White Matter Hyperintensity and Cardiovascular Disease Outcomes in the SPRINT MIND Trial.

BACKGROUND: The Systolic Blood Pressure Intervention Trial (SPRINT) randomized patients to a goal systolic blood pressure (SBP) <120 mm Hg vs. <140 mm Hg. In a subset of participants, the SPRINT MIND ancillary study performed a baseline MRI and measured white matter hyperintensity volume (WMHv). In this secondary analysis, we evaluated the association between baseline WMHv and cardiovascular events during follow-up in the overall sample. METHODS: The primary outcome was the same as SPRINT, a composite of stroke, myocardial infarction, acute coronary syndrome, decompensated congestive heart failure, or cardiovascular death. We fit Cox models to the primary outcome and report adjusted hazard ratios (HR) for log-transformed WMHv and quartiles of WMHv. RESULTS: Among 717 participants, the median (IQR) baseline WMHv was 1.62 (0.66-3.98) mL. The primary outcome occurred in 51/719 (7.1%). The median WMHv was higher in patients with the primary outcome (3.40 mL versus 1.56 mL, p < 0.001). In adjusted models, WMHv as a log-transformed continuous variable was associated with the primary outcome (HR 1.44, 95% CI 1.15-1.80). The highest quartile of WMHv, compared to the lowest, was also independently associated with the primary outcome (HR 3.21, 95% CI 1.27-8.13). CONCLUSIONS: We found that the baseline volume of WMH was associated with future CVD risk in SPRINT MIND. Prospective clinical trials with larger sample sizes than the current study are needed to determine whether intensive BP lowering can reduce the high cardiovascular risk in patients with WMH.

Serial Imaging of Virus-Associated Necrotizing Disseminated Acute Leukoencephalopathy (VANDAL) in COVID-19.

BACKGROUND AND PURPOSE: Various patterns of leukoencephalopathy have been described in coronavirus disease 2019 (COVID-19). In this article, we aimed to describe the clinical and imaging features of acute disseminated leukoencephalopathy in critically ill patients with COVID-19 and the imaging evolution during a short-term follow-up. MATERIALS AND METHODS: We identified and reviewed the clinical data, laboratory results, imaging findings, and outcomes for 8 critically ill patients with COVID-19 with acute disseminated leukoencephalopathy. RESULTS: All patients demonstrated multiple areas of white matter changes in both cerebral hemispheres; 87.5% (7/8) of patients had a posterior predilection. Four patients (50%) had short-term follow-up imaging within a median of 17 days after the first MR imaging; they developed brain atrophy, and their white matter lesions evolved into necrotizing cystic cavitations. All (8/8) patients had inflammatory cytokine release syndrome as demonstrated by elevated interleukin-6, D-dimer, lactate dehydrogenase, erythrocyte sedimentation rate, C-reactive protein, and ferritin levels. Most (7/8; 87.5%) patients were on prolonged ventilator support (median, 44.5 days; interquartile range, 20.5 days). These patients had poor functional outcomes (6/8 [75%] patients were discharged with mRS 5) and high mortality (2/8, 25%). CONCLUSIONS: Critically ill patients with COVID-19 can develop acute disseminated leukoencephalopathy that evolves into cystic degeneration of white matter lesions with brain atrophy during a short period, which we dubbed virus-associated necrotizing disseminated acute leukoencephalopathy. This may be the result of COVID-19-related endothelial injury, cytokine storm, or thrombotic microangiopathy.

Association of Albuminuria With White Matter Hyperintensities Volume on Brain Magnetic Resonance Imaging in Elderly Japanese　- The Hisayama Study.

BACKGROUND: Both chronic kidney disease and brain white matter hyperintensities (WMH) are known to be risk factors of dementia and mortality.Methods and Results:In 2012, 1,214 community-dwelling Japanese subjects aged ≥65 years underwent brain magnetic resonance imaging (MRI) scans and a comprehensive health examination. This study investigated associations of the urinary albumin : creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) with the WMH volume to intracranial volume (WMHV : ICV) ratio, and the association of the combination of UACR and the WMHV : ICV ratio with cognitive decline and mortality risk. The geometric mean of the WMHV : ICV ratio was 0.223% in the entire study population, and increased significantly with higher UACR levels after adjusting for potential confounding factors (0.213% for normoalbuminuria, 0.248% for microalbuminuria, and 0.332% for macroalbuminuria; Ptrend=0.01). In contrast, there was no clear association between eGFR and the WMHV : ICV ratio. Compared with subjects with normoalbuminuria and a smaller WMHV : ICV ratio (<0.257% [median]), subjects with albuminuria and a larger WMHV : ICV ratio (≥0.257%) had higher probabilities of cognitive decline at baseline and all-cause death during the follow-up. CONCLUSIONS: This study suggests that subjects with albuminuria have a greater risk of WMH enlargement and that the combination of albuminuria and WMH enlargement increases the risk of cognitive decline and all-cause mortality in an elderly Japanese population.

Cerebral Small Vessel Disease Burden and All-Cause Mortality: Mayo Clinic Florida Familial Cerebrovascular Diseases Registry.

GOAL: Cerebral small vessel disease (CSVD) leads to cognitive decline, gait disturbances, mood changes, and an increased risk of stroke. The goal of this study is to describe the relationship between a composite radiographic CSVD score and all-cause mortality. MATERIALS AND METHODS: Data were collected from a prospective registry of patients with and without cerebrovascular disease from November 2010 through April 2018. The radiographic Total CSVD Score (tSVD) ranges from 0 (minimal disease) to 4 (severe disease), based on detection of lacunar infarcts, cerebral microbleeds, perivascular spaces, and subcortical or periventricular white matter hyperintensities. All-cause mortality served as the primary endpoint. The independent relationship between CSVD burden and all-cause mortality was assessed using Cox regression models with significance being P < .05. FINDINGS: Four hundred and forty-nine patients were included (mean age, 63 years; 50.1% [225 of 449] women). The hazard ratio for mortality significantly increased with advancing score (1.92, P = .014 score 1; 2.92, P < .001 score 2; 4.23, P < .001 combined scores 3 and 4). Significance remained despite adjustment for coexistent cerebrovascular risk factors aside from age. CONCLUSIONS: The clinically practical tSVD score may serve as a predictor for all-cause mortality in populations with high disease prevalence. Continued investigations are needed to better understand the effects of risk factor modification on mortality and pathogenesis with the goal of developing disease modifying therapies.

Causes of mortality and severe morbidity requiring euthanasia in captive Tasmanian devils (Sarcophilus harrisii) in Tasmania.

BACKGROUND: Devil facial tumour disease (DFTD) is a contagious cancer causing marked population declines in wild Tasmanian devils. In response to this threat, a captive insurance population has been established. This study investigated causes of death in captive Tasmanian devils. METHODS: Clinical and laboratory records of captive Tasmanian devils held in seven Tasmanian captive facilities were analysed for cause of death or severe morbidity requiring euthanasia. RESULTS: Neoplasia was found to be the most common cause of mortality/severe morbidity, accounting for 27/63 of deaths. Cutaneous lymphoma was the most frequently observed tumour (10/27), at a higher incidence than previously reported. The most common cause of severe morbidity, following neoplasia, was leucoencephalomyelopathy, which caused severe, progressive hindlimb paresis and ataxia. CONCLUSION: Neoplasia, specifically cutaneous lymphoma, and degenerative neurological conditions are the most frequent causes of death in captive Tasmanian devils in Tasmania. Further work to determine the aetiologies of these conditions, as well as effective treatments, would be valuable.

Impact of white matter changes on neurologic outcomes of total arch replacement using antegrade cerebral perfusion.

OBJECTIVE: To evaluate the impact of white matter changes on neurologic outcomes after total arch replacement using antegrade cerebral perfusion. METHODS: White matter changes were assessed using a visual Fazekas scale on preoperative magnetic resonance images. From October 1999 to December 2016, 359 patients who had demonstrated changes on preoperative magnetic resonance imaging underwent elective total arch replacement using antegrade cerebral perfusion. Patients were classified into 3 severity groups: mild (100 patients), moderate (158 patients), and severe (101 patients). Mean follow-up time was 4.8 ± 3.6 years. Multivariate logistic regression methods were used to evaluate for an independent association between white matter changes and postoperative neurological outcomes. RESULTS: Hospital mortality was 2.8% (10/359), and no significant differences were found across the 3 groups (P = .604). Multivariate analysis demonstrated that the severity of white matter change was significantly associated with both postoperative permanent neurologic deficit (odds ratio, 5.77; 95% confidence interval, 1.58-38.4, P = .005) and transient neurologic deficit (odds ratio, 2.46; 95% confidence interval, 1.45-4.37, P < .001). CONCLUSIONS: White matter changes, defined using the visual Fazekas scale on preoperative magnetic resonance imaging, were significantly associated with significant postoperative adverse neurologic outcomes after total arch replacement using antegrade cerebral perfusion.

Similarities and differences between infantile and early childhood onset vanishing white matter disease.

Vanishing white matter disease (VWM) is one of the most prevalent inherited leukoencephalopathies in childhood. Infantile VWM is more severe but less understood than the classic early childhood type. We performed a follow-up study on 14 infantile and 26 childhood patients to delineate the natural history and neuroimaging features of VWM. Infantile and childhood patients shared similarities in the incidence of epileptic seizure (35.7 vs. 38.5%) and episodic aggravation (92.9 vs. 84.6%). Developmental delay before disease onset was more common in infantile patients. Motor disability was earlier and more severe in infantile VWM. In survivors with disease durations of 1-3 years, the Gross Motor Function Classification System (GMFCS) was classified as IV-V in 66.7% of infantile and only 29.4% of childhood patients. Kaplan-Meier survival curve analysis indicated that the 5-year survival rates were 21.6 and 91.3% in infantile and childhood VWM, respectively. In terms of MRI, infantile patients showed more extensive involvement and earlier rarefaction, with more common involvement of subcortical white matter, internal capsule, brain stem and dentate nuclei of the cerebellum. Restricted diffusion was more diffuse or extensive in infantile patients. In addition, four novel mutations were identified. In conclusion, we identified some similarities and differences in the natural history and neuroimaging features between infantile and early childhood VWM.

Subclinical Cerebrovascular Disease Increases the Risk of Incident Stroke and Mortality: The Northern Manhattan Study.

BACKGROUND: The effects of white matter hyperintensity volume and subclinical brain infarcts on the risk of incident stroke, its ischemic subtypes, and mortality require further study in diverse samples. METHODS AND RESULTS: Stroke-free participants in the Northern Manhattan Study underwent magnetic resonance imaging (N=1287; mean age 71±9 years, 60% women, 15% non-Hispanic white, 17% non-Hispanic black, 68% Hispanic) and were followed for a median of 8 years (interquartile range: 6-9 years). Cox models estimated proportional hazards of incident stroke of all types, ischemic stroke (and its subtypes), and mortality and stratified by race/ethnicity. In total 72 participants (6%) had incident strokes and 244 died (19%). In fully adjusted models, those with larger white matter hyperintensity volume had greater risk of all stroke types (hazard ratio [HR]: 1.4; 95% CI, 1.1-1.9), ischemic stroke (HR: 1.3; 95% CI, 1.0-1.8), and cryptogenic stroke (HR: 2.2; 95% CI, 1.1-4.4). White and black but not Hispanic participants had increased stroke risk (P<0.05 for heterogeneity for all and ischemic stroke). Those with subclinical brain infarct had greater risk for all stroke types (HR: 1.9; 95% CI, 1.1-3.3), ischemic stroke (HR: 2.2; 95% CI, 1.3-3.8), lacunar (HR: 4.0; 95% CI, 1.3-12.3), and cryptogenic stroke (HR: 3.6; 95% CI, 1.0-12.7), without significant heterogeneity across race/ethnic groups. Greater white matter hyperintensity volume increased both vascular (HR: 1.3; 95% CI, 1.1-1.7) and nonvascular (HR: 1.2; 95% CI, 1.0-1.5) mortality among Hispanic and white but not black participants (P=0.040 for heterogeneity). Subclinical brain infarct was associated with increased vascular mortality among Hispanic participants only (HR: 2.9; 95% CI, 1.4-5.8). CONCLUSIONS: In this urban US sample, subclinical cerebrovascular lesions increased the risk of clinical stroke and vascular mortality and varied by race/ethnicity and lesion type.

White Matter Hyperintensities Improve Ischemic Stroke Recurrence Prediction.

BACKGROUND: Nearly one in 5 patients with ischemic stroke will invariably experience a second stroke within 5 years. Stroke risk stratification schemes based solely on clinical variables perform only modestly in non-atrial fibrillation (AF) patients and improvement of these schemes will enhance their clinical utility. Cerebral white matter hyperintensities are associated with an increased risk of incident ischemic stroke in the general population, whereas their association with the risk of ischemic stroke recurrence is more ambiguous. In a non-AF stroke cohort, we investigated the association between cerebral white matter hyperintensities and the risk of recurrent ischemic stroke, and we evaluated the predictive performance of the CHA2DS2VASc score and the Essen Stroke Risk Score (clinical scores) when augmented with information on white matter hyperintensities. METHODS: In a registry-based, observational cohort study, we included 832 patients (mean age 59.6 (SD 13.9); 42.0% females) with incident ischemic stroke and no AF. We assessed the severity of white matter hyperintensities using MRI. Hazard ratios stratified by the white matter hyperintensities score and adjusted for the components of the CHA2DS2VASc score were calculated based on the Cox proportional hazards analysis. Recalibrated clinical scores were calculated by adding one point to the score for the presence of moderate to severe white matter hyperintensities. The discriminatory performance of the scores was assessed with the C-statistic. RESULTS: White matter hyperintensities were significantly associated with the risk of recurrent ischemic stroke after adjusting for clinical risk factors. The hazard ratios ranged from 1.65 (95% CI 0.70-3.86) for mild changes to 5.28 (95% CI 1.98-14.07) for the most severe changes. C-statistics for the prediction of recurrent ischemic stroke were 0.59 (95% CI 0.51-0.65) for the CHA2DS2VASc score and 0.60 (95% CI 0.53-0.68) for the Essen Stroke Risk Score. The recalibrated clinical scores showed improved C-statistics: the recalibrated CHA2DS2VASc score 0.62 (95% CI 0.54-0.70; p = 0.024) and the recalibrated Essen Stroke Risk Score 0.63 (95% CI 0.56-0.71; p = 0.031). C-statistics of the white matter hyperintensities score were 0.62 (95% CI 0.52-0.68) to 0.65 (95% CI 0.58-0.73). CONCLUSIONS: An increasing burden of white matter hyperintensities was independently associated with recurrent ischemic stroke in a cohort of non-AF ischemic stroke patients. Recalibration of the CHA2DS2VASc score and the Essen Stroke Risk Score with one point for the presence of moderate to severe white matter hyperintensities led to improved discriminatory performance in ischemic stroke recurrence prediction. Risk scores based on white matter hyperintensities alone were at least as accurate as the established clinical risk scores in the prediction of ischemic stroke recurrence.

Mortality Risk After AIDS-Defining Opportunistic Illness Among HIV-Infected Persons--San Francisco, 1981-2012.

OBJECTIVE: To examine whether improved human immunodeficiency virus (HIV) treatment was associated with better survival after diagnosis of AIDS-defining opportunistic illnesses (AIDS-OIs) and how survival differed by AIDS-OI. DESIGN: We used HIV surveillance data to conduct a survival analysis. METHODS: We estimated survival probabilities after first AIDS-OI diagnosis among adult patients with AIDS in San Francisco during 3 treatment eras: 1981-1986; 1987-1996; and 1997-2012. We used Cox proportional hazards models to determine adjusted mortality risk by AIDS-OI in the years 1997-2012. RESULTS: Among 20 858 patients with AIDS, the most frequently diagnosed AIDS-OIs were Pneumocystis pneumonia (39.1%) and Kaposi sarcoma (20.1%). Overall 5-year survival probability increased from 7% in 1981-1986 to 65% in 1997-2012. In 1997-2012, after adjustment for known confounders and using Pneumocystis pneumonia as the referent category, mortality rates after first AIDS-OI were highest for brain lymphoma (hazard ratio [HR], 5.14; 95% confidence interval [CI], 2.98-8.87) and progressive multifocal leukoencephalopathy (HR, 4.22; 95% CI, 2.49-7.17). CONCLUSIONS: Survival after first AIDS-OI diagnosis has improved markedly since 1981. Some AIDS-OIs remain associated with substantially higher mortality risk than others, even after adjustment for known confounders. Better prevention and treatment strategies are still needed for AIDS-OIs occurring in the current HIV treatment era.

Cerebral white matter lesions in patients with cirrhosis - causative for hepatic encephalopathy or bystanders?

BACKGROUND & AIMS: Focal white matter lesions mimicking microvascular lesions were connected to the development of hepatic encephalopathy (HE) in patients with cirrhosis. This study aims to assess the relationship between cerebrovascular risk factors and the prevalence and extent of these lesions in patients with cirrhosis, as well as their impact upon cognitive function. METHODS: 55 cirrhotic patients underwent neurological examination, psychometric testing and magnetic resonance imaging. T2-weighted images were reviewed for white matter lesions by a neuroradiologist and a neurologist, independently. Patients were allocated into three groups: (i) no or <5, (ii) 6-15 and (iii) more than 15 lesions. Allocation was confirmed by a senior neuroradiologist blinded for the clinical data. The patient groups were compared concerning age, underlying liver disease, mortality, MELD Score, history of HE, treatment for HE, cerebrovascular risk factors and psychometric test results. Regression analysis was performed to identify risk factors for the presence and extent of white matter lesions. RESULTS: Patient groups 2 and 3 were older and showed worse results in the psychometric tests than group 1 (P < 0.05). Correlation analyses showed a significant relationship between the number of white matter lesions and the grade of HE (P < 0.001) and cognitive function (P < 0.05), but no interrelationship between the lesions and cerebrovascular risk factors or other factors tested. CONCLUSIONS: Focal white matter lesions in patients with cirrhosis do not represent cerebrovascular small-vessel disease but are related to the pathology of HE. Further studies are needed to clarify the mechanisms behind in detail.

Moderate-severe traumatic brain injury causes delayed loss of white matter integrity: evidence of fornix deterioration in the chronic stage of injury.

OBJECTIVES: To examine structural integrity loss in the fornix from 5-30 months after moderate and severe traumatic brain injury (TBI) using diffusion tensor imaging. METHODS: MRIs were prospectively undertaken in 29 adults with moderate and severe TBI at two time points. Fractional anisotropy (FA) was calculated for the fornix (column/body, right crux and left crux) at 5 and 30 months post-injury. RESULTS: Paired t-tests revealed significant FA reductions with large effect sizes across time in the column/body, p < 0.001, right crux, p < 0.001 and left crux, p < 0.001. CONCLUSIONS: These data contribute to the growing body of evidence that loss of white matter continues in moderate and severe TBI even after the acute neurological effects of TBI have resolved. As the fornix plays a critical role in memory, this may be a contributing factor to the poor clinical outcomes observed in these patients.

Cerebral white matter hyperintensity predicts cardiovascular events in haemodialysis patients.

AIM: Cerebral white matter hyperintensities (WMHs), comprised of periventricular hyperintensity (PVH) and deep and subcortical white matter hyperintensity (DSWMH), have been presumed to be predictors for future stroke, cognitive impairment and dementia in the general population. However, no longitudinal studies have been performed to determine the clinical significance of WMHs in haemodialysis (HD) patients. In the present study, we investigated the influence of WMHs as a predictor of future cardiovascular disease in HD patients. METHODS: Cranial magnetic resonance imaging was performed on 179 HD patients with no past history of stroke from April 2006 to October 2009, and the prevalence of WMHs was investigated. The patients were followed prospectively until March 2012 or death or renal transplantation. The influence of WMHs on cardiovascular events was investigated using the Kaplan-Meier method and Cox proportional hazards analysis. RESULTS: The patients with advanced PVH and DSWMH had a significantly higher incidence of cardiovascular morbidity than those without advanced PVH and DSWMH by Kaplan-Meier analysis. By multivariate Cox proportional hazards analysis, the presence of advanced PVH and DSWMH increased the risk of cardiovascular events, independent of other cardiovascular risk factors. In addition, the present study revealed that of the subtypes of WMHs, PVH was a stronger predictor of cardiovascular events compared to DSWMH. CONCLUSIONS: The present study indicates that the presence of WMHs is a novel predictor of cardiovascular events in HD patients, and that PVH is more closely associated with incident cardiovascular disease.

Abnormal cerebral microstructure in premature neonates with congenital heart disease.

BACKGROUND AND PURPOSE: Abnormal cerebral microstructure has been documented in term neonates with congenital heart disease, portending risk for injury and poor neurodevelopmental outcome. Our hypothesis was that preterm neonates with congenital heart disease would demonstrate diffuse cerebral microstructural abnormalities when compared with critically ill neonates without congenital heart disease. A secondary aim was to identify any association between microstructural abnormalities, white matter injury (eg, punctate white matter lesions), and other clinical variables, including heart lesions. MATERIALS AND METHODS: With the use of tract-based spatial statistics, an unbiased, voxelwise method for analyzing diffusion tensor imaging data, we compared 21 preterm neonates with congenital heart disease with 2 cohorts of neonates without congenital heart disease: 28 term and 27 preterm neonates, identified from the same neonatal intensive care unit. RESULTS: Compared with term neonates without congenital heart disease, preterm neonates with congenital heart disease had microstructural abnormalities in widespread regions of the central white matter. However, 42% of the preterm neonates with congenital heart disease had punctate white matter lesions. When neonates with punctate white matter lesions were excluded, microstructural abnormalities remained only in the splenium. Preterm neonates with congenital heart disease had similar microstructure to preterm neonates without congenital heart disease. CONCLUSIONS: Diffuse microstructural abnormalities were observed in preterm neonates with congenital heart disease, strongly associated with punctate white matter lesions. Independently, regional vulnerability of the splenium, a structure associated with visual spatial function, was observed in all preterm neonates with congenital heart disease.

Reduced mortality rates in a cohort of long-term underground iron-ore miners.

BACKGROUND: Historically, working in iron-ore mines has been associated with an increased risk of lung cancer and silicosis. However, studies on other causes of mortality are inconsistent and in the case of cancer incidence, sparse. The aim of this study was to examine the association between iron-ore mining, mortality and cancer incidence. METHODS: A 54-year cohort study on iron-ore miners from mines in northern Sweden was carried out comprising 13,000 workers. Standardized rate ratios were calculated comparing the disease frequency, mortality, and cancer incidence with that of the general population of northern Sweden. Poisson regression was used to evaluate the association between the durations of employment and underground work, and outcome. RESULTS: Underground mining was associated with a significant decrease in adjusted mortality rate ratios for cerebrovascular and digestive system diseases, and stroke. For several outcomes, elevated standardized rate ratios were observed among blue-collar workers relative to the reference population. However, only the incidence of lung cancer increased with employment time underground (P < 0.001). CONCLUSIONS: Long-term iron-ore mining underground was associated with lower rates regarding several health outcomes. This is possibly explained by factors related to actual job activities, environmental exposure, or the selection of healthier workers for long-term underground employment.

Mood problems increase the risk of mortality in patients with lacunar infarcts: the SMART-MR study.

OBJECTIVE: A relationship between depression and mortality has been well established, but underlying mechanisms remain unclear. We investigated the influence of cerebral small vessel disease (CSVD), characterized by white matter lesions (WMLs) and lacunar infarcts, on the relationship between mood mortality during 6 years follow-up. METHODS: Mood problems were assessed with the mental component summary of the 36-item Short-Form Medical Outcomes Study in 1110 patients with symptomatic atherosclerotic disease (mean age 59 years). Volumetric WML estimates were obtained with 1.5-T magnetic resonance imaging; lacunar infarcts were scored visually. Cox regression models were adjusted for age, sex, vascular risk, physical functioning, antidepressants and infarcts. We adjusted for CSVD to examine whether it may be an intermediate or confounding factor. Second, we added interaction terms to investigate whether associations differed between patients with CSVD (absent/present). RESULTS: Patients in the lowest quartile of mental functioning, representing most severe mood problems, were at higher, although not significant, risk of death (hazard ratio [HR] = 1.47, 95% confidence interval [CI] = 0.94-2.30) compared with patients in higher quartiles. Adjustment for CSVD did not change this association. Lacunar infarcts, not WML, modified the association of mood problems with mortality (p value for interaction = .01); mood problems strongly increased the risk of mortality in patients with lacunar infarcts (HR = 2.75, 95% CI = 1.41-5.38) but not in those without it (HR = 0.78, 95% CI = 0.39-1.57). CONCLUSIONS: Patients with lacunar infarcts may be especially vulnerable for the effect of mood problems on mortality.

Selective white matter abnormalities in a novel rat model of vascular dementia.

Rats subjected to bilateral common carotid artery (CCA) occlusion or 2-vessel occlusion (2VO) have been used as animal models of subcortical ischemic vascular dementia. However, this model possesses an inherent limitation in that cerebral blood flow (CBF) drops too sharply and substantially after ligation of CCAs. To circumvent such hypoxic-ischemic conditions, we tested implantation of the ameroid constrictor device on bilateral CCAs of male Wistar-Kyoto rats and more precisely replicated chronic cerebral hypoperfusion by gradual narrowing of the CCAs (2-vessel gradual occlusion; 2VGO). The acute cerebral blood flow reduction and resultant inflammatory responses observed in the 2VO rats were eliminated in the 2VGO rats. Thus, chronic cerebral hypoperfusion was segregated, and induced selective white matter changes with relatively preserved neurovascular coupling and substantially less metabolic and histological derangements in the gray matter including the hippocampus. This led to significant spatial working memory impairment of a magnitude similar to the 2VO rats at 28 days postoperation. The 2VGO model may more closely mimic cognitive impairment subsequent to selective white matter damage.

Cerebral small vessel disease and risk of death, ischemic stroke, and cardiac complications in patients with atherosclerotic disease: the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study.

BACKGROUND AND PURPOSE: Cerebral small vessel disease may be related to vascular and nonvascular pathology. We assessed whether lacunar infarcts and white matter lesions on MRI increased the risk of vascular and nonvascular death and future vascular events in patients with atherosclerotic disease. METHODS: Brain MRI was performed in 1309 patients with atherosclerotic disease from the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study. Infarcts were scored visually and volumetric assessment of white matter lesion was performed. Patients were followed for a median of 4.5 years (range, 0.2 to 7.1 years) for death, ischemic stroke, and ischemic cardiac complications. RESULTS: Cox regression models showed that presence of lacunar infarcts (n=229) increased the risk of vascular (hazard ratio, 2.6; 95% CI, 1.4 to 4.9) and nonvascular death (hazard ratio, 2.7; 95% CI, 1.3 to 5.3), adjusted for age, sex, vascular risk factors, nonlacunar infarcts, and white matter lesion. These risks were similar for patients with silent lacunar infarcts. White matter lesion volume (relative to total intracranial volume) increased the risk of vascular death (hazard ratio per milliliter increase, 1.03; 95% CI, 1.01 to 1.05) and white matter lesions in the upper quintile compared with lower quintiles increased risk of ischemic stroke (hazard ratio, 2.6; 95% CI, 1.3 to 4.9). CONCLUSIONS: Cerebral small vessel disease, with or without a history of cerebrovascular disease, is associated with increased risk of death and ischemic stroke in patients with atherosclerotic disease.

Deletion of oligodendrocyte Cx32 and astrocyte Cx43 causes white matter vacuolation, astrocyte loss and early mortality.

CNS glia exhibit a variety of gap junctional interactions: between neighboring astrocytes, between neighboring oligodendrocytes, between astrocytes and oligodendrocytes, and as 'reflexive' structures between layers of myelin in oligodendrocytes. Together, these junctions are thought to form a network facilitating absorption and removal of extracellular K(+) released during neuronal activity. In mice, loss of the two major oligodendrocyte connexins causes severe demyelination and early mortality, while loss of the two major astrocyte connexins causes mild dysmyelination and sensorimotor impairment, suggesting that reflexive and/or oligo-oligo coupling may be more important for the maintenance of myelin than other forms. To further explore the functional relationships between glial connexins, we generated double knockout mice lacking one oligodendrocyte and one astrocyte connexin. Cx32-Cx43 dKO animals develop white matter vacuolation without obvious ultrastructural abnormalities in myelin. Progressive loss of astrocytes but not oligodendrocytes or microglia accompanies sensorimotor impairment, seizure activity and early mortality at around 16 weeks of age. Our data reveal an unexpected role for connexins in the survival of white matter astrocytes, requiring the expression of particular isoforms in both oligodendrocytes and astrocytes.