Brain hemorrhage recurrence, small vessel disease type, and cerebral microbleeds: A meta-analysis.

OBJECTIVE: We evaluated recurrent intracerebral hemorrhage (ICH) risk in ICH survivors, stratified by the presence, distribution, and number of cerebral microbleeds (CMBs) on MRI (i.e., the presumed causal underlying small vessel disease and its severity). METHODS: This was a meta-analysis of prospective cohorts following ICH, with blood-sensitive brain MRI soon after ICH. We estimated annualized recurrent symptomatic ICH rates for each study and compared pooled odds ratios (ORs) of recurrent ICH by CMB presence/absence and presumed etiology based on CMB distribution (strictly lobar CMBs related to probable or possible cerebral amyloid angiopathy [CAA] vs non-CAA) and burden (1, 2-4, 5-10, and >10 CMBs), using random effects models. RESULTS: We pooled data from 10 studies including 1,306 patients: 325 with CAA-related and 981 CAA-unrelated ICH. The annual recurrent ICH risk was higher in CAA-related ICH vs CAA-unrelated ICH (7.4%, 95% confidence interval [CI] 3.2-12.6 vs 1.1%, 95% CI 0.5-1.7 per year, respectively; p = 0.01). In CAA-related ICH, multiple baseline CMBs (versus none) were associated with ICH recurrence during follow-up (range 1-3 years): OR 3.1 (95% CI 1.4-6.8; p = 0.006), 4.3 (95% CI 1.8-10.3; p = 0.001), and 3.4 (95% CI 1.4-8.3; p = 0.007) for 2-4, 5-10, and >10 CMBs, respectively. In CAA-unrelated ICH, only >10 CMBs (versus none) were associated with recurrent ICH (OR 5.6, 95% CI 2.1-15; p = 0.001). The presence of 1 CMB (versus none) was not associated with recurrent ICH in CAA-related or CAA-unrelated cohorts. CONCLUSIONS: CMB burden and distribution on MRI identify subgroups of ICH survivors with higher ICH recurrence risk, which may help to predict ICH prognosis with relevance for clinical practice and treatment trials.

The Cerebral Haemorrhage Anatomical RaTing inStrument (CHARTS): Development and assessment of reliability.

PURPOSE: The causes, risk factors and prognosis of spontaneous intracerebral haemorrhage (ICH) are partly determined by anatomical location (specifically, lobar vs. non-lobar (deep and infratentorial) regions). We systematically developed a rating instrument to reliably classify ICH location. METHODS: We used a two-stage iterative Delphi-style method for instrument development. The resultant Cerebral Haemorrhage Anatomical RaTing inStrument (CHARTS) was validated on CT and MRI scans from a cohort of consecutive patients with acute spontaneous symptomatic ICH by three independent raters. We tested interrater and intrarater reliability using kappa statistics. RESULTS: Our validation cohort included 227 patients (58% male; median age: 72.4 (IQR: 67.1-74.6)). The interrater reliability for the main analyses (i.e. including any lobar ICH; all deep and infratentorial anatomical categories (lentiform, caudate thalamus; brainstem; cerebellum); and uncertain location) was excellent (all kappa values>0.80) both in pair-wise between-rater comparisons and across all raters. The intrarater reliability was substantial to almost perfect (k=0.83; 95%CI: 0.77-0.88 and k=0.95; 95%CI: 0.92-0.96 respectively). All kappa statistics remained consistent for individual cerebral lobar regions. CONCLUSIONS: The CHARTS instrument can be used to reliably and comprehensively map the anatomical location of spontaneous ICH, and may be helpful for studying important questions regarding causes, risk factors, prognosis, and for stratification in clinical trials.

Recurrent stroke risk and cerebral microbleed burden in ischemic stroke and TIA: A meta-analysis.

OBJECTIVE: To determine associations between cerebral microbleed (CMB) burden with recurrent ischemic stroke (IS) and intracerebral hemorrhage (ICH) risk after IS or TIA. METHODS: We identified prospective studies of patients with IS or TIA that investigated CMBs and stroke (ICH and IS) risk during ≥3 months follow-up. Authors provided aggregate summary-level data on stroke outcomes, with CMBs categorized according to burden (single, 2-4, and ≥5 CMBs) and distribution. We calculated absolute event rates and pooled risk ratios (RR) using random-effects meta-analysis. RESULTS: We included 5,068 patients from 15 studies. There were 115/1,284 (9.6%) recurrent IS events in patients with CMBs vs 212/3,781 (5.6%) in patients without CMBs (pooled RR 1.8 for CMBs vs no CMBs; 95% confidence interval [CI] 1.4-2.5). There were 49/1,142 (4.3%) ICH events in those with CMBs vs 17/2,912 (0.58%) in those without CMBs (pooled RR 6.3 for CMBs vs no CMBs; 95% CI 3.5-11.4). Increasing CMB burden increased the risk of IS (pooled RR [95% CI] 1.8 [1.0-3.1], 2.4 [1.3-4.4], and 2.7 [1.5-4.9] for 1 CMB, 2-4 CMBs, and ≥5 CMBs, respectively) and ICH (pooled RR [95% CI] 4.6 [1.9-10.7], 5.6 [2.4-13.3], and 14.1 [6.9-29.0] for 1 CMB, 2-4 CMBs, and ≥5 CMBs, respectively). CONCLUSIONS: CMBs are associated with increased stroke risk after IS or TIA. With increasing CMB burden (compared to no CMBs), the risk of ICH increases more steeply than that of IS. However, IS absolute event rates remain higher than ICH absolute event rates in all CMB burden categories.

Impaired renal function is related to deep and mixed, but not strictly lobar cerebral microbleeds in patients with ischaemic stroke and TIA.

The vasculature of the brain and kidneys are similarly vulnerable to hypertension, so their microvascular damage may be correlated. We investigated the relationship of renal function to the anatomical distribution of cerebral microbleeds (CMBs), a marker of underlying cerebral small vessel disease (hypertensive arteriopathy or cerebral amyloid angiopathy), in a Western patient cohort. This was a retrospective study of referrals to a hospital stroke service. All patients with clinical data and a T2*-weighted gradient-recalled echo (T2*-GRE) MRI were included. MRI scans were rated for CMBs using the Microbleed Anatomical Rating Scale. Renal function was assessed by estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease formula. We included 202 patients, 39 with CMBs (19.3 %); 15 had "strictly lobar", 12 had "strictly deep" and 12 had "mixed" CMBs. Patients without CMBs had a higher eGFR than those with CMBs (mean difference 6.50 ml/min/1.73 m(2), 95 % CI -14.73 to 1.72 ml/min/1.73 m(2), p = 0.121). Multivariable analysis found that those with deep and mixed CMBs had a lower eGFR than those without CMBs (mean difference -10.70 ml/min/1.73 m(2), 95 % CI -20.35 to -1.06 ml/min/1.73 m(2), p = 0.030). There was no difference in eGFR found between those with strictly lobar CMBs and those without CMBs (mean difference -1.59 ml/min/1.73 m(2), 95 % CI -13.08 to 9.89 ml/min/1.73 m(2), p = 0.79). In a Western patient cohort, there appears to be an association between eGFR and the presence of deep and mixed CMBs, but not strictly lobar CMBs. This suggests a shared vulnerability of renal afferent and cerebral deep and superficial perforating arterioles to systemic hypertension. The arteriopathy underlying strictly lobar CMBs (i.e. cerebral amyloid angiopathy), appears to be less related to renal impairment.

Prevalence and cognitive impact of medial temporal atrophy in a hospital stroke service: retrospective cohort study.

BACKGROUND: Cerebrovascular disease and neurodegeneration cause cognitive impairment and frequently coexist. AIMS: Our objectives were to investigate the prevalence and cognitive impact of medial temporal lobe atrophy - a radiological marker often associated with Alzheimer's disease - in a hospital stroke service. METHODS: Retrospective cohort study of patients from a hospital stroke service. Patients assessed for suspected ischemic stroke or transient ischemic attack, irrespective of final diagnosis, underwent neuropsychological testing and magnetic resonance imaging. medial temporal lobe atrophy, white matter hyperintensities, lacunes, and cerebral microbleeds were rated using established criteria and validated scales. The associations between medial temporal lobe atrophy and cognition were tested using multivariable logistic regression analyses, adjusted for age and imaging markers of cerebrovascular disease. RESULTS: Three hundred and ninety-three patients were included, of whom 169 (43%; 95% confidence interval: 38·1-48·1%) had medial temporal lobe atrophy; in 38 patients (9·7%), medial temporal lobe atrophy was severe (mean score ≥2). In unadjusted logistic regression analyses in the whole cohort, mean medial temporal lobe atrophy score was associated with verbal memory, nominal and perceptual skills, executive function, and speed and attention. After adjustment for age, white matter hyperintensities, number of lacunes, presence of cerebral microbleeds, previous ischemic stroke or transient ischemic attack, and premorbid intelligence quotient, mean medial temporal lobe atrophy score remained associated with impairment in verbal memory (odds ratio: 1·64; 95% confidence interval 1·04-2·58) and nominal skills (odds ratio: 1·61; 95% confidence interval 1·04-2·48). CONCLUSIONS: Medial temporal lobe atrophy is common and has an independent impact on cognitive function in a stroke service population, independent of confounding factors including age and magnetic resonance imaging markers of cerebrovascular disease. Medial temporal lobe atrophy is independently related to verbal memory and nominal skills, while small vessel pathology also contributes to speed and attention, and executive and perceptual functions.

Strictly lobar microbleeds are associated with executive impairment in patients with ischemic stroke or transient ischemic attack.

BACKGROUND AND PURPOSE: Cerebral microbleeds (CMBs) are a marker of small vessel diseases, including hypertensive arteriopathy and cerebral amyloid angiopathy, and may be associated with cognitive impairment. The relationship between CMBs and cognitive function in ischemic cerebrovascular disease remains uncertain. We, therefore, investigated the cognitive impact of CMBs in a cohort of patients with ischemic stroke or transient ischemic attack. METHODS: All patients underwent detailed and comprehensive neuropsychological testing and standardized MRI, including fluid attenuation inversion recovery, T1, T2, and gradient-recalled echo T2*-weighted sequences. CMBs, white matter changes, lacunes, and territorial cortical infarcts (defined by standardized criteria) were identified, and associations with cognition assessed. RESULTS: Three hundred twenty patients with a diagnosis of ischemic stroke or transient ischemic attack were included. Of these, 72 (22.5%) had at least 1 CMB. Of all the cognitive domains tested, only executive impairment was more prevalent in patients with CMBs than without (38% versus 25%; P=0.039). In univariate analysis, the presence of strictly lobar (but not deep) CMBs was associated with executive impairment (odds ratio, 2.49; 95% confidence interval, 1.16-5.36; P=0.019). In adjusted multivariate analyses, the presence (OR, 2.34; 95% confidence interval, 1.08-5.09; P=0.031) and number (OR, 1.33; 95% confidence interval, 1.04-1.69; P=0.022) of strictly lobar CMBs were significantly associated with executive impairment. CMBs were not associated with impairment in other cognitive domains. CONCLUSIONS: Strictly lobar CMBs are independently associated with executive dysfunction in patients with ischemic stroke or transient ischemic attack. Our findings suggest that a microangiopathy related to strictly lobar CMBs (eg, cerebral amyloid angiopathy) contributes to cognitive impairment in this population.

Spectrum of transient focal neurological episodes in cerebral amyloid angiopathy: multicentre magnetic resonance imaging cohort study and meta-analysis.

BACKGROUND AND PURPOSE: Transient focal neurological episodes (TFNE) are recognized in cerebral amyloid angiopathy (CAA) and may herald a high risk of intracerebral hemorrhage (ICH). We aimed to determine their prevalence, clinical neuroimaging spectrum, and future ICH risk. METHODS: This was a multicenter retrospective cohort study of 172 CAA patients. Clinical, imaging, and follow-up data were collected. We classified TFNE into: predominantly positive symptoms ("aura-like" spreading paraesthesias/positive visual phenomena or limb jerking) and predominantly negative symptoms ("transient ischemic attack-like" sudden-onset limb weakness, dysphasia, or visual loss). We pooled our results with all published cases identified in a systematic review. RESULTS: In our multicenter cohort, 25 patients (14.5%; 95% confidence interval, 9.6%-20.7%) had TFNE. Positive and negative symptoms were equally common (52% vs 48%, respectively). The commonest neuroimaging features were leukoaraiosis (84%), lobar ICH (76%), multiple lobar cerebral microbleeds (58%), and superficial cortical siderosis/convexity subarachnoid hemorrhage (54%). The CAA patients with TFNE more often had superficial cortical siderosis/convexity subarachnoid hemorrhage (but not other magnetic resonance imaging features) compared with those without TFNE (50% vs 19%; P=0.001). Over a median period of 14 months, 50% of TFNE patients had symptomatic lobar ICH. The meta-analysis showed a risk of symptomatic ICH after TFNE of 24.5% (95% confidence interval, 15.8%-36.9%) at 8 weeks, related neither to clinical features nor to previous symptomatic ICH. CONCLUSIONS: TFNE are common in CAA, include both positive and negative neurological symptoms, and may be caused by superficial cortical siderosis/convexity subarachnoid hemorrhage. TFNE predict a high early risk of symptomatic ICH (which may be amenable to prevention). Blood-sensitive magnetic resonance imaging sequences are important in the investigation of such episodes.

Association of cerebral microbleeds in acute ischemic stroke with high serum levels of vascular endothelial growth factor.

OBJECTIVE: To determine whether vascular endothelial growth factor (VEGF) levels are associated with the presence of cerebral microbleeds (CMBs) in patients after acute ischemic stroke. DESIGN: A cross-sectional study that used blood samples obtained within 24 hours of symptom onset from patients who experienced acute stroke to measure VEGF levels by enzyme immunoassay. A validated CMB rating scale was used to analyze acutely acquired magnetic resonance images, with the rater blind to clinical details and VEGF levels. SETTING: Accident and Emergency Department at University College Hospital, London, England. PATIENTS: Twenty patients who experienced acute ischemic stroke. MAIN OUTCOME MEASURES: Presence of CMBs and serum level of VEGF. RESULTS: Five of the 20 patients with acute ischemic stroke (25%) had CMBs. The median VEGF level in the CMB group was significantly higher than that in the group without CMBs (P = .003). CONCLUSION: An increase in vascular permeability secondary to a raised VEGF level may have a role in the genesis of CMBs in patients with acute ischemic stroke.

Acute ischaemic brain lesions in intracerebral haemorrhage: multicentre cross-sectional magnetic resonance imaging study.

Subclinical acute ischaemic lesions on brain magnetic resonance imaging have recently been described in spontaneous intracerebral haemorrhage, and may be important to understand pathophysiology and guide treatment. The underlying mechanisms are uncertain. We tested the hypothesis that ischaemic lesions are related to magnetic resonance imaging markers of the severity and type of small-vessel disease (hypertensive arteriopathy or cerebral amyloid angiopathy) in a multicentre, cross-sectional study. We studied consecutive patients with intracerebral haemorrhage from four specialist stroke centres, and age-matched stroke service referrals without intracerebral haemorrhage. Acute ischaemic lesions were assessed on magnetic resonance imaging (<3 months after intracerebral haemorrhage) using diffusion-weighted imaging. White matter changes and cerebral microbleeds were rated with validated scales. We investigated associations between diffusion-weighted imaging lesions, clinical and radiological characteristics. We included 114 patients with intracerebral haemorrhage (39 with clinically probable cerebral amyloid angiopathy) and 47 age-matched controls. The prevalence of diffusion-weighted imaging lesions was 9/39 (23%) in probable cerebral amyloid angiopathy-related intracerebral haemorrhage versus 6/75 (8%) in the remaining patients with intracerebral haemorrhage (P = 0.024); no diffusion-weighted imaging lesions were found in controls. Diffusion-weighted imaging lesions were mainly cortical and were associated with mean white matter change score (odds ratio 1.14 per unit increase, 95% confidence interval 1.02-1.28, P = 0.024) and the presence of strictly lobar cerebral microbleeds (odds ratio 3.85, 95% confidence interval 1.15-12.93, P = 0.029). Acute, subclinical ischaemic brain lesions are frequent but previously underestimated after intracerebral haemorrhage, and are three times more common in cerebral amyloid angiopathy-related intracerebral haemorrhage than in other intracerebral haemorrhage types. Ischaemic brain lesions are associated with white matter changes and cerebral microbleeds, suggesting that they result from an occlusive small-vessel arteriopathy. Diffusion-weighted imaging lesions contribute to the overall burden of vascular-related brain damage in intracerebral haemorrhage, and may be a useful surrogate marker of ongoing ischaemic injury from small-vessel damage.

Microbleed detection using automated segmentation (MIDAS): a new method applicable to standard clinical MR images.

BACKGROUND: Cerebral microbleeds, visible on gradient-recalled echo (GRE) T2* MRI, have generated increasing interest as an imaging marker of small vessel diseases, with relevance for intracerebral bleeding risk or brain dysfunction. METHODOLOGY/PRINCIPAL FINDINGS: Manual rating methods have limited reliability and are time-consuming. We developed a new method for microbleed detection using automated segmentation (MIDAS) and compared it with a validated visual rating system. In thirty consecutive stroke service patients, standard GRE T2* images were acquired and manually rated for microbleeds by a trained observer. After spatially normalizing each patient's GRE T2* images into a standard stereotaxic space, the automated microbleed detection algorithm (MIDAS) identified cerebral microbleeds by explicitly incorporating an "extra" tissue class for abnormal voxels within a unified segmentation-normalization model. The agreement between manual and automated methods was assessed using the intraclass correlation coefficient (ICC) and Kappa statistic. We found that MIDAS had generally moderate to good agreement with the manual reference method for the presence of lobar microbleeds (Kappa = 0.43, improved to 0.65 after manual exclusion of obvious artefacts). Agreement for the number of microbleeds was very good for lobar regions: (ICC = 0.71, improved to ICC = 0.87). MIDAS successfully detected all patients with multiple (≥2) lobar microbleeds. CONCLUSIONS/SIGNIFICANCE: MIDAS can identify microbleeds on standard MR datasets, and with an additional rapid editing step shows good agreement with a validated visual rating system. MIDAS may be useful in screening for multiple lobar microbleeds.

Cerebral microbleeds and vascular cognitive impairment.

MRI manifestations of small vessel diseases including white matter hyperintensities and lacunes have been recognized as potential substrates of vascular cognitive impairment for many years. Cerebral microbleeds (CMBs)--small, perviascular haemorrhages seen as small, well-demarcated, hypointense, rounded lesions on MRI sequences sensitive to magnetic susceptibility effects--are also now recognized as an imaging marker for small vessel pathology, but their clinical impact on cognition remains uncertain. CMBs are present in about a third of patients with ischaemic stroke, and in a high proportion of patients with Alzheimer's disease, cerebral amyloid angiopathy, and vascular dementia. They have also been increasingly found in normal elderly populations, particularly using sequences optimized for their detection. Some recent studies have suggested an effect of CMBs on cognition, which could relate directly to focal damage to or dysfunction of adjacent brain tissues; alternatively, CMBs may be a more general marker for the severity of small vessel pathology related to hypertension or cerebral amyloid angiopathy. CMBs may therefore play a role in understanding the underlying mechanisms of vascular cognitive impairment, in diagnosis, and in assessing its severity and prognosis; this review considers recent evidence on this topic.

Antithrombotic drug use, cerebral microbleeds, and intracerebral hemorrhage: a systematic review of published and unpublished studies.

BACKGROUND AND PURPOSE: Cerebral microbleeds (MB) are potential risk factors for intracerebral hemorrhage (ICH), but it is unclear if they are a contraindication to using antithrombotic drugs. Insights could be gained by pooling data on MB frequency stratified by antithrombotic use in cohorts with ICH and ischemic stroke (IS)/transient ischemic attack (TIA). METHODS: We performed a systematic review of published and unpublished data from cohorts with stroke or TIA to compare the presence of MB in: (1) antithrombotic users vs nonantithrombotic users with ICH; (2) antithrombotic users vs nonusers with IS/TIA; and (3) ICH vs ischemic events stratified by antithrombotic use. We also analyzed published and unpublished follow-up data to determine the risk of ICH in antithrombotic users with MB. RESULTS: In a pooled analysis of 1460 ICH and 3817 IS/TIA, MB were more frequent in ICH vs IS/TIA in all treatment groups, but the excess increased from 2.8 (odds ratio; range, 2.3-3.5) in nonantithrombotic users to 5.7 (range, 3.4-9.7) in antiplatelet users and 8.0 (range, 3.5-17.8) in warfarin users (P difference=0.01). There was also an excess of MB in warfarin users vs nonusers with ICH (OR, 2.7; 95% CI, 1.6-4.4; P<0.001) but none in warfarin users with IS/TIA (OR, 1.3; 95% CI, 0.9-1.7; P=0.33; P difference=0.01). There was a smaller excess of MB in antiplatelet users vs nonusers with ICH (OR, 1.7; 95% CI, 1.3-2.3; P<0.001), but findings were similar for antiplatelet users with IS/TIA (OR, 1.4; 95% CI, 1.2-1.7; P<0.001; P difference=0.25). In pooled follow-up data for 768 antithrombotic users, presence of MB at baseline was associated with a substantially increased risk of subsequent ICH (OR, 12.1; 95% CI, 3.4-42.5; P<0.001). CONCLUSIONS: The excess of MB in warfarin users with ICH compared to other groups suggests that MB increase the risk of warfarin-associated ICH. Limited prospective data corroborate these findings, but larger prospective studies are urgently required.

MRI detection of new microbleeds in patients with ischemic stroke: five-year cohort follow-up study.

BACKGROUND AND PURPOSE: Little is known about the development of cerebral microbleeds in patients with ischemic stroke. We studied the incidence of new microbleeds in a cohort of patients with ischemic stroke or transient ischemic attack screened for microbleeds at baseline. METHODS: Twenty-one surviving patients with ischemic stroke or transient ischemic attack were followed up after a mean interval of 5.5 years with repeat MRI and clinical assessment. Predictors of new microbleeds were tested in logistic regression. RESULTS: Of patients with microbleeds at baseline, 50% had new microbleeds at follow-up compared with 8% of those without baseline microbleeds (P=0.047). The presence of microbleeds at baseline predicted new microbleeds (OR, 12; 95% CI, 1.02 to 141.34; P=0.048), as did mean systolic blood pressure (OR, 1.28 per unit increase; 95% CI, 1.23 to 1.33; P<0.001). One patient had a stroke (intracerebral hemorrhage) during follow-up. CONCLUSIONS: Patients with ischemic stroke or transient ischemic attack are at risk of developing new microbleeds over 5.5 years, despite most surviving patients remaining clinically stable. Systolic blood pressure is the strongest predictor of microbleed development; better control of hypertension may help prevent new microbleed formation.