Dr. George Howard[/caption]
George Howard, Dr.P.H.
Professor of biostatistics
Birmingham School of Public Health
University of Alabama
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Howard: What has been known for many decades is that death rates from stroke are much higher in the black than white population, particularly between the ages of 45 – 65 (or maybe even a little older). These racial differences in stroke are among the greatest disparities for any disease, clearly it is a priority to reduce this disparity.
However, there are two reasons more blacks could die from a disease:
1) more blacks get the disease, or
2) once you get the disease, it is more likely to kill blacks.
The implications of knowing which of these is the major contributor is profound. If the driving force is more blacks are having more stroke, then we need to focus out attention on activities before stroke occur. For example, prevention of the greater prevalence of hypertension and diabetes in blacks, and also reducing the differences in the control of blood pressure and glucose. However, if the driving force is a higher chance of death in blacks once stroke occur, then we need to focus on the disparities in how black stroke patients are cared for compared to white stroke patients. That is, the former requires community-based efforts, while the latter requires hospital-based efforts.
What we found was that nearly all the difference was that blacks are having more strokes ... not that they are more likely to die once stroke occurs.
Dr. David Earnest[/caption]
David Earnest, Ph.D.
Professor in the Department of Neuroscience and Experimental Therapeutics
Texas A&M Health Science Center College of Medicine
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Earnest: When body clocks are disrupted, as they are when people engage in shift work or go to bed and get up at radically different times every few days, more severe ischemic strokes can result.
MedicalResearch.com: What should readers take away from your report?
Dr. Earnest: Whenever possible, go to bed and get up at the same time each day and keep regular mealtimes. If you do need to keep an irregular schedule, it is especially important to be mindful of stroke risk and try especially hard to eliminate other risk factors, such as hypertension and obesity.
MedicalResearch.com Interview with: Johann Auer MD Department of Cardiology and Intensive Care St Josef Hospital Braunau, Austria MedicalResearch.com: What should readers take away from...
MedicalResearch.com Interview with: [caption id="attachment_24451" align="alignleft" width="144"] Dr. Azizi Seixas[/caption] Azizi Seixas, Ph.D. Fellow NYU Langone School of Medicine Department of Population Health Center for Healthful...
Prof. Craig Anderson[/caption]
Professor Craig Anderson
Professor of Stroke Medicine and Clinical Neuroscience
Sydney Medical School at the University of Sydney
Institute of Neurosciences of Royal Prince Alfred Hospital
MedicalResearch.com: What is the background for this study?
Prof. Anderson: Intravenous use of the clot-busting drug, alteplase (or rtPA), at a dose of 0.9 mg/kg body weight is the only proven medical treatment of acute ischemic stroke. However, a major drawback to the treatment is an increased risk of major bleeding in the brain, or intracerebral hemorrhage (ICH), that occurs in about 5% of cases, and can be fatal. This balance of effectiveness (recovery from disability) and risks (ICH, and bleeding elsewhere and uncommon drug allergic reactions) has led to much of the controversy over the net benefit of the drug. The optimal dose of the drug has never been established, but the Japanese drug safety regulatory authority, has approved a lower dose (0.6mg/kg) on the basis of a small, non-randomized, open study which showed comparable outcomes and lower risk of ICH than historical controls. This ‘east-west’ divide over the approved dose of alteplase has led to much variation in the dose of alteplase used in clinical practice in Asia – according to a doctor’s perceived risk of ICH in individual patients and the affordability of this relatively expensive treatment in low resource settings. Data from the Get-with-the Guidelines Quality Registry in the United States suggests Asian patients are at higher risk of ICH after standard-dose alteplase than non-Asians.
Our research aimed to resolve this uncertainty over the optimal dose of alteplase, as an international, active-comparator, open-label, blinded outcome assessed, clinical trial of low-dose (0.6 mg/kg) versus standard-dose (0.9mg/kg) in 3310 patients recruited from over 100 hospitals in 13 countries between 2012 and 2015.
Dr. Ben Freedman[/caption]
Dr. Ben Freedman OAM
Deputy Director Research Strategy, Heart Research Institute/Charles Perkins Centre
Professor of Cardiology, Sydney Medical School
Head Vascular Biology Anzac Research Institute
Honorary VMO, Concord Repatriation General Hospital
University of Sydney
MedicalResearch.com: What is the background for this study?
Dr. Freedman: Guidelines recommend that patients with atrial fibrillation (AF) at high enough risk for stroke should be treated with anticoagulant. Anticoagulant drugs are remarkably effective in reducing stroke risk by about two thirds, and death by between a quarter and a third. Unfortunately, strokes can still occur when patients are prescribed anticoagulant for Atrial Fibrillation, and it is often presumed this residual risk of stroke represents treatment failure, though there are few data about this important issue.
MedicalResearch.com: What are the main findings?
Dr. Freedman: We were able to compare the risk of stroke in a cohort of patients with AF commenced on anticoagulant, with a very large closely-matched cohort seen in general practice at the same time but without AF. This is a unique comparison. We found that the residual risk of stroke in such anticoagulant-treated patients was virtually identical to that in the matched control cohort. The implication is that the residual risk of stroke may not be treatment failure, but the risk of non-cardioembolic stroke in people of a similar age and stroke risk profile but without Atrial Fibrillation. The residual risk of death in those on anticoagulant was higher than the matched controls, and intermediate between the control rate and the mortality rate for untreated AF.
Dr. Mat Reeves[/caption]
Mathew J. Reeves, PhD
Department of Epidemiology and Biostatistics
Michigan State University
East Lansing, MI
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Reeves:
The transfer of stroke patients with ischemic stroke to primary and comprehensive stroke centers so they can receive specialized care including tPA (thrombolysis) and endovascular (catheter based) care is becoming increasingly important with the release or trial data showing substantial benefit for endovascular treatment in eligible patients.
A major goal of integrated stroke systems of care is to ensure that stroke patients requiring specialized care beyond the capability of the initial hospital are identified and transferred to a specialist center as quickly as possible.
Surprisingly, there is relatively little written about the frequency and outcomes of stroke patients who are transferred between hospitals, especially in the context of large quality improvement registries such as the Coverdell Stroke Registry or Get-With-The- Guidelines- Stroke
Dr. Kazuomi Kario[/caption]
Kazuomi Kario, MD, PhD, FACP, FACC, FAHA, FESC
Professor, Chairman
Division of Cardiovascular Medicine, Department of Medicine
Jichi Medical University School of Medicine (JMU)
JMU Center of Excellence, Cardiovascular Research and Development (JCARD)
Hypertension Cardiovascular Outcome Prevention and Evidence in Asia (HOPE Asia) Network
Staff Visiting Professor of Medicine,
UCL Institute of Cardiovascular Science
University College London, London UK
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Kario: The relationship between out-of-office blood pressure (BP), such as ambulatory BP and home BP, and cardiovascular events has been investigated in several studies. However, there is insufficient evidence as yet regarding which BP measurement predicts coronary artery disease (CAD) events most strongly.
The HONEST Study is the largest prospective observational study in the world, which enrolled >20,000 hypertensive patients. The study observed cardiovascular events, monitoring both clinic BP and home BP on treatment of antihypertensive agent.
The present analysis shows that home BP measured in morning (morning home BP) is a strong predictor of both CAD and stroke events in future, and may be superior to clinic BP in this regard. Furthermore, there does not appear to be a J-curve in the relationship between morning home BP and CAD or stroke events.
MedicalResearch.com Interview with: [caption id="attachment_22978" align="alignleft" width="115"] Dr. Josef Anrather[/caption] Josef Anrather, VMD Finbar and Marianne Kenny Research Scholar Associate Professor, Feil Family Brain and...
Dr. Hakan Ay[/caption]
Hakan Ay MD, FAHA
Associate Professor of Neurology and Radiology
Stroke Service, Department of Neurology
Director of Stroke Research,
A.A. Martinos Center, Department of Radiology
Massachusetts General Hospital
Harvard Medical School
Boston MA, USA
Medical Research: What is the background for this study? What are the main findings?
Dr. Ay: Recurrent stroke is an important public health problem. One quarter of all strokes are recurrent strokes. Approximately one out of every 10 patients with stroke develops a second stroke within the next 2 years. The most critical period for recurrence after stroke is the first 90 days; approximately half of recurrent strokes that occur within 2 years occur within the first 90 days. The RRE tool was developed at the Massachusetts General Hospital in 2010 to assess the 90-day risk of recurrent stroke. The RRE was subsequently tested in a separate cohort of patients with transient stroke symptoms (mini strokes) admitted to the Massachusetts General Hospital in 2011. The current study expands upon prior two studies by showing that the RRE tool provides reliable risk estimates when tested in cohorts of patients recruited from different academic centers in various parts of the world. The study reports that the RRE can stratify approximately one-half of patients with stroke either at high-risk or at low-risk with a reasonable accuracy.
Dr. Georgios Tsivgoulis[/caption]
Georgios Tsivgoulis , M.D., Ph.D., MSc, FESO
Assistant Professor of Neurology
University of Athens, Athens, Greece
Visiting Associate Professor of Neurology
Director of Stroke Research
Department of Neurology
University of Tennessee Health Science Center
Medical Research: What is the background for this study? What are the main findings?
Dr. Tsivgoulis: Literature data suggest that taking statins before an acute ischemic stroke may improve early outcomes including early neurological deterioration, mortality and disability in patients with acute ischemic stroke. However,the potential beneficial effect of statin pretreatment has never been investigated in acute ischemic stroke due to large artery atherosclerosis. The research question in this specific subgroup of ischemic stroke patients is of great importance, as large-artery atherosclerotic stroke carries the highest risk of early recurrent stroke in comparison to other acute ischemic stroke subtypes.
Using prospectively collected data from over 516 consecutive patients with acute large-artery atherosclerotic stroke from seven tertiary-care stroke centers during a three-year period we found that statin pretreatment in patients with acute large-artery atherosclerotic stroke is associated with better early outcomes in terms of neurological improvement, disability, survival and stroke recurrence.
William P. Neil, MD
Vascular Neurologist
SCPMG Regional Stroke Champion
Neurology
Medical Research: What is the background for this study?
Dr. Neil: Stroke survivors are less likely to have a recurrent stroke, or other complications if they take their medications as prescribed by their doctor. Mail order pharmacies are increasingly being used to deliver medications for a variety of diseases, and their use is associated with better medication adherence. We wanted to see whether stroke patients who use mail-order pharmacies were more likely to have good medication adherence than those who used local pharmacies.
Medical Research: What are the main findings?
Dr. Neil: We looked through a large electronic medical database in California, and found a total of 48,746 people discharged from the hospital with a stroke, and who also filled either a cholesterol medication or an anticoagulant (blood thinner). Of these, 136,722 refills were from a local pharmacy and 68,363 were by mail. Overall, patients were adherent to the medications 46.5% of the time if they picked up the medication from the pharmacy and 74% of the time if they had prescriptions mailed to them.
Dr. Rolf Wachter[/caption]
Dr. Rolf Wachter
Head Senior physician
University of Goettingen
Göttingen, Germany
Medical Research: What is the background for this study? What are the main findings?
Dr. Wachter: Atrial Fibrillation is a known risk factor for stroke, and in stroke patients, it is a strong predictor of adverse outcome, if it is not adequately treated (e.g. by anticoagulation). However, in its paroxysmal form, Atrial Fibrillation (AF) may escape routine diagnostics. We aimed to show that we can increase the number of patients with detected AF if we do more monitoring for atrial fibrillation. As a unique feature of our study, we did not focus on a certain stroke subtype (i.e. cryptogenic stroke), but we aimed to consider all patients >= 60 years in whom the detection of Atrial Fibrillation has a clinical relevance.
The main finding of our study was that enhanced and prolonged Holter ECG monitoring (3x10 days of monitoring, analysed in a dedicated core lab) tripled the number of detected AF cases (from 4.5 to 13.5 %). 11 patients had to undergo enhanced and prolonged monitoring to find one additional case of Atrial Fibrillation.
Dr. Thorsten Steiner[/caption]
Thorsten Steiner, MD, PhD
Klinikum Frankfurt Hoechst and Heidelberg University Hospital
Germany
Medical Research: What is the background for this study? What are the main findings?
Dr. Steiner: Background of the study is intracranial hemorrhage (ICH) related to vitamin-K antagonists. The mortality rate is about 60%. Main reason for the high mortality rate is hematoma expansion which occurs in about 50% during the acute phase right after the start of symptoms. We performed an investigator initiated randomized controlled trial (RCT) and found that a 4-factor prothrombin complex (PCC) is superior to fresh frozen plasma (FFP) in normalizing the international normalized ratio (INR) and prevents hematoma expansion. This let to more deaths within 48 hours in the FFP-group but had no clinical impact at 3 months - but our study was powered to detect INR normalization and not a clinical endpoint.
Dr. Cheryl Bushnell[/caption]
Cheryl Bushnell, MD, MHS
Professor of Neurology
Director, Wake Forest Baptist Stroke Center
Wake Forest Baptist Health
Medical Center Boulevard
Winston Salem, NC 27157
Medical Research: What is the background for this study? What are the main findings?
Dr. Bushnell: The catalyst for the study was to see if comorbidities and the management of them might influence functional status. But, we pre-specified gender and race because we knew these could be important predictors of outcome. As it turns out, the results of our analysis did, in fact, show that gender and race were the most significant predictors of poor functional outcome.
Medical Research: What should clinicians and patients take away from your report?
Dr. Bushnell: The take-home message is that women and minorities have poorer functional outcome after stroke, but the reasons for this outcome need to be further explored. Our model showed that we only explained 31% of the variance in SIS-16 with gender, race/ethnicity, and stroke severity, so unmeasured factors are extremely important. We could speculate from this dataset and other published data that women may be more likely to have functional deficits prior to stroke, be unmarried/widowed, live alone, or institutionalized after stroke. Non-white stroke survivors may have poorer access to care, have multiple strokes, and more comorbidities.
Dr. Alexander Merkler[/caption]
Alexander Merkler, MD
Fellow in neuro critical care
Weill Cornell Medical College and
New York-Presbyterian Hospital, New York
Medical Research: What is the background for this study? What are the main findings?
Dr. Merkler: Patients with stroke often ask about what type of problems they may expect in the future. As neurologists, we often warm our patients about the risk for recurrent stroke, infections, clots, eating difficulty, and depression. Although seizures are a well-known complication of stroke, there was little data regarding the long-term rate of seizures in patients who have a stroke. Therefore, we sought to evaluate the long-term risk of seizures following stroke in order to better advise physicians and patients on the likelihood of developing seizures after suffering a stroke. We identified over 600,000 patients with stroke and found that the rate of seizures after stroke is high – 15.3% of all patients with stroke will develop seizures. Patients who have hemorrhagic stroke face an even higher rate of seizures – 24% of patients with hemorrhagic type stroke will develop seizures. The rate of seizures after ischemic stroke was significantly higher than previous literature - 13.5% of patients with an ischemic stroke had a seizure in our study.
MedicalResearch.com Interview with: [caption id="attachment_21811" align="alignleft" width="134"] Dr. Christian Stapf[/caption] Christian Stapf, MD Full Professor, Department of Neurosciences Université de Montréal Principal Scientist, CRCHUM Montréal Canada Medical...
Dr. Thomas Brott[/caption]
Thomas G. Brott, M.D.
Professor of neurology and director for research and
The Eugene and Marcia Applebaum Professor of Neurosciences and James C. and Sarah K. Kennedy Dean for Research.
Mayo Clinic in Jacksonville, Fla
Medical Research: What is the background for this study? What are the main findings?
Dr. Brott: Revascularization for carotid artery stenosis is the accepted treatment for symptomatic patients with >50% stenosis and for asymptomatic patients with >70% stenosis. The original CREST report in 2010 showed both surgery and stenting were the safe methods to treat severe carotid stenosis. But the follow-up averaged 2.5 years and Medicare-age patients live for an average of 18-20 years. These patients and their families needed to know if surgery and stenting are durable in preventing stroke.
CREST was designed to answer the questions of clinical and anatomic durability for the long-run.
Dr. Adnan Qureshi[/caption]
Dr. Adnan Qureshi MD
Professor of Neurology, Neurosurgery and Radiology
University of Minnesota
Medical Research: What is the background for this study?
Dr. Quershi: Women who have the last pregnancy at advanced age (usually defined as pregnancy at age of 40 years or greater) have higher risk of developing hypertension, hypertension related disorders, and diabetes mellitus during pregnancy. There is some evidence that disproportionately higher rates of cardiovascular risk factors continue years after the pregnancy. Perhaps there are unknown medical conditions triggered during pregnancy at advanced age. These changes continue to progress without being clinically evident until years later manifesting as a cardiovascular event.
Medical Research: What are the main findings?
Dr. Quershi: We analyzed the data for 72,221 women aged 50-79 years who were enrolled in the observational arm of the Women's Health Initiative Study. We determined the effect of pregnancy in advanced age (last pregnancy at age≥40 year) on risk of ischemic stroke, hemorrhagic stroke, myocardial infarction, and cardiovascular death over a mean period of 12 years. A total of 3306 (4.6%) of the 72,221 participants reported pregnancy in advanced age. Compared with pregnancy in normal age, the rate of ischemic stroke (2.4% versus 3.8%, p<0.0001), hemorrhagic stroke (0.5% versus 1.0%, p<0.0001), myocardial infarction (2.5% versus 3.0%, p<0.0001), and cardiovascular death (2.3% versus 3.9%, p<0.0001) was significantly higher among women with pregnancy in advanced age. In multivariate analysis, women with pregnancy in advanced age were 60% more likely to experience a hemorrhagic stroke even after adjusting for differences in age, race/ethnicity, congestive heart failure, systolic blood pressure, atrial fibrillation, alcohol use and cigarette smoking were adjusted.
Dr. Michael D. Hill[/caption]
Michael D Hill, MD MSc FRCPC
Calgary Stroke Program
Professor, Dept Clinical Neurosciences
Hotchkiss Brain Institute
Cumming School of Medicine, University of Calgary
Calgary, Canada
Medical Research: What is the background for this study? What are the main findings?
Dr. Hill: The HERMES collaboration is a pooled analysis of 5 randomized controlled trials of endovascular stroke therapy. The purpose is of this analysis is to assess the relationship between time from stroke onset and effect size.
The main finding is that there is a declining effect size as time elapses from stroke onset. Shorter onset to reperfusion times are associated with better outcomes. However, the slope of the decline is shallow compared to past estimates. We believe this is because imaging selection identifies a group a patients in whom there is slow growth of the core infarct.
Dr. Robert Friedland[/caption]
Dr. Robert Friedland MD
Mason C. and Mary D. Rudd Endowed Chair In Neurology
Professor, Dept. of Neurology
University of Louisville Health Care Outpatient Center
Louisville, KY 40292
Medical Research: What is the background for this study? What are the main findings?
Dr. Robert Friedland: Oral infectious diseases are associated with stroke. Previous research by this group has shown that oral bacteria, cnm-positive Streptococcus mutans, was associated with cerebral microbleeds and intracerebral hemorrhage. We developed this study to investigate the roles of this bacteria in patients entering the hospital for all types of stroke. Among the patients who experienced intracerebral hemorrhage (ICH), 26 percent were found to have a specific bacterium in their saliva, cnm-positive S. mutans. Among patients with other types of stroke, only 6 percent tested positive for the bacterium. We also evaluated MRIs of study subjects for the presence of cerebral microbleeds (CMB), small brain hemorrhages which may cause dementia and also often underlie ICH. We found that the number of CMBs was significantly higher in subjects with cnm-positive S. mutans than in those without.
Dr. Richard Moon[/caption]
Richard Moon, MD, CM, MSc,
FRCP(C), FACP, FCCP
Medical Director, Hyperbaric Center
Professor of Anesthesiology
Department / Division
Anesthesiology / GVTU Division
Medicine / Pulmonary
Duke University School of Medicine
Medical Research: What is the background for this study? What are the main findings?
Dr. Moon: This study was performed to investigate the reason why young, fit individuals develop a condition usually associated with severe heart disease: pulmonary edema. Immersion pulmonary edema (also known as swimming-induced pulmonary edema, SIPE) develops in certain susceptible individuals while swimming or scuba diving, usually in cold water. Some SIPE-susceptible people include highly conditioned triathletes and Navy SEAL trainees. The prevalence of SIPE in triathletes is around 1.5%, and in open sea swimming trials in naval special forces trainees has been reported to be 1.8-60%. SIPE often requires hospitalization and has caused death.
Medical Research: What should clinicians and patients take away from your report?
Dr. Moon: We directly measured arterial pressure, pulmonary artery pressure (PAP) and PA wedge pressure (PAWP) during submersed exercise in cold water. We found that both PAP and PAWP were higher in swimming-induced pulmonary edema-susceptible individuals compared with a group of volunteers of similar age who had never experienced SIPE. This confirmed that SIPE is a form of hemodynamic pulmonary edema, which is curious since all of the people we studied had normal hearts. We hypothesized that the cause could be differences between the groups in venous tone or LV diastolic compliance. When we retested the SIPE-susceptibles under the same conditions after a dose of sildenafil, pulmonary artery pressures were decreased, with no adverse effects on hemodynamics. We concluded that by dilating pulmonary vessels and systemic venous sildenafil could be an effective prophylaxis against SIPE.
Dr. William A Gray[/caption]
Dr. William A Gray, MD
Chief of the Division of Cardiovascular Disease
Main Line Health
President of Main Line Health’s Lankenau Heart Institute
Medical Research: What is the background for this study? What are the main findings?
Dr. Gray: The basis for this study was two-fold: the ACST-1 trial had shown, in asymptomatic patients with severe carotid disease, that immediate Carotid Endarterectomy reduced subsequent stroke as compared to deferred Carotid Endarterectomy---so the next logical question was, could Carotid Artery Stenting (CAS) compare as an equal alternative to Carotid Endarterectomy (CEA) in this same, standard risk, population with severe carotid stenosis.
The CREST trial, as originally constructed and at the time ACT 1 was conceived did not include this population (although it later expanded to encompass asymptomatic patients as well), so it was an open question. The second reason had to do with Abbott Vascular, the study sponsor, achieving FDA regulatory approval for their stent system in this population---as well as in the symptomatic population being studied n CREST (which they were also the device sponsor).
The main findings were that the primary endpoint of death/stroke and MI at 30 days plus ipsilateral stroke out to 1 and 5 years was not different between CAS and CEA in asymptomatic patients with severe carotid stenosis on good medical secondary prevention therapy.
Dr. Souvik Sen[/caption]
Souvik Sen, MD, MS, MPH, FAHA
Professor and Chair, Neurology Department,
South Carolina Smart State Endowed Stroke Chair
University of South Carolina School of Medicine
Medical Research: What was the catalyst for conducting this study examining the association between migraine with aura and ischemic stroke subtypes?
Dr. Souvik Sen: South Carolina, North Carolina, and Georgia are located in the “buckle” of the stroke belt, with one of the highest stroke related death rates in the country. An unfortunate trend is that younger patients are having strokes leading to death and disability. As a part of the workup for young stroke we are interested in migraine with aura and the type of stroke associated with this condition.
Medical Research: What did you conclude as a result of the findings and how did they compare with your expectations at the beginning of the study?
Dr. Waters[/caption]
MedicalResearch.com Interview with:
Michael F. Waters, MD, PhD
Department of Neurology
Department of Neuroscience
McKnight Brain Institute
University of Florida College of Medicine
Gainesville, Florida
Medical Research: What is the background for this study? What are the main findings?
Dr. Waters: This study was based on a subgroup of medically managed patients with severe, symptomatic, intracranial, atherosclerotic disease. Historically we know that these patients have a very high rate of additional strokes, and multiple studies have attempted to determine the best management for these patients. In SAMMPRIS, we were able to prove that aggressive medical management was superior to stenting in these patients. However, certain patients in the medically managed group still had a very high rate of repeat strokes, as much as 30% of those with certain risk factors. This study was an attempt to identify those risk factors to determine which patients were at the greatest risk for another stroke.
Dr. Sandeep Kumar[/caption]
MedicalResearch.com Interview with:
Sandeep Kumar, MD
Assistant Professor of Neurology
Harvard Medical School
Director, Inpatient Stroke Service
Department of Neurology, Stroke Division
Beth Israel Deaconess Medical Center
Boston, MA 02215
Medical Research: What is the background for this study? What are the main findings?
Dr. Kumar: Transient deficits that start suddenly and typically last for a few minutes to a few hours are the hallmark of a transient ischemic attack (TIA) or a minor ischemic stroke. In this single-center observational study, we have reported similar clinical presentation in some patients with intracerebral hemorrhage (ICH) that are difficult to distinguish from cerebral ischemia based only on clinical signs and symptoms.