Obstructive sleep apnea linked to wake-up strokes

Obstructive sleep apnea (OSA) has been considered as one of the risk factors for ischemic stroke, but the impact of OSA on wake-up stroke (WUS) is not well studied. We aimed to determine the relationship between OSA and WUS. We prospectively recruited 71 patients with mild to moderate ischemic stroke during hospitalization. Patients were classified into WUS and non-WUS. A full-night sleep respiratory study was performed between 3 and 14 days after stroke onset. Demographic data, sleep respiratory data, heart rate variability, stroke risk factors, stroke classification and sleep-related scales were recorded. We compared the differences in the variables between the two groups and determined the independent variables associated with WUS. Of the 71 patients, 26 (36.6%) had WUS. The patients with WUS had a significantly higher apnea-hypopnea index (23.1 ± 19.4 vs. 12.5 ± 11.9, p = 0.016), obstructive apnea index (7.8 ± 9.7 vs. 3.0 ± 4.0, p = 0.021) and lower mean blood oxygen saturation (95.1 ± 1.5 vs. 95.8 ± 1.3, p = 0.046) than the non-WUS patients. There were no significant differences in demographic data, stroke risk factors, sleep-related scales or heart rate variability. Logistic regression revealed that severe sleep-disordered breathing (apnea-hypopnea index ≥30) was the only independent variable associated with WUS (OR 6.065, 95% CI 1.451-25.350; p = 0.014). We conclude that in patients with mild to moderate ischemic stroke, OSA is the only risk factor associated with WUS, which cannot be distinguished clinically from non-WUS.     

Cognitive dysfunction after acute lacunar infarct

Vascular dementia and vascular cognitive impairment have attracted more attention recently due to their association with increased risk of death and institutionalization. The purpose of the present study was to detect and identify the characteristics of cognitive impairments during the early stage of lacunar stroke. The subjects consisted of 23 consecutive first-ever acute lacunar infarction patients who were admitted to the Department of Neurology, Kaohsiung Municipal Hsiao-Kang Hospital, Taiwan, from November 2001 to October 2002. The National Institutes of Health Stroke Scale and Cognitive Abilities Screening Instrument (CASI) were used to evaluate stroke severity and cognitive function, and assessments were performed by a neurologist and psychologist, within 10 days of stroke onset. Of the 23 patients, 21 (91.3%) had CASI scores below their respective cutoff values and all patients had cognitive impairment in at least one cognitive domain in CASI. There were no significant correlations between CASI abnormality (below the cutoff value) and patient age, education, or the interval from stroke onset. Recent memory impairment was the most often impaired cognitive domain on CASI (19 patients, 82.6%). There were significant correlations between recent memory and "attention or concentration"(correlation coefficient, 0.52; p < 0.05), and "abstraction and judgment" (correlation coefficient, 0.44; p < 0.05). The correlations between recent memory and other domains were not significant. It was concluded that cognitive impairment after acute lacunar infarct is quite common and recent memory is the most often impaired cognitive domain. This may have been caused by the location of the specific lesion as well as by the impairment in "attention or concentration" or "abstraction and judgment".     

Basal sympathetic predominance in periodic limb movements in sleep after continuous positive airway pressure

Purpose

This study investigated the basal autonomic regulation in patients with obstructive sleep apnea (OSA) showing periodic limb movements in sleep (PLMS) emerging after therapy with continuous positive airway pressure (CPAP).

Methods

Data of patients with OSA undergoing a first polysomnography for diagnosis and a second polysomnography for therapy with CPAP were reviewed. Patients with OSA showing PLMS on the first polysomnography were excluded. By using heart rate variability analysis, epochs without any sleep events and continuous effects from the second polysomnography were retrospectively analyzed.

Results

Of 125 eligible patients, 30 with PLMS after therapy with CPAP (PLMS group) and 30 not showing PLMS on both polysomnography (non-PLMS group) were randomly selected for the analysis. No significant differences in the demographic characteristics and variables of polysomnographies were identified between the groups. Although one trend of low root mean square of successive differences (RMSSD) between intervals of adjacent normal heart beats (NN intervals) in the PLMS group was observed, patients in the PLMS group had significantly low normalized high-frequency (n-HF) and high-frequency (HF) values, but high normalized low frequency (n-LF) and high ratio of LF to HF (LF/HF ratio). After adjustment for confounding variables, PLMS on the second polysomnography was significantly associated with RMSSD (β?=???6.7587, p?=?0.0338), n-LF (β?=?0.0907, p?=?0.0148), n-HF (β?=???0.0895, p?=?0.0163), log LF/HF ratio (β?=?0.4923, p?=?0.0090), and log HF (β?=???0.6134, p?=?0.0199).

Conclusions

Patients with OSA showing PLMS emerging after therapy with CPAP may have a basal sympathetic predominance with potential negative cardiovascular effects.

     

Effects of metabolic syndrome,apolipoprotein E,and CYP46 on cognition among Taiwanese Chinese

The combined effects of metabolic syndrome and the apolipoprotein E and CYP46 genotypes on the risk of cognitive decline has yet to be determined among Taiwanese Chinese. Two hundred and nine mentally healthy middle-aged and older adults were assessed for metabolic syndrome, cognitive function using the Cognitive Abilities Screening Instrument, Mini-Mental State Examination, ApoE, and CYP46 polymorphisms. There were no differences in cognitive performance, ApoE epsilon4 (ε4) carrier status, or CYP46 genotypes between participants with and those without metabolic syndrome. The ε4 carriers and participants with the AA allele of CYP46 had significantly lower mental manipulation score. Metabolic syndrome and ε4 had synergistic effects on cognitive decline. Therefore, the ε4 carriers and participants with the AA allele of CYP46 have decreased mental manipulation ability. The metabolic syndrome may play a role in subtle cognitive dysfunction in ε4 carriers among Taiwanese Chinese.     

The effects of metabolic syndrome and apolipoprotein E4 on cognitive event-related potentials

To reduce the care burden of dementia, identifying whether the combined effect of metabolic syndrome and ?4 increases the risk of cognitive decline needs to be determined. Using the Cognitive Abilities Screening Instrument (CASI), 145 mentally healthy middle-aged and older adults were recruited to investigate the influence of metabolic syndrome and ?4 on cognitive event-related potentials (ERPs). The results showed no difference in CASI scores, N100 and P300 measurements and ?4 carrier percentage between participants with and without metabolic syndrome. The ?4 carriers displayed a significant decrease in P300 amplitude, although the CASI scores and N100 component showed no difference. We conclude that metabolic syndrome exerts little effect on N100 and P300 measurements, and that ?4 carrier is an independent predictor of low P300 amplitude.     

Obstructive sleep apnea and cerebral white matter change: a systematic review and meta-analysis

Obstructive sleep apnea (OSA) can cause sleep fragmentation and intermittent hypoxemia, which are linked to oxidative stress. White matter changes (WMCs) representing cerebrovascular burden and are at risk factor for oxidative ischemic injury. The current study explores the mutual relationships between OSA and WMCs. We performed a systematic review of electronic databases for clinical studies investigating OSA and WMCs. Random-effects models were used for pooled estimates calculation. A total of 22 studies were included in the meta-analysis. The results revealed a significantly higher prevalence rate of WMCs [odds ratio (OR) 2.06, 95% confidence interval (CI) 1.52–2.80, p?<?0.001] and significantly higher severity of WMCs (Hedges’ g?=?0.23, 95% CI 0.06–0.40, p?=?0.009) in the patients with OSA than in controls. Furthermore, the results revealed a significantly higher apnea–hypopnea index (Hedges’ g?=?0.54, 95% CI 0.31–0.78, p?<?0.001) and significantly higher prevalence rate of moderate-to-severe OSA (OR 2.86, 95% CI 1.44–5.66, p?=?0.003) in the patients with WMCs than in controls, however there was no significant difference in the prevalence rate of mild OSA between the patients with WMCs and controls (OR 0.71, 95% CI 0.20–2.54, p?=?0.603). OSA was associated with a higher prevalence and more severe WMCs, and the patients with WMCs had an increased association with moderate-to-severe OSA. Future large-scale randomized controlled trials with a longitudinal design are essential to further evaluate treatment in patients with OSA.     

Apolipoprotein E polymorphism and behavioral and psychological symptoms of dementia in patients with Alzheimer disease

The aims of this study were to identify subsyndromes of behavioral and psychological symptoms of dementia (BPSD) in Alzheimer disease (AD), and to investigate whether the apolipoprotein E (ApoE) gene confers a risk of distinct BPSD subsyndromes. BPSD of 96 patients with AD were assessed using the Neuropsychiatric Inventory. Factor analysis with principal component analysis and varimax rotation was used to construct the BPSD subsyndromes. ApoE genotypes were determined using the TaqMan technology. The results showed that the 5 subsyndromes can be determined, including: agitation/aggression-delusion, euphoria-disinhibition, depression-apathy, hallucination-nighttime behavior, and appetite. ApoE ε4 carriers had higher factor scores in the agitation/aggression-delusion subsyndrome. We demonstrated that ApoE ε4 confers a higher risk for the subsyndrome of agitation/aggression delusion in AD.     

Predictive value of vertebral artery extracranial color-coded duplex sonography for ischemic stroke-related vertigo

Vertigo can be a major presentation of posterior circulation stroke and can be easily misdiagnosed because of its complicated presentation. We thus prospectively assessed the predictive value of vertebral artery extracranial color-coded duplex sonography (ECCS) for the prediction of ischemic stroke-related vertigo. The inclusion criteria were: (1) a sensation of whirling (vertigo); (2) intractable vertigo for more than 1 hour despite appropriate treatment; and (3) those who could complete cranial magnetic resonance imaging (MRI) and vertebral artery (V2 segment) ECCS studies. Eventually, 76 consecutive participants with vertigo were enrolled from Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan between August 2010 and August 2011. Demographic data, neurological symptoms, neurologic examinations, and V2 ECCS were assessed. We chose the parameters of peak systolic velocity (PSV), end diastolic velocity (EDV), PSV/EDV, mean velocity (MV), resistance index (RI), and pulsatility index (PI) to represent the hemodynamics. Values from both sides of V2 segments were averaged. We then calculated the average RI (aRI), average PI (aPI), average PSV (aPSV)/EDV, and average (aMV). Axial and coronal diffusion-weighted MRI findings determined the existence of acute ischemic stroke. We grouped and analyzed participants in two ways (way I and way II analyses) based on the diffusion-weighted MRI findings (to determine whether there was acute stroke) and neurological examinations. Using way I analysis, the “MRI (+)” group had significantly higher impedance (aRI, aPI, and aPSV/EDV ratio) and lower velocity (aPSV, aEDV, and aMV(PSV + EDV/2)), compared to the “MRI (–)” group. The cutoff value/sensitivity/specificity of aPSV, aEDV, aMV, aPI, aRI, and aPSV/EDV between the MRI (+) and MRI (–) groups were 41.15/61.5/66.0 (p = 0.0101), 14.55/69.2/72.0 (p = 0.0003), 29.10/92.1/38.0 (p = 0.0013), 1.07/76.9/64.0 (p = 0.0066), 0.62/76.9/64.0 (p = 0.0076), and 2.69/80.8/66.0 (p = 0.0068), respectively. Using way II analysis, lower aEDV and aMV, and higher aRI, aPI, and aPSV/EDV ratio could determine the “MRI (+) without focal signs” group. The cutoff value/sensitivity/specificity of aEDV, aMV, aPI, aRI, and aPSV/EDV between the MRI (+) without focal signs and MRI (–) groups were 9.10/71.4/96.0 (p = 0.0005), 15.65/57.1/96.0 (p = 0.0124), 1.10/100/70.0 (p = 0.0002), 0.64/100/70.0 (p = 0.0023), and 2.80/100/70.0 (p = 0.0017), respectively. In conclusion, using demographic data and clinical symptoms, it was difficult to determine the patients with ischemic stroke-related vertigo. Although neurological examinations still have diagnostic value, the high impedance and low velocity pattern of V2 ECCS can be an add-on method for the screening of acute ischemic stroke-related vertigo, even for those without focal neurological signs.     

Effect of cholesterol and CYP46 polymorphism on cognitive event-related potentials

The integrated effect of the cholesterol and CYP46 genotypes on the risk of cognitive decline needs to be determined. Using the Cognitive Abilities Screening Instrument (CASI), 145 mentally healthy middle-aged and older adults were recruited to investigate the influence of cholesterol and CYP46 genotypes on cognitive event-related potentials (ERPs). The subjects with a high low-density lipoprotein cholesterol (LDL-C) level displayed significantly lower amplitude ERPs, although the CASI scores showed no difference. There was no association between the CYP46 genotypes, CASI scores, cholesterol levels, and measures of ERPs. No interaction between LDL-C level and CYP46 genotypes was noted. The LDL-C level is an independent predictor of low P300 amplitude. Prevention and treatment of high cholesterol may be of potential benefit in reducing cognitive impairment.     

Factors affecting therapeutic response to Rivastigmine in Alzheimer's disease patients in Taiwan

Rivastigmine has been widely used in mild-to-moderate Alzheimer's disease (AD), but the therapeutic response rate varies from 20 to 60%. A dose-dependent effect has been suggested, but the plasma concentration of rivastigmine and its metabolite, NAP 226-90, were not measured in previous studies. The influencing factors of therapeutic response are complicated and discordant in various studies among different ethnic groups. Hence, we analyzed the therapeutic responses of rivastigmine, measured by neuropsychological assessments, among 63 clinically diagnosed AD patients taking a daily dosage of 6–9 mg in relation to their plasma concentration of rivastigmine and NAP 226-90, apolipoprotein E (APOE) genotype and demographic characteristics. Our reports revealed that 41.3% of recruited AD patients had improvement in cognition, measured by Mini-Mental Status Examination (MMSE), and 63.5% in global status, by Clinical Dementia Rating Scale Sum of Boxes (CDR-SB) score. In cognition, the clinically improving group had a significantly higher rivastigmine concentration [p = 0.049, odds ratio (OR) = 1.029, 95%CI = 1.000–1.058], lower initial MMSE score (p = 0.010, OR = 0.708, 95%CI = 0.546–0.920), and lower initial CDR-SB score (p = 0.003, OR = 0.552, 95%CI = 0.372–0.817). The patients with APOE ε4 allele had worsening cognition (p = 0.037, OR = 3.870, 95%CI = 1.082–13.840). In global status, only higher education (p = 0.043, OR = 1.222, 95%CI = 1.007–1.484) was significantly associated with clinical improvement. In conclusion, high concentrations of rivastigmine may benefit cognitive function of AD patients, especially in APOE ε4 (?) carriers.