A review of genetic causes of ischemic and hemorrhagic stroke

Genetic insights into the relationship between immune cell characteristics and ischemic stroke: A bidirectional Mendelian randomization study

BACKGROUND AND PURPOSE

Ischemic stroke, a major contributor to global disability and mortality, is underpinned by intricate pathophysiological mechanisms, notably neuroinflammation and immune cell dynamics. Prior research has identified a nuanced and often paradoxical link between immune cell phenotypes and ischemic stroke susceptibility. The aim of this study was to elucidate the potential causal links between the median fluorescence intensity (MFI) and morphological parameters (MP) of 731 immune cell types and ischemic stroke risk.

METHODS

By analyzing extensive genetic datasets, we conducted comprehensive Mendelian randomization (MR) analyses to discern the genetic correlations between diverse immune cell attributes (MFI and MP) and ischemic stroke risk.

RESULTS

Our study identified key immune cell signatures linked to ischemic stroke risk. Both B cells and T cells, among other immune cell types, have a bidirectional influence on stroke risk. Notably, the regulatory T-cell phenotype demonstrates significant neuroprotective properties, with all odds ratio (OR) values and confidence intervals (CIs) being less than 1. Furthermore, CD39 phenotype immune cells, particularly CD39+ CD8+ T cells (inverse variance weighting [IVW] OR 0.92, 95% CI 0.87-0.97; p = 0.002) and CD39+ activated CD4 regulatory T cells (IVW OR 0.93, 95% CI 0.90-0.97; p < 0.001), show notable neuroprotection against ischemic stroke.

CONCLUSION

This investigation provides new genetic insights into the interplay between various immune cells and ischemic stroke, underscoring the complex role of immune processes in stroke pathogenesis. These findings lay a foundation for future research, which may confirm and expand upon these links, potentially leading to innovative immune-targeted therapies for stroke prevention and management.

Machine learning identifies novel coagulation genes as diagnostic and immunological biomarkers in ischemic stroke

BACKGROUND

Coagulation system is currently known associated with the development of ischemic stroke (IS). Thus, the current study is designed to identify diagnostic value of coagulation genes (CGs) in IS and to explore their role in the immune microenvironment of IS.

METHODS

Aberrant expressed CGs in IS were input into unsupervised consensus clustering to classify IS subtypes. Meanwhile, key CGs involved in IS were further selected by weighted gene co-expression network analysis (WGCNA) and machine learning methods, including random forest (RF), support vector machine (SVM), generalized linear model (GLM) and extreme-gradient boosting (XGB). The diagnostic performance of key CGs were evaluated by receiver operating characteristic (ROC) curves. At last, quantitative PCR (qPCR) was performed to validate the expressions of key CGs in IS.

RESULTS

IS patients were classified into two subtypes with different immune microenvironments by aberrant expressed CGs. Further WGCNA, machine learning methods and ROC curves identified ACTN1, F5, TLN1, JMJD1C and WAS as potential diagnostic biomarkers of IS. In addition, their expressions were significantly correlated with macrophages, neutrophils and/or T cells. GSEA also revealed that those biomarkers may regulate IS via immune and inflammation. Moreover, qPCR verified the expressions of ACTN1, F5 and JMJD1C in IS.

CONCLUSIONS

The current study identified ACTN1, F5 and JMJD1C as novel coagulation-related biomarkers associated with IS immune microenvironment, which enriches our knowledge of coagulation-mediated pathogenesis of IS and sheds light on next-step in vivo and in vitro experiments to elucidate the relevant molecular mechanisms.

Association of PON-1 polymorphism with susceptibility to and severity of ischemic stroke in the Chinese population

Aim: The authors aimed to investigate whether polymorphisms of PON-1 were associated with the susceptibility to and severity of ischemic stroke (IS). Methods: In this study, 302 IS patients and 303 healthy controls were enrolled. Polymorphisms rs854560 and rs854572 of PON-1 were detected using SNaPshot single-nucleotide polymorphism typing technology. Results: The rs854572 polymorphism of the PON-1 gene showed a significant correlation with IS, and its GG genotype reduced the risk of IS (recessive model, p = 0.001). The GG genotype was also associated with mild stroke (p = 0.032). No association was observed between rs854560 and IS. Conclusion: PON-1 rs854572 polymorphism was related to the risk of IS and could be a biomarker to access the severity of IS.

Deletion in COL4A2 is associated with a three-generation variable phenotype: from fetal to adult manifestations

Genetic alterations in COL4A2 are less common than those of COL4A1 and their fetal phenotype has not been described to date. We describe a three-generation family with an intragenic deletion in COL4A2 associated with a prenatal diagnosis of recurrent fetal intracerebral hemorrhage (ICH), and a myriad of cerebrovascular manifestations. Exome sequencing, co-segregation analysis, and imaging studies were conducted on eight family members including two fetuses with antenatal ICH. Histopathological evaluation was performed on the terminated fetuses. An intragenic heterozygous pathogenic in-frame deletion; COL4A2, c.4151_4168del, (p.Thr1384_Gly1389del) was identified in both fetuses, their father with hemiplegic cerebral palsy (CP), as well as other family members. Postmortem histopathological examination identified microscopic foci of heterotopias and polymicrogyria. The variant segregated in affected individuals demonstrating varying degrees of penetrance and a wide phenotypic spectrum including periventricular venous hemorrhagic infarction causing hemiplegic CP, polymicrogyria, leukoencephalopathy, and lacunar stroke. We present radiographic, pathological, and genetic evidence of prenatal ICH and show, for what we believe to be the first time, a human pathological proof of polymicrogyria and heterotopias in association with a COL4A2 disease-causing variant, while illustrating the variable phenotype and partial penetrance of this disease. We highlight the importance of genetic analysis in fetal ICH and hemiplegic CP.

Differentially Expressed Genes and Their Clinical Significance in Ischaemic Stroke: An In-Silico Study

Background

Ischaemic stroke (IS), a multifactorial neurological disorder, is mediated by interplay between genes and the environment and, thus, blood-based IS biomarkers are of significant clinical value. Therefore, this study aimed to find global differentially expressed genes (DEGs) in-silico, to identify key enriched genes via gene set enrichment analysis (GSEA) and to determine the clinical significance of these genes in IS.

Methods

Microarray expression dataset GSE22255 was retrieved from the Gene Expression Omnibus (GEO) database. It includes messenger ribonucleic acid (mRNA) expression data for the peripheral blood mononuclear cells of 20 controls and 20 IS patients. The bioconductor-package ‘affy’ was used to calculate expression and a pairwise t-test was applied to screen DEGs (P < 0.01). Further, GSEA was used to determine the enrichment of DEGs specific to gene ontology (GO) annotations.

Results

GSEA analysis revealed 21 genes to be significantly plausible gene markers, enriched in multiple pathways among all the DEGs (n = 881). Ten gene sets were found to be core enriched in specific GO annotations. JunD, NCX3 and fibroblast growth factor receptor 4 (FGFR4) were under-represented and glycoprotein M6-B (GPM6B) was persistently over-represented.

Conclusion

The identified genes are either associated with the pathophysiology of IS or they affect post-IS neuronal regeneration, thereby influencing clinical outcome. These genes should, therefore, be evaluated for their utility as suitable markers for predicting IS in clinical scenarios.

Association of APOE Gene Polymorphism with Stroke Patients from Rural Eastern India

CONTEXT

Studies from the different ethnic regions of the world have reported variable results on association of APOE gene polymorphism in stroke.

AIM

The aim of this study is to find out the possible association of APOE polymorphism in stroke patients in ethnic Bengali population.

SETTINGS AND DESIGN

A prospective case-control study was undertaken in the Department of Neurology, Burdwan Medical College, Burdwan, West Bengal, India, over a period of 3 years.

METHODS

We collected 10 ml venous blood samples from 148 clinically and radiologically diagnosed acute stroke patients (80 of ischemic stroke and 68 of intracerebral hemorrhage) and consecutive 108 ethnic age- and sex-matched controls, in ethylenediaminetetraacetic acid vials after informed written consent. Genomic DNA was prepared at S.N. Pradhan Centre of Neurosciences, University of Calcutta, Kolkata, India. Exotic single-nucleotide polymorphisms (rs429358, rs 7412) were analyzed by polymerase chain reaction-restriction fragment length polymorphism for genotype of APOE.

RESULTS

The frequencies of different APOE allele among 80 ischemic stroke patients were 5.6% (n = 9) for E2, 75.68% (n = 121) for E3, and 18.7% (n = 30) for E4. The E3 allele is significantly over-represented (P = 0.004) in controls compared to the patients (88% in controls vs 75.6% ischemic stroke patients and 80% hemorrhagic patients). A significantly high frequency of APOE4 allele was observed in ischemic (18.7%) and hemorrhagic patients (11%) compared to controls (8%). The E4 allele plays a major risk for developing ischemic stroke [odds ratio (OR) = 2.744; 95% confidence interval (CI): 1.43-5.10] and E3 plays a protective role for hemorrhagic stroke (OR = 0.53; 95% CI: 0.29-0.96), while E4 allele plays a nonsignificant (P = 0.31) increase in trend in hemorrhage stroke (OR = 1.4).

CONCLUSIONS

There is significant association of APOE gene polymorphism in stroke patients of ethnic Bengali population. The E4 allele increases significant risk for development of ischemic strokes, and it also plays nonsignificant increase in trend in hemorrhagic strokes.

Combined Effects of MMP-7, MMP-8 and MMP-26 on the Risk of Ischemic Stroke

Ischemic stroke (IS) is multifactorial causation combining with traditional cardiovascular disease (CVD) and genetic risk factors. Combined effects of MMP-7, MMP-8 and MMP-26 on the risk of IS remain incompletely understood. We aimed to assess individual and joint effects for IS risk by weighted genetic risk score (wGRS) from these three genes and traditional CVD risk factors. A case-control study including 500 cases with IS and 500 stroke-free healthy controls frequency-matched with cases by age and sex was conducted. The wGRS was a weighted average of the number of risk genotype across selected SNPs from MMP-7, MMP-8 and MMP-26. Multivariate logistic regression models were used to analyze the relationship between wGRS and risk of IS. A wGRS in the second tertile was associated with a 1.5-fold increased risk of IS compared with the lowest tertile after adjusting for traditional CVD risk factors. Compared to subjects with low genetic and low modifiable CVD risk, those with high genetic and high modifiable CVD risk had the highest risk of IS (adjusted-OR = 5.75). In conclusion, higher wGRS was significantly associated with an increased risk for IS. A significant interaction between genetic and traditional CVD risk factors was also found on the risk of IS.

Cross-Reactivity as a Mechanism Linking Infections to Stroke

The relevance of infections as risk factor for cerebrovascular disease is being increasingly recognized. Nonetheless, the pathogenic link between the two entities remains poorly understood. Consistent with recent advances in medicine, the present work addresses the hypothesis that infection-induced immune responses may affect human proteins associated with stroke. Applying established procedures in bioinformatics, the pathogen antigens and the human proteins were searched for common sequences using pentapeptides as probes. The resulting data demonstrate massive peptide sharing between infectious pathogens-such as Chlamydia pneumoniae, Streptococcus pneumoniae, Tannerella forsythia, Haemophilus influenzae, Influenza A virus, and Cytomegalovirus-and human proteins related to risk of ischemic and hemorrhagic stroke. Moreover, the shared peptides are also evident in a number of epitopes experimentally proven immunopositive in the human host. The present findings suggest cross-reactivity as a potential mechanistic link between infections and stroke.

Genetic testing for Mendelian stroke due to cerebrovascular anomalies and other syndromes

Stroke is defined as a focal or at times global neurological impairment of sudden onset and presumed vascular origin. 85% of strokes are due to cerebral ischemia and the other 15% to primary intracerebral hemorrhage.

Ischemic stroke (IS) is characterized by complete or partial obstruction of a vessel in the brain, resulting in lack of blood supply and death of brain tissue. The most common causes of IS are atherosclerosis, cardioembolism and small-vessel disease (lacunar stroke). Genetic factors play important role. Incidence rates for IS in the 15- to 45-year age range are ≈10 per 100,000 person years.

Hemorrhagic stroke (HS) is the least treatable and the most fatal form of cerebrovascular disease. Genetic mechanisms play a role in its development. Occurrence depends on many risk factors, including hypertension, heavy alcohol intake and anticoagulant treatment. According to the World Health Organization, 15 million people suffer stroke worldwide each year. The overall incidence of spontaneous HS worldwide is 24.6 per 100,000 person years. Strokes are the third most common cause of death and the most common cause of disability in developed countries.

This Utility Gene Test was developed on the basis of an analysis of the literature and existing diagnostic protocols. It is useful for confirming diagnosis, as well as for differential diagnosis, couple risk assessment and access to clinical trials.

Towards phenotyping stroke: Leveraging data from a large-scale epidemiological study to detect stroke diagnosis

Objective

1) To develop a machine learning approach for detecting stroke cases and subtypes from hospitalization data, 2) to assess algorithm performance and predictors on real-world data collected by a large-scale epidemiology study in the US; and 3) to identify directions for future development of high-precision stroke phenotypic signatures.

Materials and methods

We utilized 8,131 hospitalization events (ICD-9 codes 430–438) collected from the Greater Cincinnati/Northern Kentucky Stroke Study in 2005 and 2010. Detailed information from patients’ medical records was abstracted for each event by trained research nurses. By analyzing the broad list of demographic and clinical variables, the machine learning algorithms predicted whether an event was a stroke case and, if so, the stroke subtype. The performance was validated on gold-standard labels adjudicated by stroke physicians, and results were compared with stroke classifications based on ICD-9 discharge codes, as well as labels determined by study nurses.

Results

The best performing machine learning algorithm achieved a performance of 88.57%/93.81%/92.80%/93.30%/89.84%/98.01% (accuracy/precision/recall/F-measure/area under ROC curve/area under precision-recall curve) on stroke case detection. For detecting stroke subtypes, the algorithm yielded an overall accuracy of 87.39% and greater than 85% precision on individual subtypes. The machine learning algorithms significantly outperformed the ICD-9 method on all measures (P value<0.001). Their performance was comparable to that of study nurses, with better tradeoff between precision and recall. The feature selection uncovered a subset of predictive variables that could facilitate future development of effective stroke phenotyping algorithms.

Discussion and conclusions

By analyzing a broad array of patient data, the machine learning technologies held promise for improving detection of stroke diagnosis, thus unlocking high statistical power for subsequent genetic and genomic studies.

Association of apolipoprotein E genotype with outcome in hospitalized ischemic stroke patients

The aim of this study was to study the ability of the genotype to predict impairment and disability in hospitalized ischemic stroke (IS) patients after hospital discharge and 6 months after the onset of stroke symptoms.A total of 786 patients with a first IS were enrolled. Apolipoprotein E (ApoE) polymorphism was examined using polymerase chain reaction. Stroke subtype was classified using the Oxfordshire Community Stroke Project classification scheme and the Trial of Org 10172 in Acute Stroke Treatment criteria. Impairment as assessed using the National Institutes of Health Stroke Scale (NIHSS), and disability as measured using the modified Rankin Scale (mRS), were compared against the ApoE genotype.There was no significant association between the type of ApoE allele present and the stroke subtype. On multivariate regression analysis, the apolipoprotein EE4 allele genotype did not predict poor outcome at discharge and or at 6 months after stroke onset. A higher NIHSS score on admission, older age, and higher fasting glucose levels did predict poor outcome at hospital discharge. Higher glucose levels and higher NIHSS scores on admission were independent risk factors predicting poor neurologic status at 6 months after stroke onset.The presence of the apolipoprotein EE4 and apolipoprotein EE2 genotypes, although related to cholesterol and triglyceride levels, do not affect recovery during rehabilitation. A higher NIHSS score on admission and a higher fasting glucose level predict poor neurologic status, both at hospital discharge and 6 months after onset.

TNFSF4 gene polymorphism rs3861950 but not rs3850641 is associated with the risk of cerebral infarction in a Chinese population

Tumor necrosis factor superfamily member 4 (TNFSF4) plays a key role in the process of atherosclerosis, a common risk factor for both myocardial and cerebral infarctions. Recent studies indicate that the single nucleotide polymorphism (SNP) rs3850641 in TNFSF4 is associated with higher risk of myocardial infarction, but little is known about the association between TNFSF4 variation and cerebral infarction (CI). A case-control study involving 385 CI patients and 385 age-matched, sex-matched non-CI controls was conducted in a Chinese population, only the most common subtype, atherosclerosis CI, was recruited. Two SNPs of TNFSF4, rs3850641 and rs3861950, were genotyped by the TaqMan SNP genotyping method, and verified partly by genomic DNA sequencing. The results revealed a significant allelic association between rs3861950 and CI (Odds ration = 1.733, 95 % confidence interval = 1.333-2.254, P = 0.000). Genotypic association analysis demonstrated that the CC genotype of rs3861950 confers susceptibility to CI (Odds ration = 2.896, 95 % confidence interval = 1.368-6.132), and it was associated with a significantly higher risk of ischemic stroke (Odds ration = 3.520, 95 % confidence interval = 1.546-8.015, P = 0.003) after adjusting for the other confirmed risk factors such as the history of hypertension, diabetes, CAD, smoking and alcohol drinking. While the odds ratio of the T allele to the C allele was 1.733 (95 % confidence interval: 1.333-2.254). However, there was no significant association between rs3850641 and CI (Odds ration = 1.288, 95 % confidence interval = 0.993-1.670, P = 0.056). TNFSF4 gene polymorphism rs3861950, but not rs3850641, is associated with the risk of atherosclerosis CI in a Chinese population.

COL4A2 mutation associated with familial porencephaly and small-vessel disease

Familial porencephaly, leukoencephalopathy and small-vessel disease belong to the spectrum of disorders ascribed to dominant mutations in the gene encoding for type IV collagen alpha-1 (COL4A1). Mice harbouring mutations in either Col4a1 or Col4a2 suffer from porencephaly, hydrocephalus, cerebral and ocular bleeding and developmental defects. We observed porencephaly and white matter lesions in members from two families that lack COL4A1 mutations. We hypothesized that COL4A2 mutations confer genetic predisposition to porencephaly, therefore we sequenced COL4A2 in the family members and characterized clinical, neuroradiological and biochemical phenotypes. Genomic sequencing of COL4A2 identified the heterozygous missense G1389R in exon 44 in one family and the c.3206delC change in exon 34 leading to frame shift and premature stop, in the second family. Fragmentation and duplication of epidermal basement membranes were observed by electron microscopy in a c.3206delC patient skin biopsy, consistent with abnormal collagen IV network. Collagen chain accumulation and endoplasmic reticulum (ER) stress have been proposed as cellular mechanism in COL4A1 mutations. In COL4A2 (3206delC) fibroblasts we detected increased rates of apoptosis and no signs of ER stress. Mutation phenotypes varied, including porencephaly, white matter lesions, cerebellar and optic nerve hypoplasia and unruptured carotid aneurysm. In the second family however, we found evidence for additional factors contributing to the phenotype. We conclude that dominant COL4A2 mutations are a novel major risk factor for familial cerebrovascular disease, including porencephaly and small-vessel disease with reduced penetrance and variable phenotype, which might also be modified by other contributing factors.

Genetics of common polygenic ischaemic stroke: current understanding and future challenges

Stroke is the third commonest cause of death and the major cause of adult neurological disability worldwide. While much is known about conventional risk factors such as hypertension, diabetes and incidence of smoking, these environmental factors only account for a proportion of stroke risk. Up to 50% of stroke risk can be attributed to genetic risk factors, although to date no single risk allele has been convincingly identified as contributing to this risk. Advances in the field of genetics, most notably genome wide association studies (GWAS), have revealed genetic risks in other cardiovascular disease and these techniques are now being applied to ischaemic stroke. This paper covers previous genetic studies in stroke including candidate gene studies, discusses the genome wide association approach, and future techniques such as next generation sequencing and the post-GWAS era. The review also considers the overlap from other cardiovascular diseases and whether findings from these may also be informative in ischaemic stroke.

Effects of vitamin E on stroke subtypes: meta-analysis of randomised controlled trials

OBJECTIVE

To evaluate the effect of vitamin E supplementation on incident total, ischaemic, and haemorrhagic stroke.

DESIGN

Systematic review and meta-analysis of randomised, placebo controlled trials published until January 2010.

DATA SOURCES

Electronic databases (Medline, Embase, Cochrane Central Register of Controlled Trials) and reference lists of trial reports. Selection criteria Randomised, placebo controlled trials with ≥1 year of follow-up investigating the effect of vitamin E on stroke. Review methods and data extraction Two investigators independently assessed eligibility of identified trials. Disagreements were resolved by consensus. Two different investigators independently extracted data. Risk ratios (and 95% confidence intervals) were calculated for each trial based on the number of cases and non-cases randomised to vitamin E or placebo. Pooled effect estimates were then calculated.

RESULTS

Nine trials investigating the effect of vitamin E on incident stroke were included, totalling 118 765 participants (59 357 randomised to vitamin E and 59 408 to placebo). Among those, seven trials reported data for total stroke and five trials each for haemorrhagic and ischaemic stroke. Vitamin E had no effect on the risk for total stroke (pooled relative risk 0.98 (95% confidence interval 0.91 to 1.05), P=0.53). In contrast, the risk for haemorrhagic stroke was increased (pooled relative risk 1.22 (1.00 to 1.48), P=0.045), while the risk of ischaemic stroke was reduced (pooled relative risk 0.90 (0.82 to 0.99), P=0.02). There was little evidence for heterogeneity among studies. Meta-regression did not identify blinding strategy, vitamin E dose, or morbidity status of participants as sources of heterogeneity. In terms of absolute risk, this translates into one additional haemorrhagic stroke for every 1250 individuals taking vitamin E, in contrast to one ischaemic stroke prevented per 476 individuals taking vitamin E.

CONCLUSION

In this meta-analysis, vitamin E increased the risk for haemorrhagic stroke by 22% and reduced the risk of ischaemic stroke by 10%. This differential risk pattern is obscured when looking at total stroke. Given the relatively small risk reduction of ischaemic stroke and the generally more severe outcome of haemorrhagic stroke, indiscriminate widespread use of vitamin E should be cautioned against.

Relevance of the genetic polymorphism of NOD1 in Chlamydia pneumoniae seropositive stroke patients

BACKGROUND AND PURPOSE

Chronic infections with certain pathogens, such as Chlamydia pneumoniae, and genetic parameters that influence inflammatory reactions have been suggested to contribute to ischaemic stroke. NOD1 is a potent cytosolic receptor for C. pneumoniae. The aim of this study was to investigate the genetic polymorphism of NOD1 from the aspect of the development of stroke.

MATERIALS AND METHODS

A total of 280 patients with ischaemic stroke were enrolled in the study; 150 healthy blood donors served as controls. The G796A (E266K) NOD1 polymorphism was determined by restriction fragment length polymorphism. Chlamydia pneumoniae seropositivity was tested by ELISA.

RESULTS

There was a significant difference in NOD1 G796A genotype distribution between the controls and the stroke patients with C. pneumoniae seropositivity. The AA homozygote and GA heterozygote mutant variants were detected in 16% (25 of 152) and in 50% (77 of 152) of the C. pneumoniae-positive stroke patients, as compared with 8% (6 of 84), and 28% (24 of 84), respectively, in the C. pneumoniae-positive healthy controls. (OR = 2.559; 95% CI = 1.105-6.517, P = 0.04 and OR = 2.567; 95% CI = 1.451-4.540 P < 0.001, respectively). The stroke patients with the large vessel pathology exhibited the highest frequency of the mutant allele A (51%). In contrast, amongst the C. pneumoniae-negative subjects, no difference in genotype frequency was observed between the stroke patients and the controls.

CONCLUSION

Polymorphism in NOD1 G796A alone did not prove to be a risk factor for stroke in general, but in association with C. pneumoniae infection it appeared to be accompanied by an increased risk of the development of stroke.

Apolipoprotein E genotype in patients with cerebrovascular diseases and its effect on the disease outcome

A total of 100 hospitalized stroke patients and 30 healthy controls were included in a study aiming to determine the predictive role of ApoE genotype polymorphism for stroke outcome in the Turkish population. The most frequent ApoE genotype was epsilon3/3 reflecting Asian population polymorphic distribution. ApoE polymorphism in the Eastern Turkish population was found to be independent of stroke type, OSCP subtypes of infarction, localization of hemorrhage, severity of carotid artery stenosis, and resultant stroke outcome. Distinct polymorphic results in populations from nearby regions suggest a multifactorial pathogenesis and presence of very complex genetic factors in the development of stroke and stroke outcome.

Lacunar stroke

Lacunar infarcts or small subcortical infarcts result from occlusion of a single penetrating artery and account for one quarter of cerebral infarctions. Patients with a lacunar infarct usually present with a classical lacunar syndrome (pure motor hemiparesis, pure sensory syndrome, sensorimotor stroke, ataxic hemiparesis or dysarthria-clumsy hand) and, less frequently, an atypical lacunar syndrome. Hypertension and diabetes mellitus are major risk factors for lacunar stroke. Lacunar infarcts show a paradoxical clinical course with a favorable prognosis in the short term, characterized by a low early mortality and reduced functional disability on hospital discharge, but with an increased risk of death, stroke recurrence and dementia in the mid- and long term. Asymptomatic progression of small-vessel disease is a typical feature of the lacunar infarcts. For this reason, lacunar infarction should be regarded as a potentially severe condition rather than a relatively benign disorder and, therefore, lacunar stroke patients require adequate and rigorous management and follow-up. Antiplatelet drugs, careful blood pressure control, the use of statins and modification of lifestyle risk factors are key elements in secondary prevention after lacunar stroke.

Acute but not chronic differences in skilled reaching for food following motor cortex devascularization vs. photothrombotic stroke in the rat

The variability in the behavioral outcome of human and nonhuman animals after stroke raises the question whether the way that a stroke occurs is a contributing factor. Photothrombotic stroke in rats has been reported to produce especially variable results, with some animals showing either slight to no impairment to other animals displaying severe impairments. The present study investigated this variability. Rats received three different-sized photothrombotic treatments and were contrasted to rats receiving a "standard" motor cortex stroke produced by pial stripping. Rats were assessed acutely and chronically on a skilled reaching for food task using end-point measures and movement assessment in a constraint-induced rehabilitation paradigm. The results indicated that as the size of the photothrombotic infarct approached the size of the pial strip infarct so did chronic behavioral deficits. Nevertheless there were differences in the time course of recovery. Rats with photothrombotic lesions of all sizes were less impaired in the acute period of recovery both on measures of learned nonuse and constrained-induced recovery. The findings are discussed in relation to the idea that whereas the course of recovery might be altered as a function of the type of stroke, chronic deficits are more closely related to the ensuing damage.