patients with obstructive sleep apnea and healthy controls.

PURPOSE: The purpose of this study was to examine how the size and shape of the maxillary sinus and its ostia (the primary maxillary ostium and accessory maxillary ostium) relate to each other in patients with OSA using computed tomography (CT) scans. Additionally, the study aimed to explore whether or not obstructive sleep apnea (OSA) had an effect on these structures. METHODS: CT images of patients diagnosed with OSAS and healthy participants were evaluated to compare the patency, location, dimension, and presence of PMOs and AMOs using the Mann-Whitney U, Student t, and chi-square tests. Also, intragroup correlations were analyzed by Spearman's correlation test. RESULTS: Among 139 patients with OSA and healthy controls, there were significant variations in the average length (p = 0.001) and width (p = 0.008) of PMOs among the study groups. The mean maxillary sinus volume was significantly decreased in the OSA group (p = 0.001). A significant decrease in the maxillary sinus volume was observed in the OSA group (p = 0.001). In the OSA group, a significant correlation was observed between PMO obstruction and the presence of AMO (p = 0.004). The healthy group had significant correlations (r = 0.755, p = 0.000) between the vertical height and the distance between PMO and the maxillary sinus floor. Correlation analyses revealed positive, strong correlations between study variables such as the mean length and width of AMO and the vertical height of the maxillary sinus (r = 0.566, p = 0.000) in the OSA group. CONCLUSIONS: The current study indicated significant differences in sinus volume, PMO occlusion, and AMO-related dimensions between patients with OSA and healthy controls.

Diffusion kurtosis imaging tractography reveals disrupted white matter structural networks in children with obstructive sleep apnea syndrome.

To assess the disruptions of brain white matter (WM) structural network in children with obstructive sleep apnea (OSA) using diffusion kurtosis imaging (DKI). We use DKI tractography to construct individual whole-brain, region-level WM networks in 40 OSA and 28 healthy children. Then, we apply graph theory approaches to analyze whether OSA children would show altered global and regional network topological properties and whether these alterations would significantly correlate with the clinical characteristics of OSA. We found that both OSA and healthy children showed an efficient small-world organization and highly similar hub distributions in WM networks. However, characterized by kurtosis fractional anisotropy (KFA) weighted networks, OSA children exhibited decreased global and local efficiency, increased shortest path length compared with healthy children. For regional topology, OSA children exhibited significant decreased nodal betweenness centrality (BC) in the bilateral medial orbital superior frontal gyrus (ORBsupmed), right orbital part superior frontal gyrus (ORBsup), insula, postcentral gyrus, left middle temporal gyrus (MTG), and increased nodal BC in the superior parietal gyrus, pallidum. Intriguingly, the altered nodal BC of multiple regions (right ORBsupmed, ORBsup and left MTG) within default mode network showed significant correlations with sleep parameters for OSA patients. Our results suggest that children with OSA showed decreased global integration and local specialization in WM networks, typically characterized by DKI tractography and KFA metric. This study may advance our current understanding of the pathophysiological mechanisms of impaired cognition underlying OSA.

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.

Wavelet transform and deep learning-based obstructive sleep apnea detection from single-lead ECG signals.

Sleep apnea is a common sleep disorder. Traditional testing and diagnosis heavily rely on the expertise of physicians, as well as analysis and statistical interpretation of extensive sleep testing data, resulting in time-consuming and labor-intensive processes. To address the problems of complex feature extraction, data imbalance, and low model capacity, we proposed an automatic sleep apnea classification model (CA-EfficientNet) based on the wavelet transform, a lightweight neural network, and a coordinated attention mechanism. The signal is converted into a time-frequency image by wavelet transform and put into the proposed model for classification. The effects of input time window, wavelet transform type and data balancing on the classification performance are considered, and a cost-sensitive algorithm is introduced to more accurately distinguish between normal and abnormal breathing events. PhysioNet apnea ECG database was used for training and evaluation. The 3-min Frequency B-Spline wavelets transform of ECG signal was carried out, and Dice Loss was used to train the classification model of sleep breathing. The classification accuracy was 93.44%, sensitivity was 88.9%, specificity was 96.2% and most indexes were better than other related work.

Identification of OSAHS patients based on ReliefF-mRMR feature selection.

Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) is a serious chronic sleep disorder. Snoring is a common and easily observable symptom of OSAHS patients. The purpose of this work is to identify OSAHS patients by analyzing the acoustic characteristics of snoring sounds throughout the entire night. Ten types of acoustic features, such as Mel-frequency cepstral coefficients (MFCC), linear prediction coefficients (LPC) and spectral entropy among others, were extracted from the snoring sounds. A fused feature selection algorithm based on ReliefF and Max-Relevance and Min-Redundancy (mRMR) was proposed for optimal feature set selection. Four types of machine learning models were then applied to validate the effectiveness of OSAHS patient identification. The results show that the proposed feature selection algorithm can effectively select features with high contribution, including MFCC and LPC. Based on the selected top-20 features and using a support vector machine model, the accuracies in identifying OSAHS patients under the thresholds of AHI = 5,15, and 30, were 100%, 100%, and 98.94%, respectively. This indicates that the proposed model can effectively identify OSAHS patients.

Obstructive sleep apnea and its association with coronary artery calcium volume in asymptomatic male subjects.

The aim of this study was to analyze the association between various parameters related to obstructive sleep apnea (OSA) and coronary artery calcium (CAC) volume. We retrospectively reviewed the medical records of 315 male subjects who underwent standard polysomnography (PSG) and coronary artery computed tomography. In this study, we found that only the apnea index (AI) and minimal oxygen saturation (minimal SaO2) were independently associated with CAC volume after adjustment for confounders; for a 1/h increase in the AI, the CAC volume increased by 1.311 mm3, and for a 1% increase in the minimal SaO2, the CAC volume decreased by 2.187 mm3. We also found that the CAC volume was significantly different between the habitual snorer and the severe OSA group (21.27 ± 40.79 vs 71.33 ± 175.00, p = 0.042). Moreover, the CAC volume was significantly different between the first and fourth quartile groups of the AI (32.42 ± 59.54% vs. 78.74 ± 198.50, p = 0.048), but not among groups according to the hypopnea index quartile. Therefore, we concluded that among various OSA-related PSG parameters, the AI and minimal SaO2 was independently associated with the CAC volume and significantly related to upcoming cardiovascular events in middle-aged men.

Evaluation of upper airway characteristics in patients with and without sleep apnea using cone-beam computed tomography and computational fluid dynamics.

OBJECTIVE: To determine if upper airway characteristics and airway pressure change significantly between low risk, healthy non-OSA subjects, and OSA subjects during respiration using cone-beam computed tomography (CBCT) imaging and steady-state k-ω model computational fluid dynamics (CFD) fluid flow simulations, respectively. MATERIALS AND METHODS: CBCT scans were collected at both end-inhalation and end-exhalation for 16 low-risk non-OSA subjects and compared to existing CBCT data from 7 OSA subjects. The CBCT images were imported into Dolphin Imaging and the upper airway was segmented into stereolithography (STL) files for area and volumetric measurements. Subject models that met pre-processing criteria underwent CFD simulations using ANSYS Fluent Meshing (Canonsburg, PA) in which unstructured mesh models were generated to solve the standard dual equation turbulence model (k-ω). Objective and supplemental descriptive measures were obtained and statistical analyses were performed with both parametric and non-parametric tests to evaluate statistical significance at P < .05. RESULTS: Regarding area and volumetric assessments, there were statistically significant mean differences in Total Volume and Minimum CSA between non-OSA and OSA groups at inhalation and exhalation (P = .002, .003, .004, and .007), respectively. There were also statistically significant mean differences in volume and min CSA between the inhalation and exhalation for the non-OSA group (P < .001 and .002), respectively. CONCLUSION: While analysis of the CFD simulation was limited by the collected data available, a finding consistent with published literature was that the OSA subject group simulation models depicted the point of lowest pressure coinciding with the area of maximum constriction.

Efficacy of Mandibular Advancement Device in the Treatment of Obstructive Sleep Apnoea by Evaluating Upper Airway Space Volume Using CBCT.

OBJECTIVE: To evaluate the efficacy of mandibular advancement device as a treatment of mild to moderate obstructive sleep apnoea and to evaluate the change in upper airway space volume by using cone beam CT (CBCT). STUDY DESIGN: In vivo observational study. Place and Duration of the Study: Department of Prosthodontics, Crown and Bridge, Sri Aurobindo College of Dentistry, Indore (M.P), India, from March 2017 to January 2021. METHODOLOGY: Patients with mild to moderate obstructive sleep apnoea patients using Berlin questionnaire were selected. Pre- and posttreatment-CBCT analysis was done to compare the changes in superior and inferior upper airway space before and after using mandibular advancement device. The pre and postoperative CBCT were also compared using a paired t-test for the quantitative variables. After two months, the patients were asked to complete a self-administered questionnaire to assess their sleep improvement, initial symptoms regression, and effectiveness of the mandibular advancement device. RESULTS: On comparative evaluation of the pre- and post-CBCT, the mean score before the mandibular advancement device placement was found to be 7.77+2.79 cc, whereas the mean score after the mandibular advancement device placement was found to be 9.75+3.34 cc (p<0.001). Significant volumetric change was seen in upper airway space after receiving treatment for the two months. The patient noticed a substantial improvement in their sleep as well as a reduction in the original symptoms. CONCLUSION: This study showed statistically significant volumetric change in the upper airway space and reduction in their symptoms after treatment with the mandibular advancement device (MAD). KEY WORDS: Obstructive sleep apnoea syndrome (OSA), Continuous positive airway pressure (CPAP), Cone beam computed tomography, Mandibular advancement device (MAD), Upper airway volume.

Screening obstructive sleep apnea patients via deep learning of knowledge distillation in the lateral cephalogram.

The lateral cephalogram in orthodontics is a valuable screening tool on undetected obstructive sleep apnea (OSA), which can lead to consequences of severe systematic disease. We hypothesized that a deep learning-based classifier might be able to differentiate OSA as anatomical features in lateral cephalogram. Moreover, since the imaging devices used by each hospital could be different, there is a need to overcome modality difference of radiography. Therefore, we proposed a deep learning model with knowledge distillation to classify patients into OSA and non-OSA groups using the lateral cephalogram and to overcome modality differences simultaneously. Lateral cephalograms of 500 OSA patients and 498 non-OSA patients from two different devices were included. ResNet-50 and ResNet-50 with a feature-based knowledge distillation models were trained and their performances of classification were compared. Through the knowledge distillation, area under receiver operating characteristic curve analysis and gradient-weighted class activation mapping of knowledge distillation model exhibits high performance without being deceived by features caused by modality differences. By checking the probability values predicting OSA, an improvement in overcoming the modality differences was observed, which could be applied in the actual clinical situation.

Associations Between Amyloid Burden, Hypoxemia, Sleep Architecture, and Cognition in Obstructive Sleep Apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is associated with an increased risk of amyloid-ß (Aß) burden, the hallmark of Alzheimer's disease, and cognitive decline. OBJECTIVE: To determine the differential impacts of hypoxemia and slow-wave sleep disruption on brain amyloid burden, and to explore the effects of hypoxemia, slow-wave sleep disruption, and amyloid burden on cognition in individuals with and without OSA. METHODS: Thirty-four individuals with confirmed OSA (mean±SD age 57.5±4.1 years; 19 males) and 12 healthy controls (58.5±4.2 years; 6 males) underwent a clinical polysomnogram, a NAV4694 positron emission tomography (PET) scan for Aß burden, assessment of APOEɛ status and cognitive assessments. Linear hierarchical regressions were conducted to determine the contributions of demographic and sleep variables on amyloid burden and cognition. RESULTS: Aß burden was associated with nocturnal hypoxemia, and impaired verbal episodic memory, autobiographical memory and set shifting. Hypoxemia was correlated with impaired autobiographical memory, and only set shifting performance remained significantly associated with Aß burden when controlling for sleep variables. CONCLUSIONS: Nocturnal hypoxemia was related to brain Aß burden in this sample of OSA participants. Aß burden and hypoxemia had differential impacts on cognition. This study reveals aspects of sleep disturbance in OSA that are most strongly associated with brain Aß burden and poor cognition, which are markers of early Alzheimer's disease. These findings add weight to the possibility that hypoxemia may be causally related to the development of dementia; however, whether it may be a therapeutic target for dementia prevention in OSA is yet to be determined.

Obstructive sleep apnea and attention deficits: A systematic review of magnetic resonance imaging biomarkers and neuropsychological assessments.

BACKGROUND AND OBJECTIVE: Obstructive sleep apnea (OSA) is a common sleep disorder that causes intermittent hypoxia and sleep fragmentation, leading to attention impairment and other cognitive deficits. Magnetic resonance imaging (MRI) is a powerful modality that can reveal the structural and functional brain alterations associated with attention impairment in OSA patients. The objective of this systematic review is to identify and synthesize the evidence on MRI biomarkers and neuropsychological assessments of attention deficits in OSA patients. METHODS: We searched the Scopus and PubMed databases for studies that used MRI to measure biomarkers related to attention alteration in OSA patients and reported qualitative and quantitative data on the association between MRI biomarkers and attention outcomes. We also included studies that found an association between neuropsychological assessments and MRI findings in OSA patients with attention deficits. RESULTS: We included 19 studies that met our inclusion criteria and extracted the relevant data from each study. We categorized the studies into three groups based on the MRI modality and the cognitive domain they used: structural and diffusion tensor imaging MRI findings, functional, perfusion, and metabolic MRI findings, and neuropsychological assessment findings. CONCLUSIONS: We found that OSA is associated with structural, functional, and metabolic brain alterations in multiple regions and networks that are involved in attention processing. Treatment with continuous positive airway pressure can partially reverse some of the brain changes and improve cognitive function in some domains and in some studies. This review suggests that MRI techniques and neuropsychological assessments can be useful tools for monitoring the progression and response to treatment of OSA patients.