摘要:

Background and PurposeThe detection of circulating particulate cerebral emboli using transcranial Doppler ultrasonography has been recently reported. It has been suggested that this method might allow discrimination between different embolic materials; this would be very useful for selecting specific pharmacological treatment in individual patients. This study was designed to identify those parameters of the Doppler signal that might prove useful in discriminating between different types and sizes of particulate cerebral emboli.MethodsAn extracorporeal circuit filled with a saline/Tween solution and driven by a peristaltic pump was used. The tubing was placed in a skull in the position of the middle cerebral artery. Using transcranial Doppler ultrasound, flow was insonated via the transtemporal window. The following embolic materials of measured sizes (range of maximum dimension, 0.5-5.0 mm) were introduced into the circuit: thrombus (n=20), platelet-rich aggregates (n=15), atheromatous material (n=20), and fat (n=20). The Doppler signal was recorded during the passage of each embolus. Off-line analysis was performed to measure the maximum amplitude and duration of the signal.ResultsFor all embolic materials there was a highly significant relation between embolus size and maximum amplitude of the Doppler signal. The closest correlation was obtained when the logarithm of maximum amplitude was used (for thrombi,r=0.74; for platelet,r=0.87; for atheroma,r=0.46; and for fat,r=0.68). The slope of the regression line differed for the different embolic materials and was significantly steeper for platelets than for atheroma (p< 0.01). Platelet emboli of maximum dimension ≤1.5 mm resulted in significantly lower maximum amplitude than similarly sized atheroma emboli (157 dB versus 206.7 dB,p<0.01). For larger emboli (>2 mm) there was little further increase in maximum amplitude with increases in embolus size. For all embolic materials there was a highly significant linear relation between embolus size and duration of the high-amplitude (>150 dB) signal (for thrombi,r=0.75; for platelet,r=0.90; for atheroma,r=0.77; and for fat,r=0.86).ConclusionsPlatelet emboli result in lower-amplitude signals, and therefore analysis of maximum amplitude may provide information on the type of embolic material. However, it may be difficult to determine whether a given signal is associated with a large platelet embolus or a small atheroma embolus. Duration of the high-amplitude signal will allow accurate estimation of the size of emboli, particularly where the emboli are all of the same material.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeNimodipine, a calcium antagonist, has been reported to have beneficial effects in acute ischemic infarction. Some calcium channel antagonists have antiplatelet effects. We investigated the effect of oral nimodipine on platelet function in healthy volunteers.MethodsTwelve healthy volunteers (6 men and 6 women, mean age 32.9 ± 5.6 years) took 30 mg nimodipine every 6 hours for 24 hours, followed by a week with no medication, followed by 60 mg every 6 hours for 24 hours. Ex vivo platelet function was measured at baseline, 1 hour after the first dose at each dosage strength, and 1 hour after the last dose at each dosage. Platelet studies included aggregation and adenosine triphosphate release in response to collagen, epinephrine, and adenosine disphosphate; maximal rate of primary aggregation; threshold adenosine diphosphate concentration for second-phase aggregation; and thromboxane B2 release at threshold aggregation. The bleeding time was measured at baseline and after the last 60-mg dose of nimodipine.ResultsNo change in any platelet function study was seen with 30 mg nimodipine every 6 hours. Platelet function studies were also unchanged after 60 mg every 6 hours, except for a slight decrease in aggregation and adenosine triphosphate release in response to suprathreshold (10 μM) adenosine diphosphate (p=0.001, Student's pairedttest). There was no significant change in bleeding times.ConclusionsOral nimodipine has minimal antiplatelet activity in young, healthy subjects.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposePlatelet-activating factor acetylhydrolase hydrolyzes platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine). It also hydrolyzes oxidized derivatives of phosphatidylycholine that have a short-chain acyl residue at thesn-2 position. This enzyme may act mainly in the degradation of oxidized phospholipids and may play a role in maintaining erythrocyte deformability. Therefore, we assessed the activity of red cell membrane platelet-activating factor acetylhydrolase in patients with ischemic stroke and studied the relation of the enzyme activity to red cell deformability.MethodsEnzyme activity was measured in the detergent extract of red cell membranes from 38 patients with cerebral thrombosis and 38 age-matched healthy volunteers. Red cell filterability, an index of red cell deformability, was also measured.ResultsThe enzyme activity in patients and control subjects was 100±74 and 148±128 nmol/g protein per minute (2.68 ±.11 and 3.79 ± 2.46 pmol/109cells per minute) (mean ± SD), respectively, and the difference was significant (p<0.05 by the Mann-WhitneyUtest, two-sided test). Enzyme activity was correlated positively with red cell filterability in the patients (n=20,r=0.565,p<0.01).ConclusionsRed blood cells from stroke patients have lower levels of platelet-activating factor acetylhydrolase activity when compared with those from healthy subjects. This may result in the accumulation of oxidized lipids in the cell membrane and lead to impaired red cell deformability in patients with cerebral thrombosis.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeDeficiencies in coagulant inhibitors protein C, protein S, and antithrombin III increase the risk of venous thrombosis. We describe 10 young adults with cerebral arterial thrombosis due to deficiencies in these factors.MethodsSixty patients younger than 45 years were hospitalized because of acute ischemic stroke diagnosed through computed tomography or magnetic resonance imaging. Cerebral angiography was performed in 54 cases. Hematologic and coagulation profiles, autoantibody screen, syphilis serology, and lupus anticoagulant were analyzed in all patients. Among the total cases, Holter monitoring was performed in 13 patients, echocardiography in 20, and cerebrospinal fluid studies for cysticercosis and tuberculosis in two. The quantitative analysis of protein C, protein S (by Laurell rocket Immunoelectrophoresis), and antithrombin III (by radial immunodiffusion) was performed on admission and 3 months after stroke in all patients and in relatives of six patients.ResultsIn 10 cases (17%) the stroke was attributed to deficiency of coagulation inhibitors: three men had protein C deficiency, two women had protein S deficiency, and five had antithrombin III deficiency (three men and two women). The cerebral infarction involved the carotid territory in these 10 patients. None had previous thromboembolic disease. Eight patients showed a complete recovery. An acquired disorder was presumed in one protein S-deficient and in two antithrombin III-deficient patients; the remainder were considered heterozygous.ConclusionsThe cerebral vasculature may be primarily involved in the deficiency of these natural anticoagulants. Young adults seem to be the most often affected. A knowledge of these new clotting defects will enable the clinician to improve the prevention and treatment of this devastating neurological disease.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeAtrial fibrillation (AF) is a risk factor for stroke, although it may not always be directly responsible for the stroke. On the other hand, cardiac arrhythmias and electrocardiographic changes have been reported after ischemic stroke and numerous other intracranial pathologies. We tested the hypothesis that some patients with acute stroke may develop transient AF as a consequence of the stroke.MethodsThis study was based on 1,661 patients with first-ever stroke consecutively hospitalized and prospectively included into the Lausanne Stroke Registry. “Recent AF” was defined as AF discovered at or after (“after-admission” AF) admission in patients without any previous history of AF. Populations with recent AF and after-admission AF were compared for AF evolution, risk factors, and lesion type and distribution with patients with previous history of AF (known AF) and with patients with another recognized cardiac source of embolism (cardioembolic).ResultsTwenty-four patients had recent AF on admission, and 17 developed it a few hours to 3 days after stroke. AF disappeared after a few days in 26 (63%; 94% of after-admission AF) patients. Stroke was a primary hematoma in 9.8% of patients with recent AF, 2.8% of patients with known AF, and 0.9% (p<0.001) of patients with cardiac source of embolism. Parietoinsular (32%) and brain stem (11%) involvement were more common in recent AF than in cardioembolic stroke in general (16.7% and 6.7%, respectively;p<0.05).ConclusionsAF discovered after an acute stroke lasted no more than a few days, suggesting that it may have occurred as a consequence of the stroke. This possibility is emphasized by the significant predominance in patients with recent AF of primary hematoma, which cannot be caused by AF, and of parietoinsular and brain stem involvement, which are experimentally known as arrhythmogenic. This hypothesis should be considered in patients with acute stroke and previously unknown AF before therapeutic decisions are made.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeA patent foramen ovale has been reported to be significantly more frequent in young stroke patients than in matched control subjects, and paradoxical embolism has been suggested as the main mechanism of stroke in this situation. The present study was designed to test this hypothesis.MethodsSixty-eight consecutive patients under 55 years of age presenting with an ischemic stroke had an extensive workup, including transesophageal echocardiography with contrast. We compared the prevalence of criteria for the diagnosis of paradoxical embolism in patients with and without a patent foramen ovale.ResultsA patent foramen ovale was found in 32 patients (47%). A Valsalva-provoking activity was present at stroke onset in six patients with a patent foramen ovale and in eight patients with no patent foramen ovale (χ2=0.1, nonsignificant). Clinical/radiological features suggestive of an embolic mechanism were not more frequent in patients with a patent foramen ovale. Clinical evidence of deep vein thrombosis was present in one patient with a patent foramen ovale and in none of the others. No occult venous thrombosis was found in a subgroup of patients with a patent foramen ovale and no definite cause for stroke who underwent venography (n=13).ConclusionsOur results do not support the hypothesis that paradoxical embolism is the primary mechanism of stroke in patients with a patent foramen ovale.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeThe etiology of ischemic stroke affects prognosis, outcome, and management. Trials of therapies for patients with acute stroke should include measurements of responses as influenced by subtype of ischemic stroke. A system for categorization of subtypes of ischemic stroke mainly based on etiology has been developed for the Trial of Org 10172 in Acute Stroke Treatment (TOAST).MethodsA classification of subtypes was prepared using clinical features and the results of ancillary diagnostic studies. “Possible” and “probable” diagnoses can be made based on the physician's certainty of diagnosis. The usefulness and interrater agreement of the classification were tested by two neurologists who had not participated in the writing of the criteria. The neurologists independently used the TOAST classification system in their bedside evaluation of 20 patients, first based only on clinical features and then after reviewing the results of diagnostic tests.ResultsThe TOAST classification denotes five subtypes of ischemic stroke: 1) large-artery atherosclerosis, 2) cardioembolism, 3) small-vessel occlusion, 4) stroke of other determined etiology, and 5) stroke of undetermined etiology. Using this rating system, interphysician agreement was very high. The two physicians disagreed in only one patient. They were both able to reach a specific etiologic diagnosis in 11 patients, whereas the cause of stroke was not determined in nine.ConclusionsThe TOAST stroke subtype classification system is easy to use and has good interobserver agreement. This system should allow investigators to report responses to treatment among important subgroups of patients with ischemic stroke. Clinical trials testing treatments for acute ischemic stroke should include similar methods to diagnose subtypes of stroke.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeThe present investigation was aimed at evaluating the incidence and prediction of a first major cerebrovascular (fatal or nonfatal) event.MethodsThe study population included the two Italian rural samples of the Seven Countries Study (namely, Montegiorgio and Crevalcore), accounting for a total of 1,712 men aged 40–59 years at entry and followed up for mortality and morbidity for 25 years. A number of individual variables measured at baseline, at the fifth year, and at the tenth year of follow-up and possibly related to cerebrovascular events were considered. Of the 1,709 subjects free from major cerebrovascular events at entry 171 developed a first major cerebrovascular event, but for the multivariate Cox model analysis only 1,572 subjects and 152 events were employed due to some exclusions for missing data.ResultsSystolic blood pressure, indexes of respiratory function (protective), and physical activity at work (protective) demonstrated significant predictive roles for all ages and all lengths of follow-up considered. Other factors (presence of arrhythmias, presence of arcus senilis, and skinfold thickness [protective]), significantly contributed to the prediction, but in only some models. Time-related changes in systolic blood pressure significantly improved the prediction of cerebrovascular events.ConclusionsThe multivariate prediction performed in this report allowed the validation of three risk factors (systolic blood pressure, respiratory function indexes, and physical activity at work) whose predictive powers remain stable with aging. The need for further studies specifically aimed at discriminating hemorrhagic from thrombotic events is suggested.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Background and PurposeWe sought to determine whether hypertension is less common in primary lobar hemorrhage than intracerebral hemorrhage in other locations and whether the frequency of hypertension in lobar hemorrhage diminishes with advancing age.MethodsWe identified all cases of intracerebral hemorrhage in Greater Cincinnati during 1988 by review of hospital and autopsy records as well as computed tomographic and magnetic resonance scans.ResultsDuring 1988, 66 primary lobar hemorrhages occurred, constituting 46% of all intracerebral hemorrhages in those under 75 years of age and 34% in those age 75 and older. A history of hypertension was present in 67% of patients with lobar, 73% of those with deep, 73% of those with cerebellar, and 78% of those with pontine hemorrhages. Left ventricular hypertrophy was present in 21% of patients with lobar, 27% of those with deep, and 47% of those with pontine/cerebellar hemorrhages. The frequency of hypertension in patients with lobar hemorrhage did not decrease with advancing age.ConclusionsThe proportion of all intracerebral hemorrhages that are lobar does not increase with advancing age. Hypertension is nearly as common in primary lobar hemorrhage as in deep, cerebellar, and pontine hemorrhages, and its importance as an associated condition for lobar hemorrhage does not diminish with advancing age.

ISSN:0039-2499    

出版商:OVID    

年代:1993

数据来源: OVID