摘要:

Various functional imaging modalities can be applied in acute ischaemic stroke to identify functionally impaired, but morphologically preserved tissue (i.e. the penumbra), and to distinguish it from irreversibly damaged tissue. Flow thresholds for irreversible tissue destruction resulting in functional impairment, as determined by positron emission tomography, perfusion and diffusion-weighted magnetic resonance imaging, single-photon computed tomography and xenon computed tomography, were comparable and ranged between 5 and 12 ml/100 g per min for the lower and 14 and 22 ml/100 g per min for the upper limit of penumbra. These imaging modalities help to select patients for thrombolytic therapy and provide evidence for the effect of this treatment on critically perfused tissue. They can also serve as surrogate markers in the evaluation of therapeutic efficacy. Further progress in interventional neuroradiology has been achieved with intra-arterial thrombolysis, which has become a treatment option beyond the 3-h therapeutic window in acute ischaemic stroke. Angioplasty and stenting of stenosis of arteries that supply the brain with blood have reached a point in their development at which a randomized trial to compare these treatments with vascular surgery is warranted.

ISSN:1350-7540    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Silent stroke is frequently recognized in elderly persons. Diffusion-weighted magnetic resonance imaging has proved to be highly sensitive in the detection of recent silent stroke, and may further applications in the future. Silent stroke in healthy and asymptomatic individuals mainly comprises lacunar infarcts, which are often associated with white matter changes. Thus, analyses of risk factors and genetic factors in small-vessel diseases such as lacunar infarct and white matter changes may provide clues regarding the pathogenesis of silent stroke. Silent stroke may be a risk factor for clinical stroke and cognitive impairment, but prospective studies are required to confirm this.

ISSN:1350-7540    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

The concept of an ischaemic penumbra, surrounding a focal cerebral lesion, is now widely accepted, although no universal definition of the ‘penumbra’ exists. In the present review, we consider the penumbra as that volume of brain tissue at the periphery of a focal, irreversibly damaged area that is threatened by recruitment into necrosis. Implicit to such a definition are several secondary concepts. First, the penumbra is both spatial, in that it surrounds the densely ischaemic core, but it is also temporal, in that its evolution toward infarction is a relatively progressive phenomenon. The pertinent literature is summarized. Second, penumbral tissue is potentially salvageable; the most recent animal studies are reviewed. Third, because electrically silent and pathologically damaged tissues have identical functional characteristics, it is evident that most clinical rating scales, be they neurological, behavioural, or psychological, are poorly adapted to address the problem of the penumbra. Finally, the penumbral tissue is remarkably and intensively ‘active’: multiple processes of cell death and repair occur and involve molecular mechanisms, electrophysiology and the vasculature.

ISSN:1350-7540    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Cerebral ischemia is accompanied by a marked inflammatory reaction that is initiated by ischemia-induced expression of cytokines, adhesion molecules, and other inflammatory mediators, including prostanoids and nitric oxide. Preclinical studies suggest that interventions that are aimed at attenuating such inflammation reduce the progression of brain damage that occurs during the late stages of cerebral ischemia. In particular, strategies that block the activity of inflammation-related enzymes, such as inducible nitric oxide synthase and cyclo-oxygenase-2, reduce ischemic damage with an extended therapeutic window. Although a clinical trial using murine antibodies against intercellular adhesion molecule-1 did not show benefit in patients with ischemic stroke, recent data indicate that immune activation induced by the heterologous protein may have played an important role in the failure of this trial. Therefore, there is a strong rationale for continuing to explore the efficacy of anti-inflammatory therapies in the treatment of the late stages of cerebral ischemia.

ISSN:1350-7540    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

During the past year epidemiological studies have linked elevated plasma total homocysteine concentrations with an increased risk of ischaemic stroke because of arterial disease. Laboratory studies have further explored the mitogenic effects of total homocysteine on vascular smooth muscle, and cytotoxic and thrombophilic effects on vascular endothelium. Also, a clinical trial has shown that lowering total homocysteine by means of multivitamin therapy decreases the rate of abnormal exercise electrocardiography tests. However, it remains to be determined whether lowering total homocysteine prevents hard clinical outcome events, such as stroke and other serious vascular events. An alternative explanation for the observed association between elevated total homocysteine and stroke is a confounding effect of factors associated with hyperhomocysteinaemia (e.g. cigarette smoking, renal impairment, an atherogenic diet, cystine deficiency, folate deficiency) or perhaps even the acute vascular events themselves, whereby the tissue damage temporarily increases total homocysteine levels. The results of ongoing clinical trials in stroke patients to determine the impact of multivitamin therapy on recurrent stroke and other serious vascular events are awaited.

ISSN:1350-7540    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

The present review focuses on evolving concepts in the pathogenesis and management of deep and lobar intracerebral hemorrhage subtypes, with particular focus on the relationship between lobar intracerebral hemorrhage, apolipoprotein E subtypes and cerebral amyloid angiopathy; deep intracerebral hemorrhage and the potential interaction between hypertension and low cholesterol; and new concepts in medical and surgical therapy for acute intracerebral hemorrhage.

ISSN:1350-7540    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:1350-7540    

出版商:OVID    

年代:2001

数据来源: OVID