Factors associated with increased carotid intima-media thickness in obstructive sleep apnea/hypopnea syndrome

Impact of obstructive sleep apnea on platelet activation and development of silent brain infarctions

Background

Obstructive sleep apnea (OSA) is a unique potent predictor for stroke compared to other predictors. By aiding in the adherence of leukocytes and platelets, soluble P-selectin (sP-selectin) contributes to the development of ischemic stroke. The objective of this study was to investigate the independent impact of OSA on platelet activation and development of silent brain infarction. Twenty-four OSA patients and 24 controls were studied in a case–control study, who underwent one-night polysomnography, magnetic resonance imaging for evaluation of silent brain infarctions (SBI), measurement of serum (sP-selectin) levels for assessment of increased platelet activation and C-reactive protein (CRP) serum levels.

Results

Out of 24 patients, 5 (20.8%) had mild OSA and 8 (33.3%) had moderate and 11 (45.8%) had severe OSA. Serum levels of sP-selectin were statistically significantly higher in moderate and severe groups (p < 0.001). Eleven (57.9%) patients in moderate and severe OSA had SBI. Fifty percent of patients with moderate OSA had elevated serum sP-selectin and 25.0% of them had SBI and 81.8% of severe OSA patients had elevated serum sP-selectin and 81.8% of them had SBI. Patients with mild OSA and controls had no SBI and normal serum sP-selectin level. CRP was statistically significantly higher in moderate and severe OSA groups (16.6% and 45.8%) than the mild and control groups (4.1% and 0%) (p < 0.001).

Conclusion

Moderate and severe obstructive sleep apnea were associated independently with elevated serum sP-selectin reflecting increased platelet function, elevated inflammatory marker CRP and an increased risk of silent brain infarctions.

Alterations in sympathetic and parasympathetic brain networks in obstructive sleep apnea

OBJECTIVE/BACKGROUND

Obstructive sleep apnea (OSA) patients experience hypoxia and, potentially, autonomic impairments stemming from neural damage. In this study, the executive control networks (ECNs), salience networks (SNs), and default mode networks (DMNs) of adult OSA patients, as well as their relationships with autonomic impairment, were investigated through independent component analysis (ICA).

PATIENTS/METHODS

A total of 41 OSA patients and 19 healthy controls volunteers were recruited and subjected to polysomnography to ascertain their degree, if any, of sleep apnea. Each participant also underwent a cardiovascular autonomic survey, with the participant's baroreflex sensitivity (BRS) being determined based on heart rate and blood pressure alterations. The resting fMRI data of the participants was separated using probabilistic ICA, and six autonomic resting-state networks were established for group comparisons. The differences in autonomic parameters, autonomic functional connectivity (FC), and clinical severity were then correlated.

RESULTS

The OSA group had significantly worse BRS values than the controls, as well as lower FC in the posterior and anterior SNs, bilateral ECNs, and the ventral DMN, and higher FC in the left ECN. These intrinsic connectivity networks showed dissociable correlations with greater baroreflex impairment and clinical disease severity. The higher FC in the left ECN was associated with the lower FC in the ventral DMN.

CONCLUSIONS

Our findings suggest that autonomic dysfunction in OSA might be accompanied by central autonomic network alterations. The stronger sympathetic-associated regions in ECNs and the weaker parasympathetic-associated regions in DMNs may represent intrinsic neural architecture fluctuations underlining their consequent processes in OSA.

Association of carotid intima-media thickness with the risk of sudden sensorineural hearing loss

Cardiovascular factors are associated with the pathophysiological features and risk of sudden sensorineural hearing loss (SSNHL). However, little is known about the link between carotid intima-media thickness (IMT), SSNHL risk, and their respective treatment outcomes. In this study, we retrospectively reviewed 47 SSNHL cases and 33 control subjects from a single medical center and compared their demographic data and clinical characteristics, including their carotid IMT and audiological data. Of the 80 enrolled subjects, the proportion of those with high carotid IMT was greater in the SSNHL group (53.2%) than in the control group (21.2%), with an odds ratio (OR) of 4.22 (95% confidence interval (CI) [1.53–11.61], P = 0.004). Notably, high carotid IMT was more common in female SSNHL patients than females in the control group (54.2% vs. 12.5%; OR, 8.27 (95% CI [1.53–44.62]), P = 0.008), particularly in female patients ≥50 years of age (75% vs. 25%; OR, 9.0 (95% CI [1.27–63.9]), P = 0.032). The multivariate regression analyses showed the association between high carotid IMT and SSNHL with an adjusted OR of 4.655 (95% CI [1.348–16.076], P = 0.015), particularly in female SSNHL patients (adjusted OR, 9.818 (95% CI [1.064–90.587], P = 0.044). The carotid IMT was not associated with the treatment outcomes of SSNHL. Our results indicate that early-stage atherosclerosis may be associated with SSNHL, particularly in female patients more than 50 years old.

White matter alteration and autonomic impairment in obstructive sleep apnea

STUDY OBJECTIVES

Autonomic impairment and white matter (WM) alterations have been noted as effects of obstructive sleep apnea (OSA). This study sought to evaluate the change of WM integrity in patients with OSA using diffusion tensor imaging (DTI) and to determine its relationship with autonomic impairment.

METHODS

A total of 30 patients with moderate and severe OSA and 19 healthy volunteers were recruited. A cardiovascular autonomic survey was performed and the baroreflex sensitivity (BRS) for each participant was derived from changes in heart rate and blood pressure during the early part of phase II of the Valsalva maneuver. DTI-related indices were derived from DTI. The fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) maps were compared using voxel-based statistics to determine differences between the patients with OSA and the healthy controls. The correlations among DTI indices, clinical severity, and autonomic parameters were investigated.

RESULTS

The BRS values were significantly worse in the OSA group than in the control patients. An exploratory group-wise comparison between the two groups revealed that the patients with OSA exhibited low FA, increased MD, AD, and RD in several brain locations. The declined DTI indices in autonomic-related areas were significantly correlated with increased clinical disease severity and baroreflex impairment.

CONCLUSIONS

OSA alters WM integrity in the cingulum and temporal lobe, and this impairment might play some role in autonomic dysfunction. The possible interaction between autonomic dysfunction and central nervous system microstructural alterations may represent variant hypoxic patterns, sympathetic activation, and their consequent processes in OSA.

Arousal index as a marker of carotid artery atherosclerosis in patients with obstructive sleep apnea syndrome

PURPOSE

It was shown in a previous cohort study that men with internal carotid artery (ICA) plaque, defined as focal wall thickness of ≥ 1.5 mm, had a threefold higher risk of stroke than those without plaque. We examined the relationship between arousal indices and sleep stages in patients with obstructive sleep apnea syndrome (OSAS) and carotid atherosclerosis.

METHODS

Carotid atherosclerosis severity was evaluated using the maximal carotid wall intima-media thickness of the ICA (ICA-maxIMT) and plaque in 83 patients with OSAS.

RESULTS

The ICA-maxIMT values were positively correlated with the apnea hypopnea index (AHI) (ρ = 0.294, P = 0.007), arousal index (ρ = 0.289, P = 0.008), oxygen desaturation index (ρ = 0.298, P = 0.006), percentage of visually scored total sleep time spent in nocturnal oxygen saturation < 90% (SpO₂ < 90%) (ρ = 0.246, P = 0.025), and the percentage of visually scored total sleep time spent in non-REM sleep stage 1 (ρ = 0.326, P = 0.003) and were negatively correlated with the percentage of visually scored total sleep time spent in non-REM sleep stages 2 and 3. Arousal index, diabetes mellitus, and age were found to be independent predictors of ICA plaque presence (OR 1.052, P = 0.003; OR 8.705, P = 0.026; OR 1.064, P = 0.023, respectively).

CONCLUSIONS

Several PSG variables that are indicative of sleep fragmentation, sleep disordered breathing, and poor sleep quality correlated with the occurrence of atherosclerosis, but total arousal index was the only independent predictive factor.

Systemic inflammation and alterations to cerebral blood flow in obstructive sleep apnea

Systemic inflammation and alterations to regional cerebral blood flow (CBF) have been reported previously in obstructive sleep apnea (OSA). This study utilized arterial spin labelling (ASL) perfusion magnetic resonance imaging (MRI) to evaluate CBF in OSA patients and determine its relationship with systemic inflammation. Twenty male patients with moderate and severe OSA [apnea-hypopnea index (AHI) >15] and 16 healthy male volunteers (AHI <5) were recruited. Early- or late-phase changes in leucocyte apoptosis and its subsets were determined by flow cytometry. Perfusion MRI data were acquired with a pulsed continuous ASL technique. The CBF maps were compared using voxel-based statistics to determine differences between the OSA and control groups. The differences in CBF, clinical severity and leucocyte apoptosis were correlated. Exploratory groupwise comparison between the two groups revealed that the OSA patients exhibited low CBF values in the vulnerable regions. The lower regional CBF values were correlated with higher clinical disease severity and leucocyte apoptosis. OSA impairs cerebral perfusion in vulnerable regions, and this deficit is associated with increased disease severity. The apparent correlation between systemic inflammation and cerebral perfusion may be indicative of haemodynamic alterations and their consequences in OSA.

Impact of inflammation and oxidative stress on carotid intima-media thickness in obstructive sleep apnea patients without metabolic syndrome

Obstructive sleep apnea (OSA) increases the risk of cardiovascular diseases, and carotid intima-media thickness (IMT) is a good indicator of the severity of atherosclerotic disease. This study tested the hypothesis that inflammation and oxidative stress determined carotid IMT in patients with OSA. The carotid IMT, mean systolic and diastolic pressure (night and morning) were significantly higher and the level of thiols and high-density lipoprotein were significantly lower in our 121 OSA patients than in 27 controls (P < 0.05). The apnea/hypopnea index was correlated positively with E-selectin (r = 0.222, P = 0.014), total cholesterol (r = 0.185, P = 0.042), low-density lipoprotein (r = 0.264, P = 0.003) and HbA1c levels (r = 0.304, P = 0.001), but inversely with high-density lipoprotein level (r = -0.203, P = 0.025) in the 121 patients with OSA. In OSA subjects, multiple linear regression analysis revealed that age, systolic blood pressure and intercellular cell adhesion molecule-1 level associated independently with carotid IMT. Besides both age and systolic blood pressure, our study demonstrated that intercellular cell adhesion molecule-1 level was associated significantly with carotid IMT in those patients who had OSA but without metabolic syndrome.

The Association Between Obstructive Sleep Apnea and Carotid Intima-Media Thickness: A Systematic Review and Meta-Analysis

Obstructive sleep apnea (OSA) has been suggested as a risk factor for carotid atherosclerosis. The present meta-analysis aimed to evaluate the association between OSA and carotid intima-media thickness (CIMT). Eighteen studies comparing CIMT of patients with OSA versus non-OSA patients were included. Quantitative data synthesis was used to pool weighted standardized difference in means (SMD) of CIMT in a random-effects model. Compared to healthy controls, patients with OSA had a significantly higher CIMT (SMD: 0.881; 95% confidence interval [CI]: 0.647-1.115; P < .001). Due to the great heterogeneity, a subgroup analysis was conducted based on the study design. The pooled SMD of CIMT between patients with OSA and healthy controls were 0.810 (95% CI: 0.676-0.943; P < .001) and 1.008 (95% CI: 0.506-1.510; P < .001) in matched and unmatched group, respectively. Moreover, the correlation of apnea-hypopnea index and CIMT was moderate ( r = .389; 95% CI: 0.315-0.459; P < .001). After adjustment for several major confounders, OSA is an independent risk factor for CIMT. These findings remind clinicians to screen for cardiovascular diseases in patients with OSA.

The Frequency and Energy of Snoring Sounds Are Associated with Common Carotid Artery Intima-Media Thickness in Obstructive Sleep Apnea Patients

Obstructive sleep apnea (OSA) is a known risk factor for atherosclerosis. We investigated the association of common carotid artery intima-media thickness (CCA-IMT) with snoring sounds in OSA patients. A total of 30 newly diagnosed OSA patients with no history of cardiovascular diseases were prospectively enrolled for measuring mean CCA-IMT with B-mode ultrasonography, body mass index, metabolic syndrome, 10-year cardiovascular disease risk score, high-sensitivity C-reactive protein, and homocysteine. Good-quality signals of full-night snoring sounds in an ordinary sleep condition obtained from 15 participants were further acoustically analyzed (Included group). All variables of interest were not significantly different (all p > 0.05) between the included and non-included groups except for diastolic blood pressure (p = 0.037). In the included group, CCA-IMT was significantly correlated with snoring sound energies of 0–20 Hz (r = 0.608, p = 0.036) and 652–1500 Hz (r = 0.632, p = 0.027) and was not significantly associated with that of 20–652 Hz (r = 0.366, p = 0.242) after adjustment for age and sex. Our findings suggest that underlying snoring sounds may cause carotid wall thickening and support the large-scale evaluation of snoring sound characters as markers of surveillance and for risk stratification at diagnosis.

Roles and Mechanisms of Obstructive Sleep Apnea-Hypopnea Syndrome and Chronic Intermittent Hypoxia in Atherosclerosis: Evidence and Prospective

The morbidity and mortality of obstructive sleep apnea-hypopnea syndrome (OSAHS) are regarded as consequences of its adverse effects on the cardiovascular system. Chronic intermittent hypoxia (CIH) induced by OSAHS can result in vascular endothelial injury, thus promoting development of atherosclerosis (AS). Studies have shown that CIH is an independent risk factor for the occurrence and development of AS, but the underlying mechanism remains unclear. Here, we review clinical and fundamental studies reported during the last 10 years on the occurrence and development of AS mediated by CIH, focusing on inflammation, oxidative stress, insulin resistance, cell apoptosis, vascular endothelial injury, platelet activation, and neuroendocrine disorders. This review will offer current evidence and perspective to researchers for the development of effective intervention strategies for OSAHS-related cardiocerebrovascular diseases.

Minimal nocturnal oxygen saturation predicts future subclinical carotid atherosclerosis: the Wisconsin sleep cohort

Previous data on the associations between nocturnal oxygen saturation parameters and carotid atherosclerosis are conflicting. We examined the prospective associations of nocturnal oxygen saturation (SaO2 ) and cardiovascular disease (CVD) risk factors with carotid intima-media thickness (IMT) and plaques. We used data on 689 Wisconsin sleep cohort participants who had baseline overnight polysomnography followed by carotid ultrasonography a mean (SD) of 7.8 (2.5) years later. Far wall common carotid IMT was measured using B-mode ultrasound. Bilateral common, bifurcation and internal carotid artery segments were evaluated for plaque score. Participants (8) were aged 56 years (55% male); 32% had hypertension and mean body mass index (BMI) was 31 (7) kg m(2). Mean and minimum nocturnal SaO2 were 95% (2) and 86% (7), respectively. Mean percentage sleep time with SaO2 < 90% was 2% (8). Both mean (odds ratio [OR]: 0.60 lower plaque count per 5% higher mean SaO2, 95% confidence interval [CI]: 0.38-0.96, P = 0.033) and minimum SaO2 (OR: 0.88 lower plaque count per 5% higher minimum SaO2, 95% CI: 0.80-0.97, P = 0.013) predicted carotid plaque score after adjusting for age, sex and BMI. Minimum SaO2 predicted future plaque score after adding adjustment for traditional CVD risk factors (OR: 0.90 lower plaque count per 5% higher minimum SaO2, 95% CI: 0.81-0.99, P = 0.038). Mean SaO2 was not associated with carotid IMT after CVD risk factor adjustment. We conclude that minimum nocturnal SaO2 is an independent predictor of future carotid plaque burden. Other nocturnal SaO2 parameters are not associated with future carotid IMT or plaques after adjusting for traditional CVD risk factors.

White matter damage and systemic inflammation in obstructive sleep apnea

STUDY OBJECTIVES

To evaluate white matter integrity in patients with obstructive sleep apnea (OSA) using diffusion tensor imaging (DTI) and to assess its relationship with systemic inflammation.

DESIGN

Cross-sectional study.

SETTING

One tertiary medical center research institute.

PATIENTS OR PARTICIPANTS

Twenty patients with severe OSA (apnea-hypopnea index [AHI] > 30, 18 men and 2 women) and 14 healthy volunteers (AHI < 5, 11 men and 3 women).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Patients with severe OSA and healthy volunteers underwent polysomnography to determine the severity of sleep apnea, and DTI scanning to determine fiber integrity. Early or late phase changes in leukocyte apoptosis and its subsets were determined by flow cytometry. DTI-related indices (including fractional anisotropy [FA], axial diffusivity [AD], radial diffusivity [RD], and mean diffusivity [MD]) were derived from DTI. The FA maps were compared using voxel-based statistics to determine differences between the severe OSA and control groups. The differences in DTI indices, clinical severity, and leukocyte apoptosis were correlated after adjusting for age, sex, body mass index, and systolic blood pressure. Exploratory group-wise comparison between the two groups revealed that patients with OSA exhibited low FA accomplished by high RD in several brain locations, without any differences in AD and MD. The FA values were negatively correlated with clinical disease severity and leukocyte early apoptosis.

CONCLUSIONS

Obstructive sleep apnea impairs white matter integrity in vulnerable regions, and this impairment is associated with increased disease severity. The possible interactions between systemic inflammation and central nervous system microstructural damage may represent variant hypoxic patterns and their consequent processes in OSA.