摘要:

Background—The collateral circulation plays a pivotal role in the pathophysiology of cerebral ischemia. Current knowledge of the collateral circulation remains sparse, largely because of prior limitations in methods for evaluation of these diminutive routes of cerebral blood flow.Summary of Review—Anatomic descriptions of the collateral circulation often focus on more proximal anastomoses at the circle of Willis, neglecting secondary collateral pathways provided by leptomeningeal vessels. Pathophysiological recruitment of collateral vessels likely depends on the temporal course of numerous compensatory hemodynamic, metabolic, and neural mechanisms. Subsequent endurance of these protective vascular pathways may determine the severity of ischemic injury. Characterization of the collateral circulation with advanced neuroimaging modalities that provide angiographic information and perfusion data may elucidate critical determinants of collateral blood flow. Such information on the status of the collateral circulation may be used to guide therapeutic interventions. Prognostication and risk stratification may also be improved by routine evaluation of collateral blood flow.Conclusions—Contemporary understanding of the collateral circulation may be greatly enhanced through further refinement of neuroimaging modalities that correlate angiographic findings with perfusion status, providing the basis for future therapeutic and prognostic applications.

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background and Purpose—Observational studies suggest that platelet inhibitors reduce the risk of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage and thereby have a beneficial effect on clinical outcome. Robust evidence, however, is lacking. We performed a systematic meta-analysis to determine whether antiplatelet therapy has a beneficial effect after SAH.Methods—We searched Medline and the Cochrane Library to identify all randomized controlled trials of antiplatelet drugs versus control and calculated relative risks with corresponding 95% confidence intervals (CIs) for poor outcome (dependence or death), the occurrence of DCI, and the occurrence of any intracranial hemorrhage.Results—We included 5 trials totaling 699 patients. The overall relative risk for poor outcome was 0.87 (95% CI, 0.65 to 1.17); for the occurrence of DCI (reported in 3 of the 5 studies), 0.65 (95% CI, 0.47 to 0.89); and for the occurrence of intracranial hemorrhage, 1.19 (reported in 4 of the 5 studies) (95% CI, 0.76 to 1.85).Conclusions—Our data indicate that antiplatelet drugs reduce the risk of DCI in patients with subarachnoid hemorrhage. A randomized clinical trial is warranted to assess the effect on overall outcome.

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background and Purpose—Reliable data on the risk of carotid endarterectomy (CEA) in relation to clinical indication and timing of surgery are necessary to target CEA more effectively, to inform patients, to adjust risks for case mix, and to understand the mechanisms of operative stroke.Methods—We performed a systematic review of all studies published from 1980 to 2000 inclusive that reported the risk of stroke and death resulting from CEA. Pooled estimates of risk by type of presenting ischemic event and time since the last event were obtained by Mantel-Haenszel meta-analysis.Results—Of 383 published studies, only 103 stratified risk by indication. Although the operative risk for symptomatic stenosis overall was higher than for asymptomatic stenosis (odds ratio [OR], 1.62; 95% confidence interval [CI], 1.45 to 1.81;P<0.00001; 59 studies), risk in patients with ocular events only tended to be lower than for asymptomatic stenosis (OR, 0.75, 95% CI, 0.50 to 1.14; 15 studies). Operative risk was the same for stroke and cerebral transient ischemic attack (OR, 1.16; 95% CI, 0.99 to 1.35;P=0.08; 23 studies) but higher for cerebral transient ischemic attack than for ocular events only (OR, 2.31; 95% CI, 1.72 to 3.12;P<0.00001; 19 studies) and for CEA for restenosis than primary surgery (OR, 1.95; 95% CI, 1.21 to 3.16;P=0.018; 6 studies). Urgent CEA for evolving symptoms had a much higher risk (19.2%, 95% CI, 10.7 to 27.8) than CEA for stable symptoms (OR, 3.9; 95% CI, 2.7 to 5.7;P<0.001; 13 studies), but there was no difference between early (<3 to 6 weeks) and late (>3 to 6 weeks) CEA for stroke in stable patients (OR, 1.13; 95% CI, 0.79 to 1.62;P=0.62; 11 studies). All observations were highly consistent across studies.Conclusions—Risk of stroke and death resulting from CEA is highly dependent on the clinical indication. Audits of risk should be stratified accordingly, and patients should be informed of the risk that relates to their presenting event.

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0039-2499    

出版商:OVID    

年代:2003

数据来源: OVID