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Biomedical subjects

V C Hachinski

Publications and source records attributed to V C Hachinski.

At least 37 records · Page 2Linked to original sources
PubMed1994

Significance of plaque ulceration in symptomatic patients with high-grade carotid stenosis. North American Symptomatic Carotid Endarterectomy Trial.

BACKGROUND AND PURPOSE: The importance of carotid plaque ulceration as a cause of cerebral ischemic symptoms remains uncertain. Moreover, its prominence in symptomatic patients with severe carotid stenosis is unknown. METHODS: The association between angiographically defined plaque ulceration and risk of subsequent stroke was assessed using Cox proportional hazards regression in 659 patients with severe (70% to 99%) carotid stenosis from the North American Symptomatic Carotid Endarterectomy Trial. RESULTS: Treatment assignment (medical versus surgical) and degree of ipsilateral stenosis were identified as having a significant influence on the results. The risk of ipsilateral stroke at 24 months for medically treated patients with ulcerated plaques increased incrementally from 26.3% to 73.2% as the degree of stenosis increased from 75% to 95%. For patients with no ulcer, the risk of stroke remained constant at 21.3% for all degrees of stenosis. The net result yielded relative risks of stroke (ulcer versus no ulcer) ranging from 1.24 (95% confidence interval, 0.61 to 2.52) to 3.43 (95% confidence interval, 1.49 to 7.88). Conversely, for surgically treated patients with antecedent presence of an ulcerated plaque, the risk of stroke increased slightly at the highest degrees of stenosis. Overall, carotid endarterectomy reduced the risk of ipsilateral stroke at 24 months by at least 50%. Similar results were obtained for risk of major ipsilateral stroke and risk of all strokes and death. CONCLUSIONS: The presence of angiographically defined ulceration for medically treated symptomatic patients is associated with an increased risk of stroke. The risk of stroke more than doubles at higher degrees of stenosis. Carotid endarterectomy is beneficial in substantially reducing the risk of stroke, regardless of plaque ulceration and degree of severe carotid stenosis.

Carotid Artery Diseases↗
PubMed1994

Angiographic detection of carotid plaque ulceration. Comparison with surgical observations in a multicenter study. North American Symptomatic Carotid Endarterectomy Trial.

BACKGROUND AND PURPOSE: Carotid plaque ulceration is used as one of the determinants in deciding which patients should be submitted to carotid endarterectomy. Uncertainties about its importance persist. Its detection by angiography is an important consideration. METHODS: The detection of ulceration by angiography was compared with observations during endarterectomy in the first 500 patients recruited into the North American Symptomatic Carotid Endarterectomy Trial. This represents the first multicenter compilation of data on this subject and the largest series of patients with both arteriographic and direct surgical observation. RESULTS: Sensitivity and specificity of detecting ulcerated plaques were 45.9% and 74.1%, respectively. The positive predictive value of identifying an ulcer was 71.8%. These results remained unchanged with differing degrees of carotid stenosis and were confirmed by analyses based on receiver operating characteristic (ROC) methodology. The area under the ROC curve (Az) was estimated to be 0.61 (95% confidence interval, 0.55 to 0.67). CONCLUSIONS: These observations from a multicenter study confirm that little agreement exists between angiography and surgical observation in detecting carotid plaque ulceration.

Angiography↗
PubMed1994

The importance of family history in cerebrovascular disease.

BACKGROUND AND PURPOSE: The role of genetics in cerebrovascular disease remains controversial. The purpose of this study was to assess the influence of family history on atherothrombotic infarction or transient ischemic attack. METHODS: Ninety patients with stroke or transient ischemic attack and 90 age- and sex-matched community control subjects were studied prospectively. Medical and family histories were obtained from all subjects, and a complete physical examination was performed. RESULTS: Eighty-five patients and 86 control subjects knew their family history for ischemic heart disease and stroke. A positive history for ischemic heart disease was present in 62 (73%) of the patients and 46 (53%) of the control subjects (P = .019), and a positive family history for stroke was present in 38 (47%) of the patients and 21 (24%) of the control subjects (P = .014). CONCLUSIONS: Although a positive vascular family history was not an independent risk factor in a multivariate analysis, it was an excellent marker of the presence of other established vascular risk factors. Personal histories of ischemic heart disease, hypertension, and hyperlipidemia were found to be significant independent risk factors for stroke.

Adult↗
PubMed1993

Cardiac and sympathetic effects of middle cerebral artery occlusion in the spontaneously hypertensive rat.

Acute increases in sympathetic activity, plasma catecholamine concentrations and myocardial damage, occur following middle cerebral artery occlusion (MCAO) in Wistar rats. Hypertension is a major risk factor for stroke. The autonomic responses to MCAO in the spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats were therefore investigated. Arterial pressure (AP), heart rate (HR), renal sympathetic nerve discharge (SND), plasma catecholamines and ECG were measured in 16 SHR and 16 WKY male urethane-anesthetized rats, which were subjected to either MCAO or sham MCAO. Cerebral infarct size did not differ between SHR and WKY rats, as shown by tetrazolium staining. Initial AP was significantly higher in SHR (96 +/- 4 mmHg) than in WKY (70 +/- 1 mmHg; P < 0.05). No significant differences in initial HR or plasma catecholamine levels were observed between SHR and WKY. By 6 hours after MCAO, AP, SND and plasma epinephrine in SHR decreased significantly, while HR showed a significant increase. SND and plasma catecholamines in the WKY showed increases that did not reach significant levels following MCAO. The QT interval of the ECG was significantly prolonged in the WKY MCAO rats, which also had a higher frequency of cardiac myocytolysis than the other groups. Unlike the increases in autonomic variables following MCAO in Wistar rats, SHR exhibit significant decreases in SND and AP, while WKY show slight, but non-significant increases. These differences in the autonomic reaction to MCAO may reflect genetic differences in the response to cerebral ischemia.

Animals↗
PubMed1993

Temporal lobe atrophy on magnetic resonance imaging in the diagnosis of early Alzheimer's disease.

OBJECTIVE: To evaluate the use of simple ratings and linear measures of atrophy in the temporal lobe structures obtained with magnetic resonance imaging coronal scans in the diagnosis of early Alzheimer's disease. DESIGN: Prospective series. The National Institute for Neurological Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease. Blinded assessment. SETTING: Dementia study in a university hospital. SUBJECTS: Patients with Alzheimer's disease (n = 34), scoring 150 or more on the Extended Scale for Dementia, and age-matched healthy community volunteers (n = 39) who had both magnetic resonance imaging coronal scans and a psychometric assessment using the Extended Scale for Dementia within 6 months were included. MEASURES MAIN MEASURES: T1-weighted magnetic resonance imaging coronal scans, a 1.5-T system. The degree of atrophy rated (0 to 4) in both sides of the temporal neocortex, entorhinal cortex, hippocampal formation, temporal horns, third ventricle, lateral ventricles, and frontal and parietal cortex. Linear measures: the area of hippocampus and the maximal transverse width of temporal horns. RESULTS: Differentiation between patients with Alzheimer's disease and controls was limited by considerable variations in sensitivity and specificity. Receiver operating characteristics analysis revealed a clear order of discrimination, the entorhinal cortex and the temporal neocortex being the two best, followed by the temporal horns and hippocampal formation. For a given specificity of 90%, the corresponding sensitivity for the entorhinal cortex, temporal neocortex, temporal horns, and hippocampal formation was 95%, 63%, 56%, and 41%, respectively. Linear measures differed significantly but showed considerable overlap. CONCLUSION: The presence of rated atrophy in selected temporal structures makes the diagnosis of Alzheimer's disease more likely, but the absence does not rule out the possibility of early Alzheimer's disease.

Adult↗
PubMed1993

Pathologic correlates of increased signals of the centrum ovale on magnetic resonance imaging.

The pathologic correlates of increased signal in the white matter of the centrum ovale in postmortem magnetic resonance imaging were investigated in an unselected series of 15 autopsies. Two types of magnetic resonance imaging hyperintensities could be separated on the basis of size (10-mm cutoff): extensive and punctate. The pathologic basis of extensive hyperintensities was large areas of pallor with ill-defined margins, located in the central white matter and sparing the subcortical U fibers on both myelin and axonal stains. Microscopically, these areas showed diffuse vacuolation and significant reduction in the areal densities of glial cells. This change was never seen in areas that did not show extensive white matter hyperdensities on magnetic resonance imaging. The correlates of punctate magnetic resonance imaging hyperintensities were less well defined; dilated Virchow-Robin spaces probably represent a common cause of this phenomenon.

Aged↗
PubMed1993

Vascular dementia.

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Cerebrovascular Disorders↗
PubMed1993

The clinical problem of brain and heart.

Observations in an intensive care stroke unit showed that patients recovering from stroke sometimes perish unexpectedly from cardiac complications or sudden death. Compared with control subjects, stroke patients more often have cardiac arrhythmias, raised cardiac enzymes, and elevated plasma norepinephrine, suggesting a hypersympathetic state. We have found that involvement of the insula by experimental cerebral infarction is crucial in mediating the cardiac complications. Age and right as opposed to left hemisphere involvement represent additional risks for the cardiac complications of experimental stroke. These experimental observations now need to be tested clinically.

Animals↗
PubMed1992

Effect of age on autonomic and cardiac responses in a rat stroke model.

The cardiovascular system and its responses change with increasing age. This has seldom been considered in experimental models of stroke, although most strokes occur in the elderly. We studied 57 male Wistar rats in three age groups: 47 to 70 days old (juvenile), 110 to 152 days old (young adult), and 186 to 245 days old (mature adult), each group being subdivided into experimental and sham operation groups. All rats underwent occlusion or sham occlusion of the left middle cerebral artery and monitoring of the mean arterial blood pressure, heart rate, sympathetic nerve activity, plasma catecholamine levels, and electrocardiogram. Eight of the 12 rats in the oldest group died within 6 hours of the middle cerebral artery occlusion; of these, the youngest was 186 days old. The mature adult rats that died before completion of the experiment showed the highest level of sympathetic nerve activity and the only significant increase in the QT interval of the electrocardiogram. Following middle cerebral artery occlusion, sympathetic nerve activity increased in the young adult rats but most strikingly in the mature adult rats that died before the end of the 6-hour experiments. Plasma norepinephrine levels were significantly elevated at 4 and 6 hours after middle cerebral artery occlusion in the oldest group and only at 6 hours in the juvenile rats. The results of this study are consistent with impaired sympathetic and cardiovascular regulation in the mature adult rat. High sympathetic activity may represent one mechanism leading to fatal cardiac arrhythmias. Age-related impairment of sympathetic regulation may contribute to the higher mortality seen among elderly patients with stroke.

Aging↗
PubMed1992

Asymmetry of sympathetic consequences of experimental stroke.

Asymmetries of sympathetic regulation at the level of the inferior cervical ganglia have long been recognized. Lateralization of autonomic representation may also occur in the brain, since inactivation of the left and right hemispheres by intracarotid amobarbital produces an increase and decrease in heart rate, respectively. However, this conclusion has remained tentative, since the differential effect of lateralized brain lesions on sympathetic activity has not been studied systematically. Forty-eight urethan-anesthetized Wistar rats were divided into three groups: a group given left middle cerebral artery occlusion, and a group given sham operation. Heart rate, mean arterial blood pressure, renal sympathetic nerve discharge, and electrocardiogram were monitored throughout the 4-hour experiments. Plasma epinephrine and norepinephrine levels were measured at baseline and 1 and 4 hours after occlusion or sham occlusion. The mean arterial pressure decreased in the group given sham operation and to lesser extent in the group given left middle cerebral artery occlusion. By contrast, mean arterial pressure did not fall in the group given right middle cerebral artery occlusion and at 4 hours was significantly higher than control values in the sham-occluded rats. Renal sympathetic nerve discharge was decreased in the sham-occluded group, increased significantly from 20 minutes to 2 hours in the group given left middle cerebral artery occlusion, and increased from about 20 minutes to the end of the experiment in the group given right middle cerebral artery occlusion. The plasma norepinephrine level was significantly elevated at 1 hour (93%) and 4 hours (44%) only in the group given right middle cerebral artery occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Prevention of ischemic stroke: the role of carotid endarterectomy in symptomatic patients.

Carotid endarterectomy (CE) has recently been proved to be beneficial in symptomatic patients with severe (70-99%) appropriate carotid stenosis. After discussing the historical evolution of CE as a possible preventive treatment of ischemic stroke, we review the results of North American and European trials in order to give practical information for the management of cerebrovascular patients.

Brain Ischemia↗
PubMed1992

An examination of psychometric properties of the extended scale for dementia in three different populations.

The Extended Scale for Dementia (ESD), a development of the Mattis Dementia Rating Scale, has been used in the evaluation of dementia and aging and has shown substantial clinical utility. We report on analyses of its properties and internal structure in three samples of older people: 153 normals, 101 psychiatric hospital residents, and 114 patients with Alzheimer disease. The results showed good internal consistency in the two clinical samples, with much lower reliability in the normals, for whom the test was too easy. A review of the item statistics led to the use of 17 of the 23 ESD items in item component analyses in the three samples. Use of Horn's parallel analysis criterion led to the retention of three components in the normal group and one in both the hospital and Alzheimer groups. The results are compared with other work and are in accordance with the view that cognitive structure becomes more simple with increasing dementia.

Aged↗
PubMed1992

The impact of magnetic resonance imaging on the management of acute ischemic stroke.

Despite rapid advances in imaging technology, the etiology of stroke remains unestablished in 40% of patients. MRI improves localization in acute stroke. However, it is not known whether "accurate localization" results in better management. We reviewed the hospital records of all patients admitted with a diagnosis of acute ischemic stroke and who had had cranial CTs and MRI within 10 days of admission. Between January 1987 and June 1990, 116 patients (69 men, 47 women; mean age, 66 years) were identified. Compared with CT localization, infarcts were better localized in nine of 39 patients with cerebral cortical lesions, in 20 of 22 patients with brainstem and cerebellar lesions, and in three of three patients with isolated cerebellar lesions. In 22 patients (18.9%), MRI showed multiple infarcts in two or more vascular territories, suggesting embolic disease and leading to anticoagulation. MRI also showed arterial occlusions in 11 patients (9.5%). Based on the information obtained with MRI, the clinical diagnosis was changed in 19 patients (16.3%), resulting in changes in the management of most of those patients. Thus, we confirm earlier reports that MRI improves localization after acute cerebral infarction and show that such information alters patient management.

Acute Disease↗
PubMed1992

Cardiovascular effects of human insular cortex stimulation.

Recent investigations indicate a site of cardiac representation within the left insular cortex of the rat. Moreover, the results of lesion studies suggest left-sided insular dominance for sympathetic cardiovascular effects. It is unclear whether similar representation exists within the human insular cortex. Five epileptic patients underwent intraoperative insular stimulation prior to temporal lobectomy for seizure control. On stimulation of the left insular cortex, bradycardia and depressor responses were more frequently produced than tachycardia and pressor effects (p less than 0.005). The converse applied for the right insular cortex. We believe this to be the first demonstration of cardiovascular changes elicitable during insular stimulation in humans, and of lateralization of such responses for a cortical site. In humans, unlike the rat, there appears to be right-sided dominance for sympathetic effects. These findings may be of relevance in predicting the autonomic effects of stroke in humans and in the explanation of sudden unexpected epileptic death.

Adolescent↗
PubMed1992

Lenin's foot.

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Famous Persons↗
PubMed1992

The cardiac consequences of stroke.

Stroke, whether ischemic or hemorrhagic, induces cardiac damage by nonischemic mechanisms. The evidence derives from autopsy studies and investigation of ECG, cardiac enzyme changes, and plasma catecholamine changes after stroke. Increased sympathoadrenal tone, resulting from damage to cortical areas involved in cardiac and autonomic control is the likely cause. Recent experimental evidence indicates that the insular cortex plays a principal role in stroke-related cardiac damage.

Animals↗
PubMed1992

Endarterectomy for symptomatic carotid stenosis. Review of the European and North American Symptomatic Carotid Surgery Trials.

The recent results of two major multicenter trials, ECST (European Carotid Surgery Trialists') and NASCET (North American Symptomatic Carotid Endarterectomy Trial), show benefit of carotid endarterectomy for patients with recent (4-6 months), nondisabling, carotid distribution, cerebral ischemic events (hemispheric and retinal TIA or stroke) and ipsilateral severe (70-99%) carotid stenosis provided that perioperative mortality remains low. ECST, in addition, failed to demonstrate the benefit of surgery for patients with mild stenosis (0-29%). The comparisons between the studies in regards to methodology, measurements, and complications are discussed.

Carotid Stenosis↗