Retropalatal Region Research Articles

Motor control of the palatoglossus and genioglossus during changes in breathing route.

High activity of upper airway dilator muscles is thought to be critical in preventing sleep-related upper airway collapse. To date, most of the research regarding upper airway dilator muscles has focused on the genioglossus muscle, which protrudes the tongue and opens the retroglossal airway. However, collapse commonly occurs in the retropalatal region. We therefore aimed to examine the motor control of the palatoglossus muscle as well as investigate breathing route-related changes in genioglossus and palatoglossus motor units. Single motor unit recordings of the genioglossus and palatoglossus were made simultaneously in healthy individuals during wakefulness while breathing through the nose with the mouth closed (NMC), nose with mouth open (NMO) or orally (OMO). The palatoglossus was found to have all 5 motor unit firing patterns that have been observed in other upper airway dilator muscles, but during nasal breathing had a higher proportion of tonically active but inspiratory modulated motor units as compared to the genioglossus (67% vs 30%). When still breathing nasally but with the mouth open, the units with an expiratory firing pattern in genioglossus, and all firing patterns in palatoglossal, increased their firing rates compared to nasal breathing with the mouth closed (GG: 17.8±4.9 vs 23.1±4.8 Hz, PG: 17.0±4.0 vs 19.3±4.0 Hz). Finally, oral breathing resulted in dramatic reductions in the number of palatoglossal motor units that were firing (35 units vs 92 during nasal breathing). Palatoglossus activity may contribute importantly to airway collapsibility and may provide an alternate pathway for preventing sleep-related airway collapse.

State-Dependent Biomechanical Behavior of Oropharyngeal Structures in Apneic and Control Subjects: A Proof-of-Concept Study.

Rationale: Apneic individuals have reduced airway caliber during sleep. The biomechanical changes in upper airway anatomy contributing to this airway narrowing are largely unknown. Objectives: We sought to investigate the state-dependent (wake vs. sleep) biomechanical behavior of the upper airway soft-tissue and craniofacial structures. Methods: Upper airway magnetic resonance imaging was performed in 15 sleep-deprived control subjects (apnea-hypopnea index, <5; 0.3 ± 0.5 events per hour) and 12 sleep-deprived apneic subjects (apnea-hypopnea index, ⩾5; 35.2 ± 18.1 events per hour) during wake and sleep and analyzed for airway measures and soft-tissue/mandibular movement. Results: In the retropalatal region, control subjects showed sleep-dependent reductions (P ⩽ 0.037) in average cross-sectional airway area (CSA), minimum CSA, and anteroposterior and lateral dimensions. Apneic subjects showed sleep-dependent reductions (P ⩽ 0.002) in average CSA, minimum CSA, and anteroposterior and lateral dimensions. In the retroglossal region, control subjects had no sleep-dependent airway reductions. However, apneic subjects had sleep-dependent reductions in minimal CSA (P = 0.001) and lateral dimensions (P = 0.014). Control subjects only showed sleep-dependent posterior movement of the anterior-inferior tongue octant (P = 0.039), whereas apneic subjects showed posterior movement of the soft palate (P = 0.006) and all tongue octants (P ⩽ 0.012). Sleep-dependent medial movement of the lateral walls was seen at the retropalatal minimum level (P = 0.013) in control subjects and at the retropalatal and retroglossal minimum levels (P ⩽ 0.017) in apneic subjects. There was posterior movement of the mandible in apneic subjects (P ⩽ 0.017). Conclusions: During sleep, control and apneic subjects showed reductions in retropalatal airway caliber, but only the apneic subjects showed retroglossal airway narrowing. Reductions in anteroposterior and lateral airway dimensions were primarily due to posterior soft palate, tongue and mandibular movement and to medial lateral wall movement. These data provide important initial insights into obstructive sleep apnea pathogenesis.

Upper airway modifications after weight loss: a systematic review.

Weight loss is one of the most often prescribed treatments to reduce the level of sleep apnea severity; however, objective assessment of airway alterations after loss of weight has only been studied in the last decades. This study aimed at evaluating alterations after weight loss reported in the literature. A literature review was performed in the medical databases: PubMed, Web of Science, Scopus and Embase. A total of 681 articles were found in the databases and after evaluation only 10 studies were selected for data extraction. Most studies observed an increase of the area in the retropalatal region; some indicating that this increase occurred mostly in the lateral pharyngeal region. Studies with volumetric reconstruction showed a significant reduction in parapharyngeal fat deposits, lateral wall and tongue fat, and volumetric reduction in all soft tissues of the pharynx, pterygoid and genioglossus muscles. Studies evaluating craniofacial bone structures showed a reduction in the airway height by bringing the hyoid closer to the posterior nasal spine and a reduction in the distance from the hyoid to the chin. There is a limited number of studies with a good level of scientific evidence evaluating changes in the upper airways after weight loss and how these changes impact obstructive sleep apnea. The studies included in this review indicate that weight loss increases the airways space by reducing the volume of the parapharyngeal structures, particularly at the retropalatal site, where there is an apparent gain in the lateral area of the airway and hyoid relocation.

Comparison of Airway Measurements in Rheumatoid Arthritis and Non-rheumatoid Patients using Lateral Cephalometric Radiographs.

The aim of this study was to investigate the potential relationship between the volumetric area of the upper airway and rheumatoid arthritis (RA) by comparing upper airway measurements between patients with and without RA. This case-control study compared upper airway measurements between patients with and without RA using lateral cephalometric radiographs. Two distinct measurements were made: the area of the upper airway, which is defined as "the area extending from the point of the retro-palatal region to the base of the epiglottis," and the distance of the upper airway, which is defined as "the distance between the anterior border of the third cervical vertebra (C3) and the anterior border of the soft tissue of the neck". A single examiner performed all measurements, and the intra-examiner reliability was assessed. Sixty-one RA patients and 95 non-RA patients were included in the case and control groups, respectively. RA patients were significantly older in age and with higher BMI values. Patients with or without RA had Angle Class II as the most prevalent orthodontic classification. The upper airway was slightly narrower in RA patients, resulting in a smaller area, and the length of the upper airway was significantly longer in RA patients. Patients with RA have narrower upper airways as measured on lateral cephalometric radiographs. This may partially explain the high prevalence of obstructive sleep apnea among patients with RA. Focusing on airways measurements when cephalometric radiographs are taken for patients with RA could give some idea about which patient is likely to have OSA.

Quantitative Morphometric Measurements of the Oropharynx in Obstructive Sleep Apnea Syndrome Using a Laser Depth Measurement Module.

IntroductionCurrent diagnostic routines in obstructive sleep apnea syndrome (OSAS), including drug-induced sleep endoscopy (DISE), provide qualitative data. Quantitative morphometric measurements of oropharyngeal structures remain challenging. This study aims to introduce a special linear laser projection device that can facilitate computer-assisted digitalized analysis and provide important quantitative information for OSAS prediction.Materials and MethodsWe used a single-wavelength green three-linear laser to provide the scaling reference, with one at an angle of 8.5 degrees with the other two which were parallel. The oropharyngeal images were divided into two groups: the non-OSAS and OSAS group, after polysomnography. A minimum of three evaluations were carried out to determine the maximum cross-sectional area of the oropharyngeal inlet (CSAOI) and the retropalatal depth.ResultsA total of 132 subjects were enrolled in this study, with 76 subjects in the non-OSAS group and 56 cases in the OSAS group. In the non-OSAS group, the CSAOI was significantly larger in males than in females. There was a trend toward deeper retropalatal region in men than in women (14.25 vs 11.76 mm). Correlation analysis revealed that retropalatal depth is significantly related to body height and the CSAOI. The body weight and BMI of patients with OSAS were significantly higher than those of participants without OSAS. The retropalatal depth and CSAOI were significantly decreased in OSAS patients as compared to those without OSAS. Our new parameter, the oropharyngeal index, showed the most outstanding discrimination by ROC analysis to predict OSAS.ConclusionOur innovative module can provide reference parameters, which make it possible to directly estimate the objective absolute values of relevant oropharyngeal structures. Our non-invasive approach can be used for outpatient screening, since it allows the identification of potential OSAS patients who should be referred for polysomnography, as many patients do not require DISE early in their evaluation.

Predictive anatomical factors of lung aerosol deposition in obese individuals. Would modified mallampati score be relevant? Clinical trial

BackgroundObesity is a highly prevalent condition worldwide that aggravates symptoms of already existing conditions such as asthma and COPD. The limited effectiveness of inhaled medications in these individuals may be related to anatomic characteristics of their upper airways, mainly due to compressive factors. MethodsControlled clinical trial with obese and nonobese individuals. The following variables were evaluated: anthropometric characteristics, Lung and airway deposition of radiolabeled aerosol (pulmonary scintigraphy), upper airways anatomy (CT scans), and modified Mallampati score. Results29 subjects (17 nonobese and 12 obese) participated. Obese volunteers presented 30% lower aerosol lung deposition compared to nonobese. Moreover, obese subjects Mallampati classification of 4 presented an aerosol lung deposition two times lower than nonobese subjects (p = 0.021). The cross-sectional area of the retropalatal region and retroglossal region were lower in obese patients (p < 0.05), but no correlation to aerosol lung deposition was observed. BMI was associated with 32% of the variance of lung deposition (p < 0.001; β −0.28; 95% CI -0.43 to −0.11). ConclusionHigh BMI correlated to reduced percentage lung deposition. Also, modified Mallampati class 4 was even more detrimental to aerosol delivery into the lungs. Obese subjects have narrower upper airways, compared to nonobese, but this is not reflected in higher radiolabeled aerosol impaction into their oropharynx and does not predict the percentage of lung deposition in this group. Clinical trial registrationNCT03031093 (clinicaltrials.org)

Building a model to precisely target the responders of a novel intermittent negative air pressure device-with mechanism definition

ObjectiveDue to the complexity of obstructive sleep apnea syndrome (OSAS), engaging patients in the right treatment poses a constant challenge. A novel oral pressure therapy device, the intermittent negative air pressure Sleep Therapy System (iNAP), has proven to ameliorate respiratory events for OSAS patients. However, the mode of action and the characteristics of its responders are not yet fully understood. Therefore, we have first disclosed the mechanism and provided systemic models to predict the treatment response. MethodsSeries of imaging studies were carried out to differentiate the anatomical features of iNAP responders versus non-responders. Compatible electroencephalography was used to evaluate sleep status during magnetic resonance imaging (MRI) assessments. ResultsThe upper airway volume was statistically widened under the iNAP treatment while patients were naturally asleep (p < 0.05). Negative predictors included several parameters related to oral-tissue redundancy, enlarged middle pharyngeal space, and longer distance of hyoidale to mandibular plane. Positive predictors included larger angulation of sella-articulate-gonion, longer distance of anterior nasal spine to posterior nasal spine, and elongated tongue, which could correspond to the fact that the iNAP had a greater ability to widen the retropalatal region. Furthermore, algorithms developed by these predictors were built to predict treatment response. ConclusionsWe were able to confirm the effect of the iNAP in widening the upper airway. Anatomic features that can be visually observed or obtained through X-ray films, accompanied with the resulting algorithms, were provided to facilitate physicians' ability to predict patients' treatment response to the iNAP with greater sensitivity and efficiency.

The morphology and resilience change of upper airway in patients with OSAHS: A MSCT study

Objective:To analyse the morphology and resilience of upper airway in patients with OSAHS using 128-slice MSCT. Method:CT imaging of the upper airway in 49 patients with OSAHS was acquired in two respiratory status (quiet respiration and Müller maneuver). The two-dimensional measurements of retropalatal and retroglossal regions, airway volume, and airway resilience were measured in patients with severe OSAHS and non-severe OSAHS. And the results were compared between those two groups. Result:① The following measurements during Müller maneuver were smaller than those during quiet respiration: the smallest cross section area of retropalatal and retroglossal region, the anteroposterior diameters(AP) and lateral diameters(L) of retropalatal region, L of retroglossal region, volume and average volume of upper airway and retropalatal area（P<0.01）.②The pharyngeal wall resilience of retropalata region was larger than those of retroglossal region in patients with severe OSAHS. The total resilience of retropalatal was larger than that of retroglossal region in patients with non-severe OSAHS. The pharyngeal wall resilience between severe and non-severe OSAHS had no significant difference. ③ L of retropalatal and retroglossal region, and average area of retropalatal region, were smaller in patients with severe OSAHS than those with non-severe OSAHS during Müller maneuver（P<0.05）.④ The cross-section of upper airway tend to be horizontal oval in retropalatal regions, and vertical oval in retroglossal regions. Conclusion:128-slice MSCT scan can achieve both positioning and quantitative analysis of the morphology and resilience changes of the upper airway in patients with OSAHS.

Dynamic Upper Airway Imaging during Wakefulness in Obese Subjects with and without Sleep Apnea.

Obesity is a major risk factor for obstructive sleep apnea. Although greater dimensional changes in the upper airway during wake respiration have been noted in patients with apnea compared with control subjects, whether these differences remain in the presence of obesity is unknown. To evaluate upper airway anatomic characteristics and airway compliance (distensibility) in obese subjects with obstructive sleep apnea compared with obese control subjects. Dynamic magnetic resonance imaging was performed in 157 obese subjects with apnea and 46 obese control subjects during wakefulness in the midsagittal and three axial upper airway regions (retropalatal, retroglossal, epiglottal). Differences in measurements between subjects with apnea and control subjects, and correlations with apnea-hypopnea index among subjects with apnea, were examined. Measurements included airway areas and linear dimensions. Subject-specific coefficients of variation were calculated to examine variability in airway size. Controlling for covariates, the retropalatal area during respiration was significantly smaller in subjects with apnea than control subjects, based on the average (P = 0.003), maximum (P = 0.004), and minimum (P = 0.001) airway area. Airway narrowing was observed in anteroposterior and lateral dimensions (adjusted P < 0.05). Results were similar in an age, sex, and body mass index-matched subsample. There were significant correlations between apnea-hypopnea index and dynamic measures of airway caliber in the retropalatal and retroglossal regions among subjects with apnea. Upper airway caliber during respiration was significantly narrower in obese subjects with apnea than obese control subjects in the retropalatal region. These findings provide further evidence that retropalatal airway narrowing plays an important role in the pathogenesis of obstructive sleep apnea in obese subjects.

The role of ultrasound in the diagnosis of obstructive sleep apnea

Abstract OBJECTIVE. This study examines the association between the severity of obstructive sleep apnea and the pharyngeal parameters using the ultrasound of the submental region. MATERIAL AND METHODS. For this study, data obtained from 40 patients, who had undergone investigations in the Galenus Medical Centre in order to diagnose sleep apnea, was analyzed. The following parameters were compared: the transverse diameter of the retrolingual region, the transverse diameter of the retropalatal region and the tongue base thickness. These regions were measured at different moments of respiration such as: during forced expiration, during forced inspiration and while the patients performed Müller’s Manoeuvre. The neck circumference, the body mass index of patients and the severity of sleep apnea obtained from polysomnography were analyzed. RESULTS. The evaluation of the results revealed: severe obstructive sleep apnea in 16 patients, respectively moderate severity in 10 patients, mild apnea in 4 patients, and no obstructive sleep apnea in 10 patients. Statistically significant results (p&lt;0.05) were found after comparing the parameters obtained in patients with severe apnea versus the parameters in patients without apnea, with mild or respectively moderate apnea. CONCLUSION. Based on the results obtained, we consider that cervical ultrasound is useful in the diagnosis of severe obstructive apnea, identifying the pathological changes of the anatomical structures that basically cause this category of disease. Due to the fact that in our country ultrasound is a relatively inexpensive method, being also a non-irradiating, repeatable and accessible method, it should be more widely applied also in the field of otorhinolaryngology in order to view structures accessible to this type of imaging.

Evaluation of morphological changes in pharynx with dynamic CT and MRI in snoring patients.

Identifying the craniofacial abnormalities that cause snoring and the narrowest area of the upper airway creating obstructions can help to determine the proper method of treatment. To identify the factors that can cause snoring and the areas of the airway that are the most likely to collapse with upper airway imaging. Axial pharynx examinations with CT (computerized tomography) and magnetic resonance imaging (MRI) were performed to 38 patients complaining of snoring and 12 patients who did not complain of snoring. The narrowest areas of nasopharynx, hypophraynx, oropharynx, bilateral para-pharyngeal fat pad and para-pharyngeal muscle thickness were measured. In snoring patients, the narrowest part of the upper airway was the retro-palatal region in the oropharynx, as measured with both imaging methods. When patients with and without snoring were compared, the former that a higher body mass index and neck diameter and a narrower oropharynx area. In dynamic examinations, we determined that as para-pharyngeal muscle thickness increased, medial-lateral airway diameter and the oropharynx area decreased. The narrowest section of the airway is the retro-palatal region of the oropharynx, measured both with CT and MRI.

Preliminary analysis of influencing factors on source of snoring sound

Objective:To investigate the main factors affecting the source of snoring sound of snoring patients.Method:Seventy-three patients with either simple snoring or obstructive sleep apnea-hypopnea syndrom(AHI≤40) underwent routine ENT examination,CT scanning(in awake condition) and drug-induced sleep endoscopy.The sources of snoring sound were observed.The neck circumference,body mass index and CT data were measured.Result:The sources of snoring sound of the 73 cases were divided into three types in general: palatal fluttering based group(Group Ⅰ),lateral wall vibration based group(Group Ⅱ) and palatal fluttering together with vibration of lateral wall based group(Group Ⅲ).The minimum lateral caliber of retropalatal region and retroglossal region,the ratio of minimum anteroposterior/ lateral caliber of the two regions,the thickness of pharyngeal lateral wall had statistical differences.The main influencing factors on the source of snoring sound between Group Ⅱ and Group Ⅰ were the ratio of minimum anteroposterior/lateral caliber of retropalatal region and the mean thickness of pharyngeal lateral wall.The influencing factor between Group Ⅲ and Group Ⅰ was the mean thickness of pharyngeal lateral wall.Conclusion:The ratio of minimum anteroposterior/lateral caliber of retropalatal region and the mean thickness of pharyngeal lateral wall are the main factors affecting the source of snoring sound of snoring patients.

Evaluation of water content around airway in obstructive sleep apnea patients using peripharyngeal mucosal T2 magnetic resonance imaging.

Obstructive sleep apnea (OSA) is common sleep disorder characterized by repetitive episodes of airway closure which usually occurs in the retropalatal region of the oropharynx. It has been known that upper airway mucosa in OSA patients is described as edematous, but not fully clarified. This study aimed to investigate and establish magnetic resonance imaging (MRI) parameter to estimate tissue water content at retropalatal level and its relationship with sleep parameters in OSA patients. Forty-eight subjects with OSA underwent overnight polysomnography and cervical MRI with 1.5-tesla [mean (SD) age 55 (14) years and apnea-hypopnea index (AHI) 45.2 (26.1) events/hour, 79.2% male]. On the axial T2-weighted images from epipharynx to oropharynx, the signal intensities of masseter muscle and peripharyngeal mucosa [T2 mucous-to-masseter intensity ratio (T2MMIR)], was used as water content estimation in the retropalatal region. Partial correlation analysis was performed to examine the correlation between T2MMIR and polysomnography parameters. We found that there were strong and positive correlations between the T2MMIR and AHI (r = 0.545, P < 0.05), supine AHI (r = 0.553, P < 0.05) and REM AHI (r = 0.640, P < 0.01) by partial correlation analysis. Besides, in patients with less efficient sleep who had more stage 1 sleep, significantly higher T2MMIR was noted (r = 0.357, P < 0.05). This study confirmed that peripharyngeal T2MMIR can be a simple parameter representing peripharyngeal tissue water contents related to severe OSA.

Endoscopic upper airway evaluation in obstructive sleep apnea: Mueller's maneuver versus simulation of snoring.

This study aimed to compare fiberoptic nasopharyngoscopy during Mueller's maneuver (FNMM) with fiberoptic nasopharyngoscopy with simulation of snoring (FNSS) for upper airway (UA) assessment in patients with obstructive sleep apnea and hypopnea syndrome. We also investigated the relationship between daytime endoscopic examinations and nocturnal pressure measurements. We conducted a prospective, case-series study at Peking Union Medical College Hospital. All patients were evaluated by daytime FNMM and FNSS. The retropalatal and retroglossal regions were continuously video recorded during quiet breathing, FNMM, and FNSS. We calculated the narrowing rate and determined the level of obstruction and pattern of collapse (lateral, anterior-posterior, or concentric). Patients also underwent nocturnal pressure measurements to identify obstruction sites. Ninety-two patients were enrolled. FNMM and FNSS detected retropalatal obstruction in every case. Fifty-six and 38 patients had retroglossal obstruction detected by FNMM and FNSS, respectively. There was diagnostic agreement between FNMM and FNSS in 72 patients when diagnosing retroglossal obstruction, but the patterns of collapse were different using each technique. Pressure measurements showed that lower apnea and hypopnea index (AHI) and the proportion of lower AHI were significantly lower in the isolated retropalatal obstruction group than in the combined obstruction group diagnosed with either FNMM or FNSS (p < 0.01). Daytime FNMM and FNSS are reliable for evaluating the level of obstruction and pattern of UA collapse, and correlate with sleep study findings. FNSS may provide some different information regarding patterns of collapse and retroglossal obstruction from FNMM. Both techniques are helpful for determining surgical strategies.

Oral appliance effectively reverses Muller’s maneuver-induced upper airway collapsibility in obstructive sleep apnea and hypopnea syndrome

To verify the effects of oral appliance (OA) on upper airway morphology under intraluminal pressure, identify specific sites of upper airway collapsibility that can be reversed by OAs, and determine the relationship between OA efficacy and dynamic upper airway changes using computed tomography (CT) with Muller's maneuver. Nineteen adult Chinese patients with symptomatic mild-to-moderate sleep apnea were recruited from our sleep center. Each patient was fitted with a two-piece OA. Dynamic changes in the retropalatal and retroglossal airway were evaluated using CT at end-expiration and during Muller's maneuver, both with and without an OA. Upper airway changes in the end-expiration phase before OA placement did not significantly differ from those after OA placement. However, under intraluminal pressure induced by Muller's maneuver, OA effectively expanded the upper airway at multiple levels. In addition, OA counteracted negative intraluminal pressure more effectively in the retropalatal region than in the retroglossal region, with 95.65, 68.75, 72.41, and 78.38% improvements in the collapsibility index of the anteroposterior dimension, transverse dimension, minimum cross-sectional area, and volume of the retropalatal region, respectively. Both nonresponders and responders to OA treatment were sensitive to the intraluminal pressure induced by Muller's maneuver. However, the collapsibility of the retropalatal airway improved significantly only in the responders, not in the nonresponders. OA effectively treats OSAHS by improving upper airway collapsibility.

Magnetic resonance imaging study of peripharyngeal mucosal intensity in obstructive sleep apnea patients

Introduction Obstructive sleep apnea (OSA) is a common sleep disorder characterized by repetitive episodes of airway closure which usually occur in the retro-palatal region of the oropharynx. It has been known that upper airway mucosa in OSA patients is described as edematous. Recurrent injuries owing to vibration of the upper airway tissues or repetitive negative pressure may contribute to this phenomenon. On the other hand, fluid redistribution from the lower to the upper body during nocturnal recumbency could shift the fluid into neck and tissue around airway. The combination of these might contribute the occurrence or worsening of OSA by compressing the airway. Therefore, this study aims to investigate and establish simple magnetic resonance imaging (MRI) parameters, namely T2 mucous-to- masseter intensity ratio (T2MMIR), to assess the degree of tissue water content at the retro-palatal level and its relationship with sleep parameters in OSA patients. Materials and methods Twenty-seven subjects with OSA underwent polysomnography and cervical MRI with 1.5-tesla during wakefulness (age 55.0 ± 16.5 y, 77.8% male, with apnea-hypopnea index (AHI) 54.1 ± 27.6 and a body mass index (BMI) 29.4 ± 5.5) were included. On the axial T2-weighted images from the epipharynx to the oropharynx, the signal intensities for masseter muscle and peripharyngeal mucosa were measured. T2 mucous-to-masseter intensity ratio was calculated, and was used as an estimate of water content in the retro-palatal region. Pearson correlation analysis was performed to examine the correlation between peripharyngeal T2MMIR and polysomnography parameters. Results T2 mucous-to-masseter intensity ratio had moderate, positive correlation with supine AHI ( r = 0.388, P r = 0.408, P r = 0.411, P r = 0.419, P r = 0.645, P r = −0.401, P Conclusion This is the first report to establish peripharyngeal T2MMIR as one simple parameter representing peripharyngeal mucosal water contents due to inflammatory edema and/or fluid redistribution during recumbency, related to severity of OSA. This finding suggested its potential usefulness in reevaluation of change of peripharyngeal mucosa after OSA treatment to confirm its success.

Real‐time 3D magnetic resonance imaging of the pharyngeal airway in sleep apnea

To investigate the feasibility of real-time 3D magnetic resonance imaging (MRI) with simultaneous recording of physiological signals for identifying sites of airway obstruction during natural sleep in pediatric patients with sleep-disordered breathing. Experiments were performed using a three-dimensional Fourier transformation (3DFT) gradient echo sequence with prospective undersampling based on golden-angle radial spokes, and L1-norm regularized iterative self-consistent parallel imaging (L1-SPIRiT) reconstruction. This technique was demonstrated in three healthy adult volunteers and five pediatric patients with sleep-disordered breathing. External airway occlusion was used to induce partial collapse of the upper airway on inspiration and test the effectiveness of the proposed imaging method. Apneic events were identified using information available from synchronized recording of mask pressure and respiratory effort. Acceptable image quality was obtained in seven of eight subjects. Temporary airway collapse induced via inspiratory loading was successfully imaged in all three volunteers, with average airway volume reductions of 63.3%, 52.5%, and 33.7%. Central apneic events and associated airway narrowing/closure were identified in two pediatric patients. During central apneic events, airway obstruction was observed in the retropalatal region in one pediatric patient. Real-time 3D MRI of the pharyngeal airway with synchronized recording of physiological signals is feasible and may provide valuable information about the sites and nature of airway narrowing/collapse during natural sleep.

The Use of Sub-Mental Ultrasonography for Identifying Patients with Severe Obstructive Sleep Apnea

ObjectiveThis study aimed to explore the association between obstructive sleep apnea (OSA) severity and pharyngeal parameters using sub-mental ultrasonography (US), and investigate the accuracy of US for identifying severe OSA patients.MethodsOne hundred and five consecutive referrals for suspected OSA were enrolled. The diameters of the retro-glossal (RG) and retro-palatal (RP) regions were measured via sub-mental US upon expiration during tidal breathing, forced inspiration, and Müller maneuver (MM). Independent factors associated with severe OSA identified from two-thirds of randomly-selected patients (model-development group) were used to construct a model for predicting severe OSA. The accuracy of the model was validated in the remaining one-third of patients (validation group).ResultsFifty severe OSA patients, 30 with mild-moderate OSA, and 25 without OSA were enrolled. Compared to non-OSA and mild-moderate OSA patients, those with severe OSA had narrower RP diameter in all three maneuvers. Using the prediction model constructed with changes of RP diameters at MM and neck circumference, the independent predictors of severe OSA in the model-development group had 100% sensitivity and 65% specificity.ConclusionSub-mental US can accurately discriminate the severity of OSA and be used to identify patients with severe OSA.Trial RegistrationClinicalTrials.gov NCT00674076

Real-time CT of upper airway in patients with obstructive sleep apnea hypopnea syndrome

To explore the technology and clinical application of real-time CT scan in obstructive sleep apnea hypopnea syndrome during awake and drug induced sleep state. Sixty-two patients with OSAHS diagnosed by polysomnography underwent 256 layer spiral CT scan during awake and drug-induced sleep apnea state, and multiplanar reconstruction and volume rendering of computed tomography images were performed. To observe the dynamic changes of upper airway and locate the sites of airway obstruction in patients with OSAHS, the minimum section area, diameter and volume of pharynx cavity were measured on reconstructed 3-dimensional computed tomography. Real-time CT scans were completed successfully in all of the patients. It was revealed that airway obstruction frequently occurred at retropalatal and retroglottal region. Real-time CT scans revealed 29 cases with airway obstruction at isolated retropalatal region, 19 cases with airway obstruction at retropalatal and retroglottal region simultaneously, 6 cases with airway obstruction at retropalatal and epiglottal region simultaneously, 7 cases with airway obstruction at retropalatal, retroglottal and retroglottal region simultaneously, 1 case without airway obstruction. There was no airway obstruction at retroglottal or retroglottal region isolatedly. Rate of single region airway obstruction was 46.8% (29/62), and rate of multiple regions airway obstruction 51.6% (32/62). The real-time CT results showed that starting from Friedman tongue position I to IV, the percentage of obstruction at retroglottal and (or) retroglottal region simultaneously were increasing, the percentage of obstruction were 0/6, 8/25, 13/20, 11/11, respectively (χ(2) = 22.00, P < 0.005). The minimum section area, volume, minimum anteroposterior diameter and left-right diameter of pharynx cavity between awake and drug-induced sleep apnea state had statistically significant difference in all region. Real-time CT scans in drug-induced sleep state could get more information about the anatomical and pathological changes of upper airway, providing relatively objective morphological basis for the diagnosis and treatment of patients with OSAHS. Therefore, real-time CT scans have important value in practical application.

Upper airway changes in obstructive sleep apnea suffers after H-uvulopalatopharyngoplasty and H-uvulopalatopharyngoplasty combined with transpalatal advancement pharyngoplasty

To compare the different postoperative changes of the pharynx in obstructive sleep apnea hypopnea syndrome (OSAHS) patients treated with H-uvulopalatopharyngoplasty (H-UPPP) combined with transpalatal advancement pharyngoplasty (PA) surgery or H-UPPP alone. The upper airway in 43 patients with OSAHS were scanned during the end of normal respiration before and after treatment. There were 17 patients undergoing H-UPPP alone, 26 patients undergoing H-UPPP combined with PA, with PSG before and after treatment. To compare the efficacy of H-UPPP with PA surgery or H-UPPP alone, upper airway characteristics were measured following each procedure in 43 patients using a quantitative 3-D CT. The 3-D CT measurement were made in lateral and anterior-posterior diameters, cross-section areas and volumes of retropalatal and retroglossal region. The changes in the structure of OSAHS patients treated with H-UPPP combined with PA surgery and H-UPPP alone were compared preoperatively and postoperatively, and the correction features that were presented in AHI and structural changes were analysed. The difference between H-UPPP combined with PA (n = 26) and H-UPPP (n = 17) in the changes in apnea hypopnea index (AHI) were (67.5 ± 18.9, 38.7 ± 42.0, t = 2.84, P < 0.05), hard palate lengths were (4.50 ± 3.72) mm and (0.06 ± 0.22) mm (t = 5.55, P < 0.01); anteroposterior diameters of the hard palate level were (3.5 ± 4.3) mm and (-1.7 ± 4.4) mm (t = 3.90, P < 0.01); the minimum anteroposterior diameters of retropalatal were (1.2 ± 2.2) mm and (-1.2 ± 2.3) mm (t = -3.49, P < 0.01); the minimum lateral diameters of retroglossal area were (4.9 ± 9.6) mm and (13.1 ± 9.1) mm (t = 2.80, P < 0.01) preoperatively and postoperatively. The changes in the hard palate lengths were positively correlated to the change in AHI (r = 0.407, P < 0.01), also the change in anteroposterior diameter of the hard palate level (r = 0.351, P < 0.05), the minimum anteroposterior diameter of retropalatal area (r = 0.381, P < 0.01), and the minimum cross-section area of retropalatal (r = 0.312, P < 0.05). H-UPPP combined with PA offers benefit over H-UPPP alone in OSAHS patients, which may be achieved by increased retropalatal airway size. Both the anteroposterior dimensions and the cross-area size are related with the efficacy of surgery.