Pravastatin improves cerebral vasomotor reactivity in patients with subcortical small-vessel disease

Cerebral autoregulation, spreading depolarization, and implications for targeted therapy in brain injury and ischemia

Cerebral autoregulation is an intrinsic myogenic response of cerebral vasculature that allows for preservation of stable cerebral blood flow levels in response to changing systemic blood pressure. It is effective across a broad range of blood pressure levels through precapillary vasoconstriction and dilation. Autoregulation is difficult to directly measure and methods to indirectly ascertain cerebral autoregulation status inherently require certain assumptions. Patients with impaired cerebral autoregulation may be at risk of brain ischemia. One of the central mechanisms of ischemia in patients with metabolically compromised states is likely the triggering of spreading depolarization (SD) events and ultimately, terminal (or anoxic) depolarization. Cerebral autoregulation and SD are therefore linked when considering the risk of ischemia. In this scoping review, we will discuss the range of methods to measure cerebral autoregulation, their theoretical strengths and weaknesses, and the available clinical evidence to support their utility. We will then discuss the emerging link between impaired cerebral autoregulation and the occurrence of SD events. Such an approach offers the opportunity to better understand an individual patient's physiology and provide targeted treatments.

Statin treatment intensity and cerebral vasomotor reactivity response in patients with ischemic stroke

BACKGROUND AND PURPOSE

Cerebral vasomotor reactivity (VMR) is vital for regulating brain blood flow and maintaining neurological function. Impaired cerebral VMR is linked to a higher risk of stroke and poor post-stroke outcomes. This study explores the relationship between statin treatment intensity and VMR in patients with ischemic stroke.

METHODS

Seventy-four consecutive patients (mean age 69.3 years, 59.4% male) with recent ischemic stroke were included. VMR levels were assessed 4 weeks after the index stroke using transcranial Doppler, measuring the breath-holding index (BHI) as an indicator of the percentage increase in middle cerebral artery blood flow (higher BHI signifies higher VMR). Multistep multivariable regression models, adjusted for demographic and cerebrovascular risk factors, were employed to examine the association between statin intensity treatment and BHI levels.

RESULTS

Forty-one patients (55%) received high-intensity statins. Patients receiving high-intensity statins exhibited a mean BHI of 0.85, whereas those on low-intensity statins had a mean BHI of 0.67 (mean difference 0.18, 95% confidence interval: 0.13-0.22, p-value<.001). This significant difference persisted in the fully adjusted model (adjusted mean values: 0.84 vs. 0.68, p-value: .008). No significant differences were observed in BHI values within patient groups on high-intensity or low-intensity statin therapy (all p-values>.05). Furthermore, no significant association was found between baseline low-density lipoprotein (LDL) levels and BHI.

CONCLUSIONS

High-intensity statin treatment post-ischemic stroke is linked to elevated VMR independent of demographic and clinical characteristics, including baseline LDL level. Further research is needed to explore statin therapy's impact on preserving brain vascular function beyond lipid-lowering effects.

Statin treatment in stroke patient with low-density lipoprotein cholesterol levels below 70 mg/dL

BACKGROUND AND PURPOSE

The effectiveness of hyperlipidemia treatment in strokes secondary prevention has been established. However, whether pretreatment with statins could confer protective effects when a patient's baseline low-density lipoprotein cholesterol (LDL-C) level is <70 mg/dL remains uncertain. Additionally, the ability of statin treatment to reduce poststroke complications, mortality, and recurrence in this patient group is unclear.

METHODS AND RESULTS

In this retrospective observational study, we enrolled patients who had experienced an ischemic stroke with LDL-C levels <70 mg/dL. We analyzed the association of statin use with baseline characteristics, stroke severity, in-hospital complications, mortality rates, stroke recurrence rate, and mortality rate. Patients who used and patients who did not use statins were similar in terms of age and sex. Patients using statins had higher rates of diabetes mellitus, hypertension, prior stroke, and coronary artery disease but a lower incidence of atrial fibrillation. Stroke severity was less pronounced in those using statins. We also evaluated the relationship between in-hospital statin use and complications. We noted that in-hospital statin use was associated with lower rates of infection, hemorrhagic transformation, gastrointestinal hemorrhage, and mortality, as well as higher rates of positive functional outcomes. The 1-year recurrence rate was similar in both groups.

CONCLUSIONS

Statin use is associated with milder strokes and improved poststroke outcomes, even in patients with well-controlled LDL levels. Neurologists may consider prescribing statins for patients with ischemic stroke who do not overt hyperlipidemia. Further research into potential underlying mechanisms is warranted.

Leukoaraiosis: Epidemiology, Imaging, Risk Factors, and Management of Age-Related Cerebral White Matter Hyperintensities

Leukoaraiosis (LA) manifests as cerebral white matter hyperintensities on T2-weighted magnetic resonance imaging scans and corresponds to white matter lesions or abnormalities in brain tissue. Clinically, it is generally detected in the early 40s and is highly prevalent globally in individuals aged >60 years. From the imaging perspective, LA can present as several heterogeneous forms, including punctate and patchy lesions in deep or subcortical white matter; lesions with periventricular caps, a pencil-thin lining, and smooth halo; as well as irregular lesions, which are not always benign. Given its potential of having deleterious effects on normal brain function and the resulting increase in public health burden, considerable effort has been focused on investigating the associations between various risk factors and LA risk, and developing its associated clinical interventions. However, study results have been inconsistent, most likely due to potential differences in study designs, neuroimaging methods, and sample sizes as well as the inherent neuroimaging heterogeneity and multi-factorial nature of LA. In this article, we provided an overview of LA and summarized the current knowledge regarding its epidemiology, neuroimaging classification, pathological characteristics, risk factors, and potential intervention strategies.

The Landscape of Randomized Clinical Trial Meta-analyses on Statins for Aneurysmal Subarachnoid Hemorrhage: A Scoping Review

INTRODUCTION

Aneurysmal subarachnoid hemorrhage (aSAH) is a type of non-traumatic SAH that can have detrimental effects on the central nervous system, resulting in severe disability or death.

METHODS

Early nimodipine is currently the only strongly recommended pharmacological treatment that has shown efficacy in improving neurological/functional outcomes in aSAH patients. Whether statin treatment is of benefit to aSAH patients is an issue that has generated considerable interest and debate. In the present scoping review, we mapped and analyzed the available literature on metaanalyses of randomized clinical trials (RCTs) examining the effect of statins on aSAH. Seventeen meta-analyses of RCTs, published between 2008 and 2023, were identified.

RESULTS

Treatments in included meta-analyses were based on various regimens of simvastatin, pravastatin, pitavastatin or atorvastatin for up to 21 days. Eleven of the included reports indicated some beneficial effect of statin treatment, reducing rates of at least one of the following: cerebral vasospasm, delayed cerebral ischemia/delayed ischemic neurologic deficit, mortality or functional/ neurological outcome. In contrast, six meta-analyses, showed no such effects.

CONCLUSION

The limitations reported by several meta-analyses, included low patient numbers or disproportionate representation of patients from certain RCTs, differences in drug treatment, patient diagnostic criteria and outcome evaluation between RCTs, as well as poor data quality or lack of RCTs data. Knowledge of the reported limitations may aid the design of future clinical trials and/or their meta-analyses.

Effect of drug interventions on cerebral hemodynamics in ischemic stroke patients

The ischemic penumbra is sensitive to alterations in cerebral perfusion. A myriad of drugs are used in acute ischemic stroke (AIS) management, yet their impact on cerebral hemodynamics is poorly understood. As part of the Cerebral Autoregulation Network led INFOMATAS project (Identifying New Targets for Management and Therapy in Acute Stroke), this paper reviews some of the most common drugs a patient with AIS will come across and their potential influence on cerebral hemodynamics with a particular focus being on cerebral autoregulation (CA). We first discuss how compounds that promote clot lysis and prevent clot formation could potentially impact cerebral hemodynamics, before focusing on how the different classes of antihypertensive drugs can influence cerebral hemodynamics. We discuss the different properties of each drug and their potential impact on cerebral perfusion and CA. With emerging interest in CA status of AIS patients, either during or soon after treatment when timely reperfusion and salvageable tissue is at its most critical, the properties of these pharmacological agents may be relevant for modelling cerebral perfusion accuracy and for setting individualised treatment strategies.

Effects of Cilostazol and Isosorbide Mononitrate on Cerebral Hemodynamics in the LACI-1 Randomized Controlled Trial

Supplemental Digital Content is available in the text.

Cerebral small vessel disease—a major cause of stroke and dementia—is associated with cerebrovascular dysfunction. We investigated whether short-term isosorbide mononitrate (ISMN) and cilostazol, alone or in combination, improved magnetic resonance imaging–measured cerebrovascular function in patients with lacunar ischemic stroke.

Effect of statins on functional outcome and mortality following aneurysmal subarachnoid hemorrhage - Results of a meta-analysis, metaregression and trial sequential analysis

OBJECTIVE

Cerebral vasospasm (CVS) and delayed ischemic neurological deficits (DIND) are a common cause of morbidity following aneurysmal subarachnoid hemorrhage (SAH). Statins have been shown to decrease CVS. The objective of this article was to ascertain the effect of statins on functional outcome and mortality following aneurysmal SAH by performing meta-analysis.

METHODS

A comprehensive search of different databases was performed to retrieve randomized controlled trials. Meta-analysis with subgroup analysis and metaregression was done. Trial sequential analysis (TSA) was performed to determine if the cumulative sample size was appropriately powered for the obtained pooled effect values and to avoid random error.

RESULTS

Twelve articles were selected for meta-analysis. Pooled OR for the change in favorable outcome, mortality, CVS, DIND and elevated transaminases was 1.07 (p = 0.55), 0.78 (p = 0.17), 0.58 (p = 0.0004), 0.54 (p = 0.0293) and 0.68 (p = 0.1774) respectively. Further, subgroup analysis and metaregression showed that the use of different statin or dose did not result in significant variation in results in the parameters studied. TSA showed that more trials and patients are required to reach to a definitive conclusion regarding any effect on statins on functional outcome and mortality as the current studies neither reached the level of confidence nor crossed the futility boundary.

CONCLUSION

Use of statins in patients with aneurysmal SAH resulted in marginal but non-significant favorable impact on functional outcome and mortality. TSA showed that more studies are required to get conclusive evidence in this regard.

Distinct association between cerebral arterial pulsatility and subtypes of cerebral small vessel disease

Background

Increased arterial resistance is a potential pathological mechanism of cerebral small vessel disease (cSVD).

Aim

In this study, we aimed to investigate the association between pulsatility index (PI) representing cerebral arterial resistance and subtypes of cSVD in patients with lacunar stroke.

Methods

We included consecutive lacunar stroke patients between 2010 and 2013. White matter hyperintensity (WMH) volume was rated using semi-automated quantitative methods. Additionally, the presence of old lacunar infarct (OLI), cerebral microbleed (CMB), or enlarged perivascular space (EPVS) was also evaluated. The relationship between PI, measured in each middle cerebral artery, and the subtype/burden of cSVD was analyzed in the relevant hemisphere.

Results

A total of 206 lacunar patients were included and 412 hemispheres were analyzed (mean age: 64 years, male: 68.4%). In multivariable analysis, PI was positively associated with the WMH volume [beta = 1.372, 95% confidence interval (CI) = 0.624 to 2.120, P < 0.001] after adjusting for confounders. PI was also related to the presence of OLI (adjusted odds ratio = 11.37, 95% CI = 2.55–48.56, P = 0.001); however, this relationship was not significant in CMB or EPVS. Regarding the cSVD burden, PI increased according to the WMH tertiles (P for trend < 0.001), the burden of OLI (P for trend < 0.001), and EPVS tertiles (P for trend < 0.001), showing a quantitative relationship.

Conclusions

Ipsilateral PI is closely associated with cSVD in patients with lacunar stroke. Furthermore, this association is different between subtypes of cSVD, which is suggestive of underlying pathophysiological differences.

Association Between Risk of Obstructive Sleep Apnea and Cerebrovascular Reactivity in Stroke Patients

Background Obstructive sleep apnea (OSA) is present in 60% to 70% of stroke patients. Cerebral vasoreactivity in patients with stroke and OSA has not been well studied and could identify a new pathophysiologic mechanism with potential therapeutic intervention. We aimed to determine whether risk categories for OSA are associated with cerebral vasoreactivity in stroke patients. Methods and Results In this cross-sectional study of a cohort of patients with stroke, we used clinical questionnaires (Sleep Obstructive Apnea Score Optimized for Stroke [SOS] and snoring, tiredness, observed, pressure, bmi, age, neck, gender [STOP-BANG] scores) to assess the risk of OSA and transcranial Doppler to assess cerebral vasoreactivity (breath-holding index and visual evoked flow velocity response). Of the 99 patients included, 77 (78%) had medium or high risk of OSA and 80 performed transcranial Doppler. Mean breath-holding index was 0.52±0.37, and median visual evoked flow velocity response was 10.8% (interquartile range: 8.8-14.5); 54 of 78 (69%) showed impaired anterior circulation vasoreactivity (breath-holding index <0.69) and 53 of 71 (75%) showed impaired posterior circulation vasoreactivity (visual evoked flow velocity response ≤14.0%). There was a significant negative correlation between the risk of OSA calculated by STOP-BANG and the breath-holding index (r_S=-0.284, P=0.012). The following variables were associated with low anterior circulation vasoreactivity: dyslipidemia (odds ratio: 4.7; 95% CI, 1.5-14.2) and STOP-BANG score (odds ratio: 1.7 per 1-point increase; 95% CI, 1.1-1.5). Conclusions A high risk of OSA and impaired vasoreactivity exists in the population that has had stroke. Dyslipidemia and STOP-BANG sleep apnea risk categories were independently associated with impaired anterior circulation vasoreactivity.

The effect of anti-dementia drugs on Alzheimer disease-induced cognitive impairment: A network meta-analysis

BACKGROUND

Cognitive impairment is a principal manifestation of Alzheimer disease (AD). To provide a clinical reference for the treatment of AD, a network meta-analysis (NMA) was performed to evaluate the effects of different anti-dementia drugs on the cognitive impairment exhibited by patients with AD.

METHODS

Relevant randomized controlled trials are found through the Pubmed database, Web of Science, Clinical Trials, Embase, Cohranne library, Chinese National Knowledge Infrastructure database, CBM databases, and Wanfang among others. A total of 33 articles were collected, with the earliest document collected having been published in February 2017. The included reports were screened for quality of papers by using strict inclusion and exclusion criteria. All analyses were based on previously published studies reporting de-identified data; thus, no ethical approval or patient consent were required. The Mini-Mental State Examination scores informed the classification of the 33 articles into a mild subgroup, which featured 11 articles, and 12 drugs (besides a placebo); a moderate subgroup, which featured 17 articles and 15 drugs (besides a placebo); and a severe subgroup, which featured 5 articles and 3 drugs (besides a placebo).

RESULTS

While donepezil, galanthamine, and huperzine demonstrated the highest efficacy in the mild cognitive dysfunction subgroup (mean difference = 5.2, 2.5, and 2.4, respectively). Donepezil, huperzine A, and rivastigmine achieved the most significant effects in the moderate cognitive dysfunction subgroup (MD = 3.8, 2.9, and 3.0 respectively). In the severe subgroup, donepezil was demonstrably superior to memantine. Donepezil was thus found to effectively address cognitive impairment in patients with AD regardless of the degrees of cognitive decline.

CONCLUSIONS

Evaluation of the clinically common anti-dementia drugs using NMA affirmed the utility of cholinesterase inhibitors, especially donepezil, in alleviating cognitive dysfunction of patients with AD. This study may therefore help to inform the clinical selection of pharmacotherapeutic interventions addressing cognitive dysfunction in patients with AD.

Minimization of Intraparenchymal Hemorrhagic Stroke Size by Optimization of Serum Lipids

Introduction

Intraparenchymal hemorrhages (IPHs) are the most common type of hemorrhagic stroke. One of the main associated risk factors is total cholesterol (TC) above 200. A severely decreased level of TC potentially interferes with the stabilization of the cell membrane and can potentially lead to a larger hemorrhage. Previous population-based studies have confirmed an association between low TCs and a high incidence of hemorrhagic stroke. It has been established that a TC below 200 decreases the potential for cardiovascular disease. This study suggests that the balance that needs to be achieved between these two extremes presents a unique possibility for an optimal therapeutic range of total cholesterol levels.

Materials & methods

Inclusion criteria included all adult patients with International Classification of Diseases (ICD)-9/10 code for hemorrhagic stroke, from June 2007 to June 2017. A total of 300 patients met the criteria (N=300). For each patient, the following data were collected: NIH Stroke Scale, TC level, triglyceride level, low-density lipoprotein (LDL) and high-density lipoprotein (HDL), cholesterol reducing medications, size of hemorrhage on computed tomography (CT) of the head, location of hemorrhage, and patient disposition. Statistical analysis was done using the Generalized Linear Modeling with Wald Chi-square as the statistical determinant.

Results

Intracerebral hemorrhage size is dependent on the intracranial location with brain lobes having larger bleeds. Minimum hemorrhage size was noted in TC 188-196 and this effect was statistically significant independent of location. HDL has a significant independent effect on hemorrhage size with overall minimum bleed occurring in the range of 43-51 mg/dL HDL (98-106 mg/dL for men and 43-51 mg/dL for women). This sex effect within HDL on hemorrhage size is statistically significant. There was a differential effect of HDL dependent on patient race. Asian and black patients had least IPH volume with HDL 70-79 mg/dL, while Hispanic patients had a minimum at 43-51 mg/dL. White patients required a higher HDL, 80-88 mg/dL to minimize the IPH size. The triglyceride level had a statistically significant independent effect on the bleed size with the minimum hemorrhage size occurring in the range of 205-224 mg/dL. This effect was nuanced by patient race with statistically significant minimum IPH size occurring at 144-164 mg/dL for white patients, 124-143 mg/dL for Hispanic and black patients, and 84-103 mg/dL for Asian patients. Post-hospital patient disposition was not significantly affected by any of the above predictor variables.

Conclusion

This study found TC, HDL and triglycerides in specific ranges are associated with significantly decreased hemorrhage size across all genders and hemorrhage locations. The ranges with the strongest hemorrhage-limiting effect are as follows: TC 188-196 mg/dL, HDL 43-51 mg/dL (98-106 mg/dL for men and 43-51 mg/dL for women), triglycerides 205-224 mg/dL. Lipids both below and above these ranges yield larger bleeds. It also found larger brain areas will have more extensive hemorrhage than smaller brain areas. Future work in this arena should include collaboration with cardiology to determine ideal ranges for both cardio- and neuroprotection as well as a prospective study to validate the applicability of these findings in patient care.

Cerebral and skin microcirculatory dysfunction in type 1 diabetes

Introduction

An increase in cerebral pulsatility index (PI), measured by transcranial Doppler, reflects the presence of cerebral microangiopathy. A decrease in distance between skin capillaries (DISTANCE) and an increase in the ratio between the area of capillaries and total area of examined skin (COVERAGE), revealed by capillaroscopy, reflects skin microangiopathy. However, little is known about the association between the cerebral and skin microvasculature function in patients at risk of microcirculatory dysfunction.

Aim

To assess PI of the middle cerebral artery by transcranial Doppler and the DISTANCE and COVERAGE of the nailfold capillaries by quantitative capillaroscopy in patients with type 1 diabetes and control subjects without diabetes, and to investigate relationships between these parameters.

Material and methods

The study group consisted of 51 patients with type 1 diabetes (median age: 37.5 years) and 23 volunteers free from chronic diseases (median age: 37.9 years).

Results

Median PI was higher in patients than in control subjects (0.82 vs. 0.75; p < 0.01). Median DISTANCE was lower in patients than in control subjects (220.9 µm vs. 239.7 µm; p = 0.03), while median COVERAGE was higher in patients than in control subjects (20.4% vs. 18.3%; p = 0.01). No correlations between PI and DISTANCE or COVERAGE were found, but PI was correlated with patients’ age and diabetes duration.

Conclusions

In spite of simultaneous presence of cerebral and skin microangiopathy, we found no association between cerebral and skin microvasculature dysfunction. This seems to indicate independent progression of microcirculatory injury in cerebral and peripheral vascular beds.

Relationship Between HIV Infection, Antiretroviral Therapy, Inflammatory Markers, and Cerebrovascular Endothelial Function Among Adults in Urban China

BACKGROUND

Cerebrovascular risk is increased in people living with HIV infection compared with age-matched uninfected individuals. Cerebrovascular endothelial dysfunction related to antiretroviral therapy (ART) and inflammation may contribute to higher stroke risk in HIV infection.

METHODS

We compared cerebral vasoreactivity-a measure of cerebrovascular endothelial function assessed by the breath-holding index (BHI) using transcranial Doppler ultrasound-between virologically suppressed Chinese HIV-infected individuals followed in an HIV clinic in Beijing, China, and uninfected controls. We constructed mixed-effects models to evaluate the association of HIV, ART, and inflammatory markers with cerebral vasoreactivity.

RESULTS

In an unadjusted model, HIV infection was associated with a trend toward lower cerebral vasoreactivity (BHI 1.08 versus 1.26, P = 0.079). In multivariable analyses, cholesterol modified the association between HIV infection and cerebral vasoreactivity (P = 0.015 for interaction). At a lower total cholesterol of 4.15 mmol/L, HIV was associated with lower cerebral vasoreactivity (BHI -0.28, P = 0.019), whereas at a cholesterol of 5.15 mmol/L, the reduction in cerebral vasoreactivity associated with HIV was no longer statistically significant (BHI -0.05, P = 0.64). Among HIV-infected individuals, use of lopinavir/ritonavir compared with efavirenz was associated with lower cerebral vasoreactivity (BHI -0.24, P = 0.040). We did not find a significant association between inflammatory markers and cerebral vasoreactivity.

CONCLUSIONS

Cerebrovascular endothelial dysfunction associated with HIV infection may be most relevant for individuals with less traditional vascular risk, such as those with lower cholesterol. Further study of the impact of ART on cerebrovascular endothelial function is warranted to aid with ART selection in individuals at high cerebrovascular risk.

Statin Use and Cognitive Impairment in Patients With Type 1 Diabetes: An Observational Study

OBJECTIVE

We aimed to assess a wide range of cognitive functions in patients with type 1 diabetes (DM1) compared with healthy control subjects and to evaluate the effects of statins on cognitive functions in DM1 patients.

MATERIALS AND METHODS

The sample studied consisted of 55 DM1 patients (80.0% with hyperlipidemia, 20% with statin treatment) and 36 age-matched control subjects (77.8% with hyperlipidemia) without diabetes or statin use. Their cognitive functions (attention, memory, and executive functions) were evaluated with the trail making test, controlled oral word association test (COWAT), Rey-Osterrieth complex figure test, brain damage test (diagnosticum für cerebralschädigung, DCS), Wisconsin card sorting test (WCST), and digit span and block design tests from the revised Wechsler adult intelligence scale.

RESULTS

Cognitive performance was impaired in DM1 patients when compared with the control group with regard to semantic verbal fluency (COWAT_animals), visual learning (DCS), conceptual-level responses, executive functions (WCST random errors), and WCST trials to complete the first category. Subgroups of DM1 patients distinguished on the basis of statin therapy did not differ with regard to verbal fluency (COWAT_animals), visual learning (DCS), conceptual-level responses, executive functions (WCST random errors), and WCST trials to complete the first category. Multivariate analysis also does not show the impact of statin therapy on cognitive functioning regardless of the duration of education, microangiopathic evidence, the presence of hyperlipidemia, or antihypertensive therapy.

CONCLUSIONS

We find impairment of cognitive functions in DM1 patients when compared with control subjects without diabetes. However, we show neither the effect of statins nor the significant influence of metabolic control, microangiopathic complications, or the presence of hyperlipidemia on cognitive functions in DM1 patients.

The Effect of Chunghyul-Dan on Hyperventilation-Induced Carbon Dioxide Reactivity of the Middle Cerebral Artery in Normal Subjects: A Dose-Dependent Study

Background. This study was conducted to show the prompt effect of chunghyul-dan (CHD) on cerebral hemodynamics in order to provide evidence for its use in stroke prevention. Methods. Hyperventilation-induced CO₂ reactivity of the middle cerebral artery was measured in 12 healthy male volunteers (mean age: 26.3 ± 1.1 years) using transcranial Doppler sonography. All subjects were examined before and for 3 hours after administration, with an interval of 1 week between measurements. Results. Compared to baseline, the CO₂ reactivity of the middle cerebral artery increased significantly at 2 and 3 hours after the administration of CHD (600 mg and 1200 mg). The mean blood pressure and heart rate did not vary from the baseline values in all groups. Conclusion. These data suggest that CHD administration (especially 600 mg) immediately improves cerebral blood flow.

Cerebral vasoreactivity is impaired in treated, virally suppressed HIV-infected individuals

OBJECTIVE

To compare cerebral vasoreactivity, a measure of cerebrovascular endothelial function, between treated, virally suppressed HIV-infected individuals and HIV-uninfected controls and to evaluate the effect of HIV-specific factors on cerebral vasoreactivity.

METHODS

Cross-sectional study of 65 antiretroviral therapy-treated, virally suppressed HIV-infected individuals and 28 HIV-uninfected controls. Participants underwent noninvasive assessment of cerebral vasoreactivity using transcranial Doppler ultrasound and inhaled carbon dioxide (CO2). We used mixed effects multivariable linear regression to determine the association of HIV infection and HIV-specific factors with cerebral vasoreactivity.

RESULTS

Mean age was 57.2 years for HIV-infected participants and 53.5 years for HIV-uninfected controls. Most participants (95%) were men. Twenty-six per cent of HIV-infected participants were nonwhite compared to 32% of controls. Among HIV-infected participants, mean CD4 cell count was 596 cells/μl, and mean duration of viral suppression was 7.8 years. Cerebral vasoreactivity in response to hypercapnia (cerebral VRhyper) was lower in HIV-infected individuals compared to uninfected controls (3.23 versus 3.81%, P = 0.010). After adjusting for demographic and vascular risk factors, HIV infection was independently associated with lower cerebral vasoreactivity (-0.86%, 95% CI -1.30 to -0.42%, P < 0.001). We did not find a statistically significant effect of recent or nadir CD4 cell count on cerebral vasoreactivity. There was a trend toward higher cerebral vasoreactivity for each additional year of viral suppression.

CONCLUSION

Treated, virally suppressed HIV infection negatively impacted cerebral vasoreactivity even after adjustment for traditional vascular risk factors. These data highlight the potential contribution of cerebrovascular endothelial dysfunction to the elevated risk of stroke observed in HIV-infected individuals.

Pharmacological modulation of dietary lipid-induced cerebral capillary dysfunction: Considerations for reducing risk for Alzheimer's disease

An increasing body of evidence suggests that cerebrovascular dysfunction and microvessel disease precede the evolution of hallmark pathological features that characterise Alzheimer's disease (AD), consistent with a causal association for onset or progression. Recent studies, principally in genetically unmanipulated animal models, suggest that chronic ingestion of diets enriched in saturated fats and cholesterol may compromise blood-brain barrier (BBB) integrity resulting in inappropriate blood-to-brain extravasation of plasma proteins, including lipid macromolecules that may be enriched in amyloid-β (Aβ). Brain parenchymal retention of blood proteins and lipoprotein bound Aβ is associated with heightened neurovascular inflammation, altered redox homeostasis and nitric oxide (NO) metabolism. Therefore, it is a reasonable proposition that lipid-lowering agents may positively modulate BBB integrity and by extension attenuate risk or progression of AD. In addition to their robust lipid lowering properties, reported beneficial effects of lipid-lowering agents were attributed to their pleiotropic properties via modulation of inflammation, oxidative stress, NO and Aβ metabolism. The review is a contemporary consideration of a complex body of literature intended to synthesise focussed consideration of mechanisms central to regulation of BBB function and integrity. Emphasis is given to dietary fat driven significant epidemiological evidence consistent with heightened risk amongst populations consuming greater amounts of saturated fats and cholesterol. In addition, potential neurovascular benefits associated with the use of hypolipidemic statins, probucol and fenofibrate are also presented in the context of lipid-lowering and pleiotropic properties.

Statins and brain integrity in older adults: secondary analysis of the Health ABC study

INTRODUCTION

We examined whether statins are associated with better cerebral white (WM) and gray matter (GM) indices in community-dwelling elders.

METHODS

In 295 older adults, we compared white matter hyperintensities (WMH) on brain magnetic resonance imaging and, total WM fractional anisotropy (FA) and GM mean diffusivity (MD) on diffusion tensor imaging, of Alzheimer's disease (AD) relevant regions in statin-exposed and statin-unexposed participants stratified by Modified Mini-Mental Status Examination (3MS) score.

RESULTS

There was no overall effect of statin exposure on cerebral structural indices. The interaction between statin exposure and 3MS was significant for total-WMH and WM FA (both P < .05) but not GM MD. In the lowest 3MS tertile (mean: 86), statin-exposed individuals had lower total-WMH and higher WM FA (P = .005 and P = .044) and FA of tracts linked to clinical AD (P-value range= .005-.04) despite statistical adjustments. These differences were not significant in the two higher 3MS tertiles.

DISCUSSION

Statins may benefit WM in older adults vulnerable to dementia.

A novel trigger for cholesterol-dependent smooth muscle contraction mediated by the sphingosylphosphorylcholine-Rho-kinase pathway in the rat basilar artery: a mechanistic role for lipid rafts

Hyperlipidemia is a risk factor for abnormal cerebrovascular events. Rafts are cholesterol-enriched membrane microdomains that influence signal transduction. We previously showed that Rho-kinase-mediated Ca(2+) sensitization of vascular smooth muscle (VSM) induced by sphingosylphosphorylcholine (SPC) has a pivotal role in cerebral vasospasm. The goals of the study were to show SPC-Rho-kinase-mediated VSM contraction in vivo and to link this effect to cholesterol and rafts. The SPC-induced VSM contraction measured using a cranial window model was reversed by Y-27632, a Rho-kinase inhibitor, in rats fed a control diet. The extent of SPC-induced contraction correlated with serum total cholesterol. Total cholesterol levels in the internal carotid artery (ICA) were significantly higher in rats fed a cholesterol diet compared with a control diet or a β-cyclodextrin diet, which depletes VSM cholesterol. Western blotting and real-time PCR revealed increases in flotillin-1, a raft marker, and flotillin-1 mRNA in the ICA in rats fed a cholesterol diet, but not in rats fed the β-cyclodextrin diet. Depletion of cholesterol decreased rafts in VSM cells, and prevention of an increase in cholesterol by β-cyclodextrin inhibited SPC-induced contraction in a cranial window model. These results indicate that cholesterol potentiates SPC-Rho-kinase-mediated contractions of importance in cerebral vasospasm and are compatible with a role for rafts in this process.

Cerebral blood flow velocity and vasomotor reactivity during autonomic challenges in heart failure

BACKGROUND

Significant alterations in autonomic nervous system (ANS) function, vasomotor reactivity, and cerebral blood flow may develop from damage to brain ANS regulatory areas in heart failure (HF). This preferentially right-sided injury occurs largely in autonomic structures perfused by the middle cerebral artery. Indications of altered, asymmetrical perfusion raise the potential for further neural damage.

OBJECTIVE

To determine whether the extent of middle cerebral artery blood flow velocity and vasomotor reactivity is altered on one side of the brain over the other in HF versus control subjects, three ANS challenges were administered-each challenge recruited ANS regulatory areas potentially injured in HF.

METHODS

Transcranial Doppler ultrasonography was used to measure cerebral blood flow velocity and vasomotor reactivity in 40 HF (mean age = 52.7 years, SD = 7.5; 27 men; left ventricular ejection fraction = 26.8, SD = 8.3) and 42 control subjects (mean age = 48.3 years, SD = 6.0; 22 men) during 5% CO2 and hyperventilation, Valsalva, and orthostatic (upper body tilt) challenges.

RESULTS

Lower cerebral blood flow velocity and abnormal vasomotor reactivity (p < .01) were noted in HF middle cerebral arteries during all challenges. More right-sided flow velocity reductions appeared in HF, with laterality differences noted during CO2 and orthostatic (p < .05), but not Valsalva challenges.

DISCUSSION

Diminished cerebral blood flow velocity and altered vasomotor reactivity were associated with HF, changes being preferentially on the right side; the asymmetry was more pronounced during CO2 and orthostatic challenges. The impaired blood flow regulation may contribute to the lateralized brain pathology in ANS areas, undermining autonomic control in HF.

Cardiovascular effects of statins, beyond lipid-lowering properties

The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, better known as 'statins', are amongst the most widely used medications in the world. They have become a pivotal component in the primary and secondary prevention of coronary artery and vascular disease. However, a growing amount of evidence has suggested that statins also possess strong pleiotropic effects irrespective of their lipid-lowering properties, which include enhancement of endothelial function, anti-inflammatory and anti-atherothrombotic properties, and immunomodulation. The following provides a comprehensive and updated review of the clinical evidence regarding the pleiotropic effects of statins in cardiovascular disorders and their potential therapeutic benefits.

Statins and cerebral hemodynamics

HMG-CoA reductase inhibitors (statins) are associated with improved stroke outcome. This observation has been attributed in part to the palliative effect of statins on cerebral hemodynamics and cerebral autoregulation (CA), which are mediated mainly through the upregulation of endothelium nitric oxide synthase (eNOS). Several animal studies indicate that statin pretreatment enhances cerebral blood flow after ischemic stroke, although this finding is not further supported in clinical settings. Cerebral vasomotor reactivity, however, is significantly improved after long-term statin administration in most patients with severe small vessel disease, aneurysmal subarachnoid hemorrhage, or impaired baseline CA.

Dynamic cerebral autoregulation assessed by respiratory manoeuvres in non-insulin-treated Type 2 diabetes mellitus

AIMS

This study investigated dynamic cerebral autoregulation in Type 2 diabetes, where dynamic cerebral autoregulation may be impaired as a consequence of microvascular changes and/or autonomic neuropathy.

METHODS

Eleven healthy control subjects and 11 age- and sex-matched patients with Type 2 diabetes controlled with lifestyle modifications or oral anti-diabetes treatment were recruited. Dynamic cerebral autoregulation was calculated by the autoregressive moving average autoregulatory index from a continuous blood pressure and R-R interval (time between each ventricular systole) recording. End-tidal carbon dioxide was also monitored and changes in response to breath holding and hyperventilation as a metabolic stimulus were measured.

RESULTS

No significant differences were seen in cerebral blood flow velocity at baseline, or in response to breath holding between people with diabetes and control subjects, although the cerebral blood flow velocity response associated with hyperventilation was significantly reduced in the diabetes group. No significant differences in dynamic cerebral autoregulation were seen at baseline or in response to respiratory manoeuvres between the groups.

CONCLUSIONS

Dynamic cerebral autoregulation is not impaired in patients with Type 2 diabetes, although a small difference could not be excluded as the study was only powered to detect an autoregulatory index difference > 2 units. Further study in a larger population with a spectrum of disease severity may reveal clinically important differences.

Memory loss, behavioral changes, and slurred speech in a 49-year-old man

A 49-year-old man presented with slurred speech, memory loss, and behavioral changes. His clinical course was marked by decline in functional status and cognition. He had poorly controlled hypertension and hyperlipidemia. Neuroimaging was remarkable for multiple subcortical white matter lesions. We discuss the diagnostic and therapeutic approach of rapidly progressing cognitive decline in the given clinical setting.

Pleiotropic effects of the HMG-CoA reductase inhibitors

The HMG-CoA reductase inhibitors (statins) are used extensively in the treatment of hyperlipidemia. They have also demonstrated a benefit in a variety of other disease processes. These secondary actions are known as pleiotropic effects. Our paper serves as a focused and updated discussion on the pleiotropy of statins and emphasizes the importance of randomized placebo-controlled trials to further elucidate this interesting phenomenon.

Doppler study of cerebral arteries in hypercholesterolemia

Background:

Hypercholesterolemia is one of the major modifiable risk factors for atherosclerosis of the coronary and carotid arteries. Although transcranial Doppler (TCD) studies of the cerebral arteries are indicative of decreased cerebral blood flow velocities in patients with hypercholesterolemia, the number of these studies has been limited. The aim of this study was to assess the hemodynamic status of the cerebral arteries in patients with hypercholesterolemia using TCD.

Methods:

In a case-control study, 60 individuals, including 30 hypercholesterolemic cases (low-density lipoprotein [LDL] > 160 mg/dL) and 30 healthy controls were enrolled. Other arterial risk factors, including diabetes mellitus, hypertension, smoking, and obesity (body mass index > 30), were evaluated and matched as well. TCD was used to assess the hemodynamics of the intracranial arteries as well as the internal carotid arteries. The mean blood flow velocity, pulsatility index, and resistance index were recorded in all the arteries.

Results:

The mean blood flow velocity, pulsatility index, and resistance index of the intracranial arteries and internal carotid arteries were not significantly different between the two groups (P > 0.05). However, those with higher levels of LDL (>180 mg/dL) showed significantly lower mean blood flow velocity and resistance index of the internal carotid arteries than the healthy controls. In addition, individuals with high-density lipoprotein (HDL) <35 mg/dL had significantly lower mean blood flow velocity in the internal carotid arteries.

Conclusion:

Hypercholesterolemia (LDL >160 mg/dL) does not seem to have a detrimental effect on the hemodynamic status of the intracranial arteries and internal carotid arteries. However, in cases of higher LDL (>180 mg/dL) and lower HDL, decreased TCD parameters in the internal carotid arteries, as a surrogate of the peripheral arteries, are prominent.

High-dose atorvastatin enhances impaired cerebral vasomotor reactivity

The influence of statin therapy on cerebral vasomotor function has not been fully characterized. We report the effects of high-dose atorvastatin therapy on cerebral vasomotor reactivity (VMR) in patients with controlled hypertension and dyslipidemia. We prospectively enrolled 36 patients with controlled hypertension and a low-density lipoprotein (LDL) cholesterol concentration >100 mg/dL. Atorvastatin 80 mg was given daily for 6 months and then discontinued. VMR was assessed by hypercapnic and hypocapnic transcranial Doppler challenge in both the right and left middle cerebral artery (MCA) at baseline, and after 3 and 6 months of therapy. Forty-five days after statin cessation, a repeat VMR was performed. VMR impairment was defined as ≤70%. Blood pressure, lipid levels, liver function, and creatine kinase level were monitored. Mean patient age was 60 years, 16 were men, and 13 had a previous history of subcortical infarction. Mean LDL cholesterol level before treatment was 154 ± 30 mg/dL. Atorvastatin lowered LDL by 53% at 3 months and by 46% at 6 months. Baseline VMR was 71% ± 21% in the right MCA and 70% ± 19% in the left MCA. No significant effect of atorvastatin on VMR was seen at 3 months and 6 months in the study population as a whole. In the subgroup of patients with baseline VMR impairment, atorvastatin therapy was associated with significantly improved VMR at both 3 and 6 months. This effect persisted for at least 45 days after discontinuation of therapy. Our findings indicate that high-dose atorvastatin therapy can significantly improve impaired cerebral VMR, and that the effects of atorvastatin on VMR persist for 1.5 months after discontinuation of therapy. We found no benefit of atorvastatin therapy in patients with preserved baseline vasoreactivity.

Improvement of exhausted cerebral vasoreactivity in carotid occlusion: benefit of statins?

In internal carotid artery occlusion (ICAO), a spontaneous increase of cerebral vasoreactivity (CVR) may occur over time. Statins are known to increase CVR. We analyzed the influence of statin treatment and other cofactors on CVR improvement in patients with ICAO. Sixty-six patients with ICAO were reexamined after 15 ± 6 months. CVR in both middle cerebral arteries was assessed by transcranial Doppler and inhalation of 7% CO(2). Pre-defined cut-off values were used to define exhausted CVR. Cofactors analyzed were: age, sex, hypertension, diabetes, statin treatment, degree of contralateral stenosis, quality of intracranial collateral flow, duration of ICAO. Mean CVR did not differ between the two studies. Twenty patients had exhausted CVR at baseline, 11 of them improved above the cut-off at follow-up (55%). Factors significantly associated with this improvement were good collateral pattern at baseline (p = 0.0065) and statin treatment (p = 0.0179). Odds ratios for improving CVR were 36.0 [95% CI 2.7-476.3] for good collateral flow and 20.0 [95% CI 1.7-238.6] for statin treatment. In conclusion, exhausted CVR frequently improves during the course of ICAO. Good collateral function and statin treatment are significantly associated with improving CVR.

Cerebral vasomotor reactivity and extent of white matter lesions in middle-aged men with arterial hypertension: a pilot study

BACKGROUND

Cerebrovascular reactivity (CVR) impairment and cerebral white matter lesions (WMLs) are associated in elderly or patients with overt cerebral ischemia. Such association has not been confirmed for asymptomatic middle-aged individuals with risk factors for stroke. We assessed the relationship between the CVR and the presence of WMLs in a middle-aged population-based cohort of hypertensive men.

METHODS

Magnetic resonance imaging (MRI) and transcranial Doppler (TCD) examination were performed in 54 hypertensive men, all at 60 years of age, without a history of stroke, neurologic deficits, or carotid stenosis. The CVR of the middle cerebral artery (MCA) was expressed as the vasomotor reactivity reserve (VMRr).

RESULTS

WMLs were detected in 22 men (40.7%); all WMLs were classified as mild (first grade of the Fazekas modified scale). The VMRr was lower in patients with WMLs (mean 55%; s.e. 3%) compared to those without WMLs (mean 65%; s.e. 3%; P = 0.03). The lower VMRr in patients with WMLs was consistent after controlling for confounders. A higher pulsatility index (PI) in subjects with WMLs (mean 1.08; s.e. 0.05) compared to those without WMLs (mean 0.90; s.e. 0.05; P = 0.01) was not consistent after controlling for confounders.

CONCLUSIONS

The CVR was lower in middle-aged hypertensive men with WMLs compared to those without WMLs indicating that even a low load of WMLs may reflect some functional impairment of the cerebral microvasculature.

3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors in the treatment of central nervous system diseases

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) are among the most prescribed medications in the United States. Statins act on the rate-limiting step in cholesterol biosynthesis (the conversion of HMG-CoA to mevalonate) and are effective in treating dyslipidemia. However, statins decrease other downstream products of the mevalonate pathway, and it is via these pathways that statins may affect inflammation, nitric oxide synthesis, the coagulation cascade, and other processes. Through these pleiotropic effects, statins may have an effect on neurologic diseases, including ischemic and hemorrhagic stroke, Alzheimer disease, Parkinson disease, and multiple sclerosis. This article reviews the basic biochemistry of statins as it relates to these pleiotropic effects, the potential role of statins in several neurologic disorders, and the results of clinical trials performed for several of these conditions.

Alterations in nitric oxide and endothelin-1 bioactivity underlie cerebrovascular dysfunction in ApoE-deficient mice

Hypercholesterolemia is associated with decreased nitric oxide (NO) bioavailability and endothelial dysfunction, a phenomenon thought to have a major role in the altered cerebral blood flow evident in stroke. Therefore, strategies that increase endothelial NO production have potential utility. Vascular reactivity of the middle cerebral artery (MCA) from C57BL/6J wild-type (WT) mice, apolipoprotein-E knockout (ApoE(-/-)) mice, and mice treated with the phosphodiesterase inhibitor cilostazol (100 mg/kg) was analyzed using the tension myograph. Contractile responses to endothelin-1 were significantly enhanced in MCA from ApoE(-/-) mice compared with WT mice (P<0.01), an effect absent in cilostazol-treated ApoE(-/-) mice. Acetylcholine-induced relaxation (which is entirely NO-dependent) was significantly impaired in MCA of ApoE(-/-) mice compared with WT mice (P<0.05), again an effect prevented by cilostazol treatment. Endothelial NOS phosphorylation at Ser(1179) was decreased in the aorta of ApoE(-/-) mice compared with WT mice (P<0.05), an effect normalized by cilostazol. Taken together, our data suggest that the endothelial dysfunction observed in MCA associated with hypercholesterolemia is prevented by cilostazol, an effect likely due to the increase in eNOS phosphorylation and, therefore, activity.

Statins: multiple neuroprotective mechanisms in neurodegenerative diseases

Statins have been widely used for the treatment of a variety of conditions beyond their original role in lowering cholesterol. Since statins have relatively few side effects, they have been recognized as useful medicine to ameliorate neurodegenerative disorders. Current studies on the applications of statins have demonstrated their neuroprotective and clinical significance among neurodegenerative diseases like cerebral ischemic stroke, vascular dementia, Alzheimer's disease, and Parkinson's disease, though the neuroprotective mechanisms are not completely understood. This review will discuss recent development in the use of statins in slowing down the progression of these neurodegenerative diseases. It will summarize the potential mechanisms for statin-mediated neuroprotective effects in neurodegenerative diseases. In detail, this review discuss the roles of statins in lowering cholesterol, reducing reactive oxygen species, impairing β-amyloid production and serum apolipoprotein E levels, enhancing the levels of endothelial nitric oxide synthase and cerebral blood flow, and modulating cognitive related receptors and matrix metalloproteases. Finally, different alterations of various receptors in brain regions following statin treatment and their correlations with cognitive dysfunction in Parkinson's disease will also be reviewed, as well as the potential for therapy in ameliorating the progression of Parkinson's disease. This article is part of a Special Issue entitled "Interaction between repair, disease, & inflammation."

The effect of allopurinol on the cerebral vasculature of patients with subcortical stroke; a randomized trial

AIMS

New preventative strategies for stroke are required. One promising strategy is uric acid reduction and xanthine oxidase inhibition with allopurinol. We sought to investigate whether allopurinol improves cerebrovascular reactivity (CVR) following subcortical stroke.

METHODS

We performed a randomized, double-blind, controlled study to investigate the effect of a 3-month course of 300 mg allopurinol once daily vs. placebo on CVR in individuals with recent (within 6 months) subcortical stroke. Participants were randomized on a 1:1 basis. CVR was defined as the percentage change in middle cerebral artery flow velocity following an intravenous injection of 15 mg kg(-1) of acetazolamide. Our primary end-point was the CVR difference between baseline and 3 months. Secondary end-points included measures of peripheral vascular reactivity and blood markers of inflammation and endothelial activation.

RESULTS

We enrolled 50 participants; 45 completed the protocol. Baseline serum urate was 0.35 mmol l(-1) (SD 0.1) and 0.34 mmol l(-1) (SD 0.1) in the allopurinol and placebo groups, respectively. There were no serious adverse events related to treatment. CVR did not change following treatment with allopurinol [median CVR change 0.89% after allopurinol (n = 20) and -0.68% after placebo (n = 25); 95% confidence interval for estimated difference in medians -13.4, 25.5, P = 0.64]. Urate was significantly lowered by allopurinol but no change in other secondary end-points was seen.

CONCLUSION

Xanthine oxidase inhibition with allopurinol has previously been shown to improve cerebrovascular function, but no benefit was seen in this study. It may therefore be that previous encouraging findings will not translate into important clinical benefits.

Cerebrovascular reactivity over time-course - from major depressive episode to remission

INTRODUCTION

Depression is a prospective risk factor for stroke. Little is known, however, about the pathophysiologic links leading to this association. Cerebrovascular reactivity (CVR) reflects the compensatory dilatory capacity of cerebral arterioles to a dilatory stimulus and is an important mechanism to provide constant cerebral blood flow. In the absence of major arterial stenosis, an impaired CVR has been associated with a higher risk of stroke. We hypothesized that CVR might be continuously reduced in patients with major depression even after successful remission thus contributing to the association between depression and stroke.

MATERIALS AND METHODS

We investigated CVR in a group of patients (N=29) in the acute episode of depressive illness and after 21months under euthymic condition. A healthy control group (N=33) was investigated at comparable time intervals. All patients and controls were otherwise healthy. CVR was investigated by calculating the increase in cerebral blood flow velocity after stimulation with acetazolamide. Blood flow velocities were measured by transcranial doppler ultrasound.

RESULTS

A group of acutely depressed patients presented a significantly reduced CVR compared to controls. On follow-up 21months later after treatment and remission, CVR in the patient group had significantly improved, whereas CVR in the control group remained unchanged. Confounding factors had no significant influence.

DISCUSSION

CVR is impaired during major depression. Since CVR seems to improve after treatment of depression, the contribution to an increased stroke risk among depressive patients may be true for a subgroup only and needs to be further investigated.

Statin use before and after acute ischemic stroke onset improves neurological outcome

The devastating consequences of stroke, both in terms of morbidity and mortality, and the economic implications it has worldwide, coupled with a growing knowledge regarding its pathophysiology, has led to the development of novel therapeutic strategies in recent years that have had an enormous impact on clinical practice and the outcome of stroke patients. While thrombolysis is regarded as the most important of these developments, its relatively narrow therapeutic window and complexity of administration imply that only a minority of stroke patients can benefit from it. Among other strategies, in an attempt to overcome this limitation, research has focused on the development of neuroprotection aimed to salvage ischemic brain tissue by means complementary to reperfusion. Among these approaches, the use of statins stands out, which, by inhibiting the HMG CoA reductase, interfere with the formation of isoprenoid intermediates in the biosynthesis of cholesterol, and have been shown to have a positive impact in both the incidence and outcome of acute stroke. The main results of animal models, observational studies, clinical trials and opinion articles available in the medical literature covering the effect of statins on acute brain ischemia will be reviewed in order to provide in-depth information regarding their mode of action and current evidence regarding their potential benefits for ischemic stroke patients.

Carotid endarterectomy improves cerebrovascular reserve capacity preferentially in patients with preoperative impairment as indicated by asymmetric BOLD response to hypercapnia

PURPOSE

In patients with symptomatic carotid artery disease the predominant mechanism causing ischaemic injury is considered to be thromboembolic, however compromise of cerebral haemodynamics is considered to be a significant factor. Removal of the embolic source is accepted as the major benefit from carotid endarterectomy (CEA), however improvement in cerebral haemodynamics may be another beneficial outcome as suggested by transcranial doppler (TCD). Blood oxygen level-dependent (BOLD) hypercapnia functional magnetic resonance imaging (fMRI) can be used to map the cerebrovascular reserve (CVR). The aim of this study was to assess the effects of carotid surgery on cerebral haemodynamics in patients with carotid artery disease using a hypercapnia BOLD fMRI and assessment of hemispheric asymmetry.

MATERIALS AND METHODS

Seventeen patients with symptomatic internal carotid artery stenosis were scanned using a clinical 1.5T MR scanner. Scanning was done immediately prior to and between 4 and 8 weeks after CEA. 10% carbon dioxide was administered to achieve transient episodes of hypercapnia. The data was analyzed using FMRIB Software Library (FSL) software to derive percentage signal change (PSC) for the grey matter of the middle cerebral artery (MCA-GM) territory for both hemispheres. MCA-GM PSC was furthermore normalized to the contralateral hemisphere to derive an Hemispheric Asymmetry Index (hAI) for all patients pre- and postoperatively.

RESULTS

Ipsilateral GM CVR improved significantly following CEA (2.47% preoperatively vs. 2.73% postoperatively, p=0.038). There was no change in CVR in the contralateral grey and white matter MCA territories (p=0.27, p=0.1). Also, the hAI was significantly more shifted to the ipsilateral hemisphere after CEA (preoperative hAI -0.56, vs. -3.90 postoperatively, p=0.02). Patients with an impaired hAI preoperatively were found to show the greatest improvement in PSC and hAI following CEA (p=0.007).

CONCLUSIONS

CEA resulted in improved CVR in patients with carotid artery disease as shown by the absolute and hemispheric asymmetry of BOLD response to hypercapnia.. These findings show that benefits from recanalisation may go beyond removal of the embolic source, by improving the cerebrovascular reserve. Moreover, hypercapnia BOLD fMRI may be a useful clinical tool in predicting this therapeutic potential in patients with severe carotid artery disease.

Psychoneuroimmunology of stroke

Stroke is the major cause of disability in the Western world and is the third greatest cause of death, but there are no widely effective treatments to prevent the devastating effects of stroke. Extensive and growing evidence implicates inflammatory and immune processes in the occurrence of stroke and particularly in the subsequent injury. Several inflammatory mediators have been identified in the pathogenesis of stroke including specific cytokines, adhesion molecules, matrix metalloproteinases, and eicosanoids. An early clinical trial suggests that inhibiting interleukin-1 may be of benefit in the treatment of acute stroke.

Cerebrovascular reactivity, intima-media thickness, and nephropathy presence in patients with type 1 diabetes

OBJECTIVE

Cerebrovascular reactivity impairment was reported as a marker of cerebral microangiopathy in long-term type 1 diabetes. Intima-media complex thickening reflects early stages of macroangiopathy in type 1 diabetes. The analysis of the relationship between these variables and other microangiopathic complications might serve as a beneficial indicator for early prophylaxis in these patients.

RESEARCH DESIGN AND METHODS

Vasomotor reactivity reserve (VMRr) and breath-holding index (BHI) of the middle cerebral artery were measured with transcranial Doppler in 59 patients (median age 32.0 years, range 20-51, 36 females) with type 1 diabetes, without history of cerebrovascular events, and 30 healthy control subjects (median age 31.5 years, range 25-39, 15 females). The relationships between the presence of selected vascular complications of type 1 diabetes and biochemical parameters, intima-media thickness (IMT), and VMRr and BHI in patients were analyzed.

RESULTS

VMRr and BHI were lower in patients with type 1 diabetes when compared with healthy subjects (81.5 vs. 100%, P < 0.01, and 1.6 vs. 2.2, P = 0.04, respectively), whereas IMT was significantly higher in patients then in healthy control subjects (0.36 vs. 0.30 mm, P = 0.001). However, no association of IMT with VMRr was found. We found a significant reduction of VMRr and BHI in patients with diabetic nephropathy.

CONCLUSIONS

The presence of diabetic nephropathy, but not IMT, can be regarded as an indicator of cerebral microangiopathy severity in patients with type 1 diabetes.

Effects of poor bone window on the assessment of cerebral autoregulation with transcranial Doppler sonography - a source of systematic bias and strategies to avoid it

BACKGROUND

The consequences of poor insonation conditions on autoregulation parameters assessed with transcranial Doppler (TCD) are unclear.

METHODS

We present two new complementary methods to assess the quality of a TCD signal. Inserting a thin aluminium foil between TCD probe and skin makes a simple model to artificially worsen a good insonation window. Validation studies are presented. We assessed insonation quality and cerebral autoregulation parameters with transfer function analysis and cross correlation in 46 healthy volunteers with and without the aluminium foil model. The same studies were operated on 45 patients with good insonation windows, naïve, after worsening the bone window and during constant infusion of an ultrasound contrast agent. For studying reproducibility, we assessed autoregulation twice in 30 patients with poor bone windows, with and without constant contrast infusion.

RESULTS

Both methods to measure insonation quality are valid and reproducible. The aluminium foil model realistically simulates a natural poor bone window, reducing the signal quality (e.g. energy of the signal spectrum from 33.4+/-3.5 to 26.2+/-2.5 dB, p<0.001). Thereby, the autoregulation parameters are systematically biased (e.g. phase difference from 37.3+/-10.1 degrees to 25.9+/-15.1 degrees , p<0.001); while with the use of an ultrasound contrast agent this can be largely compensated (phase difference 35.7+/-10.7 degrees , p<0.001). The reproducibility is significantly improved (ICC from 0.76 to 0.90, p<0.05).

CONCLUSIONS

Poor bone windows can cause considerable bias in TCD autoregulation parameters. This bias might be avoided by the use of ultrasound contrast agents, which may greatly improve the credibility of TCD autoregulation assessment in elderly patients.