Silent Stroke

Lung cancer is associated with acute ongoing cerebral ischemia: A population-based study

BACKGROUND AND OBJECTIVES

Cerebral microinfarcts (CMIs) are the most common type of brain ischemia; however, they are extremely rare in the general population. CMIs can be detected by magnetic resonance diffusion-weighted imaging (MRI-DWI) only for a very short period of approximately 2 weeks after their formation and are associated with an increased stroke risk and cognitive impairment. We aimed to examine CMI detection rate in patients with lung cancer (LC), which is strongly associated with ischemic stroke risk relative to other cancer types.

METHODS

We used the Clalit Health Services record (representing more than 5 million patients) to identify adults with LC and breast, pancreatic, or colon cancer (non-lung cancer, NLC) who underwent brain magnetic resonance diffusion (MRI) scan within 5 years following cancer diagnosis. All brain MRI scans were reviewed, and CMIs were documented, as well as cardiovascular risk factors.

RESULTS

Our cohort contained a total of 2056 MRI scans of LC patients and 1598 of NLC patients. A total of 143 CMI were found in 73/2056 (3.5%) MRI scans of LC group compared to a total of 29 CMI in 22/1598 (1.4%) MRI scans of NLC (p < 0.01). Cancer type (e.g. LC vs NLC) was the only associated factor with CMI incidence on multivariate analysis. After calculating accumulated risk, we found an incidence of 2.5 CMI per year in LC patients and 0.5 in NLC.

DISCUSSION

CMIs are common findings in cancer patients, especially in LC patients and therefore might serve as a marker for occult brain ischemia, cognitive decline, and cancer-related stroke (CRS) risk.

Cerebral Microinfarcts Are Common in Undiagnosed Lung Cancer Patients: A Population-Based Study

Background. Cerebral microinfarcts (CMI) represent covert brain ischemia and were associated with stroke risk and cognitive impairment. Magnetic resonance imaging diffusion-weighted imaging (DWI) hyperintensities have been suggested to represent acute CMI. The relationship between malignancy and CMI is unknown. Aims. We aimed to examine whether CMI is more common in patients with undiagnosed lung cancer, and therefore might serve as a prediction marker for cognitive impairment or cancer-related stroke. Methods. We used the computerized database of Clalit Health Services (the largest healthcare provider in Israel) to identify adults diagnosed with lung cancer who had an MRI brain scan for any indication prior to cancer diagnosis. We analyzed DWI sequences, in order to evaluate CMI incidence in this population, and compared it to control groups of patients with other undiagnosed malignancies and patients without known cancer. Results. Altogether, we reviewed 1822 MRI brain scans, of which 497 scans were taken in patients with undiagnosed lung cancer, 543 scans of noncancer patients, and 793 scans of patients with other undiagnosed malignancies. In the lung cancer group, we found 24 CMI, compared with 4 in the noncancer group ( $p=0.04$ ) and 8 in the other cancer group ( $p=0.07$ ). Conclusions. CMI is common in undiagnosed lung cancer patients compare to other undiagnosed cancer types or noncancer patients. At the time of lung cancer diagnosis patients may be at risk for future stroke or cognitive decline.

Silent brain infarcts, peripheral vascular disease and the risk of cardiovascular events in patients with hypertension

BACKGROUND AND AIMS

We aimed to study the relationship between cerebral small vessel disease (cSVD) lesions, as markers of subclinical target organ damage (TOD) in the brain, and incident cardiovascular events (CVE).

METHODS

Data from the ISSYS (Investigating Silent Strokes in hYpertensives Study), which is a longitudinal and observational study conducted in patients with hypertension aged 50-70 years, and stroke-free at the inclusion. At the baseline visit, participants underwent a clinical interview, a brain MRI, urine and blood sampling collection and vascular testing studies. Therefore, we obtained markers of TOD from the brain [white matter hyperintensities, silent brain infarcts (SBI), cerebral microbleeds and enlarged perivascular spaces (EPVS)], from kidney (microalbuminuria, glomerular filtration) and regarding large vessels [ankle-to-brachial index (ABI), carotid-femoral pulse wave velocity]. Survival analyses were used to assess the relationship between these predictors and the incidence of cardiovascular events (CVE).

RESULTS

We followed-up 964 individuals within a median time of 5 years (4.7-5), representing 4377.1 persons-year. We found 73 patients presenting incident CVE, which corresponds to a rate of 8.2%. We found ABI less than 0.9 [hazard ratio, 2.2; 95% confidence interval (CI) 1.17-4.13, P value = 0.014] and SBI (hazard ratio, 2.9; 95% CI 1.47-5.58, P value = 0.002) independently associated with higher risk of incident CVE. The inclusion of both variables in a clinical model resulted in an increased discrimination of individuals with new CVE of 4.72%, according to the integrated discrimination index.

CONCLUSION

Assessment of SBI and ABI less than 0.9 may refine the cardiovascular risk stratification in patients with hypertension.

Tamoxifen offers long-term neuroprotection after hippocampal silent infarct in male rats

Silent infarcts (SI) are a cerebral small vessel disease characterized by small subcortical infarcts. These occur in the absence of typical ischemia symptoms but are linked to cognitive decline and dementia. While there are no approved treatments for SI, recent results from our laboratory suggest that tamoxifen, a selective estrogen receptor modulator, is a viable candidate. In the present study, we induced SI in the dorsal hippocampal CA1 region of rats and assessed the effects of systemic administration of tamoxifen (5 mg/kg, twice) 21 days after injury on cognitive and pathophysiological measures, including cell loss, apoptosis, gliosis and estrogen receptors (ERs). We found that tamoxifen protected against the SI-induced cognitive dysfunction on the hippocampal-dependent, place recognition task, cell and ER loss, and increased apoptosis and gliosis in the CA1. Exploratory data analyses using a scatterplot matrix and principal component analysis indicated that SI-tamoxifen rats were indistinguishable from sham controls while they differed from SI rats, who were characterized by enhanced cell loss, apoptosis and gliosis, lower ERs, and recognition memory deficit. Supervised machine learning using support vector machine (SVM) determined predictors of progression from the early ischemic state to the dementia-like state. It showed that caspase-3 and ERα in the CA1 and exploration proportion were reliable and accurate predictors of this progression. Importantly, tamoxifen ameliorated SI-induced effects on all three of these variables, providing further evidence for its viability as a candidate treatment for SI and prevention of associated dementia.

The selective estrogen receptor modulator tamoxifen protects against subtle cognitive decline and early markers of injury 24 h after hippocampal silent infarct in male Sprague-Dawley rats

Silent infarcts (SI) are subcortical cerebral infarcts occurring in the absence of typical ischemia symptoms and are linked to cognitive decline and dementia development. There are no approved treatments for SI. One potential treatment is tamoxifen, a selective estrogen receptor modulator. It is critical to establish whether treatments effectively target the early consequences of SI to avoid progression to complete injury. We induced SI in the dorsal hippocampal CA1 of rats and assessed whether tamoxifen is protective 24 h later against cognitive deficits and injury responses including gliosis, apoptosis, inflammation and changes in estrogen receptors (ERs). SI led to subtle cognitive impairment on the object place task, an effect ameliorated by tamoxifen administration. SI did not lead to detectable hippocampal cell loss but increased apoptosis, astrogliosis, microgliosis and inflammation. Tamoxifen protected against the effects of SI on all measures except microgliosis. SI increased ERα and decreased ERβ in the hippocampus, which were mitigated by tamoxifen. Exploratory data analyses using scatterplot matrices and principal component analysis indicated that SI rats given tamoxifen were indistinguishable from controls. Further, SI rats were significantly different from all other groups, an effect associated with low levels of ERα and increased apoptosis, gliosis, inflammation, ERβ, and time spent with the unmoved object. The results demonstrate that tamoxifen is protective against the early cellular and cognitive consequences of hippocampal SI 24 h after injury. Tamoxifen mitigates apoptosis, gliosis, and inflammation and normalization of ER levels in the CA1, leading to improved cognitive outcomes after hippocampal SI.

Neuropsychiatric symptoms associated with cerebral small vessel disease: a systematic review and meta-analysis

BACKGROUND

Cerebral small vessel disease, a common cause of vascular dementia, is often considered clinically silent before dementia or stroke become apparent. However, some individuals have subtle symptoms associated with acute MRI lesions. We aimed to determine whether neuropsychiatric and cognitive symptoms vary according to small vessel disease burden.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, EMBASE, and PsycINFO for articles published in any language from database inception to Jan 24, 2020. We searched for studies assessing anxiety, apathy, delirium, emotional lability, fatigue, personality change, psychosis, dementia-related behavioural symptoms or cognitive symptoms (including subjective memory complaints), and radiological features of cerebral small vessel disease. We extracted reported odds ratios (OR), standardised mean differences (SMD), and correlations, stratified outcomes by disease severity or symptom presence or absence, and pooled data using random-effects meta-analyses, reporting adjusted findings when possible. We assessed the bias on included studies using the Risk of Bias for Non-randomized Studies tool. This study is registered with PROSPERO, CRD42018096673.

FINDINGS

Of 7119 papers identified, 81 studies including 79 cohorts in total were eligible for inclusion (n=21 730 participants, mean age 69·2 years). Of these 81 studies, 45 (8120 participants) reported effect estimates. We found associations between worse white matter hyperintensity (WMH) severity and apathy (OR 1·41, 95% CI 1·05-1·89) and the adjusted SMD in apathy score between WMH severities was 0·38 (95% CI 0·15-0·61). Worse WMH severity was also associated with delirium (adjusted OR 2·9, 95% CI 1·12-7·55) and fatigue (unadjusted OR 1·63, 95% CI 1·20-2·22). WMHs were not consistently associated with subjective memory complaints (OR 1·34, 95% CI 0·61-2·94) and unadjusted SMD for WMH severity between these groups was 0·08 (95% CI -0·31 to 0·47). Anxiety, dementia-related behaviours, emotional lability, and psychosis were too varied or sparse for meta-analysis; these factors were reviewed narratively. Overall heterogeneity varied from 0% to 79%. Only five studies had a low risk of bias across all domains.

INTERPRETATION

Apathy, fatigue, and delirium associated independently with worse WMH, whereas subjective cognitive complaints did not. The association of anxiety, dementia-related behaviours, emotional lability, and psychosis with cerebral small vessel disease require further investigation. These symptoms should be assessed longitudinally to improve early clinical detection of small vessel disease and enable prevention trials to happen early in the disease course, long before cognition declines.

FUNDING

Chief Scientist Office of the Scottish Government, UK Dementia Research Institute, Fondation Leducq, Stroke Association Garfield-Weston Foundation, Alzheimer's Society, and National Health Service Research Scotland.

Pandemic of the aging society - sporadic cerebral small vessel disease

Age-related sporadic cerebral small vessel disease (CSVD) has gained increasing attention over the past decades because of its increasing prevalence associated with an aging population. The widespread application of and advances in brain magnetic resonance imaging in recent decades have significantly increased researchers’ understanding in the in vivo evolution of CSVD, its impact upon the brain, its risk factors, and the mechanisms that explain the various clinical manifestation associated with sporadic CSVD. In this review, we aimed to provide an update on the pathophysiology, risk factors, biomarkers, and the determinants and spectrum of the clinical manifestation of sporadic CSVD.

Hippocampal silent infarct leads to subtle cognitive decline that is associated with inflammation and gliosis at twenty-four hours after injury in a rat model

Silent infarcts (SI) are subcortical cerebral infarcts that occur in the absence of clinical symptoms commonly associated with ischemia and are linked to dementia development. Little is known about the pathophysiology underlying the cognitive dysfunction associated with SI, and few studies have examined the early cellular responses and neurobiological underpinnings. We induced SI in adult male Sprague-Dawley rats using an infusion of endothelin-1 in the CA1 dorsal hippocampus. Twenty-four hours later, we assessed cognition using the hippocampal-dependent object place recognition task. We also examined whether the resulting cognitive effects were associated with common markers of ischemia, specifically cell and synapse loss, gliosis, and inflammation, using histology and immunohistochemistry. Hippocampal SI led to subtle cognitive impairment on the object place recognition task 24 -hs post-injury. This was characterized by a significant difference in exploration proportion relative to a pre-injury baseline and a positive association between time spent with both the moved and unmoved objects. SI did not result in any detectable cell or synaptophysin loss, but did increase apoptosis, gliosis and inflammation in the CA1. Principal component analysis indicated the main variables associated with hippocampal SI included increased time spent with the unmoved object, gliosis, apoptosis and inflammation as well as decreased exploration proportion and CA1 cells. Our data demonstrate that hippocampal SI can lead to cognitive dysfunction 24 -hs after injury. Further, this appears to be driven by early degenerative processes including apoptosis, gliosis and inflammation, suggesting that these may be targets for early interventions treating hippocampal SI and its cognitive consequences.

Clinical management of cerebral small vessel disease: a call for a holistic approach

ABSTRACT

Cerebral small vessel disease (SVD) is a common global brain disease that causes cognitive impairment, ischemic or hemorrhagic stroke, problems with mobility, and neuropsychiatric symptoms. The brain damage, seen as focal white and deep grey matter lesions on brain magnetic resonance imaging (MRI) or computed tomography (CT), typically accumulates "covertly" and may reach an advanced state before being detected incidentally on brain scanning or causing symptoms. Patients have typically presented to different clinical services or been recruited into research focused on one clinical manifestation, perhaps explaining a lack of awareness, until recently, of the full range and complexity of SVD.In this review, we discuss the varied clinical presentations, established and emerging risk factors, relationship to SVD features on MRI or CT, and the current state of knowledge on the effectiveness of a wide range of pharmacological and lifestyle interventions. The core message is that effective assessment and clinical management of patients with SVD, as well as future advances in diagnosis, care, and treatment, will require a more "joined-up"' approach. This approach should integrate clinical expertise in stroke neurology, cognitive, and physical dysfunctions. It requires more clinical trials in order to improve pharmacological interventions, lifestyle and dietary modifications. A deeper understanding of the pathophysiology of SVD is required to steer the identification of novel interventions. An essential prerequisite to accelerating clinical trials is to improve the consistency, and standardization of clinical, cognitive and neuroimaging endpoints.

Cerebral microinfarcts disruption of remote cortical thickness

INTRODUCTION

Cerebral microinfarcts (CMI) are common lesions, carrying an important contribution to small-vessel-related cognitive impairment. CMIs were previously found to cause local microstructural damage and disruption of white matter integrity. This study examines CMIs influence on cortical thickness in remote brain areas.

METHODS

Six small silent diffuse weighted imaging (DWI) lesions corresponding to subacute CMI were identified among five patients who underwent baseline and follow-up MRI scans from the Tel-Aviv Acute Brain Stroke Cohort (TABASCO). Regions of interest (ROIs) corresponding to the site of the DWI lesions and of the non-lesioned contralateral hemisphere (control ROI) were co-registered. DTI tractography was additionally performed to reconstruct the white matter tracts containing the ROIs. The normalized cortical thickness was calculated for the DWI lesional tract as well as for the contralateral non-lesional tract, and the lesion-to-control cortical thickness ratio (CTR) was calculated.

RESULTS

Post-lesional scans, performed 25.1 ± 1.2 months after CMI detection, demonstrated reduced mean CTR within the ROI from 1.8 to 1.1 (p = 0.032). There was no difference between the CTR of the right hemisphere relative to those on the left hemisphere, or between the CTR change of the cortical and non-cortical CMI.

DISCUSSION

This study demonstrated the prolonged influence of CMI on cortical thickness in remote ROI. The total number of CMIs is difficult to determine, however it has been shown that detecting even a single CMI suggests the existence of hundreds to thousands lesions. Therefore, the cumulative impact of these widely distributed lesions on cerebral cortex may have a significant contribution to the development of vascular cognitive impairment.

Diagnostics and treatment of chronic cerebral ischemia

5560 patients with the diagnosis “Other cerebral vascular diseases” per 100 000 of elderly population were registered in RF in 2017. Usually this is a code for chronic brain ischemia (CBI) – the most popular diagnosis in Russian neurological practice. However, diagnostic criteria of CBI are not well defined and need to be ascertained. Recent studies show that the most reliable clinical feature of CBI could be cognitive impairment. It is developed before other clinical signs and correlate with severity of vascular brain lesions. Typically, cognitive impairment is subcortical with prominent bradyphrenia, attentional, dysexecutive and visuospatial deficit and relative sparing of memory. However clinical diagnosis of CBI could be only hypothetical. Diagnosis should be verified by MRI or other visualization technic. Diagnosis is verified if neuroimaging revealed silent strokes, microbleeds and vascular leukoencephalopathy. The most important objective of chronic brain ischemia management is the control of basic vascular disease. Besides this, pathogenetic therapy should be performed to improve cerebral microcirculation, neuronal metabolism and to provide neuroprotection. There is positive data on dipyridamole usage in chronic brain ischemia. It has desagregative, vasotropic, antioxidative and antiinflammation properties. Dypiridamole treatment in CBI patients lead to decrease of neuropsychiatric symptoms and improvement of well-being.

Rationale and design of a longitudinal study of cerebral small vessel diseases, clinical and imaging outcomes in patients presenting with mild ischaemic stroke: Mild Stroke Study 3

Background

Cerebral small vessel disease is a major cause of dementia and stroke, visible on brain magnetic resonance imaging. Recent data suggest that small vessel disease lesions may be dynamic, damage extends into normal-appearing brain and microvascular dysfunctions include abnormal blood–brain barrier leakage, vasoreactivity and pulsatility, but much remains unknown regarding underlying pathophysiology, symptoms, clinical features and risk factors of small vessel disease.

Patients and Methods: The Mild Stroke Study 3 is a prospective observational cohort study to identify risk factors for and clinical implications of small vessel disease progression and regression among up to 300 adults with non-disabling stroke. We perform detailed serial clinical, cognitive, lifestyle, physiological, retinal and brain magnetic resonance imaging assessments over one year; we assess cerebrovascular reactivity, blood flow, pulsatility and blood–brain barrier leakage on magnetic resonance imaging at baseline; we follow up to four years by post and phone. The study is registered ISRCTN 12113543.

Summary

Factors which influence direction and rate of change of small vessel disease lesions are poorly understood. We investigate the role of small vessel dysfunction using advanced serial neuroimaging in a deeply phenotyped cohort to increase understanding of the natural history of small vessel disease, identify those at highest risk of early disease progression or regression and uncover novel targets for small vessel disease prevention and therapy.

Long-Term Premorbid Blood Pressure and Cerebral Small Vessel Disease Burden on Imaging in Transient Ischemic Attack and Ischemic Stroke

Supplemental Digital Content is available in the text.

Background and Purpose—

Studies of causes of cerebral small vessel disease (SVD) should fully adjust for blood pressure (BP), but most etiological studies use a single BP measurement or history of hypertension, which might underestimate the role of hypertension. In patients with transient ischemic attack and ischemic stroke, we therefore compared the associations of baseline and long-term premorbid BP with measures of SVD on magnetic resonance imaging brain.

Methods—

We studied 1009 transient ischemic attack/ischemic stroke patients who had a brain magnetic resonance imaging, in the population-based OXVASC (Oxford Vascular Study), and related baseline and 20-year premorbid BP (median: 15 readings/patient) to the total SVD score on imaging.

Results—

SVD score was associated with increasing mean baseline systolic BP (SBP; odds ratio of top versus bottom BP quartile: 2.28; [95% CI, 1.62–3.21]; P<0.0001) and with prior hypertension (2.53; [95% CI, 2.01–3.20]; P<0.0001), but the association was much stronger with mean premorbid SBP (6.09; [95% CI, 4.34–8.55]; P<0.0001). Mean diastolic BP at baseline was negatively associated with SVD score (0.71; [95% CI, 0.51–1.00]; P=0.050), and a positive association was only evident for diastolic BP 10 to 20 years previously (3.35; [95% CI, 2.33–4.84]; both P<0.0001). Relationships between overall mean premorbid BP and SVD burden were strongest in patients age <70 (SBP: 6.99; 4.11–11.86; diastolic BP: 3.13; 1.95–5.07; both P<0.0001) versus ≥70 years (2.37; 1.42–3.94; P=0.001; and 1.16; 0.74–1.84; P=0.52).

Conclusions—

Mean premorbid SBP is more strongly associated with SVD burden than baseline SBP or history of hypertension, and baseline diastolic BP yields a misleading estimate of the likely etiological importance of midlife hypertension for the subsequent development of SVD. Studies of novel potential etiological factors for SVD should aim to adjust for long-term prior BP, and trials of BP lowering with only a few years of follow-up may underestimate the overall impact on SVD.

Effect of Pro-kin visual feedback balance training system on gait stability in patients with cerebral small vessel disease

Due to the indistinct nature of symptoms for Cerebral Small Vessel Disease (CSVD), diagnosis is often missed. With significant deterioration of movement disorder, risk of falls increases dramatically.Comparison study was conducted to explore the association between balance function and gait instability, and the treatment effectiveness of visual feedback balance training on the gait disorder in CSVD patients.Fifty-six patients with CSVD were studied. They were randomly divided into observation and control groups, and were given conventional gait rehabilitation training, including single-leg weight, shift of the center of gravity, step and hip extension training, stepping up and down on stairs with the affected leg, standing up with hip extension and support of the leg, lateral walking, and in situ walking. Training was performed twice a day for 20 minutes each for 4 consecutive weeks. In addition, the observation group received balance training using Pro-Kin visual feedback balance training system. Both groups were evaluated prior and post-treatment using the Tinetti Scale and the Pro-Kin Visual Feedback Balance Training System. For the Tinetti Scale, lower score indicates more serious gait balance dysfunction. For the Pro-Kin, greater length means poorer balance function. Larger area means poorer balance function. Smaller value of the 2 parameters indicates better balance function.After training, the trajectory lengths and areas of orbital motions were significantly decreased (P < .05). However greater decrease was seen in the observation group (P < .01). The trajectory length and area for both groups were less when the eyes open than closed (P < .01). The Tinetti scores for balance and gait functions of both groups improved significantly (P < .05). However, the observation group showed even greater results than the control group (P < .01). Results from Person test showed there was a significant correlation between balance and gait functions.Combination of visual feedback balance training with conventional rehabilitation treatment could gain a greater result than conventional rehabilitation alone. It indicates that balance training may serve as an additional method for gait stability training for CSVD patients.

Genetic and lifestyle risk factors for MRI-defined brain infarcts in a population-based setting

OBJECTIVE

To explore genetic and lifestyle risk factors of MRI-defined brain infarcts (BI) in large population-based cohorts.

METHODS

We performed meta-analyses of genome-wide association studies (GWAS) and examined associations of vascular risk factors and their genetic risk scores (GRS) with MRI-defined BI and a subset of BI, namely, small subcortical BI (SSBI), in 18 population-based cohorts (n = 20,949) from 5 ethnicities (3,726 with BI, 2,021 with SSBI). Top loci were followed up in 7 population-based cohorts (n = 6,862; 1,483 with BI, 630 with SBBI), and we tested associations with related phenotypes including ischemic stroke and pathologically defined BI.

RESULTS

The mean prevalence was 17.7% for BI and 10.5% for SSBI, steeply rising after age 65. Two loci showed genome-wide significant association with BI: FBN2, p = 1.77 × 10-8; and LINC00539/ZDHHC20, p = 5.82 × 10-9. Both have been associated with blood pressure (BP)-related phenotypes, but did not replicate in the smaller follow-up sample or show associations with related phenotypes. Age- and sex-adjusted associations with BI and SSBI were observed for BP traits (p value for BI, p [BI] = 9.38 × 10-25; p [SSBI] = 5.23 × 10-14 for hypertension), smoking (p [BI] = 4.4 × 10-10; p [SSBI] = 1.2 × 10-4), diabetes (p [BI] = 1.7 × 10-8; p [SSBI] = 2.8 × 10-3), previous cardiovascular disease (p [BI] = 1.0 × 10-18; p [SSBI] = 2.3 × 10-7), stroke (p [BI] = 3.9 × 10-69; p [SSBI] = 3.2 × 10-24), and MRI-defined white matter hyperintensity burden (p [BI] = 1.43 × 10-157; p [SSBI] = 3.16 × 10-106), but not with body mass index or cholesterol. GRS of BP traits were associated with BI and SSBI (p ≤ 0.0022), without indication of directional pleiotropy.

CONCLUSION

In this multiethnic GWAS meta-analysis, including over 20,000 population-based participants, we identified genetic risk loci for BI requiring validation once additional large datasets become available. High BP, including genetically determined, was the most significant modifiable, causal risk factor for BI.

Clinical vascular imaging in the brain at 7T

Stroke and related cerebrovascular diseases are a major cause of mortality and disability. Even at standard-field-strengths (1.5T), MRI is by far the most sensitive imaging technique to detect acute brain infarctions and to characterize incidental cerebrovascular lesions, such as white matter hyperintensities, lacunes and microbleeds. Arterial time-of-flight (TOF) MR angiography (MRA) can depict luminal narrowing or occlusion of the major brain feeding arteries, and this without the need for contrast administration. Compared to 1.5T MRA, the use of high-field strength (3T) and even more so ultra-high-field strengths (7T), enables the visualization of the lumen of much smaller intracranial vessels, while adding a contrast agent to TOF MRA at 7T may enable the visualization of even more distal arteries in addition to veins and venules. Moreover, with 3T and 7T, the arterial vessel walls beyond the circle of Willis become visible with high-resolution vessel wall imaging. In addition, with 7T MRI, the brain parenchyma can now be visualized on a submillimeter scale. As a result, high-resolution imaging studies of the brain and its blood supply at 7T have generated new concepts of different cerebrovascular diseases. In the current article, we will discuss emerging clinical applications and future directions of vascular imaging in the brain at 7T MRI.

Evolution of DWI lesions in cerebral amyloid angiopathy: Evidence for ischemia

OBJECTIVE

To address the pathophysiologic nature of small diffusion-weighted imaging (DWI) lesions in patients with cerebral amyloid angiopathy (CAA) who underwent serial MRI. Specifically, we tested (1) whether DWI lesions occurred preferentially in individuals with prior DWI lesions, (2) the cross-sectional association with chronic cortical cerebral microinfarcts (CMIs), and (3) the evolution of DWI lesions over time.

METHODS

Patients with probable CAA (n = 79) who underwent at least 2 MRI sessions were included. DWI lesions were assessed at each available time point. Lesion appearance and characteristics were assessed on available structural follow-up images. Presence and burden of other neuroimaging markers of small vessel disease (white matter hyperintensities, cerebral microbleeds, cortical superficial siderosis, and chronic cortical CMIs) were assessed as well.

RESULTS

Among 221 DWI scans (79 patients with 2 DWI scans; 40 with ≥3), 60 DWI lesions were found in 28 patients. Patients with DWI lesions at baseline were not more likely to have additional DWI lesions on follow-up compared to patients without DWI lesions at baseline. DWI lesions were associated with chronic cortical CMIs and cortical superficial siderosis, but not with other markers. For 39/60 DWI lesions, >1 MRI sequence was available at follow-up to determine lesion evolution. Twenty-four (62%) were demarcated as chronic lesions on follow-up MRI. Five appeared as cavitations, 18 as noncavitated infarcts, and 1 underwent hemorrhagic transformation.

CONCLUSIONS

Based on their neuroimaging signature as well as their association with chronic cortical CMIs, DWI lesions appear to have an ischemic origin and represent one part of the CMI spectrum.

Detection, risk factors, and functional consequences of cerebral microinfarcts

Cerebral microinfarcts are small lesions that are presumed to be ischaemic. Despite the small size of these lesions, affected individuals can have hundreds to thousands of cerebral microinfarcts, which cause measurable disruption to structural brain connections, and are associated with dementia that is independent of Alzheimer's disease pathology or larger infarcts (ie, lacunar infarcts, and large cortical and non-lacunar subcortical infarcts). Substantial progress has been made with regard to understanding risk factors and functional consequences of cerebral microinfarcts, partly driven by new in-vivo detection methods and the development of animal models that closely mimic multiple aspects of cerebral microinfarcts in human beings. Evidence from these advances suggests that cerebral microinfarcts can be manifestations of both small vessel and large vessel disease, that cerebral microinfarcts are independently associated with cognitive impairment, and that these lesions are likely to cause damage to brain structure and function that extends beyond their actual lesion boundaries. Criteria for the identification of cerebral microinfarcts with in-vivo MRI are provided to support further studies of the association between these lesions and cerebrovascular disease and dementia.

Simultaneous transient global amnesia and right MCA stroke after Valsalva manoeuvre

A 61-year-old man suffered an episode of transient confusion and anterograde amnesia after a Valsalva-related manoeuvre. The MRI diffusion weighted imaging (DWI) sequences showed a left hippocampal and two right parietal lesions that were deemed as acute. The MR angiography disclosed a high-grade stenosis in the right middle cerebral artery as was described by a transcranial colour-coded ultrasound as well. Ultrasound investigation of the jugular veins showed a right jugular venous reflux after a Valsalva manoeuvre. The patient was diagnosed with transient global amnesia based on clinical grounds and the right parietal lesions were considered as silent strokes. The Valsalva manoeuvre could have played as a common trigger for both diseases.

MRI of Cerebellar Infarction

BACKGROUND

MRI is the imaging modality of choice for diagnosing brain infarction. Because of few or atypical clinical symptoms and a relatively low sensitivity of CT scans, many cerebellar infarctions may be detected only with MRI. With adequate recognition of cerebellar infarction on MRI and prompt initiation or optimisation of preventive therapeutic measures, more dramatic strokes may be avoided in selected cases.

SUMMARY

We first briefly review the clinical presentation of cerebellar infarctions, followed by a short refresher on cerebellar anatomy and pathophysiological mechanisms of cerebellar infarcts. Then, we review the arterial cerebellar perfusion territories recently made visible with territorial arterial spin labeling (ASL), followed by a discussion and illustration of the MRI appearance of cerebellar infarcts in different stages. Similar to large cerebellar infarcts, recent studies investigating volumetric MRI datasets have now shown that small cerebellar infarcts occur in typical spatial patterns, knowledge of which may help in the diagnosis of even the smallest of cerebellar infarcts on MRI. Key Messages: MRI is the modality of choice for diagnosing cerebellar infarction. The posterior inferior cerebellar artery (PICA)-territories can be visualised with super-selective territorial ASL MRI. The PICA supplies at least the medial part of the posterior cerebellar surface. Anterior inferior cerebellar artery-infarcts can be mistaken for lateral PICA-infarcts. Small infarcts typically affect the cortex and often present as incidental cavities. Subacute cerebellar infarcts may be missed on imaging due to a phenomenon called "fogging."

A Versatile Murine Model of Subcortical White Matter Stroke for the Study of Axonal Degeneration and White Matter Neurobiology

Stroke affecting white matter accounts for up to 25% of clinical stroke presentations, occurs silently at rates that may be 5-10 fold greater, and contributes significantly to the development of vascular dementia. Few models of focal white matter stroke exist and this lack of appropriate models has hampered understanding of the neurobiologic mechanisms involved in injury response and repair after this type of stroke. The main limitation of other subcortical stroke models is that they do not focally restrict the infarct to the white matter or have primarily been validated in non-murine species. This limits the ability to apply the wide variety of murine research tools to study the neurobiology of white matter stroke. Here we present a methodology for the reliable production of a focal stroke in murine white matter using a local injection of an irreversible eNOS inhibitor. We also present several variations on the general protocol including two unique stereotactic variations, retrograde neuronal tracing, as well as fresh tissue labeling and dissection that greatly expand the potential applications of this technique. These variations allow for multiple approaches to analyze the neurobiologic effects of this common and understudied form of stroke.

Cerebrovascular disease

With 16.9 million people who suffered a first-ever stroke in 2010 worldwide, stroke is a very common vascular disease. Epidemiologic studies have played an essential role in assessing this burden and in detecting the risk factors for stroke. Primary prevention of these risk factors, primarily hypertension, smoking, diabetes, and atrial fibrillation, has reduced the incidence in high-income countries. However, stroke remains a major cause of death and disability, and therefore research should be continued. Subarachnoid hemorrhages are less prevalent than strokes but have an even higher risk of death. Similar to stroke, epidemiologic studies identified smoking and hypertension as its most important risk factors, together with excessive alcohol intake. Although rare, arterial dissections, CADASIL, arteriovenous malformations, venous sinus thrombosis, moyamoya disease, and vasculitis can lead to serious symptoms. The burden and risk factors of those rare diseases are more challenging to assess. Whenever possible, they should be recognized in a timely manner for their increased risk of stroke, but most often they are diagnosed only at the time of stroke. Some cerebrovascular abnormalities do not result in immediate symptoms. This subclinical cerebrovascular disease includes silent infarcts, white-matter lesions, and microbleeds, and is incidentally found by neuroimaging. These lesions are not innocent, as several epidemiologic studies have associated subclinical cerebrovascular disease with an increased risk of stroke, cognitive decline, dementia, and death.

Cerebellar Cortical Infarct Cavities

Background and Purpose—

Small cerebellar infarct cavities have been recently found on magnetic resonance imaging (MRI) to preferentially involve the cerebellar cortex, but epidemiological studies are lacking. We aimed to determine the prevalence and risk factor profiles of cerebellar cortical infarct cavities (≤1.5 cm) as well as their association with MRI markers of cerebrovascular disease and functioning.

Methods—

We analyzed the 1.5 Tesla MRI of 636 patients (mean age, 62±9 years; 81% men) from the Second Manifestations of Arterial Disease-Memory, Depression and Aging (SMART-Medea) study. Logistic regression analyses were performed to estimate the associations of age, sex, vascular risk factors, MRI markers of cerebrovascular disease, and functioning with cerebellar cortical cavities, adjusted for age and sex.

Results—

Cerebellar cortical infarct cavities occurred on MRI in 10% of patients and were significantly associated with age, intima-media thickness (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.1–3.7), high levels of homocysteinemia (OR, 1.8; 95% CI, 1.0–3.3), cortical infarcts (OR, 2.9; 95% CI, 1.6–5.4), gray matter lacunes of presumed vascular origin (OR, 3.0; 95% CI, 1.6–5.8), brain stem infarcts (OR, 5.1; 95% CI, 1.9–13.6), and decreased brain parenchymal fraction (OR, 0.84; 95% CI, 0.74–0.94), but not with white matter hyperintensities (OR, 1.2; 95% CI, 0.8–1.8) or white matter lacunes of presumed vascular origin (OR, 1.1; 95% CI, 0.5–2.5). They were also associated with worse physical functioning (OR 0.96; 95% CI, 0.94 to 0.99) but not with mental functioning.

Conclusions—

Cerebellar cortical infarct cavities are far more common than previously assumed based on symptomatic case series and are associated with markers of atherothromboembolic cerebrovascular disease.

Estimating Total Cerebral Microinfarct Burden From Diffusion-Weighted Imaging

BACKGROUND AND PURPOSE

Cerebral microinfarcts (CMI) are important contributors to vascular cognitive impairment. Magnetic resonance imaging diffusion-weighted imaging (DWI) hyperintensities have been suggested to represent acute CMI. We aim to describe a mathematical method for estimating total number of CMI based on the presence of incidental DWI lesions.

METHODS

We reviewed magnetic resonance imaging scans of subjects with cognitive decline, cognitively normal subjects and previously reported subjects with past intracerebral hemorrhage (ICH). Based on temporal and spatial characteristics of DWI lesions, we estimated the annual rate of CMI needed to explain the observed rate of DWI lesion detection in each group. To confirm our estimates, we performed extensive sampling for CMI in the brain of a deceased subject with past lobar ICH who found to have a DWI lesion during life.

RESULTS

Clinically silent DWI lesions were present in 13 of 343 (3.8%) cognitively impaired and 10 of 199 (5%) cognitively intact normal non-ICH patients, both lower than the incidence in the past ICH patients (23 of 178; 12.9%; P<0.0006). The predicted annual incidence of CMI ranges from 16 to 1566 for non-ICH and 50 to 5041 for ICH individuals. Histological sampling revealed a total of 60 lesions in 32 sections. Based on previously reported methods, this density of CMI yields an estimated total brain burden maximum likelihood estimate of 9321 CMIs (95% confidence interval, 7255-11 990).

CONCLUSIONS

Detecting even a single DWI lesion suggests an annual incidence of hundreds of new CMI. The cumulative effects of these lesions may directly contribute to small-vessel-related vascular cognitive impairment.

A comparison of location of acute symptomatic vs. 'silent' small vessel lesions

Background

Acute lacunar ischaemic stroke, white matter hyperintensities, and lacunes are all features of cerebral small vessel disease. It is unclear why some small vessel disease lesions present with acute stroke symptoms, whereas others typically do not.

Aim

To test if lesion location could be one reason why some small vessel disease lesions present with acute stroke, whereas others accumulate covertly.

Methods

We identified prospectively patients who presented with acute lacunar stroke symptoms with a recent small subcortical infarct confirmed on magnetic resonance diffusion imaging. We compared the distribution of the acute infarcts with that of white matter hyperintensity and lacunes using computational image mapping methods.

Results

In 188 patients, mean age 67 ± standard deviation 12 years, the lesions that presented with acute lacunar ischaemic stroke were located in or near the main motor and sensory tracts in (descending order): posterior limb of the internal capsule (probability density 0·2/mm³), centrum semiovale (probability density = 0·15/mm³), medial lentiform nucleus/lateral thalamus (probability density = 0·09/mm³), and pons (probability density = 0·02/mm³). Most lacunes were in the lentiform nucleus (probability density = 0·01–0·04/mm³) or external capsule (probability density = 0·05/mm³). Most white matter hyperintensities were in centrum semiovale (except for the area affected by the acute symptomatic infarcts), external capsules, basal ganglia, and brainstem, with little overlap with the acute symptomatic infarcts (analysis of variance, P < 0·01).

Conclusions

Lesions that present with acute lacunar ischaemic stroke symptoms may be more likely noticed by the patient through affecting the main motor and sensory tracts, whereas white matter hyperintensity and asymptomatic lacunes mainly affect other areas. Brain location could at least partly explain the symptomatic vs. covert development of small vessel disease.

Are acute infarcts the cause of leukoaraiosis? Brain mapping for 16 consecutive weeks

Neuroimaging of older adults commonly reveals abnormality (leukoaraiosis) in the cerebral white matter. Studies have established that extensive leukoaraiosis predicts dementia and disability, but the pathogenesis of leukoaraiosis remains unclear. We recruited 5 patients with leukoaraiosis and performed magnetic resonance mapping of the brain for 16 consecutive weeks. We observed tiny lesions arising de novo in the cerebral white matter. These lesions were clinically silent. They had the signature features of acute ischemic stroke. With time, the characteristics of these lesions approached those of pre-existing leukoaraiosis. Together, these findings suggest that tiny silent acute infarcts are a cause of leukoaraiosis.

School performance as a marker of cognitive decline prior to diagnosis of multiple sclerosis

Background:

For many years, cognitive impairment has been established as a well-known symptom of multiple sclerosis. Moreover, we know that it was present even at the beginning of the disease.

Objective:

In this case-control study, we decided to evaluate whether there is an impairment of cognitive functions even before onset in those patients who will eventually suffer from multiple sclerosis.

Methods:

We evaluated the overall school performance, and particularly school performance in math and language in a group of patients who would later develop the disease and we compared our findings with a control group.

Results:

We found that school performance was poorer in subjects who were to become patients. And we found that the later the start of the first symptom, the better the qualifications.

Conclusion:

Testing a premorbid cognitive deficit by a validated indirect evaluation method allowed us to verify that there was evidence of neurological compromise even before a clinical diagnosis or the completion of the first magnetic resonance imaging in patients who would then suffer from multiple sclerosis.

Incidental magnetic resonance diffusion-weighted imaging-positive lesions are rare in neurologically asymptomatic community-dwelling adults

BACKGROUND AND PURPOSE

Incidental magnetic resonance diffusion-weighted imaging (DWI)-positive lesions, considered to represent small acute infarcts, have been detected in patients with cerebral small vessel diseases or cognitive impairment, but the prevalence in the community population is unknown.

METHODS

DWI sequences collected in 793 participants in the Prospective Urban Rural Epidemiological (PURE) study were reviewed for DWI lesions consistent with small acute infarcts.

RESULTS

No DWI-positive lesions were detected (0%, 95% confidence interval, 0-0.5).

CONCLUSIONS

DWI-positive lesions are rare in an asymptomatic community population. The prevalence of DWI-positive lesions in the community seems to be lower than in patients with cerebral amyloid angiopathy, intracerebral hemorrhage, or cognitive impairment.

Multiple sclerosis: diagnosis, differential diagnosis, and clinical presentation

The diagnosis of multiple sclerosis (MS) is based on demonstrating evidence of inflammatory-demyelinating injury within the central nervous system that is disseminated in both time and space. Diagnosis is made through a combination of the clinical history, neurologic examination, magnetic resonance imaging and the exclusion of other diagnostic possibilities. Other so-called "paraclinical" tests, including the examination of the cerebrospinal fluid, the recording of evoked potentials, urodynamic studies of bladder function, and ocular coherence tomography, may be helpful in establishing the diagnosis for individual patients, but are often unnecessary. Differential diagnosis in MS must be guided by clinical presentation and neurologic localization. While the list of conditions that can mimic MS clinically or radiologically is long, in clinical practice there are few conditions that truly mimic MS on both fronts. A positive test for a putative MS "mimic" does not unto itself exclude the diagnosis of MS. Typical symptoms of MS include discrete episodes ("attacks" or "relapses") of numbness, tingling, weakness, vision loss, gait impairment, incoordination, imbalance, and bladder dysfunction. In between attacks, patients tend to be stable, but may experience fatigue and heat sensitivity. Some MS patients go on to experience, or only experience, an insidious worsening of neurologic function and accumulation of disability ("progression") that is not associated with discrete relapse activity. Progression accounts for most of the long-term disability in MS. Diagnostic criteria for MS have evolved over the past several decades, with each revision impacting the apparent prevalence and prognosis of the disorder - the result has been to encourage earlier diagnosis without compromising accuracy.

Association of sleep apnea with clinically silent microvascular brain tissue changes in acute cerebral ischemia

The aim of this study was to determine the importance of sleep apnea in relation to clinically silent microvascular brain tissue changes in patients with acute cerebral ischemia. Patients with acute cerebral ischemia prospectively underwent nocturnal respiratory polygraphy within 5 days from symptom-onset. Sleep apnea was defined as apnea-hypopnea-index (AHI) ≥5/h. Experienced readers blinded to clinical and sleep-related data reviewed brain computed tomography and magnetic resonance imaging scans for leukoaraiosis and chronic lacunar infarctions. Ischemic lesions were considered clinically silent when patients did not recall associated stroke-like symptoms. Functional outcome was assessed with modified Rankin Scale at discharge, 6 and 12 months. Fifty-one of 56 (91 %) patients had sleep apnea of any degree. Patients with moderate-to-severe leukoaraiosis (Wahlund score ≥5) were found to have higher mean AHI than those with none or mild leukoaraiosis (34.4 vs. 12.8/h, p < 0.001). Moderate-to-severe sleep apnea (AHI ≥15/h) was found to be an independent predictor of moderate-to-severe leukoaraiosis (adjusted OR 6.03, 95 % CI 1.76-20.6, p = 0.0042) and of moderate-to-severe leukoaraiosis associated with clinically silent chronic lacunar infarctions (adjusted OR 10.5, 95 % CI 2.19-50.6, p = 0.003). The higher the Wahlund score and the AHI, the more likely unfavorable functional outcome resulted over time (p = 0.0373). In acute cerebral ischemia, sleep apnea is associated with clinically silent microvascular brain tissue changes and may negatively influence functional outcome. Routine sleep apnea screening and further investigation of possible long-term effects of non-invasive ventilatory treatment of sleep apnea appear warranted in this at-risk population.

Neuroimaging standards for research into small vessel disease and its contribution to ageing and neurodegeneration

Cerebral small vessel disease (SVD) is a common accompaniment of ageing. Features seen on neuroimaging include recent small subcortical infarcts, lacunes, white matter hyperintensities, perivascular spaces, microbleeds, and brain atrophy. SVD can present as a stroke or cognitive decline, or can have few or no symptoms. SVD frequently coexists with neurodegenerative disease, and can exacerbate cognitive deficits, physical disabilities, and other symptoms of neurodegeneration. Terminology and definitions for imaging the features of SVD vary widely, which is also true for protocols for image acquisition and image analysis. This lack of consistency hampers progress in identifying the contribution of SVD to the pathophysiology and clinical features of common neurodegenerative diseases. We are an international working group from the Centres of Excellence in Neurodegeneration. We completed a structured process to develop definitions and imaging standards for markers and consequences of SVD. We aimed to achieve the following: first, to provide a common advisory about terms and definitions for features visible on MRI; second, to suggest minimum standards for image acquisition and analysis; third, to agree on standards for scientific reporting of changes related to SVD on neuroimaging; and fourth, to review emerging imaging methods for detection and quantification of preclinical manifestations of SVD. Our findings and recommendations apply to research studies, and can be used in the clinical setting to standardise image interpretation, acquisition, and reporting. This Position Paper summarises the main outcomes of this international effort to provide the STandards for ReportIng Vascular changes on nEuroimaging (STRIVE).

Mechanisms of sporadic cerebral small vessel disease: insights from neuroimaging

The term cerebral small vessel disease (SVD) describes a range of neuroimaging, pathological, and associated clinical features. Clinical features range from none, to discrete focal neurological symptoms (eg, stroke), to insidious global neurological dysfunction and dementia. The burden on public health is substantial. The pathogenesis of SVD is largely unknown. Although the pathological processes leading to the arteriolar disease are associated with vascular risk factors and are believed to result from an intrinsic cerebral arteriolar occlusive disease, little is known about how these processes result in brain disease, how SVD lesions contribute to neurological or cognitive symptoms, and the association with risk factors. Pathology often shows end-stage disease, which makes identification of the earliest stages difficult. Neuroimaging provides considerable insights; although the small vessels are not easily seen themselves, the effects of their malfunction on the brain can be tracked with detailed brain imaging. We discuss potential mechanisms, detectable with neuroimaging, that might better fit the available evidence and provide testable hypotheses for future study.

Thrombolysis Despite Recent Stroke

Background and Purpose—

Thrombolysis in ischemic stroke is contraindicated in patients who have had a stroke within 3 months. However, it is unclear whether thrombolytic therapy is associated with adverse outcomes in this population. We report the characteristics and outcomes of patients treated with systemic recombinant tissue-type plasminogen activator in the context of known or unknown recent stroke.

Methods—

We identified patients who received recombinant tissue-type plasminogen activator despite recent stroke (within 3 months of acute thrombolysis). Clinical and radiological findings were collected, including early neurological worsening and hemorrhagic transformation on unenhanced computed tomography at 24 hours. Clinical outcome measured by modified Rankin Scale was determined at 3 months from onset.

Results—

Six patients presenting with acute stroke within 3 months of previous stroke were identified (median age, 76 years; median National Institutes of Health Stroke Scale, 8.5). Hemorrhagic transformation was seen in the follow-up computed tomography scan in 3 of 6 cases: all were hemorrhagic transformation 1 (petechial hemorrhage), asymptomatic, and mostly located within the area of subacute infarction. There was no early neurological deterioration, and 3 patients had modified Rankin Scale ≤2 after 3 months.

Conclusions—

In our center, we thrombolysed 6 patients despite recent stroke. Three patients had asymptomatic petechial hemorrhagic transformation within the area of subacute infarct, without apparent neurological worsening. Prospective studies are needed to explore the possible safety of tissue-type plasminogen activator in the context of previous subacute stroke in otherwise eligible patients.