Relationship of deep white matter hyperintensities and cerebral blood flow in severe carotid artery stenosis

Association between intracranial and extracranial atherosclerosis and white matter hyperintensities: a systematic review and meta-analysis

Background

White matter hyperintensities (WMHs) are key neuroimaging markers of cerebral small vessel diseases. This study aimed to investigate whether intracranial and extracranial atherosclerotic stenosis is associated with WMHs.

Methods

Following a previously registered protocol (PROSPERO protocol: CRD42023407465), PubMed, Web of Science, and Embase were systematically searched for relevant literature published until March 2023. Cross-sectional studies examining the association between intracranial and extracranial atherosclerotic stenosis and WMHs were included. Random effects models were used to calculate the pooled estimates.

Results

Twenty-one eligible studies, including 10,841 participants, were identified. Intracranial and extracranial atherosclerotic stenosis was associated with an increased risk of WMHs (OR 1.80, 95% CI 1.25-2.57, I2 = 75%) and increased WMH volumes (SMD 0.40, 95% CI 0.18-0.63, I2 = 63%). Heterogeneity resulted from the WMHs rating method and the location. Extracranial atherosclerotic stenosis (ECAS) was significantly associated with WMHs (OR 2.10, 95% CI 1.22-3.62, I2 = 71%), but intracranial atherosclerotic stenosis (ICAS) was insignificantly associated with WMHs (OR 1.75, 95% CI 0.97-3.15, I2 = 84%). The association was stable in the subgroup analysis based on WMHs location, which included deep WMHs and periventricular WMHs.

Conclusion

Intracranial and extracranial atherosclerotic stenosis is associated with WMHs. This association is significant in ECAS, but attenuated in ICAS.

Pre-operative Cerebral Small Vessel Disease on MR Imaging Is Associated With Cerebral Hyperperfusion After Carotid Endarterectomy

Objectives: To determine whether pre-operative cerebral small vessel disease is associated with cerebral hyperperfusion (CH) after carotid endarterectomy (CEA). Methods: Seventy-seven patients (mean age of 66 years and 58% male) undergoing CEA for carotid stenosis were investigated using brain MRI before and after surgery. CH was defined as an increase in cerebral blood flow > 100% compared with pre-operative values on arterial spin labeling MR images. The grade or the number of four cerebral small vessel disease markers (white matter hyperintensities, lacunes, perivascular spaces, and cerebral microbleeds) were evaluated based on pre-operative MRI. Cerebral small vessel disease markers were correlated with CH by using multivariate logistic regression analysis. The cutoff values of cerebral small vessel disease markers for predicting CH were assessed by receiver-operating characteristic curve analysis. Results: CH after CEA was observed in 16 patients (20.78%). Logistic regression analysis revealed that white matter hyperintensities (OR 3.09, 95% CI 1.72-5.54; p < 0.001) and lacunes (OR 1.37, 95% CI 1.06-1.76; p = 0.014) were independently associated with post-operative CH. Receiver-operating characteristic curve analysis showed that Fazekas score of white matter hyperintensities ≥3 points [area under the curve (AUC) = 0.84, sensitivity = 81.3%, specificity = 73.8%, positive predictive value (PPV) = 44.8% and negative predictive value (NPV) = 93.8%] and number of lacunes ≥ 2 (AUC = 0.73, sensitivity = 68.8%, specificity = 78.7%, PPV = 45.8% and NPV = 90.6%) were the optimal cutoff values for predicting CH. Conclusion: In patients with carotid stenosis, white matter hyperintensities and lacunes adversely affect CH after CEA. Based on the NPVs, pre-operative MR imaging can help identify patients who are not at risk of CH.

Borderzone Infarction and Small Vessel Disease in a Sample of Egyptian Stroke Patients: Differences and Similarities

Background

The anatomical location of white matter hyperintense lesions in small vessel disease are apparently similar to those of borderzone infarction. The objective of this study is to find clinical and radiological points of differentiation between the two vascular disorders in a sample of Egyptian patients which might have an impact on primary and secondary prevention.

Methods

Ischemic stroke patients with white matter lesions were categorized into two groups: small vessel disease and borderzone infarctions. NIHSS was done on admission. Risk factor profile was reported, and investigations done including: HbA1C, lipid profile, CRP, ECG, echocardiography, carotid duplex, brain MRI, MRA and MR perfusion study.

Results

46 patients completed the study, 29 with SVD and 17 with BZI. Smoking, hypertension and recurrent stroke were more common in borderzone infarctions, but only diabetes was significantly higher (p = 0.047). Limb shaking was more observed in borderzone infarctions (p = 0.049). Radiologically: lacunar pattern was observed more in small vessel disease, while rosary pattern was more in borderzone infarctions (p = 0.04). FLAIR symmetrical lesions and microbleeds were more significant in small vessel disease (p = <0.001; 0.048, respectively). Perfusion study time to peak denoted evidence of significant hypoperfusion in all regions of interest in borderzone infarctions.

Conclusion

Limb shaking, retinal claudication or syncope, with MRI showing rosary pattern of white matter hyperintensity, few microbleeds and markedly impaired perfusion favor the diagnosis of borderzone infarctions. On the other hand, presence of lacunae, FLAIR showing symmetrical WMH and microbleeds with minimal or no perfusion deficit suggests the diagnosis of small vessel disease.

Brain imaging biomarkers of carotid artery disease

Extracranial carotid artery atherosclerotic disease is a major contributor to ischemic stroke. Carotid atherosclerotic disease can present with a spectrum of findings ranging from mild carotid intima-media thickness to high-risk vulnerable carotid plaque features and carotid stenosis. Before leading to clinically overt stroke or transient ischemic attack, there may be other markers of downstream ischemia secondary to carotid atherosclerotic disease. In this review article, we will review some of the imaging findings that may be seen downstream to carotid artery disease on various imaging modalities, including hemodynamic and perfusional abnormalities which may be seen on CT, MR, or using other advanced imaging techniques, white matter hyperintensities on brain imaging, silent or covert brain infarctions, cerebral microbleeds, and regional and generalized cerebral volume loss. Many of these imaging findings are seen routinely on brain magnetic resonance imaging in patients without overt clinical symptoms. Despite frequently being asymptomatic, many of these imaging findings are also strongly associated with increased risk of future stroke, cognitive impairment, and even mortality. We will review the existing evidence underpinning the associations between these frequently encountered imaging findings and carotid artery atherosclerotic disease. Future validation of these imaging findings could lead to them being powerful biomarkers of cerebrovascular health.

The study on analysis of risk factors for severity of white matter lesions and its correlation with cerebral microbleeds in the elderly with lacunar infarction

This study aimed to explore the risk factors for severity of white matter lesions and its correlation with in the elderly with lacunar infarction.Patients (range, 70-85 years) with lacunar infarction treated in a hospital in China from 2016 to 2017were enrolled. Fazekas rating scale (0-6 points) was used to assess severity of white matter lesions. Risk factors for the severity of white matter lesions and correlation between cerebral microbleeds and white matter lesions in the elderly with lacunar infarction were studied.The elderly (81-85 years' old, odds ratio [OR]: 2.423, 95% confidence interval [CI]: 1.795-3.271, P = .018; 76∼80 years' old, OR: 3.113, 95% CI: 1.723-5.625, P = .043), carotid atherosclerosis (OR: 3.062, 95% CI:1.715-5.468, P < .001), history of hypertension (OR: 3.694, 95% CI: 2.031-6.717, P < .001) were risk factors for the severity of white matter lesions. The white matter lesions score increased corresponding to increase in the cerebral microbleeds grade (P < .001). The white matter lesions score was higher in the cerebral microbleeds combined with the white matter lesions group than in the white matter lesions group (P < .01). After correcting the effects of age, there was a correlation between white matter lesions and cerebral microbleeds (P < .001). Logistic analysis revealed that the patients' age (81-85 years' old, OR: 2.722, 95% CI: 1.985-3.734, P = .019; 76∼80 years' old, OR: 1.857, 95% CI: 1.075-3.207, P = .031), history of hypertension (OR: 2.931, 95% CI: 1.136-7.567, P = 0.0.036), systolic blood pressure (OR: 1.049, 95% CI: 1.015-1.084, P = .007), high-sensitivity C-reactive protein (OR: 1.504, 95% CI: 1.254-1.803, P < .001), homocysteine (OR: 1.076, 95% CI: 1.020-1.136, P = .009), and carotid atherosclerosis (OR: 1.389, 95% CI: 1.103-1.748, P = .010) were significant risk factors for combined cerebral microbleeds with white matter lesions in patients with lacunar infarction.The elderly, carotid atherosclerosis, history of hypertension were risk factors for the severity of white matter lesions. Cerebral microbleeds were positively correlated with the severity of white matter lesions.

Correlation of Brain Perfusion with White Matter Hyperintensity, Brain Atrophy, and Cognition in Patients with Posterior Cerebral Artery Stenosis and Subjective Cognitive Decline

BACKGROUND This study aimed to investigate the correlation of brain perfusion with white matter hyperintensity (WMH), brain atrophy, and cognition in patients with moderate to severe posterior cerebral artery stenosis (PCAS). MATERIAL AND METHODS 65 patients with memory decline as the main complaint and no history of brain infarction were recruited from the Department of Neurology of Tongji Hospital. Patients with moderate to severe PCAS were included in case group, and subjects with normal intracranial blood vessels served as controls. The demographics and vascular risk factors were recorded. Montreal Cognitive Assessment (MoCA) was used to evaluate the cognition. CT perfusion imaging was performed, and WASID was employed for the assessment of intracranial artery stenosis. The region of interest (ROI) was analyzed based on the whole brain perfusion. Cranial MRI was performed, and Scheltens scoring system was used for the assessment of WMH on FLAIR. T1 weighed images were obtained, and global cortical atrophy (GCA) scale was employed for the assessment of brain atrophy. The detections of brain perfusion, WMH and brain atrophy were done at centrum ovale, parietal lateral ventricle and basal ganglia layers. RESULTS In PCAS patients we found low perfusion in the antecornu and postcornu blood supply areas at the lateral ventricle, the blood supply area of the anterior cerebral artery, the blood supply area of the posterior cerebral artery, and the blood supply area at the hippocampus as compared with control subjects (p<0.05). As compared with control subjects, the incidence of WMH in the blood supply areas at the deep brain and lateral ventricle was significantly higher in PCAS patients (p<0.05). When compared with controls, the incidence of brain atrophy increased significantly in PCAS patients (p<0.01). Correlation analysis showed the brain perfusion at the blood supply area of the posterior cerebral artery was positively correlated to the total MoCA score and negatively correlated to the severity of WMH at the blood supply area of the posterior cerebral artery (p<0.05). Further analysis showed the brain perfusion at the blood supply area of the posterior cerebral artery was negatively associated with cortex supplied by the posterior cerebral artery, posterior cingulate, and hippocampus (p<0.01). CONCLUSIONS PCAS patients have a higher incidence of brain atrophy, and the perfusion at the area supplied by the posterior cerebral artery is correlated to the severity of brain atrophy and of WMH, as well as to cognition decline.

White matter hyperintensities and their subtypes in patients with carotid artery stenosis: a systematic review and meta-analysis

OBJECTIVE

We aimed to perform a systematic review and meta-analysis to clarify the association between white matter hyperintensities (WMHs) and carotid artery (CA) stenosis.

STUDY DESIGN

Systematic review and meta-analysis.

PARTICIPANTS

CA stenosis was set at ≥50%, and WMHs were assessed by MRI and evaluated quantitatively or semiquantitatively.

DATA SOURCES

A comprehensive literature search was performed in PubMed, EMBASE and Cochrane Library for studies evaluating the association between WMHs and CA stenosis ≥50% from inception to 13 September 2017.

MAIN OUTCOMES AND MEASURES

Standardised mean difference (SMD) with 95% CI was used to evaluate the association between WMHs and CA stenosis. Results were presented in a forest plot with a fixed-effects model or random-effects model. We assessed the quality of included studies using the Newcastle-Ottawa Scale. Funnel plots and Egger's and Begg's tests were conducted to assess publication bias. Sensitivity analysis was performed to evaluate the influence of each individual study.

RESULTS

Eight studies enrolling 677 patients were included. There was a positive relationship between the total WMHs and CA stenosis, with a pooled fixed-effects SMD of 0.326 (95% CI 0.194 to 0.459, p=0.000). Heterogeneity and publication bias were low among these studies. Subgroup analysis of three studies enrolling 225 patients showed an association between periventricular WMHs and CA stenosis, with a pooled fixed-effects SMD of 0.412 (95% CI 0.202 to 0.622, p=0.000).

CONCLUSION

This meta-analysis showed that the total WMHs and periventricular WMHs were associated with CA stenosis. WMHs may be considered as an individual risk stratification score when choosing a proper plan for therapy of CA stenosis.

Multiple Factors Involved in the Pathogenesis of White Matter Lesions

White matter lesions (WMLs), also known as leukoaraiosis (LA) or white matter hyperintensities (WMHs), are characterized mainly by hyperintensities on T2-weighted or fluid-attenuated inversion recovery (FLAIR) images. With the aging of the population and the development of imaging technology, the morbidity and diagnostic rates of WMLs are increasing annually. WMLs are not a benign process. They clinically manifest as cognitive decline and the subsequent development of dementia. Although WMLs are important, their pathogenesis is still unclear. This review elaborates on the advances in the understanding of the pathogenesis of WMLs, focusing on anatomy, cerebral blood flow autoregulation, venous collagenosis, blood brain barrier disruption, and genetic factors. In particular, the attribution of WMLs to chronic ischemia secondary to venous collagenosis and cerebral blood flow autoregulation disruption seems reasonable. With the development of gene technology, the effect of genetic factors on the pathogenesis of WMLs is gaining gradual attention.

Long-term effects of white matter changes on the risk of stroke recurrence after carotid artery stenting in patients with symptomatic carotid artery stenosis

INTRODUCTION

Cerebral white matter changes (WMC) are associated with increased 30-day perioperative risk of stroke in patients undergoing carotid artery stenting (CAS). However, there is no data showing their impact on postoperative long-term stroke recurrence or survival. It remains unknown whether this effect is independent of classic cardiovascular risk factors or not. We tried to assess the effects of WMC on long-term stroke recurrence after CAS in patients with symptomatic carotid stenosis.

METHODS

A database of patients with symptomatic carotid stenosis who had undergone CAS was sampled in a single Chinese medical center from 2007 to 2014. Copies of baseline brain imaging were analyzed by two investigators to evaluate the severity of WMC. We analyzed the association between WMC and stroke recurrence after CAS by reviewing case histories and conducting telephone interviews, with a mean follow-up time of 28months.

RESULTS

107 patients with an average age of 66years fulfilled the inclusion criteria, of which 70 were examined with CT and the remainder by MRI. In our cohort, 91.6% of the participants were male. There were 29 patients with diffuse WMC. In univariate analysis, patients with diffuse WMC had more contralateral occlusion than those with non-diffuse WMC. In patients with diffuse WMC, more stroke recurrences were observed compared with those with non-diffuse WMC (hazard ratio [HR] 3.516; 95% CI 1.176, 10.510, P=0.024).

CONCLUSIONS

In patients with symptomatic carotid artery stenosis, diffuse WMC were a risk factor for stroke recurrences after CAS. Larger studies are warranted to confirm this finding and explore the potential clinical impact of WMC so as to better determine treatment strategies for patients with symptomatic carotid artery stenosis.

Dilated perivascular spaces in the Basal Ganglia are a biomarker of small-vessel disease in a very elderly population with dementia

BACKGROUND AND PURPOSE

Dilated perivascular spaces have been shown to be a specific biomarker of cerebral small-vessel disease in young patients with dementia. Our aim was to examine the discriminative power of dilated cerebral perivascular spaces as biomarkers of small-vessel disease in a very elderly population of patients with dementia.

MATERIALS AND METHODS

We studied healthy volunteers (n = 65; mean age, 78 ± 5.6 years) and subjects with vascular dementia (n = 39; mean age, 76.9 ± 7.7 years) and Alzheimer disease (n = 47; mean age, 74.1 ± 8.5 years). We compared white matter hyperintensity and 2 semiquantitative perivascular space scoring systems (perivascular space-1 and perivascular space-2). Intra- and interobserver agreement was assessed by using a weighted Cohen κ statistic. Multinomial regression modeling was used to assess the discriminative power of imaging features to distinguish clinical groups.

RESULTS

White matter hyperintensity scores were higher in vascular dementia than in Alzheimer disease (P < .05) or healthy volunteers (P < .01). The perivascular space-1 score was higher in vascular dementia and Alzheimer disease than in healthy volunteers (P < .01). The perivascular space-2 score in the centrum semiovale showed no intergroup differences. However, perivascular space-2 in the basal ganglia was higher in vascular dementia than in Alzheimer disease (P < .05) or healthy volunteers (P < .001) and higher in Alzheimer disease than in healthy volunteers (P < .001). Modeling of dementia versus healthy volunteers, Alzheimer disease versus healthy volunteers, and vascular dementia against Alzheimer disease demonstrated perivascular space-2basal ganglia as the only imaging parameter with independent significant discriminative power (P < .01, P < .01, and P < .05) with areas under the receiver operating characteristic curve of 0.855, 0.774, and 0.71, respectively. Modeling of vascular dementia versus healthy volunteers showed that perivascular space-2basal ganglia (P < .01) and the modified Scheltens score (P < .05) contributed significant, independent discriminatory power, accounting for 34% and 13% of the variance in the model respectively.

CONCLUSIONS

Dilated perivascular spaces remain a valuable biomarker of small-vessel disease in an elderly population.

Excessive lowering of blood pressure is not beneficial for progression of brain white matter hyperintensive and cognitive impairment in elderly hypertensive patients: 4-year follow-up study

OBJECTIVES

This study was designed to explore the appropriate blood pressure (BP) target required to reduce cognitive decline and brain white matter lesions (WMLs) in elderly hypertensive patients.

METHODS

Elderly patients (n = 294, ≥80 years of age) being treated for hypertension were enrolled in a longitudinal study examining cognitive impairment after an initial assessment and a period of 4 years. All patients underwent neurological and cognitive assessment, laboratory examination, and magnetic resonance imaging of the brain.

RESULTS

The 4-year follow-up examination revealed that body mass index, alcohol consumption, systolic blood pressure (SBP), diastolic blood pressure, and Mini-Mental State Examination (MMSE) all showed a significant decline, whereas fasting plasma glucose, white matter hyperintensities (WMH) volume, and the WMH/total intracranial volume (TIV) ratio were significantly increased when compared with baseline observations. Interestingly, the decline in MMSE, as well as the increment of WMH and WMH/TIV ratio was smaller in patients with SBP ranging from 140 to 160 mm Hg than in those whose SBP was lower than 140 mm Hg or higher than 160 mm Hg (P < .05). Furthermore, we observed that a 15 to 35 mm Hg targeted lowering of SBP in the elderly patients was more beneficial to our cognitive analysis than treatments that achieved less than 15 mm Hg or greater than 35 mm Hg (P < .05).

CONCLUSIONS

In elderly hypertensive patients, there exists a beneficial target for SBP lowering beyond which treatment may not be beneficial for improving or delaying the progression of cognitive impairment and WMLs.

The association between leukoaraiosis and carotid atherosclerosis: a systematic review and meta-analysis

The association between large-artery atherosclerosis and leukoaraiosis (LA) has been increasingly reported with inconsistent conclusion. This systematic review examines the relationship between LA and carotid atherosclerosis, manifested as atherosclerotic stenosis, plaques and increased intima-media thickness (IMT). PubMed, Embase, and Web of Science were searched for articles published up to February 2014. Thirty-two studies that examined the relationship between LA and carotid atherosclerosis were included. All statistical analysis was conducted with Review Manager 5.2.4. Finally, 32 studies including 17,721 patients were identified. There were 7 (30%) out of 23 studies reporting significant association between LA and carotid stenosis; 11 (79%) out of 14 studies reporting significant association between LA and carotid plaque; all 9 studies reporting significant association between LA and carotid IMT; one study showing an association between LA and CAWT (similar to the role of the IMT). The quantitative meta-analysis of 10 studies showed that carotid atherosclerosis was not associated with LA (OR: 1.10; 95% CI: 0.61-1.98). A significant association was found between LA and carotid plaque (OR = 3.53; 95% CI = 1.83-6.79), and the result of IMT group showed that IMT increased risk of LA (MD = 0.11; 95% CI = 0.01-0.22). This systematic review suggested that LA has a tendency of association with carotid plaques but no association with simple carotid stenosis.

Preoperative white matter lesions are independent predictors of long-term survival after internal carotid endarterectomy

Background

Cerebral white matter lesions (WMLs) predict long-term survival of conservatively treated acute stroke patients with etiology other than carotid stenosis. In carotid endarterectomy patients, WMLs are associated with severe carotid stenosis and unstable plaques, with the risk of perioperative complications and with increased 30-day perioperative risk of death. However, no data exist on their effect on postoperative long-term survival, a factor important when considering the net benefit from carotid endarterectomy. Whether this effect is independent of classical risk factors and indications for surgery is not known either. We hypothesized that WMLs could be evaluated from preoperative routine computed tomography (CT) scans and are predictors of postoperative survival, independent of classical cardiovascular risk factors, indication category and degree of carotid stenosis.

Methods

A total of 353 of 481 (73.4%) consecutive patients subjected to carotid endarterectomy due to different indications, i.e. asymptomatic stenosis (n = 28, 7.9%), amaurosis fugax (n = 52, 14.7%), transient ischemic attack (n = 135, 38.2%) or ischemic stroke (n = 138, 39.1%), from prospective vascular registries during the years 2001-2010 with digital preoperative CT scans, were included in the study. WMLs were rated by a radiologist (Wahlund criteria) in a blinded fashion. Internal carotid artery (ICA) stenoses were angiographically graded (<50, 50-69, 70-99 and 100%). Odds ratios (ORs) and hazard ratios (HRs) are reported (ORs and HRs ≤1 indicate a beneficial effect). The median follow-up time was 67 months (interquartile range 45.5, range 0-129 months). Spearman's rho was used to estimate intraobserver agreement. Binary logistic regression was performed to analyze the association of risk factors with WMLs. Cox regression proportional hazards analysis was used to study the effect of different factors on survival.

Results

WML severity could be assessed with a substantial intraobserver agreement (Spearman's rho 0.843, p < 0.0001). Only age (OR 1.10, 95% CI 1.06-1.15; p < 0.0001 per year), degree of ipsilateral ICA stenosis (OR 2.22, 95% CI 1.08-4.55; p < 0.05 per stenosis grade) and indication category (OR 1.63, 95% CI 1.19-2.24; p < 0.01 per category) remained independently associated with WMLs. Age (HR 1.04, 95% CI 1.01-1.08; p < 0.05 per year), diabetes (HR 1.59, 95% CI 1.01-2.49; p < 0.05), peripheral arterial disease (HR 2.47, 95% CI 1.46-4.15; p < 0.01), degree of ipsilateral ICA stenosis (HR 2.56, 95% CI 1.12-5.87; p < 0.05 per stenosis grade) and WMLs (HR 3.83, 95% CI 1.17-12.5; p < 0.05) remained independently associated with increased long-term mortality.

Conclusions

WMLs in a preoperative CT scan provide a substantially reliable estimate of postoperative long-term survival of carotid endarterectomy patients independent of currently used criteria, i.e. cardiovascular risk factors, indication category and degree of ipsilateral ICA stenosis.

Effect of acute resistance exercise on carotid artery stiffness and cerebral blood flow pulsatility

Arterial stiffness is associated with cerebral flow pulsatility. Arterial stiffness increases following acute resistance exercise (RE). Whether this acute RE-induced vascular stiffening affects cerebral pulsatility remains unknown. Purpose: To investigate the effects of acute RE on common carotid artery (CCA) stiffness and cerebral blood flow velocity (CBFv) pulsatility. Methods: Eighteen healthy men (22 ± 1 yr; 23.7 ± 0.5 kg·m⁻²) underwent acute RE (5 sets, 5-RM bench press, 5 sets 10-RM bicep curls with 90 s rest intervals) or a time control condition (seated rest) in a randomized order. CCA stiffness (β-stiffness, Elastic Modulus (Ep)) and hemodynamics (pulsatility index, forward wave intensity, and reflected wave intensity) were assessed using a combination of Doppler ultrasound, wave intensity analysis and applanation tonometry at baseline and 3 times post-RE. CBFv pulsatility index was measured with transcranial Doppler at the middle cerebral artery (MCA). Results: CCA β-stiffness, Ep and CCA pulse pressure significantly increased post-RE and remained elevated throughout post-testing (p < 0.05). No changes in MCA or CCA pulsatility index were observed (p > 0.05). There were significant increases in forward wave intensity post-RE (p < 0.05) but not reflected wave intensity (p > 0.05). Conclusion: Although acute RE increases CCA stiffness and pressure pulsatility, it does not affect CCA or MCA flow pulsatility. Increases in pressure pulsatility may be due to increased forward wave intensity and not pressure from wave reflections.

Early detection of microstructural white matter changes associated with arterial pulsatility

Increased cerebral blood flow pulsatility is common in vascular dementia and is associated with macrostructural damage to cerebral white matter or leukoaraiosis (LA). In this study, we examine whether cerebral blood flow pulsatility is associated with macrostructural and microstructural changes in cerebral white matter in older adults with no or mild LA and no evidence of dementia. Diffusion Tensor Imaging was used to measure fractional anisotropy (FA), an index of the microstructural integrity of white matter, and radial diffusivity (RaD), a measure sensitive to the integrity of myelin. When controlling for age, increased arterial pulsation was associated with deterioration in both measures of white matter microstructure but not LA severity. A stepwise multiple linear regression model revealed that arterial pulsatility index was the strongest predictor of FA (R = 0.483, adjusted R (2) = 0.220), followed by LA severity, but not age. These findings suggest that arterial pulsatility may provide insight into age-related reduction in white matter FA. Specifically, increased arterial pulsatility may increase perivascular shear stress and lead to accumulation of damage to perivascular oligodendrocytes, resulting in microstructural changes in white matter and contributing to proliferation of LA over time. Changes in cerebral blood flow pulsatility may therefore provide a sensitive index of white matter health that could facilitate the early detection of risk for perivascular white matter damage and the assessment of the effectiveness of preventative treatment targeted at reducing pulsatility.

Leukoaraiosis is a chronic atherosclerotic disease

Background and Purpose. White matter changes (WMCs), or leukoaraiosis (LA), are associated with increased age, hypertension, diabetes mellitus, and history of stroke. Although several lines of evidence suggest a role of atherosclerosis in atherothrombotic vascular events, their involvement in LA remains to be determined. Our study examines this association in ischemic stroke patients. Methods. One hundred and seventy consecutive ischemic stroke or transient ischemic attack (TIA) patients were included. All patients underwent brain computed tomography (CT) with assessment of the extension and severity of WMCs, carotid arteries duplex scan with measurements of intima-media thickness (IMT) and plaques. Results. Seventy-two patients (42.4%) were found to have white matter lesions, of whom 28.8% had advanced LA. Mean IMT was significantly higher in patients with LA and with advanced LA (P = 0.002, P = 0.003, resp.). In addition, LA and LA severity were associated with existence of carotid plaque (P = 0.007, P = 0.004, resp.). In multivariate logistic regression analysis, including all vascular risk factors, LA was found to be associated with age and IMT. Conclusion. This study reinforces the tight association between LA and carotid atherosclerosis in ischemic stroke patients. We conclude that a chronic atherosclerotic disease underlies the pathophysiology of leukoaraiosis and its progression.

Potential surrogate markers of cerebral microvascular angiopathy in asymptomatic subjects at risk of stroke

Cerebral microvascular angiopathy (MVA) is associated with clinical vascular risk factors and is characterised by histological changes, including thickening of the walls of arterial vessels and dilatation of the Virchow-Robin spaces (VRS). We have previously described two novel biomarkers of MVA based on magnetic resonance imaging (MRI), VRS dilatation and abnormalities in the transfer of systolic arterial pulsation to the ventricular CSF, which occur as a result of decreased cerebral arterial compliance. These are associated with vascular dementia and treatment-resistant late onset depression. We studied a group of normal subjects at risk of cerebrovascular disease to determine if these biomarkers are present in patients who have no evidence of symptomatic vascular disease. We studied 31 subjects, 16 with three or more vascular risk factors and 15 with one or less significant risk factors. We measured arterial blood flow and CSF flow in the cerebral aqueduct, white matter lesion load, and the distribution and number of VRS. There were significant differences in CSF pulsatility and in VRS in the basal ganglia between the two groups, but no differences in white matter lesion load. We conclude that asymptomatic subjects at risk of stroke have MRI evidence of MVA before white matter lesions become apparent.

The brain-derived neurotrophic factor VAL66MET polymorphism and cerebral white matter hyperintensities in late-life depression

OBJECTIVE

In animal models, brain-derived neurotrophic factor (BDNF) appears to protect against cerebral ischemia. The authors examined whether the BDNF Val66Met polymorphism, which affects BDNF distribution, was associated with greater volumes of hyperintense lesions as detected on magnetic resonance imaging in a cohort of depressed and nondepressed elders.

DESIGN

Subjects completed cross-sectional assessments, including clinical evaluation and a brain magnetic resonance imaging scan, and provided blood samples for Val66Met genotyping.

SETTING

The study was conducted at a university-based academic hospital.

PARTICIPANTS

Participants included 199 depressed and 113 nondepressed subjects aged 60 years or older.

MEASUREMENT

Hyperintensity lesion volumes were measured using a semiautomated segmentation procedure. Statistical models examined the relationship between genotype and lesion volume while controlling for depression, presence of hypertension, age, and sex.

RESULTS

After controlling for covariates, Met66 allele carriers exhibited significantly greater white matter hyperintensity volumes (F(1,311) = 4.09, p = 0.0442). This effect was independent of a diagnosis of depression or report of hypertension. Genotype was not significantly related to gray matter hyperintensity volume (F(1,311) = 1.14, p = 0.2871).

CONCLUSIONS

The BDNF Met66 allele is associated with greater white matter hyperintensity volumes in older individuals. Further work is needed to determine how this may be associated with other clinically relevant findings in late-life depression.