George Hademenos

Guidelines for the Early Management of Patients With Ischemic Stroke: A Scientific Statement From the Stroke Council of the American Stroke Association

In 1994, a panel appointed by the Stroke Council of the American Heart Association authored guidelines for the management of patients with acute ischemic stroke.1 After the approval of the use of intravenous recombinant tissue plasminogen activator (rtPA) for treatment of acute ischemic stroke by the Food and Drug Administration, the guidelines were supplemented by a series of recommendations 2 years later.2 Several promising interventions for the treatment of acute ischemic stroke have subsequently been tested in clinical trials, and other components of acute management have been evaluated since the previous guidelines were published. These new data have prompted the present revision of the prior guideline statement. The goal of these guidelines is to provide updated recommendations that can be used by primary care physicians, emergency medicine physicians, neurologists, and other physicians who provide acute stroke care from admission to an emergency department through the first 24 to 48 hours of hospitalization by addressing the diagnosis and emergent treatment of the acute ischemic stroke in addition to the management of its acute and subacute neurological and medical complications. Several groups have now written statements about management of stroke.3–7 These statements also include recommendations about public educational programs, the organization of stroke resources, and other aspects of patient management. For example, the Brain Attack Coalition published recommendations for organizing stroke services in a community, and the recommendations of the American Heart Association Emergency Cardiovascular Care Committee provide an outline for emergency medical services.6 The current panel elected not to duplicate these recent efforts. Therapies to prevent recurrent stroke, also a component of acute management, are similar to prophylactic medical or surgical therapies used for patients with transient ischemic attacks and other high-risk patients. The reader is referred to relevant recent statements for additional information.8,9 In developing …

Recommendations for the Management of Intracranial Arteriovenous Malformations A Statement for Healthcare Professionals From a Special Writing Group of the Stroke Council, American Stroke Association

Intracranial arteriovenous malformations (AVMs) are relatively uncommon but increasingly recognized lesions that can cause serious neurological symptoms or death. Although AVMs can present with hemorrhage or seizure, since the advent of contemporary brain imaging techniques, an increasing number are detected before rupture. Over the last decade, there have been significant developments in the management of intracranial AVMs. There has been an evolution of microsurgical as well as endovascular and radiosurgical techniques to treat these lesions. As the management options have evolved, individual and combined modality treatment protocols have been developed in different institutions for the management of AVMs. A writing group was formed by the Stroke Council of the American Stroke Association to review published data for intracranial AVMs to develop practice recommendations regarding epidemiology, natural history, potential treatment strategies, and outcomes. The reports reviewed for this synthesis were selected on the basis of study design, sample size, and relevance to a particular topic. Each report was graded according to previously defined criteria.1 2 After review of the available literature, recommendations for current practice standards have been made according to 3 separate grades (Table 1⇓). View this table: Table 1. Levels of Evidence in Grading of Recommendations for Treatment of Patients With Subarachnoid Hemorrhage By the design of this type of review, the recommendations in this report represent an overview of existing treatment protocols that may vary considerably. These guidelines were developed to serve as a basis for the development of treatment strategies for AVMs, which overall represent a fairly heterogeneous group of cerebrovascular lesions and which may demonstrate different natural histories. In addition, for brain AVMs, no level I or II data are available in the literature. Because of the heterogeneity of these lesions and their relatively infrequent occurrence, strictly defined subcategories for comparison of the efficacy of various treatment modalities …

Recommendations for the management of patients with unruptured intracranial aneurysms: A statement for healthcare professionals from the Stroke Council of the American Heart Association.

Aneurysmal subarachnoid hemorrhage (SAH) has a 30-day mortality rate of 45%, with approximately half the survivors sustaining irreversible brain damage.1 On the basis of an annual incidence of 6 per 100 000, ≈15 000 Americans will have an aneurysmal SAH each year. Population-based incidence rates vary considerably from 6 to 16 per 100 000, with the highest rates reported from Japan and Finland.2 3 4 5 Approximately 5% to 15% of stroke cases are secondary to ruptured saccular aneurysms. Although the prevention of hemorrhage has been advocated as the most effective strategy aimed at lowering mortality rates,6 the optimal management of patients with unruptured intracranial aneurysms (UIAs) remains controversial. Management decisions require an accurate assessment of the risks of various treatment options compared with the natural history of the condition. The natural history of UIAs and treatment outcomes are influenced by (1) patient factors, such as previous aneurysmal SAH, age, and coexisting medical conditions; (2) aneurysm characteristics, such as size, location, and morphology; and (3) factors in management, such as the experience of the surgical team and the treating hospital. These many influences have contributed to considerable variability in the reported risks for aneurysmal SAH and the treatment of UIAs. There are no prospective randomized trials of treatment interventions versus conservative management to date, and it is possible that no such studies will be carried out in the future. According to a classification system suggested by Cook et al,7 randomized clinical trials with low likelihoods of false-positive and false-negative errors provide the highest level of evidence (level I) that can be applied to a clinical recommendation. Randomized trials with high likelihoods of false-negative and positive errors provide level II evidence. Level III evidence is generated with nonrandomized concurrent cohort comparisons between contemporaneous patients who did and …

Primary Prevention of Ischemic Stroke A Statement for Healthcare Professionals From the Stroke Council of the American Heart Association

Stroke ranks as the third leading cause of death in the United States. It is now estimated that there are more than 700 000 incident strokes annually and 4.4 million stroke survivors.1 2 The economic burden of stroke was estimated by the American Heart Association to be

Guidelines and Recommendations for Perfusion Imaging in Cerebral Ischemia A Scientific Statement for Healthcare Professionals by the Writing Group on Perfusion Imaging, From the Council on Cardiovascular Radiology of the American Heart Association

51 billion (direct and indirect costs) in 1999.3 Despite the advent of treatment of selected patients with acute ischemic stroke with tissue plasminogen activator and the promise of other experimental therapies, the best approach to reducing the burden of stroke remains prevention.4 5 High-risk or stroke-prone individuals can be identified and targeted for specific interventions.6 This is important because epidemiological data suggest a substantial leveling off of prior declines in stroke-related mortality and a possible increase in stroke incidence.7 8 The Stroke Council of the American Heart Association formed an ad hoc writing group to provide a clear and concise overview of the evidence regarding various established and potential stroke risk factors. The writing group was chosen based on expertise in specific subject areas, and it used literature review, reference to previously published guidelines, and expert opinion to summarize existing evidence and formulate recommendations (Table 1⇓). View this table: Table 1. Levels of Evidence and Grading of Recommendations As given in Tables 2 through 4⇓⇓⇓, risk factors or risk markers for a first stroke were classified according to potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented, less well documented).5 The tables give the estimated prevalence, population attributable risk, relative risk, and risk reduction with treatment for each factor when known. Population attributable risk reflects the proportion of ischemic strokes in the population that can be attributed to a particular risk factor and is given by the formula 100×[prevalence(relative risk−1)/prevalence(relative risk−1)+1]). …

Recommendations for the Management of Patients With Unruptured Intracranial Aneurysms A Statement for Healthcare Professionals From the Stroke Council of the American Heart Association

A number of techniques have been developed during the past four decades to evaluate cerebral perfusion. The oldest used 133Xe, a lipophilic radioactive tracer that easily diffuses through the blood-brain barrier (BBB). It was either injected or inhaled, and probes placed over the scalp were used to measure perfusion to the cerebral cortex.1,2 In the mid-1970s, the development of a scanner to detect the emission of positrons led to positron emission tomography (PET) in humans.3 Using a number of radioisotopes, this technology can measure cerebral blood flow (CBF) and various metabolic processes, but until recently it has been primarily used as a research tool. Stable (“cold”) xenon was found to attenuate x-rays in a manner similar to iodine, and there were a number of projects in the 1970s to use this gas as a contrast agent for the rapidly emerging technology of computed tomography (CT), particularly as a perfusion tracer.4 This resulted in the development of the xenon-enhanced CT (XeCT) technique to calculate CBF in patients.5 With improvements in single photon emission CT (SPECT) during the 1980s, a number of compounds that are metabolized in the central nervous system (CNS) were found to be appropriate for perfusion imaging.6,7 Perfusion-weighted and diffusion-weighted magnetic resonance (MR) imaging (PWI and DWI) were developed in the late 1980s,8,9 and that technology has continued to improve. Finally, with the evolution of helical and spiral multislice CT technology, CT perfusion (CTP) imaging is becoming a potentially important clinical technique.10 Although the development of these technologies has been fascinating, their role in evaluating a variety of diseases of the CNS is controversial. It might seem obvious that a disorder of blood flow, such as acute stroke or chronic vascular occlusive disease, should be studied with a perfusion imaging technique. …

Recommendations for the Endovascular Treatment of Intracranial Aneurysms A Statement for Healthcare Professionals from the Committee on Cerebrovascular Imaging of the American Heart Association Council on Cardiovascular Radiology

Aneurysmal subarachnoid hemorrhage (SAH) has a 30-day mortality rate of 45%, with approximately half the survivors sustaining irreversible brain damage.1 On the basis of an annual incidence of 6 per 100 000, ≈15 000 Americans will have an aneurysmal SAH each year. Population-based incidence rates vary considerably from 6 to 16 per 100 000, with the highest rates reported from Japan and Finland.2 3 4 5 Approximately 5% to 15% of stroke cases are secondary to ruptured saccular aneurysms. Although the prevention of hemorrhage has been advocated as the most effective strategy aimed at lowering mortality rates,6 the optimal management of patients with unruptured intracranial aneurysms (UIAs) remains controversial. Management decisions require an accurate assessment of the risks of various treatment options compared with the natural history of the condition. The natural history of UIAs and treatment outcomes are influenced by (1) patient factors, such as previous aneurysmal SAH, age, and coexisting medical conditions; (2) aneurysm characteristics, such as size, location, and morphology; and (3) factors in management, such as the experience of the surgical team and the treating hospital. These many influences have contributed to considerable variability in the reported risks for aneurysmal SAH and the treatment of UIAs. There are no prospective randomized trials of treatment interventions versus conservative management to date, and it is possible that no such studies will be carried out in the future. According to a classification system suggested by Cook et al,7 randomized clinical trials with low likelihoods of false-positive and false-negative errors provide the highest level of evidence (level I) that can be applied to a clinical recommendation. Randomized trials with high likelihoods of false-negative and positive errors provide level II evidence. Level III evidence is generated with nonrandomized concurrent cohort comparisons between contemporaneous patients who did and …

Biophysical Mechanisms of Stroke

Intracranial aneurysms are common, with a prevalence of 0.5% to 6% in adults, according to angiography and autopsy studies.1 Most intracranial aneurysms are asymptomatic and are never detected. Some are discovered incidentally in neuroimaging studies and some produce symptoms due to compression of neighboring nerves or adjacent brain tissue. Others are detected only after they have ruptured and caused subarachnoid hemorrhage, a devastating type of stroke asso-ciated with 32% to 67% case fatality and 10% to 20% long-term dependence in survivors due to brain damage.2 To prevent subarachnoid hemorrhage, physicians have developed methods to treat aneurysms. For ruptured aneurysms, early treatment within 24 to 72 hours has been recommended because the risk of subsequent rupture is high, with approximately 20% risk of rerupture in the first 2 weeks after subarachnoid hemorrhage.3 Each additional rupture substantially increases the risk of mortality and morbidity. Treatment has also been recommended for most unruptured aneurysms,4 although there is uncertainty about treatment of some small aneurysms <10 mm because their risk of rupture appears low.5,6⇓ The American Heart Association formed this special writing group to summarize the literature and create recommendations on endovascular therapy of ruptured and unruptured intracranial aneurysms. This statement is meant to extend previous statements on treatment of subarachnoid hemorrhage3 and on treatment of unruptured aneurysms.4 During the review, it became evident that any recommendations would be based primarily on expert opinion weighing evidence only from nonrandomized cohort studies and case series. In 1937, Walter Dandy reported the first successful surgical clipping of the neck of an aneurysm. Microsurgical techniques have steadily evolved since then, with development of a variety of surgical approaches and metal aneurysm clips. Repair of aneurysms in nearly all intracranial locations is possible by placing a clip made from a …

Anatomical and morphological factors correlating with rupture of intracranial aneurysms in patients referred for endovascular treatment

BACKGROUND Stroke is the third leading cause of death and the leading cause of long-term disability in the United States. Although a host of genetic, biochemical, physiological, anatomic, and histological factors have been implicated, to varying degrees, in the pathogenesis of stroke, biophysical factors are believed to play a significant role in the development, diagnosis, and therapy of stroke. The purpose of this review article is to identify, describe, and illustrate these causes and biophysical and hemodynamic mechanisms predisposing a person to stroke, which often form the basis for novel methods of diagnosis and therapy. SUMMARY OF REVIEW This mini-review begins by describing the physical principles that govern the flow of blood through normal and stenosed carotid artery bifurcations. In addition to the tortuosity, curvature, and tensile forces of the carotid artery bifurcation, the effects of biophysical phenomena from flowing blood such as viscous forces, pressure forces, velocity, kinetic energy, momentum, impulse, shear stress, and vibrational displacements exerted by the flowing blood on the vessel wall are conducive to abnormal flow behavior and patterns, degrading the vessel wall and creating the potential for stroke. CONCLUSIONS Recent advances in the treatment of stroke are based on increasing knowledge of its underlying biophysical mechanisms, as well as on better-publicized advances in imaging instrumentation and procedures for the management and treatment of patients.

Advances in the genetics of cerebrovascular disease and stroke

Abstract The size of intracranial aneurysms is the only characteristic shown to correlate with their rupture. However, the critical size for rupture has varied considerably among previous accounts and remains a point of controversy. Our goal was to identify statistically significant clinical and morphological factors predictive of the occurrence of rupture and aneurysm size in patients referred for endovascular treatment. We retrospectively recorded the following factors from 74 patients who presented with ruptured (40) or unruptured (34) aneurysms: aneurysm morphology (uni/multilobulated), location (anterior/posterior), maximum diameter, diameter of the neck, and the patients age and sex. We performed stepwise discriminant, and stepwise and logistic regression analysis to identify factors predicting rupture and the size of the aneurysm at rupture. The mean diameter of the ruptured aneurysms was 11.9 ± 6.3 mm, range 3.0–33.0 mm, and that of the unruptured aneurysm 13.5 ± 5.8 mm, range 5.0–30 mm. Stepwise discriminant analysis identified aneurysm morphology (P < 0.001) and location in the intracranial circulation (P < 0.001) as statistically significant factors in predicting rupture. Stepwise regression analysis revealed that aneurysm morphology and the size of the neck were predictors of aneurysm size at rupture.