Reduced severity of strokes in patients with silent brain infarctions

Effects of silent brain infarction on the hemorrhagic transformation and prognosis in patients with acute ischemic stroke after intravenous thrombolysis

Background

Silent brain infarction (SBI) is a special type of stroke with no definitive time of onset, which can be found on pre-thrombolysis imaging examination in some patients with acute ischemic stroke (AIS). However, the significance of SBI on intracranial hemorrhage transformation (HT) and clinical outcomes after intravenous thrombolysis therapy (IVT) is uncertain. We aimed to explore the effects of SBI on intracranial HT and the 3-month clinical outcome in patients with AIS after IVT.

Methods

We consecutive collected patients who were diagnosed with ischemic stroke and received IVT from August 2016 to August 2022, and conducted a retrospective analysis in this study. The clinical and laboratory data were obtained from hospitalization data. Patients were divided into SBI and Non-SBI groups based on clinical and neuroimaging data. We use Cohen's Kappa to assess the interrater reliability between the two evaluators, and multivariate logistic regression analysis was used to further assess the association between SBI, HT and clinical outcomes at 3 months after IVT.

Results

Of the 541 patients, 231 (46.1%) had SBI, 49 (9.1%) had HT, 438 (81%) had favorable outcome, 361 (66.7%) had excellent outcome. There was no significant difference in the incidence of HT (8.2 vs. 9.7%, p = 0.560) and favorable outcome (78.4% vs. 82.9%, p = 0.183) between patients with SBI and Non-SBI. However, patients with SBI had a lower incidence of excellent outcome than the patients with Non-SBI (60.2% vs. 71.6%%, p = 0.005). After adjustment for major covariates, multivariate logistic regression analysis disclosed that SBI was independently associated with the increased risk of worse outcome (OR = 1.922, 95%CI: 1.229-3.006, p = 0.004).

Conclusion

We found that SBI was no effect for HT after thrombolysis in ischemic stroke patients, and no effect on favorable functional outcome at 3 months. Nevertheless, SBI remained an independent risk factor for non-excellent functional outcomes at 3 months.

Phenotypes of Chronic Covert Brain Infarction in Patients With First-Ever Ischemic Stroke: A Cohort Study

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Background and Purpose:

The aim of this study was to assess the rate of chronic covert brain infarctions (CBIs) in patients with acute ischemic stroke (AIS) and to describe their phenotypes and diagnostic value.

Methods:

This is a single-center cohort study including 1546 consecutive patients with first-ever AIS on magnetic resonance imaging imaging from January 2015 to December 2017. The main study outcomes were CBI phenotypes, their relative frequencies, location, and association with vascular risk factors.

Results:

Any CBI was present in 574/1546 (37% [95% CI, 35%–40%]) of patients with a total of 950 CBI lesions. The most frequent locations of CBI were cerebellar in 295/950 (31%), subcortical supratentorial in 292/950 (31%), and cortical in 213/950 (24%). CBI phenotypes included lacunes (49%), combined gray and white matter lesions (30%), gray matter lesions (13%), and large subcortical infarcts (7%). Vascular risk profile and white matter hyperintensities severity (19% if no white matter hyperintensity, 63% in severe white matter hyperintensity, P<0.001) were associated with presence of any CBI. Atrial fibrillation was associated with cortical lesions (adjusted odds ratio, 2.032 [95% CI, 1.041–3.967]). Median National Institutes of Health Stroke Scale scores on admission were higher in patients with an embolic CBI phenotype (median National Institutes of Health Stroke Scale, 5 [2–10], P=0.025).

Conclusions:

CBIs were present in more than a third of patients with first AIS. Their location and phenotypes as determined by MRI were different from previous studies using computed tomography imaging. Among patients suffering from AIS, those with additional CBI represent a vascular high-risk subgroup and the association of different phenotypes of CBIs with differing risk factor profiles potentially points toward discriminative AIS etiologies.

Use of anticoagulant therapy and cerebral microbleeds: a systematic review and meta-analysis

BACKGROUND

Anticoagulant therapy increases the risk that cerebral microbleeds (CMBs) progress to intracerebral hemorrhage, but whether the therapy increases risk of CMB occurrence is unclear. We performed a systematic review and meta-analysis to investigate the potential association between anticoagulant use and CMB occurrence in stroke and stroke-free individuals.

METHODS

We searched observational studies in PubMed, Ovid EMBASE, and Cochrane Library from their inception until September 2019. We calculated the pooled odds ratio (OR) and 95% confidence interval (CI) for the prevalence and incidence of CMBs in anticoagulant users relative to non-anticoagulant users.

RESULTS

Forty-seven studies with 25,245 participants were included. The pooled analysis showed that anticoagulant use was associated with CMB prevalence (OR 1.54, 95% CI 1.26-1.88). The association was observed in subgroups stratified by type of participants: stroke-free, OR 1.86, 95% CI 1.25-2.77; ischemic stroke/transient ischemic attack, OR 1.33, 95% CI 1.06-1.67; and intracerebral hemorrhage, OR 2.26, 95% CI 1.06-4.83. Anticoagulant use was associated with increased prevalence of strictly lobar CMBs (OR 1.68, 95% CI 1.22-2.32) but not deep/infratentorial CMBs. Warfarin was associated with increased CMB prevalence (OR 1.64, 95% CI 1.23-2.18), but novel oral anticoagulants were not. Anticoagulant users showed higher incidence of CMBs during long-term follow-up (OR 1.72, 95% CI 1.22-2.44).

CONCLUSION

Anticoagulant use is associated with higher prevalence and incidence of CMBs. This association appears to depend on location of CMBs and type of anticoagulants. More longitudinal investigations with adjustment for confounders are required to establish the causality.

Multiple Silent Brain Infarcts Are Associated with Severer Stroke in Patients with First-Ever Ischemic Stroke without Advanced Leukoaraiosis

BACKGROUND

Silent brain infarct (SBI) is associated with symptomatic stroke, but the association between SBI and acute ischemic stroke severity is uncertain. We aimed at investigating the association between SBI number and stroke severity in patients with first-ever ischemic stroke without advanced leukoaraiosis.

METHODS

This study included 115 patients with first-ever ischemic stroke without advanced leukoaraiosis. National Institutes of Health Stroke Scale (NIHSS) scores were measured. Magnetic resonance imaging (MRI) was performed to detect the acute ischemic infarct and SBI. The location of infarct was divided into anterior and posterior circulations. The size of infarct was divided into large (≥15 mm) and small (<15 mm) infarctions. The number of SBIs was divided into single and multiple (r2) subgroups. The association between SBI and the NIHSS score was analyzed by stratification of stroke locations. The associations between SBI and the NIHSS score and the size of the acute ischemic infarct were analyzed by logistic regression.

RESULTS

Of the 74 patients with SBI, single SBI was 30 (40.5%) and multiple SBIs were 44 (59.5%). Age (odds ratio [OR] = 1.125, P < .001) and hypertension (OR = 3.562, P < .05) were independent risk factors for SBI. When adjusted for all the other vascular risk factors, multiple SBIs had a higher percentage of more than 3 NIHSS scores (OR = 3.59, 95% confidence interval [CI]: 1.00-12.99, P = .048) and a large acute ischemic infarct (OR = 3.71, 95% CI: 1.23-11.22, P = .020) than no SBI.

CONCLUSION

Multiple SBIs have severer neurological deficits and larger infarcts for ischemic stroke than no SBI, which may suggest the large-artery or cardiovascular vasculopathy evolution and poor collateral circulation in patients with multiple SBIs.

Leukoaraiosis is Associated with Worse Short-Term Functional and Cognitive Recovery after Minor Stroke

Whether leukoaraiosis burden retards short-term recovery after minor stroke is unclear. We investigated the association between leukoaraiosis and early recovery of neurological function after a first minor ischemic stroke in 217 acute stroke patients (National Institutes of Health Stroke Scale (NIHSS) score ≤5). Leukoaraiosis severity was graded according to the Fazekas scale and categorized into none to mild (0-2; n = 143) or severe (3-6; n = 74) groups. NIHSS and Minimum Mental State Examination (MMSE) were assessed at baseline and at 30 days. Univariate analysis revealed that the severe leukoaraiosis group was older in age (P < 0.001) and had fewer low MMSE patients than non-mild group at baseline (39.1% vs 55.9%, P = 0.003). However, the MMSE improved in none to mild group but not in the severe group at 30-day (15.4% vs 36.5%, P < 0.001). At 30-day, the severe leukoaraiosis group had higher NIHSS scores than the none-mild group (P = 0.04). Multiple linear regression analyses demonstrated that leukoaraiosis severity and admission NIHSS were independently associated with the NIHSS score on day 30 (P = 0.034, 95% CI 0.004-0.091 and P = 0.001, 95% CI 0.011-0.04). Binary regression analyses showed that leukoaraiosis severity and admission MMSE were significantly associated with MMSE (dichotomized) at 30-day (OR 2.1, P < 0.01, 95% CI 1.7-2.6 and OR 5.1, P < 0.01, 95% CI 2.1-12.8). Leukoaraiosis burden is an independent predictor of worse short-term functional and cognitive recovery after a minor ischemic stroke.

Increased VEGF and decreased SDF-1α in patients with silent brain infarction are associated with better prognosis after first-ever acute lacunar stroke

BACKGROUND

Pre-existing silent brain infarctions (SBIs) have been reported to be associated with better outcomes after first-ever symptomatic ischemic stroke, although the mechanism of this remains unclear. We investigated the association between SBIs, outcomes of acute lacunar infarction, and biomarkers including vascular endothelial growth factor (VEGF), stromal cell-derived factor-1α (SDF-1α), macrophage migration inhibitory factor (MIF), and high-mobility group box-1 (HMGB1).

METHODS

A total of 68 consecutive patients diagnosed with first-ever lacunar infarction (<20 mm) within 24 hours of symptom onset were included in this study. Clinical, laboratory, and imaging data were obtained. Plasma levels of VEGF, SDF-1α, MIF, and HMGB1 were assessed using Enzyme-Linked Immunosorbent Assay kits.

RESULTS

SBIs were noted in 31 of the 68 patients. Although the initial National Institutes of Health Stroke Scale scores were not related with the presence of SBIs (P = .313), patients with SBIs had better outcomes at 3 months (P = .029). Additionally, plasma VEGF levels were higher (P = .035) and SDF-1α levels were lower (P < .001) in patients with SBIs. Logistic regression analysis indicated that VEGF and SDF-1α were independently associated with the presence of SBIs.

CONCLUSIONS

SBIs are associated with favorable outcomes in patients with first-ever acute lacunar infarction and higher levels of VEGF, and lower levels of SDF-1α in these patients may contribute to their more favorable prognosis.

Differential impact of unrecognised brain infarction on stroke outcome in non-valvular atrial fibrillation

There has been little information regarding the impact of unrecognised brain infarctions (UBIs) on stroke outcome in patients with non-valvular atrial fibrillation (NVAF). By using volumetric analysis of ischaemic lesions, we evaluated the potential impact of UBIs on clinical outcome according to their presence and categorised type. This study enrolled 631 patients with NVAF having no clinical stroke history. UBIs were categorised into three types as territorial, lacunar, or subcortical. We collected stroke severity, functional outcome at three months, and the total volume of UBIs and acute infarction lesions. We investigated the association between clinical outcome and the type or volume of UBI, using a linear mixed model and logistic regression analysis. UBIs were detected in 285 (45.2 %) patients; territorial UBIs were observed in 24.4 % of patients (154/631), lacunar UBIs in 25 % (158/631), and subcortical UBIs in 15.7 % (99/631). Although initial stroke severity was not different between patients with UBIs and those without, those with UBIs had less improvement during hospitalisation, leading to poorer outcome at three months. Among the three types of UBIs, only territorial UBIs were associated with poor outcome, especially in patients with relatively smaller acute infarction volume. UBIs, in particular, territorial UBIs, may be considered as predictors for poor outcome after ischaemic stroke in patients with NVAF. Our results suggest that the impact of UBIs on clinical outcome differs according to the type of UBIs and the acute stroke severity.

Topographical disorientation after ischemic mini infarct in the dorsal hippocampus: whispers in silence

Silent focal ischemic mini infarcts in the brain are thought to cause no clinically overt symptoms. Some populations of hippocampal cells are particularly sensitive to ischemic events, however, rendering hippocampal functions especially vulnerable to ischemia-induced deficits. The present study investigated whether an otherwise silent ischemic mini infarct in the hippocampus (HPC) can produce impairments in spatial performance in rats. Spatial performance was assessed in the ziggurat task (ZT) using a 10-trial spatial learning protocol for 4 days prior to undergoing hippocampal ischemic lesion or sham surgery. Hippocampal silent ischemia was induced by infusion of endothelin-1 (ET-1), a potent vasoconstrictor, into either the dorsal or the ventral hippocampus (dHPC and vHPC). When tested postoperatively in the ZT using a standard testing protocol for 8 days, rats with hippocampal lesions exhibited no spatial deficit. Although spatial learning and memory in the ZT were not affected by the ET-1-induced silent ischemia, rats with dHPC stroke showed more returns when navigating the ZT as opposed to the vHPC rats. Comparison of region-specific HPC lesions in the present study indicated that dorsal hippocampal function is critically required for topographic orientation in a complex environment. Topographic disorientation as reflected by enhanced return behaviors may represent one of the earliest predictors of cognitive decline after silent ischemic insult that may be potentially traced with sensitive clinical examination in humans.

Small vessel disease and memory loss: what the clinician needs to know to preserve patients' brain health

Small vessel disease (SVD) in the brain manifests in the periventricular and deep white matter and radiographically is described as "leukoaraiosis". It is increasingly recognized as a cause of morbidity from middle age onward and this clinical relevance has paralleled advances in the field of neuroradiology. Overall, SVD is a heterogenous group of vascular disorders that may be asymptomatic, or a harbinger of many conditions that jeopardize brain health. Management and prevention focuses on blood pressure control, lifestyle modification, and symptomatic treatment.

Association of ambulatory blood pressure and heart rate with advanced white matter lesions in ischemic stroke patients

BACKGROUND

White matter lesions (WMLs) are a common finding in stroke patients, and the most important risk factors are old age and hypertension. Although many studies have described the association between WMLs and ambulatory blood pressure monitoring (ABPM) parameters in healthy subjects and hypertensive patients, little is known about the association in hypertensive ischemic stroke patients.

METHODS

From July 2009 to June 2012, 169 consecutive hypertensive noncardioembolic ischemic stroke patients were recruited within 1 week of suffering a stroke, and ABPM was applied 1 or 2 weeks after stroke onset. The subjects were classified into 2 groups according to the presence of advanced WMLs, and their ABPM parameters were compared. Finally, multivariable logistic regression analyses were performed to investigate the independent relationships between WMLs and ABPM parameters.

RESULTS

Seventy (41%) patients had advanced WMLs. In univariable analysis, higher 24-hour, awake, and asleep systolic blood pressure (SBP)/diastolic blood pressure levels and 24-hour pulse pressure were associated with advanced WMLs. However, circadian blood pressure parameters such as 24-hour BP variability, morning surge, and nocturnal dipping pattern were not associated with advanced WMLs. After adjustments, old age (odds ratio (OR) = 1.063; 95% confidence interval (CI) = 1.024-1.104; P = 0.002), high 24-hour SBP levels (OR = 1.055; 95% CI = 1.028-1.082; P < 0.001), and high 24-hour heart rate (OR = 1.041; 95% CI = 1.006-1.078; P = 0.023) were independently associated with advanced WMLs.

CONCLUSIONS

In addition to old age and elevated 24-hour SBP, increased heart rate is associated with advanced WMLs in ischemic stroke patients. Heart rate deserves more attention in predicting advanced WMLs in those patients.

The 'silence' of silent brain infarctions may be related to chronic ischemic preconditioning and nonstrategic locations rather than to a small infarction size

OBJECTIVE

Silent brain infarctions are the silent cerebrovascular events that are distinguished from symptomatic lacunar infarctions by their 'silence'; the origin of these infarctions is still unclear. This study analyzed the characteristics of silent and symptomatic lacunar infarctions and sought to explore the mechanism of this 'silence'.

METHODS

In total, 156 patients with only silent brain infarctions, 90 with only symptomatic lacunar infarctions, 160 with both silent and symptomatic lacunar infarctions, and 115 without any infarctions were recruited. Vascular risk factors, leukoaraiosis, and vascular assessment results were compared. The National Institutes of Health Stroke Scale scores were compared between patients with only symptomatic lacunar infarctions and patients with two types of infarctions. The locations of all of the infarctions were evaluated. The evolution of the two types of infarctions was retrospectively studied by comparing the infarcts on the magnetic resonance images of 63 patients obtained at different times.

RESULTS

The main risk factors for silent brain infarctions were hypertension, age, and advanced leukoaraiosis; the main factors for symptomatic lacunar infarctions were hypertension, atrial fibrillation, and atherosclerosis of relevant arteries. The neurological deficits of patients with only symptomatic lacunar infarctions were more severe than those of patients with both types of infarctions. More silent brain infarctions were located in the corona radiata and basal ganglia; these locations were different from those of the symptomatic lacunar infarctions. The initial sizes of the symptomatic lacunar infarctions were larger than the silent brain infarctions, whereas the final sizes were almost equal between the two groups.

CONCLUSIONS

Chronic ischemic preconditioning and nonstrategic locations may be the main reasons for the 'silence' of silent brain infarctions.