Combined assessment of obstructive sleep apnea syndrome with dynamic MRI and parallel EEG registration: initial results

Gender-specific cephalometric features related to obesity in sleep apnea patients: trilogy of soft palate-mandible-hyoid bone

Background

The aim of this study is to investigate the relationship between gender-specific and obesity-related airway anatomy in patients with obstructive sleep apnea (OSA) by using cephalometric analyses.

Methods

We retrospectively evaluated 206 patients with suspected OSA undergoing polysomnography and anthropometric measurements such as body mass index, neck circumference, and waist-hip ratio. We checked lateral cephalometry to measure tissue landmarks including angle from A point to nasion to B point (ANB), soft palate length (SPL), soft palate thickness (SPT), retropalatal space (RPS), retrolingual space (RLS), and mandibular plane to hyoid (MPH).

Results

Male with OSA showed significantly increased SPL (P = .006) compared with controls. SPL and MPH had significant correlation with apnea-hypopnea index (AHI) and central obesity. Female with OSA showed significantly increased ANB (P = .013) and SPT (P = .004) compared with controls. The receiver operating characteristic curves revealed that SPT in male and ANB and SPT in female were significant in model 1 (AHI ≥ 5) and model 2 (AHI ≥ 15). MPH was also significant for male in model 2.

Conclusion

Male and female with OSA had distinct anatomic features of the upper airway and different interactions among soft palate, mandible, and hyoid bone.

Upper airway visualization in pediatric obstructive sleep apnea

Pediatric Obstructive Sleep Apnea (OSA) is a condition that may lead to a variety of comorbidities in adolescence and adulthood. The gold standard of diagnosing OSA is polysomnography (PSG). Over the past fifteen years numerous publications have explored how to better visualize the upper airway to further assess OSA in the pediatric population, and eventually institute personalized treatment. Lateral neck radiograph, cephalometry, computed axial tomography, and magnetic resonance imaging are all unique imaging techniques that are used in the diagnosis of OSA. Drug Induced Sleep Endoscopy is a direct visualization technique that is gathering momentum in pediatrics. Each approach has respective benefits and weaknesses. However, none of them at this time can replace PSG. They are a helpful supplement in those patients with complicated upper airway anatomy and in those with residual OSA.

Tracking Dynamic Tongue Motion in Ultrasound Images for Obstructive Sleep Apnea

Obstructive sleep apnea (OSA), a breathing disorder characterized by repetitive collapse of the pharyngeal airway during sleep, can cause intermittent hypoxemia and frequent arousal. The evaluation of dynamic tongue motion not only provides the biomechanics and pathophysiology for OSA diagnosis, but also helps doctors to determine treatment strategies for these patients with OSA. The purpose of this study was to develop and verify a dedicated tracking algorithm, called the modified optical flow (OF)-based method, for monitoring the dynamic motion of the tongue base in ultrasound image sequences derived from controls and patients with OSA. The performance of the proposed method was verified by phantom and synthetic data. A common tracking method, the normalized cross-correlation method, was included for comparison. The efficacy of the algorithms was evaluated by calculating the estimated displacement error. All results indicated that the modified OF-based method exhibited higher accuracy in verification experiments. In the human subject experiment, all participants performed the Müller maneuver (MM) to simulate the contour changes of the tongue base with a negative pharyngeal airway pressure in sleep apnea. Ultrasound image sequences of the tongue were obtained during 10 s of a transition from normal breathing to the MM, and these were measured using the modified OF-based method. The results indicated that the displacement of the tongue base during the MM was larger in the controls than in the patients with OSA (p < 0.05); the calculated areas of the tongue in the controls and patients with OSA were 24.9 ± 3.0 and 27.6 ± 3.3 cm², respectively, during normal breathing (p < 0.05), and 24.7 ± 3.6 and 27.3 ± 3.8 cm², respectively, at the end of the MM. The percentage changes in the tongue area were 2.2% and 1.3% in the controls and patients with OSA, respectively. We found that quantitative assessment of tongue motion by ultrasound imaging is suitable for evaluating pharyngeal airway behavior in OSA patients with minimal invasiveness and easy accessibility.

[Endoscopy in sleep medicine]

Endoscopic evaluation of the upper airway in patients with sleep disordered breathing (SDB) using rigid and flexible endoscopes is a typical investigation in otorhinolaryngology. Visualizing the anatomic structure as well as the dynamic mechanism of snoring and pharyngeal obstruction during wakefulness, natural sleep, and under sedation are of special interest. The results obtained have increased our understanding of SDB with obstruction of the upper airway. Videoendoscopy under sedation (ViSe) has become increasingly established as a tool to identify the therapeutic concept in cases of CPAP failure, leading to changes compared to the concept derived from basic awake endoscopy. The success of mandibular advancement devices can be adequately predicted. However, it remains unclear to what extent the success rate of surgery can be improved by ViSe. Further research into these approaches is needed in order to become valuable tools in the diagnostic work-up of patients with sleep apnea.

Assessment of obstruction level and selection of patients for obstructive sleep apnoea surgery: an evidence-based approach

Introduction:

Obstructive sleep apnoea has long been recognised as a clinical syndrome; however, high quality evidence on the effects of surgery for this condition is still missing. Despite this, a consensus seems to be evolving, albeit based on limited evidence, that surgery should be offered as a second line treatment to suitable patients with obstructive sleep apnoea.

Aims:

This article aims to assess the different methods of investigating upper airway obstruction in patients with obstructive sleep apnoea, in respect to these methods' relevance to surgical treatment, via a systematic review of the literature.

Methods:

The Cochrane Controlled Trials Register, Medline and EMBASE were searched from 1966 onwards. The search was performed in August 2008. A total of 2001 citations were retrieved.

Results and conclusion:

There is not yet a generally accepted way to assess surgical candidacy based on the level of obstruction. Better organised clinical studies with well defined endpoints are needed. In the meanwhile, it appears that sleep nasendoscopy, acoustic reflectometry and pressure catheters can all provide useful information, and their use may be decided upon based on the experience and resources available in individual departments.

[Update on upper airway evaluation in obstructive sleep apnea]

During the past two decades, different methods of upper airway evaluation for patients with obstructive sleep apnea (OSA) have been investigated. Although clinical assessment is the basis of any diagnostic workflow in OSA, the Mueller maneuver is apparently of no importance. Imaging techniques have increased our knowledge of the pathophysiology of OSA. Cephalometry is done only if maxillomandibular advancement is planned; dynamic investigations such as computed tomography and magnetic resonance imaging are able to picture the pharyngeal collapse and have the capacity to simulate the effect of interventions on OSA severity. So far, video endoscopy under sedation can only predict the success of oral appliances. Multichannel pressure recordings depict the distribution of obstructive events in the upper or lower pharyngeal segment during the entire night. The impact of sophisticated upper airway evaluation remains limited compared with standard clinical assessment. Further research is needed to develop valuable tools for the diagnostic workup of patients with OSA.

Diagnostic imaging and sleep medicine

Obstructive sleep apnea syndrome (OSAS) is a relatively common disorder characterized by recurrent episodes of upper airway collapse and obstruction during sleep. It results in apneic events (or in the case of partial obstruction, hypopneic events) that lead to loud snoring, hypoxia, and arousals that interrupt the normal sleep cycle. Typically, these nocturnal arousals cause patients to complain of excessive daytime sleepiness, which may interfere with routine daily activities. More importantly, when moderate to severe, OSAS can lead to a wide variety of medical complications, some of which can result in severe consequences or even death.

Diagnostic Studies in Obstructive Sleep Apnea

The standard for the diagnosis of obstructive sleep apnea (OSA) is polysomnography (PSG). Although PSG helps identify individuals who have OSA and guides medical management, it does not identify the obstruction site or predict surgical results. Radiologic and diagnostic studies have been used to direct surgical intervention and predict outcomes of sleep apnea surgery. These studies include lateral cephalometric radiographs, CT, MRI, asleep fluoroscopy, asleep and awake endoscopy, upper airway manometry, and acoustic reflection techniques. The ideal diagnostic study would identify individuals who have OSA, be cost-effective and readily accessible, and guide therapeutic, site-specific intervention with predictable results. In this article, the various modalities are reviewed in terms of their capability to effectively diagnose and guide treatment of OSA.

Age-related changes in cerebral lactate metabolism in sleep-disordered breathing

Thirty-one patients, aged 22-71 years, with nocturnal apneic episodes and/or habitual snoring were studied with magnetic resonance spectroscopy (MRS) and diagnostic polysomnography separately to determine whether accumulation of lactate caused by cerebral hypoxia during sleep is associated with sleep-disordered breathing (SDB), aging and co-morbidities related to SDB. Eight proton magnetic resonance spectra for sleep and two for periods of arousal were obtained from the right centrum semiovale. All patients were evaluated for the presence or absence of co-morbidities including hypertension, cardiac disease, diabetes mellitus, and hyperlipidemia. Significant lactate signals were found in seven patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) during sleep periods, and none during periods of arousal. Aging was significantly related to the presence or absence of significant lactate signals during sleep periods as determined by logistic regression analysis (beta=0.2480; 95% confidence interval, 0.0905-0.5094; P=0.0001). Apnea index (AI), apnea-hypopnea index (AHI), and minimum value of peripheral oxyhemoglobin saturation each significantly interacted with age (P=0.0081, 0.0284, and 0.0302, respectively). Our findings suggest that SDB combined with aging is related to accumulation of lactate during sleep.

Upper airway motion depicted at cine MR imaging performed during sleep: comparison between young Patients with and those without obstructive sleep apnea

PURPOSE

To compare the patterns of dynamic airway motion depicted on cine magnetic resonance (MR) images obtained during sleep between young patients with and those without obstructive sleep apnea (OSA).

MATERIALS AND METHODS

Fast gradient-echo sequences were performed in the sagittal midline by using a 1.5-T unit to create cine MR images. Cine MR images obtained during sleep in 16 young patients with OSA were compared with those obtained in 16 young patients with no airway symptoms of airway disease. The nasopharynx, oropharynx, and hypopharynx were characterized in terms of airway motion as static patent (SP), dynamic patent, intermittent collapsed (IC), or static collapsed (SC); and the maximal diameter and greatest change in diameter (in millimeters) of these airways were calculated. Adenoid tonsil size and mouth position (ie, opened or closed) were determined. Differences in the frequency of MR imaging parameters in the different anatomic regions were evaluated by using Fisher exact, chi 2, and sample t tests.

RESULTS

There were statistically significant differences in the following parameters between the two groups: nasopharynx SP (P <.001) and IC (P <.001); hypopharynx SP (P <.001) and IC (P <.001); and mean change in airway diameter of the nasopharynx (P <.001) and hypopharynx (P <.001). The mean adenoid tonsil size in the patients with OSA was larger (P =.006).

CONCLUSION

There are significant differences in the patterns of dynamic airway motion between young patients with and those without OSA.