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Combined diffusion and perfusion MRI with correlation to single-photon emission CT in acute ischemic stroke. Ischemic penumbra predicts infarct growth.

BACKGROUND AND PURPOSE: More effective imaging methods are needed to overcome the limitations of CT in the investigation of treatments for acute ischemic stroke. Diffusion-weighted MRI (DWI) is sensitive in detecting infarcted brain tissue, whereas perfusion-weighted MRI (PWI) can detect brain perfusion in the same imaging session. Combining these methods may help in identifying the ischemic penumbra, which is an important concept in the hemodynamics of acute stroke. The purpose of this study was to determine whether combined DWI and PWI in acute (<24 hours) ischemic stroke can predict infarct growth and final size. METHODS: Forty-six patients with acute ischemic stroke underwent DWI and PWI on days 1, 2, and 8. No patient received thrombolysis. Twenty-three patients underwent single-photon emission CT in the acute phase. Lesion volumes were measured from DWI, SPECT, and maps of relative cerebral blood flow calculated from PWI. RESULTS: The mean volume of infarcted tissue detected by DWI increased from 46.1 to 75.6 cm(3) between days 1 and 2 (P<0.001; n=46) and to 78.5 cm(3) after 1 week (P<0.001; n=42). The perfusion-diffusion mismatch correlated with infarct growth (r=0. 699, P<0.001). The volume of hypoperfusion on the initial PWI correlated with final infarct size (r=0.827, P<0.001). The hypoperfusion volumes detected by PWI and SPECT correlated significantly (r=0.824, P<0.001). CONCLUSIONS: Combined DWI and PWI can predict infarct enlargement in acute stroke. PWI can detect hypoperfused brain tissue in good agreement with SPECT in acute stroke.

Acute Disease↗

Vascular endothelial growth factor and its receptor, KDR, in human brain tissue after ischemic stroke.

Ischemic stroke results from a reduction in cerebral blood flow to a focal region of the brain after the occlusion of an artery, causing damage to nervous tissue. There is a region of cerebral ischemic tissue (penumbra) surrounding an acute cerebral infarct that is dysfunctional but potentially viable. Restoration of perfusion in the penumbra may ameliorate the tissue damage. The identity and the role of growth factors that control the extent of tissue damage and its repair are poorly understood. Angiogenesis has been demonstrated to occur in brain tissues of patients surviving an acute ischemic stroke. In this paper we have investigated the status of a potent angiogenesis factor, vascular endothelial growth factor (VEGF), in patients after acute ischemic brain stroke. Western blotting and immunohistochemistry were used to determine protein expression, and in situ hybridization was used to quantify and localize mRNA synthesis. The expression of VEGF protein was increased in the penumbra compared with infarcted brain and contralateral hemisphere. Neurones, endothelial cells, and astrocytes in the penumbra in all patients studied had significant up-regulation of both VEGF165 and VEGF189 mRNA (p < 0.01, Wilcoxon Matched-Pairs Signed-Ranks Test) compared with infarcted tissue and the normal looking contralateral hemisphere that was used as a control. Immunohistochemistry demonstrated that kinase insert domain receptor was present in blood vessels within the infarct/penumbra and absent from the normal contralateral hemisphere. VEGF, which is important in angiogenesis, may also influence long term neuronal survival, and possibly its modulation may prove to be of therapeutic value for patients with ischemic stroke.

Aged↗

Pharmacological treatment of acute ischemic stroke.

Ischemic stroke is devastating. It is the third leading cause of death in the United States. Each year, 480,000 people fall victim to ischemic stroke, which is estimated to cost 71.8 billion dollars (Hinkle JL, Bowman L. J Neurol Nurs. 2003;35:1-8. New treatment is available. Acute ischemic stroke is no longer considered an accident resulting in damage that must simply be dealt with. Now termed a brain attack, like a heart attack it must be treated immediately. Education is key to improving outcomes. Health care professionals must be trained to recognize early signs and symptoms of stroke. The public must be educated to understand the urgency of early evaluation once symptoms of stroke occur Brown M. Clin Med. 2001; 1:60-65). Television commercials, billboards, and public health lectures can be advantageous in a campaign to educate about stroke and the need to seek help immediately when experiencing symptoms, to halt the ischemic damage Brown M. Clin Med. 2001; 1:60-65.

Brain Ischemia↗

[Acute therapy of ischemic stroke].

Ischemic stroke is a neurological emergency as transition form reversible to irreversible lesions of the brain may be prevented by starting the therapy within six hours after the onset of the neurological deficits. Intravenous thrombolysis may be administered within the first three hours and intraarterial thrombolysis within the first six hours after considering inclusion and exclusion criteria. Neuroprotective drugs are under investigation and may enlarge the spectrum of acute therapy in the near future. Ischemic strokes that do not qualify for thrombolysis may be treated with unfractionated heparin, aspirin or low-molecular weight heparin. Indications for the administration of antithrombotic drugs are discussed. Blood pressure is frequently elevated in acute ischemic stroke, but rarely needs therapy or careful lowering. Fever, hypo- und hyperglycemia, epileptic seizures and intracranial hypertension should be treated.

Acute Disease↗

Factor V Leiden, prothrombin gene G20210A variant, and methylenetetrahydrofolate reductase C677T genotype in young adults with ischemic stroke.

Ischemic stroke in young adults is a well-known disease, but despite extensive clinical and laboratory investigations, its etiology remains unclear in approximately half of the cases. We examined the prevalence of factor V Leiden, the prothrombin G20210A genotype, and the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene in 100 patients (51 males and 49 females) who survived an ischemic stroke without a cardiac embolic source at an age < or = 45 years, and in 238 healthy control subjects from the same geographic area. The patients were selected for study only if the diagnosis of stroke was documented by computed tomography scan or nuclear magnetic resonance (NMR) of the brain, or both. Heterozygosity for the FV Leiden mutation was found in 3 patients (3.0%) and in 10 control subjects (4.2%). Two patients (2.0%) and five control subjects (2.1%) were heterozygous for the prothrombin G20210A mutation. The frequencies of the MTHFR 677TT, CT, and CC genotypes in the patient group were 12%, 37%, and 51%, respectively, and were not significantly different from those in control subjects (11%, 40%, and 49%, respectively). In conclusion, our results indicate that FV Leiden mutation, prothrombin G20210A genotype, and homozygosity for the C677T mutation in the MTHFR gene are not associated with an increased risk for ischemic stroke in young adults.

Adolescent↗

Angiogenesis and stem cell transplantation as potential treatments of cerebral ischemic stroke.

Ischemic stroke is a leading cause of human death and disability. Although stroke survivors may gain spontaneous partial functional recovery, they often suffer from sensory-motor dysfunctions, behavioral/neurological alterations, and various degrees of paralysis. Currently, limited clinical intervention is available to prevent ischemic damage and restore lost function in stroke victims. In addition to the extensive research on protective maneuvers against ischemia-induced cell death, increasing attention has been focused on potential strategies of promoting tissue repair and functional recovery in the damaged post-ischemic brain. Angiogenesis, or the growth of new blood vessels, may contribute to cell survival and functional recovery of the area of insult. The study of angiogenesis will increase the understanding of the mechanism underlying post-ischemia neurovascular plasticity and regeneration. Additionally, stem cell transplantation has emerged in the last few years as a potential therapy for ischemic stroke, because of their capability to differentiate into multiple cell types and the possibility that they may provide trophic support for cell survival, tissue repair, and functional recovery.

Journal Article↗

Emerging biomarkers in ischemic stroke.

Ischemic stroke is a devastating global public health problem and the leading cause of acute death and chronic disability. Despite being the diagnostic cornerstone, limitations in neuroimaging, including availability, cost, and therapeutic window, have rekindled interest in biomarker-based approaches. Biomarkers will be employed to facilitate the eventual prediction, early diagnosis, and prognosis of strokes, as well as to inform person-centered medicine. This review summarizes recent advances in the search for biomarkers related to inflammatory, endothelial, metabolic, and neuroaxonal pathways. Interleukin-6 (IL-6), asymmetric dimethylarginine (ADMA), endothelial microparticles (EMP), and homocysteine serve as predictive biomarkers corresponding to vascular risk and inflammatory priming. Glial fibrillary acidic protein (GFAP), D-dimer, and neuron-specific enolase (NSE) are diagnostic markers that can already subtype stroke and estimate lesion burden. Prognostic biomarkers, such as serum neurofilament light chain (sNfL), N-terminal pro-B-type natriuretic peptide (NT-pro-BNP), and growth differentiation factor 15 (GDF-15), are associated with infarct size and long-term outcomes. The -omic sciences (genomic, proteomic, and metabolomic) have discovered defined molecular signatures and panels with high specificity to describe heterogeneity in stroke. Cerebrospinal fluid (CSF) biomarkers and newer imaging modalities, such as those provided through positron emission tomography/computed tomography (PET/CT), offer valuable adjuncts to blood biomarkers in the diagnosis of conditions. Translational potential is hindered by heterogeneity in the transcriptional landscape.

Ischemic stroke↗

Distribution territories and causative mechanisms of ischemic stroke.

Ischemic stroke prognosis, risk of recurrence, clinical assessment, and treatment decisions are influenced by stroke subtype (anatomic distribution and causative mechanism of infarction). Stroke subtype diagnosis is better achieved in the early phase of acute ischemia with the use of multimodal MR imaging. The pattern of brain lesions as shown by brain MR imaging can be classified according to a modified Oxfordshire method, based on the anatomic distribution of the infarcts into six groups: (1) total anterior circulation infarcts, (2) partial anterior circulation infarcts, (3) posterior circulation infarcts, (4) watershed infarcts, (5) centrum ovale infarcts, and (6) lacunar infarcts. The subtype of stroke according to its causative mechanism is based on the TOAST method, which classifies stroke into five major etiologic groups: (1) large-vessel atherosclerotic disease, (2) small-vessel atherosclerotic disease, (3) cardioembolic source, (4) other determined etiologies, and (5) undetermined or multiple possible etiologies. The different MR imaging patterns of acute ischemic brain lesions visualized using diffusion-weighted imaging and the pattern of vessel involvement demonstrated with MR angiography are essential factors that can suggest the most likely causative mechanism of infarction. This information may have an impact on decisions regarding therapy and the performance of additional diagnostic tests.

Acute Disease↗

Antithrombotic treatments in acute ischemic stroke.

Ischemic stroke results most commonly from cerebral arterial thrombosis. Antithrombotic agents can reduce the incidence of cerebral embolic events or the extent of tissue injury and neurological outcome. The antiplatelet agents aspirin, ticlopidine, and the combination of dipyridamole and aspirin are associated with a significant reduction in second focal cerebral ischemic events. Oral anticoagulants have a role to reduce the incidence of cardiogenic emboli in patients with mechanical cardiac valves or nonvalvular atrial fibrillation. Both antithrombotics are untested in the acute setting. The recombinant tissue plasminogen activator rt-PA has been shown to significantly increase the number of stroke patients with no or minimal deficit when treated within 3 hours of symptom onset. Additional studies of this and other plasminogen activators by both intravenous and intra-arterial delivery have highlighted limitations to this approach, but also support its role in acute intervention. The risk of intracerebral hemorrhage attends the use of all antithrombotic agents, most notably plasminogen activators. Strategies to decrease this risk are likely to add to beneficial outcome.

Acute Disease↗

Haplotypes of the plasminogen activator gene associated with ischemic stroke.

Ischemic stroke (IS) is thought to be a multifactorial disorder associated with genetic backgrounds and environmental factors. In the circulating plasma, tissue plasminogen activator (tPA) catalyzes the reaction from plasminogen to plasmin. If there is a functional disability of tPA, induction of thrombosis and infarction disorders can occur. The aim of this study was to perform a haplotype-based case-control study using single nucleotide polymorphisms (SNPs) in the human tPA gene, and to assess the association between the tPA gene and IS. We genotyped 182 IS individuals and 403 controls for five SNPs in the human tPA gene, rs7007329, rs732612, rs8178750, rs2020922, and rs4471024. Using these five SNPs, a haplotype-based case control study was performed. There were seven SNP combinations that exhibited significant differences in the overall distribution between the IS and control groups. Linkage disequilibrium analysis showed that the combination of rs7007329 and rs8178750 was useful in identification of the susceptibility haplotype. The frequency of the G-T haplotype at rs7007329-rs8178750 was significantly higher in the IS group (1.2%) as compared to the control group (0.0%) (p = 0.003). Diplotype analysis also showed a significant association of the diplotype with the G-T haplotype at rs7007329-rs8178750 (OR:11.4, 95%CI:1.32-97.9, p = 0.013). These results suggest that the G-T haplotype at rs7007329-rs8178750 of the tPA gene is a genetic marker for IS, and that tPA or a neighboring gene is a susceptibility gene for IS.

Aged↗

AMPA receptor subunit GluR2 gates injurious signals in ischemic stroke.

Ischemic stroke, or a brain attack, is the third leading cause of death in developed countries. A critical feature of the disease is a highly selective pattern of neuronal loss; certain identifiable subsets of neurons--particularly CA1 pyramidal neurons in the hippocampus are severely damaged, whereas others remain intact. A key step in this selective neuronal injury is Ca2+/Zn2+ entry into vulnerable neurons through alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor channels, a principle subtype of glutamate receptors. AMPA receptor channels are assembled from glutamate receptor (GluR)1, -2, -3, and -4 subunits. Circumstance data have indicated that the GluR2 subunits dictate Ca2+/Zn2+ permeability of AMPA receptor channels and gate injurious Ca2+/Zn2+ signals in vulnerable neurons. Therefore, targeting to the AMPA receptor subunit GluR2 can be considered a practical strategy for stroke therapy.

Brain Ischemia↗

Outcomes among valvular heart disease patients experiencing ischemic stroke or transient ischemic attack in Olmsted County, Minnesota.

OBJECTIVE: To estimate the rates and predictors of survival and recurrence among residents of Olmsted County, Minnesota, who received an Initial diagnosis based on 2-dimensional color Doppler echocardiography of moderate or severe mitral or aortic stenosis or regurgitation and who experienced a first ischemic stroke, transient ischemic attack (TIA), or amaurosis fugax. PATIENTS AND METHODS: At the Mayo Clinic in Rochester, Minn, we used the resources of the Rochester Epidemiology Project to identify Individuals who met the criteria for inclusion in the study and to verify exclusion criteria. The study included all residents of Olmsted County, Minnesota, who experienced a first Ischemic stroke, TIA, or amaurosis fugax within 30 days of or subsequent to receiving a first-time 2-dimensional color Doppler echocardlography-based diagnosis of moderate or severe mitral or aortic stenosis or regurgitation between January 1, 1985, and December 31, 1992. The Kaplan-Meier product-limit method was used to estimate the rates of subsequent stroke and death after the ischemic stroke, TIA, or amaurosis fugax. The Cox proportional hazards model was used to assess the effect of several potential risk factors on subsequent stroke occurrence and death. RESULTS: For the 125 patients in the study, the Kaplan-Meier estimates of the risk of death and the risk of stroke at 2-year follow-up were 38.6% (95% confidence interval [CI], 29.9%-47.5%) and 18.5% (95% CI, 10.0%-27.0%), respectively. Compared with the general population, death rates were significantly Increased (standardized mortality ratio = 1.75; 95% CI, 1.38-2.19; P < .001) but rates of subsequent stroke occurrence were not (standardized morbidity ratio = 1.20; 95% CI, 0.75-1.84; P = .40). After adjustment for age, sex, and cardiac comorbidity, neither the type nor severity of valvular heart disease was an independent determinant of survival or subsequent stroke occurrence. CONCLUSIONS: Patients with mitral or aortic valvular heart disease who experience Ischemic stroke, TIA, or amaurosis fugax have Increased rates of death, but not recurrent stroke, compared with expected rates. Other cardiovascular risk factors are more important determinants of survival In these patients than the type or echocardiographic severity of the valvular heart disease.

Aged↗

[Myocardial infarction revealed by ischemic stroke].

Ischemic cerebral infarction associated with myocardial infarction is yet a real diagnosis challenge. If during the acute myocardial phase the mechanism is mostly embolic, at long-term, the mechanism is not clearant and other causes should be searched. We report a 50 year old man with ischaemic stroke with strong evidence of myocardial infarction in the late phase with wall-motion abnormality and mural clot revealed by echocardiography and Q waves. Atrial fibrillation was suspected and no other abnormalities could be found. The diagnosis of cardio-embolic ischaemic stroke could not be made with certainly.

Atrial Fibrillation↗

Adhesive glycoproteins CD11a and CD18 are upregulated in the leukocytes from patients with ischemic stroke and transient ischemic attacks.

Leukocytes may have an important role in the pathogenesis of brain injury after ischemia. Expression of adhesion molecules on leukocytes and/or endothelia is needed for leukocytes to adhere to endothelia and infiltrate into the injured brain. The purpose of the present pilot study is to delineate whether the expression of leukocyte adhesion molecules, CD11a and CD18, are upregulated in patients with ischemic stroke and transient ischemic attack. Ten patients with ischemic stroke, 6 with transient ischemic attack (TIA), and 11 age and risk factor matched controls were studied. Using immunofluorescence phenotyping and flow cytometry, leukocyte membrane expression of CD11a and CD18 were measured within 72 h after onset of ischemia. Follow-up measurements were performed at 5-7 days after ictus in 6 patients with stroke, and at 3-5 days after ictus in 3 patients with TIA. CD11a immunofluorescence (IF) was significantly increased within 72 h after onset of symptoms in patients with stroke as well as TIA compared with the control group (p < 0.017). IF of CD18 also increased in both patient groups, but significance was reached only in the TIA group (p < 0.05). No difference of CD11a and CD18 IF was detected between stroke and TIA groups. Follow-up measurement of CD11a and CD18 showed a trend of decrease, but CD11a IF remained significantly elevated compared with the control group (p < 0.017). Expression of leukocyte adhesion molecules CD11a, and CD18 are upregulated in patients with ischemic stroke and TIA. Although these data are preliminary, our data suggest that these molecules are associated with cerebrovascular disorders including ischemic stroke and TIA.

Aged↗

[Leukocytosis in the first day of acute ischemic stroke as a prognostic factor of disease progression].

It has been reported that white blood cells (WBC) may contribute to the initiation and further development of stroke. WBC count could have influence on hemorheology, thrombosis and induction of vasoconstriction in cerebral arteries. The aim of this work was to determine whether WBC count assessed in patients with acute stroke in the first day of the disease have a predictive value for the late clinical outcomes. Peripheral WBC count was measured at the admission to the hospital in 100 consecutive patients with acute stroke. Ischemic stroke was confirmed in all patients by head CT. Neurological status was evaluated with the use of modified Rankin's Scale. We assessed the following clinical outcomes: in-hospital mortality, the lack of neurological improvement on the 21st day of disease, and the need for hospital stay longer than 21 days. Odds ratio (OR) with 95% confidence interval (95% CI) adjusted for patient's age, gender, cardiovascular diseases, diabetes mellitus and previous stroke was calculated with the use of logistic regression. OR was evaluated both for the presence of WBC count > 10.000 cells/microliter and for each 1000 leukocytes/microliter increase. WBC count greater than 10.000 cells/microliter was associated with a more than seventy-fold greater risk for death (OR--75.18; 95% CI: 8.89-635.84; p = 0.0001), nearly eight times increased risk for the no-improvement status (OR--7.78; 95% CI: 2.51-24.17; p = 0.0004) and approximately four times increased risk for the prolonged hospital stay (OR--4.20; 95% CI: 1.50-11.72; p = 0.0062). Each 1000 cell/microliter increase in WBC count at the admission was associated with increased risk for in-hospital mortality (OR--2.24; 95% CI: 1.39-3.57; p = 0.0008), no neurological improvement (OR--1.43; 95% CI: 1.15-1.76; p = 0.0009) and the need for prolonged hospitalization (OR--1.26; 95% CI: 1.07-1.49; p = 0.0066). Increased WBC count within the first 12 hours of stroke is an independent and strong risk factor for mortality, no neurological improvement, and the need for prolonged hospitalization in the course of acute ischemic stroke.

Aged↗

Emergency department evaluation of ischemic stroke and TIA: the BASIC Project.

OBJECTIVE: To identify demographic and clinical variables of emergency department (ED) practices in a community-based acute stroke study. METHODS: By both active and passive surveillance, the authors identified cerebrovascular disease cases in Nueces County, TX, as part of the Brain Attack Surveillance in Corpus Christi (BASIC) Project, a population-based stroke surveillance study, between January 1, 2000, and December 31, 2002. With use of multivariable logistic regression, variables independently associated with three separate outcomes were sought: hospital admission, brain imaging in the ED, and neurologist consultation in the ED. Prespecified variables included age, sex, ethnicity, insurance status, NIH Stroke Scale score, type of stroke (ischemic stroke or TIA), vascular risk factors, and symptom presentation variables. Percentage use of recombinant tissue plasminogen activator (rt-PA) was calculated. RESULTS: A total of 941 Mexican Americans (MAs) and 855 non-Hispanic whites (NHWs) were seen for ischemic stroke (66%) or TIA (34%). Only 8% of patients received an in-person neurology consultation in the ED, and 12% did not receive any head imaging. TIA was negatively associated with neurology consultations compared with completed stroke (odds ratio [OR] 0.35 [95% CI 0.21 to 0.57]). TIA (OR 0.14 [0.10 to 0.19]) and sensory symptoms (OR 0.59 [0.44 to 0.81]) were also negatively associated with hospital admission. MAs (OR 0.58 [0.35 to 0.98]) were less likely to have neurology consultations in the ED than NHWs. Only 1.7% of patients were treated with rt-PA. CONCLUSIONS: Neurologists are seldom involved with acute cerebrovascular care in the emergency department (ED), especially in patients with TIA. Greater neurologist involvement may improve acute stroke diagnosis and treatment efforts in the ED.

Aged↗

Incidence trends of ischemic stroke and transient ischemic attacks in a well-defined French population from 1985 through 1994.

BACKGROUND AND PURPOSE: The changing incidence of ischemic stroke is of major concern in view of its public health impact, to define the population concerned, to identify risk factors, and to set up health-care systems. The aim of this study was to evaluate the time trends associated with the incidence of all the subtypes of ischemic stroke and transient ischemic attacks in a well-defined population for 10 years. METHODS: Since 1985, a population registry has recorded each patient living in Dijon (France) who suffered from a cerebrovascular disease (CVD) regardless of the type of management. This study involved all patients suffering from their first ischemic stroke and their first transient ischemic attacks (TIAs) during 1 calendar year between January 1, 1985 and December 31, 1994. The incidence changes according to age, sex, and type of cerebral ischemic event (cortico-subcortical infarct, lacunar infarct, and TIA) were studied on the basis of their annual variations. RESULTS: During the 10-year study period, 834 cortico-subcortical infarcts (52.1%), 296 lacunar infarcts (18.5%), 369 TIAs (23.1%), and 101 undetermined ischemic strokes (6.3%) were collected. The incidence of all ischemic events was relatively stable in both sexes over the 10-year period. However, the incidence rates differed according to age and type of ischemia. An increased incidence of cerebral cortico-subcortical infarct was observed in patients older than 75 years of age (+5.45% annual change [AC] in men, P<0.05; +5. 09% AC in women, NS). In parallel, a higher proportion of emboligenic cardiac arrhythmias was observed in these patients (P<0. 001). The incidence of lacunar infarcts tended to decrease, regardless of age but mainly in men under younger than 75 years of age (-12.74% AC in men, NS; +0.31% AC in women, NS). The incidence of TIAs was relatively stable in both sexes. Because our population consisted of a large number of elderly subjects, the increase in cardioembolic causes could partially explain the increased incidence of cerebral cortico-subcortical infarcts in patients older than 75 years of age. CONCLUSIONS: These preliminary data emphasize the importance of stroke surveillance in considering the variations of the different mechanisms of ischemic cerebrovascular disease. Although the incidence of TIA is stable and the incidence of lacunes tends to decrease in men, mainly before 75 years of age, we emphasize the rise of the crude incidence of cortico-subcortical infarcts in men older than 75 years of age, induced by an increase in cardioembolic causes.

Age Factors↗