ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Background and PurposeA randomized, double-blind, multicenter clinical trial of placebo versus nimodipine was conducted to test the hypothesis that nimodipine would reduce the frequency of death and of worsening by 30% compared with placebo.MethodsNimodipine was used in doses of 60 mg, 120 mg, and 240 mg daily in 1,064 patients treated for 21 days. Treatment was begun within 48 hours of stroke due to infarction as inferred by initial computed tomographic scan findings. The Toronto and motor scales were analyzed by analysis of covariance, using covariance-adjusted means, the last-value-carried-forward, to compare the baseline value with the 3 assessment days (days 4, 10, and 21).ResultsNo difference in mortality or neurological outcome was found with any of the rating scales for the overall cohort. Planned but post hoc subgroup analysis showed a reduction in worsening frequency of 30% compared with placebo and significantly better outcome scores with 120 mg nimodipine daily started within 18 hours of stroke as measured by the Toronto scale (p<0.005) and when the pretreatment computed tomographic scan was negative (p<0.003).ConclusionsNimodipine had no overall effect when treatment was begun within 48 hours. Confirmation of the benefits suggested by post hoc analyses for the subgroup treated with 120 mg nimodipine within 18 hours, and who had negative computed tomographic scans, would require a separate trial.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Background and PurposeThe purpose of this study was to assess the ability of transcranial Doppler ultrasonography to detect selective circulatory changes during cognitive activity.MethodsWe measured cerebral artery flow velocity in 21 normal volunteers by transcranial Doppler ultrasonography during rest followed by cerebral activation. Mean and peak systolic flow velocities of the anterior, middle, and posterior cerebral arteries were measured during the performance of a commercial video game. We also measured flow velocity of the anterior cerebral arteries in 18 subjects during a mental arithmetic task. Serial measurements of the right and left sides were made with a headband with two probes.ResultsWe observed a global increase in the flow velocity above baseline measurements during task performance. During the video game, both middle cerebral arteries (f=2.6,p=0.02 for the left; f=33,p=0.004 for the right) and the left posterior cerebral artery (l=2.2,p=0.004) had selective increase in mean flow velocity compared with the ipsilateral anterior cerebral artery. This selective activation was most prominent in the right middle cerebral artery, which had a greater degree of activation than the right posterior cerebral artery (f=2.8,p=0.013). We did not observe a statistically significant difference between the right and left middle cerebral arteries, but there was a trend toward a greater activation on the right for both the mean velocity (t=1.7,p=0.098) and the peak velocity (f=1.9,p=0.079).ConclusionsOur preliminary investigation suggests that this noninvasive technique has the potential to correlate selective cerebral artery flow dynamics with cognitive activity.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Background and PurposeThe aim of this study was to determine the ability of transcranial Doppler ultrasonography when used to assess cerebral vasoreactivity. The results of this method were compared with regional cerebral blood flow measurements.MethodsForty-three patients with symptoms suggesting cerebrovascular disease took part Transcranial Doppler findings in the middle cerebral arteries were compared with regional cerebral blood flow in the corresponding perfusion territories before and after acetazolamide administration.ResultsThere was a significant positive correlation between the absolute increase in cerebral blood flow in milliliters per 100 g per minute and the percent increase in velocity (r=0.63). The right-left, side-to-side difference of the acetazolamide response obtained by the two methods also showed a positive correlation (r=0.80). Control limits obtained from healthy subjects were used for both the blood flow increase (absolute values and asymmetry in absolute values) and the velocity increase (percent increase and asymmetry in percent increase). The two methods then agreed in their evaluation of vasoreactivity in 74 (86%) of the 86 middle cerebral artery perfusion territories; 20 (23%) were assessed by both methods as having a reduced vasodilatory reserve. Eleven hemispheres with a slightly reduced regional cerebral blood flow response to acetazolamide were not detected by transcranial Doppler, whereas all territories with a marked reduction were identified by Doppler. Only one hemisphere with a normal cerebral blood flow increase after acetazolamide administration was assessed by Doppler as having reduced vasoreactivity.ConclusionsTranscranial Doppler and the acetazolamide test may be used in clinical situations to assess cerebral vasoreactivity.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Background and PurposeThe benefits and safety of thrombolytic therapy was studied in patients with acute brain embolism.MethodsWe intravenously administered recombinant tissue plasminogen activator (20–30 MU for 1 hour) to 10 patients with acute (<6 hours) brain embolism and examined the neurological outcomes in relation to the findings on computed tomography and angiography.ResultsThe symptoms ameliorated in four patients within 24 hours after onset, and reopening of the occluded arteries occurred in two of the patients immediately after recombinant tissue plasminogen activator infusion. On the initial computed tomographic scan (<3 hours), four patients had already demonstrated early indications of brain ischemia, that is, an obscure margin of the lentiform nuclei, reduced tissue attenuation, or effacement of cortical sulci. These patients failed to demonstrate reopening of the occluded arteries, and one developed a massive brain hemorrhage with clinical deterioration. Of the remaining six patients, two obtained clinical improvement with recanalization soon after the therapy and demonstrated little to slight hemorrhagic complications. The outcomes at 1 month were favorable in five patients and poor in three; death occurred in two.ConclusionsThrombolytic therapy with recombinant tissue plasminogen activator may be safe and effective when there are no early computed tomographic findings within 3 hours from the onset of embolic stroke.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Background and PurposeSeasonal variation in the incidence of cerebral hemorrhage has been previously demonstrated. In this study, we sought to identify the climatological data best correlated with this seasonal variation.MethodsIn a retrospectively studied sequential series of 236 patients with nontraumatic cerebral hemorrhage observed in Brussels over a period of 8 years, we cumulatively grouped the dates of stroke occurrence into a single calendar year.ResultsWe found marked seasonal variation in incidence, with the highest value (23%) observed in November–December and the lowest (10%) in July–August Seasonal variations in incidence of cerebral hemorrhage were shown to be correlated not only with the inverse of ambient temperature, but also with the inverse of hours of sunshine and with ambient humidity. We found no difference between hypertensive and normotensive patients.ConclusionsOur study fails to bear out the hypothesis that the higher incidence of cerebral hemorrhage in late autumn and winter is due to the influence of low ambient temperature on blood pressure.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Background and PurposeTemporal trends in stroke incidence in Denmark have not been previously reported. The Copenhagen City Heart Study is a prospective study based on a randomly selected sample of an urban population of, initially, 19,698 participants followed since 1976. Over a period of 12 years, we studied three important aspects of stroke incidence in 848 identified cases: temporal trends, dependence on age and sex, and comparison of responders and nonresponders.MethodsThe participants were invited to two health examinations at 5-year intervals. The participants who attended at least one of the two examinations are termed responders and those who attended none nonresponders. The cases of first-ever stroke were collected from responders, the National Patient Register, and the National Register of Deaths and were verified by study of hospital records and death certificates.ResultsFor responders aged 35–64 years and ≥65 years, there were no significant changes in the weighted rates in four consecutive 3-year periods. There was a tendency toward decreasing rates among younger women, but not in older women or men. The age- and sex-adjusted rates per 1,000 (based on the Danish population in 1982) in responders in the entire 12-year follow-up period were 1.61 in women, 2.67 in men, and 2.14 in both sexes combined. Stroke incidence rates increased exponentially with age in both sexes, with rates in men generally twice those in women, even in the ≥75 years of age group. Age-adjusted rates were higher in nonresponders than in responders. For women, this ratio was 1.7; for men, 1.1.ConclusionsThe stroke incidence in Copenhagen is relatively high and has shown no decreasing tendency over the period 1976–1988.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Background and PurposeImpaired rheological properties of as well as cytotoxic substances produced by granulocytes may contribute to tissue damage in acute ischemic stroke. To assess changes in the properties of circulating granulocytes, we measured their adhesion, deformability, and superoxide generation in the first 3 days after ischemic stroke.MethodsGranulocytes from 18 male patients and 20 age- and risk-matched controls were investigated. Adhesion to murine laminin-, human fibronectin-, and bovine serum albumincoated surfaces was measured with and without the stimulus phorbol myristate acetate and the antiadhesion antibody IB4. Superoxide anion formation was assessed by the reduction of ferricytochrome C. In a subgroup of 10 patients and 11 controls, granulocyte deformability was determined using the micropipette aspiration technique.ResultsThe patients had significantly greater granulocyte adhesion to laminin (p<0.005) and fibronectin (p<0.05) but not bovine serum albumin. Cell stimulation enhanced the differences between the groups, whereas the antiadhesion antibody inhibited adhesion in both patients and controls. There were no significant differences in granulocyte deformability. Superoxide production by granulocytes was significantly lower in the patients without the stimulus (p<0.05) and with 10 nM phorbol myristate acetate (p< 0.005).ConclusionsThese findings suggest that circulating granulocytes in ischemic stroke exhibit increased adhesive properties, a feature that represents one of the risk factors for granulocyte entrapment, impairment of microvascular flow, and tissue injury.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Background and PurposeWe developed a model of acute focal ischemia in the territory of the anterior cerebral artery in baboons to study the ischemic pattern following occlusion and changes in regional cerebral blood flow.MethodsIn nine anesthetized animals, a Scoville clip was placed on the proximal segment of the common anterior cerebral artery via a unilateral transorbital approach. Regional cerebral blood flow was measured by hydrogen clearance in the cortex and corpus callosum. Postexperimentally, arteries were selectively injected.ResultsThe resulting ischemia involved both hemispheres symmetrically and the corpus callosum. Cortical flows were significantly reduced within a region 15 mm from the midline on each side (p<0.01). A gradient of cortical flow reduction was produced between 10 and 25 mm from the midline. This area defines the boundary region between the territories of the anterior and middle cerebral arteries, and is identified as the “penumbra” of the ischemic core, which itself lies within 10 mm of the midline. Blood flows in the corpus callosum decreased from an average of 21.0 to 6.7 ml/100 g/min in the body (p<0.01) and from 22.5 to 10.7 ml/100 g/min in the genu (p<0.05).ConclusionsThis ischemic model has close physiological and morphological relevance to stroke-related clinical circumstances, in particular the acute conditions of focal cerebral ischemia associated with vascular surgery. It also provides a new framework for experimental investigation of the ischemic penumbra.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

BackgroundImproved neurological outcome with postarrest hypertensive hemodilution in an earlier study could be the result of more homogeneous cerebral perfusion and improved O2delivery. We explored global, regional, and local cerebral blood flow by stable xenon-enhanced computed tomography and global cerebral metabolism in our dog cardiac arrest model.MethodsVentricular fibrillation cardiac arrest of 12.5 minutes was reversed by brief cardiopulmonary bypass, followed by life support to 4 hours postarrest We compared control group I (n=5; mean arterial blood pressure, 100 mm Hg; hematocrit, ≥35%) with immediately postarrest reflow-promoted group II (n=5; mean arterial blood pressure, 140–110 mm Hg; hypervolemic hemodilution with plasma substitute to hematocrit, 20–25%).ResultsAfter initial hyperemia in both groups, during the “delayed hypoperfusion phase” at 1–4 hours postarrest, global cerebral blood flow was 51–60% of baseline in group I versus 85–100% of baseline in group II (p<6.01). Percentages of brain tissue voxels with no flow, trickle flow, or low flow were lower (p<0.01) and mean regional cerebral blood flow values were higher in group II (p<0.0l). Global cerebral oxygen uptake recovered to near baseline values at 3–4 hours postarrest in both groups. Postarrest arterial O2content, however, in hemodiluted group II was 40–50% of that in group I. Thus, the O2uptake/delivery ratio was increased (worsened) in both groups at 2–4 hours postarrest.ConclusionsAfter prolonged cardiac arrest, immediately induced moderate hypertensive hemodilution to hematocrit 20–25% can normalize cerebral blood flow patterns (improve homogeneity of cerebral perfusion), but does not improve cerebral O2delivery, since the flow benefit is offset by decreased arterial O2content Individualized titration of hematocrit or hemodilution with acellular O2carrying blood substitute (stroma-free hemoglobin or fluorocarbon solution) would be required to improve O2uptake/delivery ratio.

ISSN:0039-2499    

出版商:OVID    

年代:1992

数据来源: OVID