Sleep-disordered breathing and neuropsychological deficits. A population-based study

Regional associations between inspiratory tongue dilatory movement and genioglossus activity during wakefulness in people with obstructive sleep apnoea

Inspiratory tongue dilatory movement is believed to be mediated via changes in neural drive to genioglossus. However, this has not been studied during quiet breathing in humans. Therefore, this study investigated this relationship and its potential role in obstructive sleep apnoea (OSA). During awake supine quiet nasal breathing, inspiratory tongue dilatory movement, quantified with tagged magnetic resonance imaging, and inspiratory phasic genioglossus EMG normalised to maximum EMG were measured in nine controls [apnoea-hypopnea index (AHI) ≤5 events/h] and 37 people with untreated OSA (AHI >5 events/h). Measurements were obtained for 156 neuromuscular compartments (85%). Analysis was adjusted for nadir epiglottic pressure during inspiration. Only for 106 compartments (68%) was a larger anterior (dilatory) movement associated with a higher phasic EMG [mixed linear regression, beta = 0.089, 95% CI [0.000, 0.178], t(99) = 1.995, P = 0.049, hereafter EMG↗/mvt↗]. For the remaining 50 (32%) compartments, a larger dilatory movement was associated with a lower phasic EMG [mixed linear regression, beta = -0.123, 95% CI [-0.224, -0.022], t(43) = -2.458, P = 0.018, hereafter EMG↘/mvt↗]. OSA participants had a higher odds of having at least one decoupled EMG↘/mvt↗ compartment (binary logistic regression, odds ratio [95% CI]: 7.53 [1.19, 47.47] (P = 0.032). Dilatory tongue movement was minimal (>1 mm) in nearly all participants with only EMG↗/mvt↗ compartments (86%, 18/21). These results demonstrate that upper airway dilatory mechanics cannot be predicted from genioglossus EMG, particularly in people with OSA. Tongue movement associated with minimal genioglossus activity suggests co-activation of other airway dilator muscles. KEY POINTS: Inspiratory tongue movement is thought to be mediated through changes in genioglossus activity. However, it is unknown if this relationship is altered by obstructive sleep apnoea (OSA). During awake supine quiet nasal breathing, inspiratory tongue movement, quantified with tagged magnetic resonance imaging (MRI), and inspiratory phasic genioglossus EMG normalised to maximum EMG were measured in four tongue compartments of people with and without OSA. Larger tongue anterior (dilatory) movement was associated with higher phasic genioglossus EMG for 68% of compartments. OSA participants had an ∼7-times higher odds of having at least one compartment for which a larger anterior tongue movement was not associated with a higher phasic EMG than controls. Therefore, higher genioglossus phasic EMG does not consistently translate into tongue dilatory movement, particularly in people with OSA. Large dilatory tongue movements can occur despite minimal genioglossus inspiratory activity, suggesting co-activation of other pharyngeal muscles.

Dupilumab efficacy in high sleep disturbance management among patients with type 2 asthma

BACKGROUND

Patients with asthma often experience sleep disturbances. We assessed the 5-item Asthma Control Questionnaire (ACQ-5) score ≥2.5 as a useful threshold to identify patients with moderate-to-severe type 2 asthma and high sleep disturbance (HSD) and investigated dupilumab efficacy on clinical and sleep-related outcomes among patients with HSD.

METHODS

QUEST (NCT02414854) data were used in this post hoc analysis. A composite endpoint from validated patient-reported outcomes was developed to identify patients with HSD using sleep-related items from the ACQ-5, Asthma-Related Quality-of-Life Questionnaire, Rhino-Conjunctivitis Quality-of-Life Questionnaire, and Sino-Nasal Outcome Test-22. Impairment in at least 1 item was considered an indication of HSD. Change from baseline to Week 52 in nighttime symptoms, ACQ-5 score, lung function, annualized severe exacerbation rates (AER), and short-acting β-agonists use during treatment was used to assess dupilumab efficacy.

RESULTS

In type 2 asthma patients, 64% had HSD at baseline; of those with ACQ-5 ≥2.5 at baseline, 82% had HSD. In this population, dupilumab reduced nighttime symptoms and ACQ-5 score by 0.31 and 0.56 points, respectively, by Week 52 versus placebo, and led to a 66% reduction in AER during QUEST and 0.34 L improvement in pre-bronchodilator (pre-BD) forced expiratory volume in 1 s (FEV1) at Week 52.

CONCLUSION

A majority of patients with moderate-to-severe type 2 asthma with ACQ-5 ≥2.5 at baseline had HSD. Dupilumab reduced nighttime symptoms and exacerbations, and improved lung function, overall asthma control, and quality of life. Further studies are needed to confirm the association between ACQ-5 score ≥2.5 and higher sleep disturbance rates.

Racial/ethnic disparities in sleep-disordered breathing during pregnancy in the nuMoM2b study

OBJECTIVE

The aim of this study was to assess the prevalence and severity of sleep-disordered breathing (SDB) across racial/ethnic groups in 3702 pregnant people at 6 to 15 and 22 to 31 weeks gestational age, examine whether BMI modifies the association between race/ethnicity and SDB, and investigate whether interventions to reduce weight might reduce racial/ethnic disparities in SDB.

METHODS

Differences by race/ethnicity in SDB prevalence and severity were quantified via linear, logistic, or quasi-Poisson regression. Controlled direct effect was used to estimate whether intervening on BMI would remove/diminish differences by race/ethnicity in SDB severity.

RESULTS

This study comprised 61.2% non-Hispanic White (nHW), 11.9% non-Hispanic Black (nHB), 18.5% Hispanic, and 3.7% Asian people. SDB prevalence was higher for nHB compared with nHW pregnant people at 6 to 15 weeks (odds ratio [OR] 1.81, 95% CI [1.07, 2.97]), whereas at 21 to 32 weeks, Asian pregnant people had a higher SDB prevalence than nHW (OR 2.2, 95% CI [1.1, 4.0]). The severity of SDB differed across racial/ethnic groups in early pregnancy, with nHB pregnant people having a higher apnea-hypopnea index (AHI) (OR 1.35, 95% CI [1.07, 1.69]) compared with nHW. Having overweight/obesity was associated with a higher AHI (β = 2.36, 95% CI [1.97, 2.84]). Controlled direct effect analyses indicated that in early pregnancy, nHB and Hispanic pregnant people would have a lower AHI compared with nHW people had they had normal weight.

CONCLUSIONS

This study extends knowledge on racial/ethnic disparities in SDB to a pregnant population.

Development and Internal Validation of a Prediction Model for Surgical Success of Maxillomandibular Advancement for the Treatment of Moderate to Severe Obstructive Sleep Apnea

Background: Maxillomandibular advancement (MMA) has been shown to be the most effective surgical therapy for obstructive sleep apnea (OSA). Despite high success rates, there are patients who are considered as non-responders to MMA. In order to triage and inform these patients on their expected prognosis of MMA before the surgery, this study aimed to develop, internally validate, and calibrate a prediction model for the presence of surgical success for MMA in patients with OSA. Methods: A retrospective cohort study was conducted that included patients that had undergone MMA for moderate to severe OSA. Baseline clinical, polysomnographic, cephalometric, and drug-induced sleep endoscopy findings were recorded as potential predictors. Presence or absence of surgical success was recorded as outcome. Binary logistic regression analyses were conducted to develop the model. Performance and clinical values of the model were analyzed. Results: One hundred patients were included, of which sixty-seven (67%) patients reached surgical success. Anterior lower face height (ALFH) (OR: 0.93 [0.87−1.00], p = 0.05), superior posterior airway space (SPAS) (OR: 0.76 [0.62−0.92], p < 0.05), age (OR: 0.96 [0.91−1.01], p = 0.13), and a central apnea index (CAI) <5 events/hour sleep (OR: 0.16 [0.03−0.91], p < 0.05) were significant independent predictors in the model (significance level set at p = 0.20). The model showed acceptable discrimination with a shrunken area under the curve of 0.74, and acceptable calibration. The added predictive values for ruling in and out of surgical success were 0.21 and 0.32, respectively. Conclusions: Lower age at surgery, CAI < 5 events/hour, lower ALFH, and smaller SPAS were significant predictors for the surgical success of MMA. The discrimination, calibration, and clinical added values of the model were acceptable.

Validity of a New Prediction Model to Identify Patients at Risk for Obstructive Sleep Apnea Hypopnea Syndrome

OBJECTIVES

To develop and validate a new clinical prediction model for screening patients at risk for obstructive sleep apnea-hypopnea syndrome (OSAHS).

METHODS

This study used 2 data sets to develop and validate the model. To build the model, the first data set comprised 892 patients who had diagnostic polysomnography (PSG); data were assessed by multivariate logistic regression analysis. To validate the new model, the second data set comprised 374 patients who were enrolled to undergo overnight PSG. Receiver operating characteristic analysis and all predictive parameters were validated.

RESULTS

In the model development phase, univariate analysis showed 6 parameters were significant for prediction apnea-hypopnea index ≥15 events/hour: male sex, choking or apnea, high blood pressure, neck circumference >16 inches (female) or 17 inches (male), waist circumference ≥80 (female) or 90 cm (male), and body mass index >25 kg/m². Estimated coefficients showed an area under the curve of 0.753. In the model validation phase, the sensitivity and specificity were approximately 93% and 26%, respectively, for identifying OSAHS. Comparison with the Epworth Sleepiness Scale score of ≥10 and STOP-Bang score ≥3 showed sensitivity of 42.26% and 56.23%, respectively, for detecting patients at risk.

CONCLUSIONS

This new prediction model gives a better result on identifying patients at risk for OSAHS than Epworth Sleepiness Scale and STOP-Bang in terms of sensitivity. Moreover, this model may play a role in clinical decision-making for a comprehensive sleep evaluation to prioritize patients for PSG.

The multisystemic effects of oral appliance therapy for obstructive sleep apnea: A narrative review

Obstructive sleep apnea (OSA) is a chronic condition accompanied by repeated obstruction of the upper airway during sleep despite respiratory efforts, resulting in intermittent hypoxemia, altered sleep structure, and sympathetic activation. Previous studies have shown a significant association between OSA and general health issues such as cardiovascular diseases, endocrine disorders, neurocognitive function decline, and poor quality of life. Continuous positive airway pressure (CPAP) has been considered as the first line treatment for OSA. However, accumulating evidence supports the role of oral appliance (OA) therapy, including mandibular advancement devices, as an alternative option for snoring and OSA patients who do not comply with or refuse CPAP usage. Despite a generally favorable outcome of OA therapy for OSA related respiratory indices, studies focusing on the impact of systemic effects of OA therapy in OSA patients are relatively scarce compared with the extensive literature focusing on the systemic effects of CPAP. Therefore, this article aimed to provide an overview of the current evidence regarding the multisystemic effects of OA therapy for OSA.

Referral rate for obstructive sleep apnea in a pre-doctoral dental clinic using the STOP-Bang Questionnaire

OBJECTIVES

Obstructive sleep apnea (OSA) is a common condition that can result in significant illness when untreated. Only 10%-20% of individuals with OSA are believed to be properly diagnosed. Consequently, dentists are encouraged to identify patients at high risk for OSA. The aim of this study was to determine whether patients in a dental school student clinic were referred for evaluation of OSA when appropriate.

MATERIALS AND METHODS

All patients 18 or older admitted to the College of Dentistry between July 2017 and March 2020 completed a medical history form. Data were extracted from their responses to determine a STOP-Bang score, as well as data regarding a previous diagnosis of OSA and a list of referrals. Students are expected to refer patients appropriately where there are indications of a high risk of undiagnosed disease. In the case of a sleep apnea evaluation, this would include any patient whose STOP-Bang score was 5 or greater, per the lecture on sleep disorders. For patients identified as high risk, notes and referral forms were reviewed to determine if the appropriate referral occurred.

RESULTS

Of the 21,312 new patients, 1098 (5.2%) were identified as high-risk for OSA. Of those, 398 (36%) had not been previously diagnosed with OSA. None of these 398 patients received a referral for further evaluation of OSA.

CONCLUSION

The rate of referral for further evaluation for patients deemed at high risk for OSA was inadequate. Continued education and changes to the electronic health record are needed to ensure those at high-risk for OSA are appropriately managed.

Interrelationship Between Obstructive Sleep Apnea Syndrome and Severe Asthma: From Endo-Phenotype to Clinical Aspects

Sleep-related breathing disorders (SBDs) are characterized by abnormal respiration during sleep. Obstructive sleep apnea (OSA), a common SBD increasingly recognized by physicians, is characterized by recurrent episodes of partial or complete closure of the upper airway resulting in disturbed breathing during sleep. OSA syndrome (OSAS) is associated with decreased patients' quality of life (QoL) and the presence of significant comorbidities, such as daytime sleepiness. Similarly to what seen for OSAS, the prevalence of asthma has been steadily rising in recent years. Interestingly, severe asthma (SA) patients are also affected by poor sleep quality—often attributed to nocturnal worsening of their asthma—and increased daytime sleepiness and snoring compared to the general population. The fact that such symptoms are also found in OSAS, and that these two conditions share common risk factors, such as obesity, rhinitis, and gastroesophageal reflux, has led many to postulate an association between these two conditions. Specifically, it has been proposed a bidirectional correlation between SA and OSAS, with a mutual negative effect in term of disease severity. According to this model, OSAS not only acts as an independent risk factor of asthma exacerbations, but its co-existence can also worsen asthma symptoms, and the same is true for asthma with respect to OSAS. In this comprehensive review, we summarize past and present studies on the interrelationship between OSAS and SA, from endo-phenotype to clinical aspects, highlighting possible implications for clinical practice and future research directions.

Shifting and reducing breathing disturbance in patients with very severe obstructive sleep apnea by modified Z-palatoplasty with one-layer closure in one-stage multilevel surgery

Very severe obstructive sleep apnea (OSA) with apnea-hypopnea index (AHI) ≥ 60 events/h differs in several areas from OSA with other severities, including having a low-level daytime partial pressure of oxygen and residual on-CPAP (continuous positive airway pressure) AHIs greater than 20/h. Patients with very severe OSA show narrow retroglossal space and confined framework, which is difficult to be enlarged via conventional Uvulopalatopharyngoplasty (UPPP) surgery, resulting in poor response to non-framework surgeries. Our latest report showed efficacy and efficiency for subjects undergoing modified Z-palatoplasty (ZPP) with one-layer closure in a one-stage multilevel surgery. It is unclear whether and how this procedure could help patients with very severe OSA characterized with confined framework. From Mar. 2015 to May 2018, we enrolled 12 patients with very severe OSA receiving one-stage multi-level surgery with modified ZPP with one-layer closure, CO2 laser partial tongue-base glossectomy, and bilateral septomeatoplasty. Our results show that the surgery reduced AHI from 73.8 ± 10.7 to 30.8 ± 23.2 events/h and achieved a mean AHI reduction of 58.3% (p < 0.001 against 0 reduction or no surgery). The surgery shifted components of the breathing disturbances. It reduced more apnea than hypopnea and might convert some apnea to hypopnea.

Treatment of Obstructive Sleep Apnea: Choosing the Best Positive Airway Pressure Device

Positive airway pressure (PAP) remains primary therapy for most patients with obstructive sleep apnea (OSA). CPAP, APAP, and BPAP are all reasonable therapies that can be used for patients with uncomplicated OSA across the spectrum of disease severity. BPAP should be considered for patients who are nonadherent to CPAP or APAP therapy because of pressure intolerance. Several additional factors should be considered when choosing the type of PAP device for a given patient, including associated symptoms and comorbid medical problems, cost, access to online data management and patient portals, and the portability for the device for patients who travel frequently.

Increasing Hypopnea in Sleep Breathing Disturbance Improves Postoperative Oxygen Saturation in Patients with Very Severe Obstructive Sleep Apnea

In patients of very severe obstructive sleep apnea (OSA) with confined framework, reducing volume is difficult to achieve a postoperative apnea-hypopnea index (AHI) qualifying the classical surgical success. However, a higher AHI with a larger part of hypopneas may have similar or even less severity of oxygen (O2) desaturation, compared to a lower index mostly made of apneas. Here, in 27 consecutive enrolled patients, we show that besides the improvement of mean AHI, the multilevel surgery increased hypopnea in AHI from 29.1% to 77.3%, and improves postoperative O2 saturation by reducing desaturation frequency (mean desaturation index decreased from 62.5 to 24.4 events/h) and level (mean oxyhemoglobin saturation of pulse oximetry (SpO2) desaturation cut down from 10.0 to 5.8%). The mean SpO2 improved from 92.3% to 94.7%, and the improvement was positively related to the proportion increase of hypopnea/AHI. The results suggest that the non-framework surgery could help patients with very severe OSA whose AHIs are ≥60 events/h in terms of improving postoperative O2 saturation. Due to the improvement also presented in those not qualified as classical surgical success, further studies are needed to clarify the connection between O2 desaturation and various consequences to reconsider defining a surgical success.

Diagnosis of Obstructive Sleep Apnea during Wakefulness Using Upper Airway Negative Pressure and Machine Learning

Background and Rational: Obstructive Sleep Apnea (OSA) is a common disorder, affecting almost 10% of adults, but very underdiagnosed. This is largely due to limited access to overnight sleep testing using polysomnography (PSG). Our goal was to distinguish OSA from healthy individual using a simple maneuver during wakefulness in combination with machine learning methods. Methods: Participants have undergone an overnight PSG to determine their ground truth OSA severity. Separately, they were asked to breathe through a nasal mask or a mouth piece through which negative pressure (NP) was applied, during wakefulness. Airflow waveforms were acquired and several features were extracted and used to train various classifiers to predict OSA. Results and Discussion: The performance of each classifier and experimental setup was calculated. The best results were obtained using Random Forest classifier for distinguishing OSA from healthy individuals with a very good area under the curve of 0.80. To the best of our knowledge, this is the first study to deploy machine learning and NP with promising path to diagnose OSA during wakefulness.

Is severe obstructive sleep apnea associated with less depressive symptoms?

PURPOSE

To investigate the relationship between obstructive sleep apnea (OSA) and symptoms of depression and anxiety in OSA patients.

METHODS

Symptoms were assessed using the Beck Depression Inventory (BDI) and the state part of the State-Trait Anxiety Inventory (STAI-S). BDI scores of ≥10 and STAI-S scores of ≥40 were considered to indicate the presence of depression and anxiety, respectively. Apnea severities measured using polysomnography were categorized into mild, moderate, and severe subgroups bounded by the 33rd and 66th percentiles of each polysomnographic parameter. Data were stratified by age, gender, and level of daytime sleepiness.

RESULTS

The study population comprised 795 adult patients (86.9% men). Symptoms of depression and anxiety were present in 46.2% and 49.2% of patients, respectively. Excessive daytime sleepiness was present in 40.0% of patients and did not differ depending on the level of apnea severity. Results of crude logistic regression analyses indicated that depressive symptoms were more prevalent in patients with mild OSA than those with severe OSA, regardless of the categorizing method. These results remained statistically significant following adjustment for several confounding factors. These relationships were similar but less prominent in measures of anxiety. In the sub-analyses, such negative associations between severity of OSA and depressive symptoms tended to be observed only in patients with daytime sleepiness.

CONCLUSIONS

Symptoms of depression and anxiety were found to be more prevalent in patients with mild OSA than those with severe OSA. Excessive daytime sleepiness was shown to affect the severity of depressive symptoms.

Sleep-Disordered Breathing and Idiopathic Normal-Pressure Hydrocephalus: Recent Pathophysiological Advances

Purpose of Review

Idiopathic normal-pressure hydrocephalus (iNPH) is characterized clinically by ventriculomegaly, abnormal gait, falls, incontinence, and cognitive decline. This article reviews recent advances in the pathophysiology of iNPH concerning sleep-disordered breathing (SDB) and glymphatic circulation during deep sleep.

Recent Findings

The authors found iNPH frequently associated with obstructive sleep apnea (OSA). A critical factor in iNPH is intracranial venous hypertension delaying drainage of cerebrospinal fluid (CSF) into the cerebral venous sinuses. CSF-venous blood circulates in the jugular veins and finally drains into the heart. During SDB, repeated reflex attempts to breathe induce strong respiratory efforts against a closed glottis thereby increasing the negative intrathoracic pressure. This causes atrial distortion and decreases venous return to the heart resulting in retrograde intracranial venous hypertension. Additionally, repeated awakenings from OSA impede sleep-associated circulation of interstitial CSF into the glymphatic circulation contributing to hydrocephalus.

Summary

Sleep has become a critical element in the cognitive changes of aging including iNPH.

Influence of short-term side effects on oral sleep appliance compliance among CPAP-intolerant patients: An objective monitoring of compliance

OBJECTIVES

To investigate the predictive value of side effects on usage times during the initial titration phase of oral appliance therapy for sleep apnoea. The secondary objective was to assess the correlation between subjective and objective usage times.

METHODS

A total of 21 subjects diagnosed with sleep apnoea and a history of non-compliance with CPAP therapy were enrolled in the 4-week clinical study. Objective compliance was assessed through an intra-oral compliance monitor embedded in a Thornton Adjustable Positioner. Subjective compliance was evaluated through self-reporting and questionnaire for side effects.

RESULTS

Excess salivation, xerostomia and tooth discomfort were the most common side effects (61%-67%). Noises (OR = 10, 95% CI = 0.85-117.02, P = 0.067), jaw discomfort (OR = 15, 95% CI = 1.21-185.20, P = 0.035) and gum discomfort (OR = 8.86, 95% CI = 1.0-∞, P = 0.038) were highly predictive of non-compliance. Subjects with either "none" or "mild" side effects recorded a mean oral appliance usage time ≥5.5 hours/night, while subjects reporting "severe" side effects recorded a mean usage time ≤4 hours/night. The mean usage time was 5.49 hours/night, with nightly compliance (defined as >4 hours per night for 70% the nights per week) at 33%. Nonetheless, compliance increased from 26%-50% from week 1 to week 4. The subjective and objective usage times were highly correlated (r = 0.81).

CONCLUSIONS

There was a high correlation between subjective and objective compliance reporting data. Moderate/severe side effects had the greatest effect on compliance.

Objective Relationship Between Sleep Apnea and Frequency of Snoring Assessed by Machine Learning

STUDY OBJECTIVES

Snoring is perceived to be directly proportional to sleep apnea severity, especially obstructive sleep apnea (OSA), but this notion has not been thoroughly and objectively evaluated, despite its popularity in clinical practice. This might lead to overdiagnosis or underdiagnosis of OSA. The goal of this study is to examine this notion and objectively quantify the relationship between sleep apnea and snoring detected using advanced signal processing algorithms.

METHODS

We studied adults referred for polysomnography, from which the apnea-hypopnea index (AHI) was derived. Breath sounds were recorded simultaneously, from which snoring was accurately quantified using acoustic analysis of breath sounds and machine-learning computer algorithms. The snore index (SI) was calculated as the number of snores per hour of sleep.

RESULTS

In 235 patients, the mean AHI was 20.2 ± 18.8 and mean SI was 320.2 ± 266.7 events/h. On the one hand, the overall correlation between SI and AHI was weak but significant (r = .32, P < .0001). There was a significant stepwise increase in SI with increasing OSA severity, but with a remarkable overlap in SI among OSA severity categories. On the other hand, SI had weak negative correlation with central AHI (r = -.14, P = .035). SI had modest positive and negative predictive values for OSA (0.63 and 0.62 on average, respectively) and good sensitivity but low specificity (0.91 and 0.31 on average, respectively) attributed to the large number of snorers without OSA.

CONCLUSIONS

Snoring on its own is probably of limited usefulness in assessing sleep apnea presence and severity, because of its weak relationship with AHI. Thus, the complaint of snoring should be interpreted with caution to avoid unnecessary referrals for sleep apnea testing. Conversely, clinicians should be aware of the possibility of missing diagnosis of patients with sleep apnea who have minimal snoring.

Pharyngeal distensibility during expiration is an independent predictor of the severity of obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Pharyngeal distensibility and collapsibility reflect the passive properties of tissue in the airway, are an indicator of the ease with which an airway can be deformed and are related to the severity of obstructive sleep apnoea (OSA). During normal tidal respiration, the collapsibility of the pharynx during expiration is passive without confounding by neuromuscular activation that occurs during inspiration. We evaluated the distensibility and collapsibility of the upper airway in subjects with OSA during wakefulness using sophisticated dynamic computed tomography (CT) imaging. We hypothesized that the dynamic changes of the upper airway during expiration would be related to the severity of OSA.

METHODS

Twenty-three patients with OSA and eight normal subjects underwent simultaneous measurement of respiratory flow and airway calibre using ultrafast CT. The change in pharyngeal cross-sectional area divided by the change in concomitant flow (as distensibility or collapsibility) was measured and compared across different severities of OSA.

RESULTS

The slope of this relationship between delta area and delta flow during expiration was significantly higher in severe OSA when compared with normal controls and mild-moderate OSA. Differences in airway distensibility or collapsibility between severity groups were significant in expiration but not in inspiration. Distensibility or collapsibility contributed most to the apnoea-hypopnoea index in regression modelling. Age, gender, and body mass index (BMI) were not significant independent predictors.

CONCLUSION

Our study demonstrates that airway distensibility during the expiratory phase of awake respiration is correlated with the severity of OSA.

When a patient with depression is feeling sleepy, be aware of sleep apnoea

A 67-year-old man was referred to an outpatient clinic of geriatric psychiatry because of persistent symptoms of depression and anxiety, accompanied by sleepiness. The latter had been evaluated multiple times in the general practice over several years; each time it was considered to be a symptom of depression. After referral, the patient was diagnosed with severe obstructive sleep apnoea (OSA), comorbid to a depressive and anxiety disorder. Retrospectively, we conclude that affective symptoms accompanying OSA and sleepiness were wrongfully interpreted as depression, but after having led to problems at work, they have triggered psychiatric comorbidity. Treatment of OSA in addition to the psychiatric disorders resulted in a full recovery over time. The delayed diagnosis of OSA has certainly diminished the patient’s quality of life and might have precipitated the depressive disorder. Moreover, OSA poses patients at an increased risk of cardiovascular disease, hypertension, stroke and traffic accidents.

Aberrant Interhemispheric Connectivity in Obstructive Sleep Apnea-Hypopnea Syndrome

Objective

To determine the changes in interhemispheric functional coordination in patients with obstructive sleep apnea–hypopnea syndrome (OSAHS) relative to controls, using a recently introduced method of analysis: voxel-mirrored homotopic connectivity (VMHC).

Methods

Twenty-nine patients with OSAHS and twenty-six normal sex-, age-, and education-matched controls were recruited and resting-state functional magnetic resonance imaging data were obtained. We employed VMHC to analyze the interhemispheric functional connectivity differences between groups. The z-values of alterations in VMHC in brain region were correlated with clinical characteristics.

Results

Compared with controls, patients with OSAHS had significantly higher scores for body mass index (t = 5.749, P < 0.001), apnea–hypopnea index (AHI; t = 7.706, P < 0.001), oxygen desaturation index (t = 6.041, P < 0.001), and Epworth sleepiness scale (t = 3.711, P < 0.001), but significantly lower scores on the Rey–Osterrieth complex figure test-immediate recall (t = −3.727, P < 0.05). On the same basis, the VMHC showed significant increases in bilateral calcarine cortex and precuneus. Moreover, significant, positive correlations were found in only these areas between the AHI and the VMHC change coefficients (r = 0.399, P = 0.032; r = 0.378, P = 0.043).

Conclusion

We found a memory defect in patients with OSAHS. The correlation between the abnormal VMHC and the AHI in patients with OSAHS suggested that AHI might be a key factor in cognitive dysfunction, which might offer new insights into the neural pathophysiology underlying OSAHS-related cognitive deficits.

Impaired Neurobehavioural Performance in Untreated Obstructive Sleep Apnea Patients Using a Novel Standardised Test Battery

Objective/Background

Although polysomnography (PSG) is the gold-standard measure for assessing disease severity in obstructive sleep apnea (OSA), it has limited value in identifying individuals experiencing significant neurobehavioural dysfunction. This study used a brief and novel computerised test battery to examine neurobehavioural function in adults with and without OSA.

Patients/Methods

204 patients with untreated OSA [age 49.3 (12.5) years; body mass index, [BMI] 33.6 (8.0) kg/m²; Epworth sleepiness scale 12 (4.9)/24; apnea hypopnea index 33.6 (25.8)/h] and 50 non-OSA participants [age 39.2 (14.0) years; BMI 25.8 (4.2) kg/m², ESS 3.6 (2.3)/24]. All participants completed a computerised neurobehavioural battery during the daytime in the sleep clinic. The OSA group subsequently underwent an overnight PSG. The 30 min test battery assessed cognitive domains of visual spatial scanning and selective attention (Letter Cancellation Test), executive function (Stroop task) and working memory (2- and 3-Back tasks), and a validated sustained attention task (psychomotor vigilance task, PVT). Group differences in performance were compared. Associations between disease severity and performance were examined in the OSA group.

Results

After controlling for age, gender and education, OSA patients demonstrated impaired performance on the Stroop-Text, 2 and 3-Back tasks, and the PVT compared with the non-OSA group. OSA patients had worse performance on the LCT with fewer average hits albeit with better accuracy. Some OSA polysomnographic disease severity measures were weakly correlated with performance.

Conclusions

This brief test battery may provide a sensitive, standardised method of assessing daytime dysfunction in OSA.

Sleep Apnea and Sleep-Disordered Breathing

Older adults undergo gradual changes in their sleep patterns. It is important to differentiate normal age-related sleep changes from sleep disorders. Because sleep disorders can impact an older adult's day-to-day life and contribute to various comorbidities, these patients should be carefully screened by using a detailed medical history, combined with a detailed sleep history. There is a high prevalence of undiagnosed and untreated sleep apnea in the elderly. Early identification and appropriate management of this disorder may not only provide improvement in quality of life but also decrease disease-associated morbidity and mortality.

Recognition and Diagnosis of Obstructive Sleep Apnea in Older Americans

OBJECTIVES

To estimate the proportion of older Americans at risk for obstructive sleep apnea (OSA) who receive OSA evaluations, diagnosis, and treatment.

DESIGN

Cross sectional study.

SETTING

National Health and Aging Trends Study (NHATS), Round 3 survey.

PARTICIPANTS

Community-dwelling Medicare beneficiaries age 65 and older (N=1,052).

MEASUREMENTS

NHATS participants were asked specific questions about sleep disturbances, including items that resembled critical elements of a validated instrument used to assess OSA risk (the STOP-Bang questionnaire). The proportion of older Americans at risk for OSA who received evaluations with home or in-laboratory sleep studies, OSA diagnosis, and OSA treatment was examined, as well as clinical, social, and demographic correlates of OSA.

RESULTS

Of 1,052 participants who completed the sleep module, 56% (95% confidence interval (CI)=53-59%) were estimated to be at high risk of OSA. Only 8% (95% CI=5-11%) of the high-risk individuals had been tested for it. Of those tested, 94% (95% CI=87-100%) were diagnosed with OSA. Treatment with positive airway pressure was prescribed for 82% (95% CI=65-99%) of participants with an OSA diagnosis.

CONCLUSIONS

Evidence from this nationally representative sample of community-dwelling Medicare beneficiaries suggests that high OSA risk is common but seldom investigated. When investigated, OSA is almost always confirmed and usually treated. These findings suggest a significant gap in OSA assessment for older Americans that could have public health implications.

Neurobehavioral Impairment and CPAP Treatment Response in Mild-Moderate Obstructive Sleep Apneas

STUDY OBJECTIVES

The degree of neurobehavioral impairment and treatment response in mild-moderate obstructive sleep apnea (OSA) compared to that of an appropriate control group are unclear. This study compared neurobehavioral function and response to continuous positive airway pressure (CPAP) treatment in patients with mild to moderate OSA with those of a non-sleep apneic community sample of similar demography.

METHODS

One hundred ten patients with OSA and 31 asymptomatic community dwellers underwent overnight polysomnography and neurobehavioral testing. Participants with OSA (n = 88) were treated with CPAP for 3 months, and repeat evaluations were performed at the end of the treatment period.

RESULTS

Compared to the community sample, participants with OSA were significantly sleepier, had impaired mood and quality of life, and showed decrements in neuropsychological function, specifically psychomotor function, working memory and vigilance. Some neuropsychological and mood outcomes were normalized with CPAP, but significant decrements persisted in most outcomes even in those participants with adequate device usage.

CONCLUSIONS

Patients with mild to moderate OSA have significant neurobehavioral morbidity. During "gold standard" treatment, normal function was not achieved, even with adequate device usage. CPAP efficacy for improving sleepiness and neuropsychological function in this milder end of the OSA spectrum may be poor, which may affect CPAP adherence. These findings suggest that there may be neurological changes related to OSA that do not respond to CPAP treatment, the etiology of which requires further investigation.

Impact of an oral appliance on obstructive sleep apnea severity, quality of life, and biomarkers

OBJECTIVE/HYPOTHESIS

To investigate outcomes including efficacy, quality of life, and levels of inflammatory markers of a mandibular advancement device (MAD) for moderate-to-severe obstructive sleep apnea (OSA).

STUDY DESIGN

Case-control study.

METHODS

Patients with apnea-hypopnea index (AHI) ≥ 15/hr who only accepted MAD therapy (study group) or who refused any treatment (control group) were recruited. At baseline and at 6 months, polysomnography, Epworth Sleepiness Scale (ESS), Functional Outcomes of Sleep Questionnaire (FOSQ), C-reactive protein (CRP), interleukin 1β, interleukin 6, and tumor necrosis factor α (TNF-α) were assessed in both groups.

RESULTS

At baseline, the study group (n = 30) showed a higher percentage of rapid eye movement sleep and higher CRP levels (P < .05) than the control group (n = 10). At 6 months, the MAD significantly improved AHI and lowest oxygen saturation (P < .01), non-rapid eye movement (N)1 and N3 sleep stages (P < .05), ESS score (P < .05), FOSQ total score (P < .01), interleukin 1β (P < .05), and TNF-α (P < .01) compared with the untreated group. In the overall, moderate, and severe OSA groups, 63.3%, 75%, and 50%, respectively, achieved at least good response.

CONCLUSIONS

Use of a MAD significantly improved polysomnographic parameters, quality of life, and some inflammatory markers (CRP, IL-β, and TNF-α) in a significant proportion of patients with moderate OSA and in some patients with severe OSA. Hence, a MAD may be a viable alternative therapy in patients with moderate-to-severe OSA who refuse continuous positive airway pressure.

LEVEL OF EVIDENCE

3b. Laryngoscope, 128:1720-1726, 2018.

Association of Mild Obstructive Sleep Apnea With Cognitive Performance, Excessive Daytime Sleepiness, and Quality of Life in the General Population: The Korean Genome and Epidemiology Study (KoGES)

Study Objectives

Research points to impaired cognitive performance in sleep clinic patients with obstructive sleep apnea (OSA). However, inconsistent findings from various epidemiologic studies make this relationship less generalizable. The current study investigated the association between OSA and functional outcome measures, such as cognition, daytime sleepiness, and quality of life, in a Korean general population sample.

Methods

A total of 1492 participants from the Korean Genome and Epidemiology Study (KoGES) were included in the analyses. The presence of OSA measured by overnight polysomnography (PSG) was defined by apnea-hypopnea index (AHI) >5. Cognitive performance was determined with scores from a comprehensive neuropsychological battery. Excessive daytime sleepiness and quality of life were additionally measured through subjective reports.

Results

After adjusting for various demographic and medical characteristics, OSA was independently associated with lower performance in the Digit Symbol Test (52.73 ± 17.08 vs. 58.72 ± 18.03, OSA vs. not, p = .02). Hypoxia measures were not related to cognitive performance. OSA was associated with higher odds of displaying excessive daytime sleepiness (odds ratio = 1.72, 95% CI: 1.05-2.80), but there was no significant relationship between OSA and quality of life.

Conclusions

Cognition was unexpectedly unaffected overall. However, OSA was associated with impairment in a multidomain test that taps skills generally associated with frontal lobe function. The results suggest that research on protective and adaptive brain mechanisms to OSA stress can provide unique insights into the brain-sleep interface. As the study runs longitudinally, it will enable future studies on the impact of OSA on cognitive decline.

Exome-Wide Meta-Analysis Identifies Rare 3'-UTR Variant in ERCC1/CD3EAP Associated with Symptoms of Sleep Apnea

Obstructive sleep apnea (OSA) is a common sleep breathing disorder associated with an increased risk of cardiovascular and cerebrovascular diseases and mortality. Although OSA is fairly heritable (~40%), there have been only few studies looking into the genetics of OSA. In the present study, we aimed to identify genetic variants associated with symptoms of sleep apnea by performing a whole-exome sequence meta-analysis of symptoms of sleep apnea in 1,475 individuals of European descent. We identified 17 rare genetic variants with at least suggestive evidence of significance. Replication in an independent dataset confirmed the association of a rare genetic variant (rs2229918; minor allele frequency = 0.3%) with symptoms of sleep apnea (p-value_meta = 6.98 × 10⁻⁹, β_meta = 0.99). Rs2229918 overlaps with the 3′ untranslated regions of ERCC1 and CD3EAP genes on chromosome 19q13. Both genes are expressed in tissues in the neck area, such as the tongue, muscles, cartilage and the trachea. Further, CD3EAP is localized in the nucleus and mitochondria and involved in the tumor necrosis factor-alpha/nuclear factor kappa B signaling pathway. Our results and biological functions of CD3EAP/ERCC1 genes suggest that the 19q13 locus is interesting for further OSA research.

Treatment of Obstructive Sleep Apnea: Choosing the Best Positive Airway Pressure Device

Positive airway pressure (PAP) remains primary therapy for most patients with obstructive sleep apnea (OSA). CPAP, APAP, and BPAP are all reasonable therapies that can be used for patients with uncomplicated OSA across the spectrum of disease severity. BPAP should be considered for patients who are nonadherent to CPAP or APAP therapy because of pressure intolerance. Several additional factors should be considered when choosing the type of PAP device for a given patient, including associated symptoms and comorbid medical problems, cost, access to online data management and patient portals, and the portability for the device for patients who travel frequently.

Upper Airway Changes After Mandibular Setback and/or Advancement Genioplasty in Obese Patients

PURPOSE

Orthognathic surgeries, such as bilateral sagittal split ramus osteotomy (BSSO) and genioplasty, can influence the pharyngeal airway space (PAS) and this has been supported by previous studies. The purpose of this study was to assess changes of the PAS in patients with a high body mass index (BMI) likely to have narrow airways before and after setback BSSO with or without advancement genioplasty surgery by 3-dimensional computed tomography.

MATERIALS AND METHODS

Thirty-five adults with a BMI of at least 24.0 kg/m² were treated from 2010 to 2016. Samples were grouped mandibular setback (group A; n = 11), advancement genioplasty (group B; n = 12), and mandibular setback plus advancement genioplasty (group C; n = 12). Computed tomograms were obtained 1 week preoperatively (T0), 1 week postoperatively (T1), and at least 1 year postoperatively (T2). The area of the posterior nasal spine and posterior plane (PPA), the soft palate plane (SPA), the plane of the most posterior point of the tongue base (PTA), the plane of the root of the epiglottis (EA), and the volumes of the palatopharyngeal part (VP), oropharyngeal part (VO), glossopharyngeal part (VG), and laryngeal part (VL) were measured and compared within groups using analysis of variance. The P value was set at .05.

RESULTS

In group A, all results showed statistically significant differences (P < .05) from T0 to T2 except for VO, VG, VL, SPA, PTA, and EA. In group B, VO, VG, VL, SPA, PTA, and EA showed statistically significant increases (P < .05) from T0 to T2. The hyoid at T2 showed significant advancement compared with T0 (P < .05). In group C, there were statistically significant decreases (P < .05) from T0 to T1 for VG, VL, PTA, and EA.

CONCLUSION

In adults with a high BMI, mandibular setback BSSO could decrease the PAS, whereas advancement genioplasty could enlarge the PAS, after surgery. Therefore, undergoing advancement genioplasty concurrently with mandibular setback BSSO could help in lessening the negative effects of a PAS decrease.

Disparities in Utilization of Jaw Surgery for Treatment of Sleep Apnea: A Nationwide Analysis

BACKGROUND

Maxillomandibular advancement has been shown to be one of the most effective operations for management of severe obstructive sleep apnea, yet pharyngeal surgery is more commonly performed. The goal of this study was to identify socioeconomic factors associated with this phenomenon.

METHODS

Patients aged 14 or older with a primary hospital diagnosis of sleep apnea were identified using the National Inpatient Sample from 2005 to 2012. ICD9 codes were used to determine whether a pharyngeal or jaw procedure was performed. Patient demographics, comorbidities, and complications were compared.

RESULTS

Among 6316 sleep surgeries, 5964 (94.4%) were pharyngeal and 352 (5.6%) were jaw procedures. Women were significantly more likely to receive jaw surgery than men (odds ratio [OR] = 1.68, P = 0.0007). African Americans (OR = 0.19, P < 0.0001), Hispanics (OR = 0.42, P = 0.0009), Asians (OR = 0.41, P = 0.0009), and other non-Caucasians (OR = 0.19, P = 0.0008) had a significantly lower odds of receiving jaw surgery than Caucasians. Patients falling into lower-income brackets (OR = 0.39 and 0.57, P = 0.02 and 0.04) and patients with Medicare compared with private or Health Maintenance Organization insurance (OR = 0.46, P = 0.008) also had significantly decreased odds of undergoing jaw surgery. Comorbidities were similar between surgical groups, and there were no significant differences in bleeding, infection, or cardiopulmonary complications.

CONCLUSIONS

We identified no significant difference in complication rates between pharyngeal and jaw procedures. Nonetheless, African American, Hispanic, and Asian patients, in addition to lower-income patients and patients with Medicare, had a significantly lower odds of receiving jaw surgery. Awareness of these disparities may help guide efforts to improve patients' surgical options for sleep apnea.

Obstructive sleep apnea and its controversial effects on cognition

Obstructive sleep apnea syndrome is a sleep disorder that may affect many brain functions. We are interested in the cognitive consequences of the condition with regard to the quality of life of individuals with this disorder. A debate is still underway as to whether cognitive difficulties caused by obstructive sleep apnea actually induce a "pseudodementia" pattern. This work provides a brief overview of the main controversies currently surrounding this issue. We report findings and opinions on structural and cognitive brain changes in individuals affected by obstructive sleep apnea by highlighting the involvement of executive functions and the possible reversibility of signs following-treatment with continuous positive airway pressure. Much research has been done on this issue but, to the best of our knowledge, a review of the present state of the literature evaluating different points of view has not yet been carried out.

Factors affecting executive functions in obstructive sleep apnea syndrome and volumetric changes in the prefrontal cortex

PURPOSE

Obstructive sleep apnea syndrome (OSAS) is associated with cognitive changes and executive functions are among the cognitive domains most affected. However, it is not completely understood which of the factor(s) among hypoxemia, repeated arousal, and sleepiness affect the executive functions. This study aims to evaluate the possible relationship between the executive functions and nocturnal parameters, Epworth Sleepiness Scale (ESS) scores, and prefrontal cortex (PFC) volumes.

PATIENTS AND METHODS

A total of 28 patients aged between 18 and 60 years who were newly diagnosed with OSAS were included in this study. The Wisconsin Card Sorting Test (WCST) and Stroop test which were used in the evaluation of executive functions were applied to all patients. Cranial magnetic resonance imaging (MRI) and volumetric measurements of the PFC were performed. Polysomnography (PSG), WCST, Stroop test, and cranial MRI were also applied to the control group which consisted of age- and education status-matched 15 healthy subjects. The correlation of WCST and Stroop tests and PFC volume, PSG parameters, and ESS scale was examined.

RESULTS

The WCST-6 test scores were statistically significantly higher in the patient group (p = 0.022; p < 0.05). Additionally, the Stroop test 5 (p = 0.043) and Stroop test-5 correction (p = 0.005) measurements were statistically significantly higher in the patient group (p < 0.05). A negative and statistically significant correlation was found between the WCST-4 and WCST-10 and ESS measurements in the patient group (r -0.452; p 0.016; p < 0.05; r -0.437; p 0.020; p < 0.05). However, there was no correlation between the PSG parameters and WCST and Stroop test scores. No statistically significant differences in the MRI volumetric measurements of the PFC were found between the patient and control groups.

CONCLUSIONS

Impairment in the attentive and executive functions in OSAS is evident. The most influential factor is excessive daytime sleepiness, rather than hypoxemia and severity of the disease.

Surgical Management of Obstructive Sleep Apnea

Surgical management of snoring and obstructive sleep apnea is indicated when a surgically correctable abnormality is believed to be the source of the problem. Many patients opt for surgical treatment after noninvasive forms of treatment have been proven ineffective or difficult to tolerate. With increasing frequency, functional rhinoplasty, septoplasty, turbinoplasty, palatal surgery, and orthognathic surgery are being used in the management of snoring and obstructive sleep apnea. Plastic surgeons' experience with aesthetic nasal surgery, nasal reconstruction, palatal surgery, and craniofacial surgery puts them at the forefront of performing surgery for snoring and sleep apnea. The role of functional septorhinoplasty, turbinoplasty, palatal surgery, genioglossal advancement, and orthognathic surgery is indispensable in the surgical management of obstructive sleep apnea. Multidisciplinary management of these patients is critical, and plastic surgeons are encouraged to work collaboratively with sleep medicine clinicians and centers.

Relationship of Snoring and Sleepiness as Presenting Symptoms in a Sleep Clinic Population

Objectives:

Sleepiness has traditionally been considered medically the cardinal symptom of obstructive sleep apnea syndrome. Snoring is perceived as a social or cosmetic complaint. Without independent medical morbidity, snoring identification and treatment is not a major focus in sleep medicine. We speculate that snoring is a major independent symptom. To evaluate how patients rated snoring symptom severity, we compared the relative significance of a sleep clinic population's presenting symptoms of snoring and sleepiness.

Methods:

We performed a retrospective analysis of 770 consecutive patients who completed sleep intake evaluation forms at the initial clinic visit, including standardized forms for both sleepiness and snoring using previously validated visual analog scales. Data on symptom magnitude (scale of 1 to 10), symptom importance (scale of 1 to 5), a combined symptom product score consisting of magnitude multiplied by importance (MIP; scale of 1 to 50), the Epworth Sleepiness Scale (ESS; n = 599), and the apnea-hypopnea index (AHI; n = 482; mean ± SD, 35.6 ± 31.9 events per hour) were collected.

Results:

The mean snoring measures (magnitude, importance, and MIP) were greater than those for sleepiness (MIPsnoring of 32.7 ± 14.8 versus MIPsleepiness of 22.4 ± 14.2, p <.001). Snoring scored higher than sleepiness in 72% of individuals. To assess whether sleep apnea or sleepiness severity affected symptom scores, we stratified the subgroup with sleep studies into quartiles by AHI and ESS score. Snoring consistently scored higher than sleepiness in most AHI and ESS quartiles (p <.01). Only in the most severe ESS quartile did any sleepiness measure (importance) score higher than the snoring measure (p <.05).

Conclusions:

The presenting symptoms of snoring are larger in magnitude, importance, and severity than those of sleepiness in a broad population of patients with sleep disorders and sleep-disordered breathing irrespective of severity of sleep apnea or sleepiness. Symptoms of major significance are clinically relevant to identifying, diagnosing, and treating patients. Failure of medical providers to appreciate the impact of snoring on this population may affect attempts to identify, diagnose, and treat patients with sleep-disordered breathing.

A review of neurocognitive function and obstructive sleep apnea with or without daytime sleepiness

Excessive daytime sleepiness (EDS) and neurocognitive dysfunction are commonly observed in patients with obstructive sleep apnea (OSA), and these daytime functional deficits can be reversed partly or completely with treatment such as continuous positive airway pressure (CPAP). Although daytime sleepiness is a possible etiology for neurocognitive dysfunction in OSA patients, EDS is not universally present in all patients with OSA. The objective of this review is to summarize the relationship between neurocognitive function and EDS in OSA, as well as the difference in cognitive domains, improvement, and application of CPAP therapy between patients with and without EDS. Two authors independently searched PubMED/Medline, The Cochrane Library and Scopus through May 27, 2015. Sixty-five articles were included in this review. The literature demonstrated a wide range of neurocognitive deficits in OSA patients with EDS, but no more extensive and complex cognitive domains (eg, executive function) in patients without EDS. However, the current literature had very few studies with large sample sizes and extended follow-up that evaluated the effect of CPAP for OSA in patients with and without sleepiness. CPAP failed to improve cognitive dysfunction in OSA patients without EDS after short-term therapy. The evidence suggests that daytime sleepiness possibly relates to the domain and extent of cognitive impairments in OSA, and CPAP therapy has little effect on the improvement of cognitive deficits in OSA patients without EDS. We recommend that additional prospective studies be performed to further quantify the relationship between neurocognitive function in OSA patients with and without EDS.

Aberrant spontaneous low-frequency brain activity in male patients with severe obstructive sleep apnea revealed by resting-state functional MRI

BACKGROUND

The majority of previous neuroimaging studies have demonstrated both structural and functional abnormalities in obstructive sleep apnea (OSA). However, few studies have focused on the regional intensity of spontaneous fluctuations during the resting state and the relationship between the abnormal properties and the behavioral performances. In the present study, we employed the amplitude of low-frequency fluctuation (ALFF) method to explore the local features of spontaneous brain activity in OSA patients (OSAs).

METHODS

Twenty-five untreated male severe OSAs and 25 age-matched and years-of-education-matched male good sleepers (GSs) were included in this study. The ALFF method was used to assess the local features of spontaneous brain activity. The mean signal values of the altered ALFF areas were analyzed with receiver operating characteristic curve. Partial correlation analysis was used to explore the relationship between the observed mean ALFF values of the different areas and the behavioral performances.

RESULTS

Compared with GSs, OSAs had significantly higher scores for body mass index, apnea-hypopnea index, arterial oxygen saturation <90%, arousal index, and Epworth Sleepiness Scale (ESS) score; furthermore, OSAs had significantly lower scores for rapid eye movement sleep and in the Montreal Cognitive Assessment (MoCA). Compared with GSs, OSAs showed significant lower-ALFF areas in the cluster of the right precuneus and bilateral posterior cingulate gyrus, as well as a higher-ALFF area in the left inferior frontal gyrus. The area under the curve values of the lower- and higher-ALFF areas were 0.90 and 0.93, respectively. Further diagnostic analysis exhibited that the sensibility and specificity of the two clusters were 80% and 92%, respectively. The mean signal value of the lower-ALFF cluster displayed significant positive correlations with lowest oxygen saturation (r=0.447, P=0.025) and MoCA score (r =0.405, P=0.045).

CONCLUSION

OSAs may involve in a dysfunction in the default mode network and an adaptive compensatory response in the frontal lobe, which reflect the underlying pathophysiology of cognitive impairment.

Sleep apnea is not associated with worse outcomes in kidney transplant recipients

Obstructive sleep apnea(OSA) is one of the most common sleep disorders in kidney transplant recipients, however its long-term consequences have only rarely been investigated. Here, we hypothesized that the presence of OSA would be associated with higher risk of mortality and faster decline of graft function in kidney transplant recipients. In a prospective cohort study 100 prevalent kidney transplant recipients who underwent one-night polysomnography at baseline and were followed for a median 75 months. Generalized linear mixed-effects models and Cox regression models were used to assess the association between OSA and the rate of progression of chronic kidney disease(CKD) and mortality. The estimated slopes of estimated glomerular filtration rate(eGFR) in patients with and without OSA were compared using a two-stage model of eGFR change including only OSA as a variable. In this model patients with OSA (eGFR versus time was −0.93 ml/min/1.73 m²/yr(95%CI:−1.75 to−0.11) had a similar slope as compared to patients without OSA(eGFR versus time was −1.24 ml/min/1.73 m²/yr(95%CI: −1.67 to −0.81). In unadjusted Cox proportional regression analyses OSA was not associated with higher all-cause mortality risk (Hazard Ratio(HR) = 1.20; 95% Confidence Interval(CI): 0.50–2.85). No association was found between the presence of OSA and the rate of progression of CKD or all-cause mortality in prevalent kidney transplant recipients.

Carotid body, insulin, and metabolic diseases: unraveling the links

The carotid bodies (CB) are peripheral chemoreceptors that sense changes in arterial blood O2, CO2, and pH levels. Hypoxia, hypercapnia, and acidosis activate the CB, which respond by increasing the action potential frequency in their sensory nerve, the carotid sinus nerve (CSN). CSN activity is integrated in the brain stem to induce a panoply of cardiorespiratory reflexes aimed, primarily, to normalize the altered blood gases, via hyperventilation, and to regulate blood pressure and cardiac performance, via sympathetic nervous system (SNS) activation. Besides its role in the cardiorespiratory control the CB has been proposed as a metabolic sensor implicated in the control of energy homeostasis and, more recently, in the regulation of whole body insulin sensitivity. Hypercaloric diets cause CB overactivation in rats, which seems to be at the origin of the development of insulin resistance and hypertension, core features of metabolic syndrome and type 2 diabetes. Consistent with this notion, CB sensory denervation prevents metabolic and hemodynamic alterations in hypercaloric feed animal. Obstructive sleep apnea (OSA) is another chronic disorder characterized by increased CB activity and intimately related with several metabolic and cardiovascular abnormalities. In this manuscript we review in a concise manner the putative pathways linking CB chemoreceptors deregulation with the pathogenesis of insulin resistance and arterial hypertension. Also, the link between chronic intermittent hypoxia (CIH) and insulin resistance is discussed. Then, a final section is devoted to debate strategies to reduce CB activity and its use for prevention and therapeutics of metabolic diseases with an emphasis on new exciting research in the modulation of bioelectronic signals, likely to be central in the future.

Obstructive sleep apnea-hypopnea results in significant variations in cerebral hemodynamics detected by diffuse optical spectroscopies

The objective of this study was to adapt a novel near-infrared diffuse correlation spectroscopy (DCS) flow-oximeter for simultaneous and continuous monitoring of relative changes in cerebral blood flow (rCBF) and cerebral oxygenation (i.e. oxygenated/deoxygenated/total hemoglobin concentration: Δ[HbO2]/Δ[Hb]/ΔTHC) during overnight nocturnal polysomnography (NPSG) diagnostic test for obstructive sleep apnea-hypopnea (OSAH). A fiber-optic probe was fixed on subject's frontal head and connected to the DCS flow-oximeter through a custom-designed fiber-optic connector, which allowed us to easily connect/detach the optical probe from the device when the subject went to bathroom. To minimize the disturbance to the subject, the DCS flow-oximeter was remotely operated by a desktop located in the control room. The results showed that apneic events caused significant variations in rCBF and ΔTHC. Moreover, the degrees of variations in all measured cerebral variables were significantly correlated with the severity of OSAH as determined by the apnea-hypopnea index (AHI), demonstrating the OSAH influence on both CBF and cerebral oxygenation. Large variations in arterial blood oxygen saturation (SaO2) were also found during OSAH. Since frequent variations/disturbances in cerebral hemodynamics may adversely impact brain function, future study will investigate the correlations between these cerebral variations and functional impairments for better understanding of OSAH pathophysiology.