Biomedical subjects

V C Hachinski

Publications and source records attributed to V C Hachinski.

At least 19 recordsLinked to original sources

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.

Explore the source record for details and available documents.

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↗

PubMed1992

The cardiac factor in stroke.

Cardiac disorders associated with cerebral embolism including cardiac surgery, myocardial infarction, endocarditis and non-valvular atrial fibrillation (NVAF) are reviewed along with methods to detect cardioembolic sources. Warfarin and aspirin are effective in the primary prevention of stroke in NVAF but the relative efficacy remains to be determined.

Cerebrovascular Disorders↗

PubMed1991

Mechanisms and management of stroke in the elderly.

OBJECTIVE: To highlight the mechanisms, common causes and management of stroke in the elderly. DATA SOURCES: MEDLINE was searched for articles published from 1967 to 1990. The following key words were used: "stroke," "cerebrovascular disease," "elderly," "aging," "hypertension," "drug interactions," "etiology," "evaluation," "management" and "recovery of function." Original articles with large series of patients were reviewed in detail. STUDY SELECTION: Of about 750 original articles reviewed 116 were finally selected for detailed analysis. Those that dealt with cause, pathophysiologic features and management of stroke with emphasis on the elderly were chosen. DATA SYNTHESIS: With increasing age the incidence of stroke increases, cardiovascular reserve decreases, catecholamine responsiveness diminishes and cardiac arrhythmias become more common. Blood pressure, especially systolic, rises, and the benefits of its treatment become both more difficult to assess and less certain. In the elderly population embolic stroke, particularly that due to nonvalvular atrial fibrillation, is seen with increasing frequency. Because of postural hypotension, cardiac arrhythmias and overmedication, watershed infarction occurs more frequently with increasing age. Amyloid angiopathy now represents the most common cause of spontaneous intracerebral hemorrhage. CONCLUSIONS: Because of the altered drug metabolism and pharmacodynamics in the elderly the therapeutic armamentarium is growing, and so are the risks of such treatments. Stroke in the elderly poses unique problems that deserve distinctive solutions. Further research is needed to study the effect of cerebral ischemia to understand better how the older brain handles the stress of the ischemic insult.

Age Factors↗

PubMed1991

Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis.

BACKGROUND: Without strong evidence of benefit, the use of carotid endarterectomy for prophylaxis against stroke rose dramatically until the mid-1980s, then declined. Our investigation sought to determine whether carotid endarterectomy reduces the risk of stroke among patients with a recent adverse cerebrovascular event and ipsilateral carotid stenosis. METHODS: We conducted a randomized trial at 50 clinical centers throughout the United States and Canada, in patients in two predetermined strata based on the severity of carotid stenosis--30 to 69 percent and 70 to 99 percent. We report here the results in the 659 patients in the latter stratum, who had had a hemispheric or retinal transient ischemic attack or a nondisabling stroke within the 120 days before entry and had stenosis of 70 to 99 percent in the symptomatic carotid artery. All patients received optimal medical care, including antiplatelet therapy. Those assigned to surgical treatment underwent carotid endarterectomy performed by neurosurgeons or vascular surgeons. All patients were examined by neurologists 1, 3, 6, 9, and 12 months after entry and then every 4 months. End points were assessed by blinded, independent case review. No patient was lost to follow-up. RESULTS: Life-table estimates of the cumulative risk of any ipsilateral stroke at two years were 26 percent in the 331 medical patients and 9 percent in the 328 surgical patients--an absolute risk reduction (+/- SE) 17 +/- 3.5 percent (P less than 0.001). For a major or fatal ipsilateral stroke, the corresponding estimates were 13.1 percent and 2.5 percent--an absolute risk reduction of 10.6 +/- 2.6 percent (P less than 0.001). Carotid endarterectomy was still found to be beneficial when all strokes and deaths were included in the analysis (P less than 0.001). CONCLUSIONS: Carotid endarterectomy is highly beneficial to patients with recent hemispheric and retinal transient ischemic attacks or nondisabling strokes and ipsilateral high-grade stenosis (70 to 99 percent) of the internal carotid artery.

Aged↗

PubMed1991

Clinical correlates of white-matter changes on magnetic resonance imaging scans of the brain.

We report our observations on the clinical and radiologic correlates of changes in cerebral white matter based on 94 subjects undergoing magnetic resonance imaging in a prospective study of dementia. Periventricular hyperintensity occurred twice as often in patients with Alzheimer's disease as in healthy control subjects. Within the control group, the presence of periventricular hyperintensity correlated significantly with one measure of cerebral atrophy and with the presence of changes in the adjoining deep white matter. The significance of white-matter changes distinct from the ventricles (leuko-araiosis) remains unsettled. Leuko-araiosis on the magnetic resonance imaging scan, unlike its correlate on the computed tomographic scan, was not shown to relate to cognitive decline or to the presence of focal abnormalities on neurologic examination. This is likely to reflect the heterogeneity of the changes detected with magnetic resonance imaging and their limited extent in our subjects.

Aged↗

PubMed1991

Improved recognition of leukoaraiosis and cognitive impairment in Alzheimer's disease.

We identified 85 patients in a longitudinal study of dementia who had uncomplicated Alzheimer's disease and in whom computed tomography of the head and psychometric testing were conducted within a 6-month period following their entry into the study. Thirty-four patients (40%) had leukoaraiosis, which was disproportionately common in female patients (62% vs 15% in male patients). Analysis of covariance demonstrated a relative reduction of scores on the Extended Scale for Dementia in those patients who had leukoaraiosis, after adjusting for the confounding effects of age, sex, educational level, and duration of illness. Leukoaraiosis was also much more common in women, even after adjusting for the possible confounding effects of age, duration of illness, Extended Scale for Dementia score, and hypertension. Multiple regression analysis showed that leukoaraiosis accounted for 11.6% of the variance of the Extended Scale for Dementia scores. Leukoaraiosis, together with duration of illness, accounted for 18.2% of the variance. Leukoaraiosis is associated with a greater degree of cognitive impairment in patients with Alzheimer's disease.

Aged↗

PubMed1991

Stroke and hypertension and its prevention.

Systolic and diastolic hypertension in both men and women is a well-established risk factor for the development of ischemic and hemorrhagic stroke. Antihypertensive treatment decreases the risk, but questions remain as to the precise level of hypertension to be treated, whether the effects of antihypertensive treatment are blunted with increasing age, and the best type of antihypertensive drug or combination of drugs to be used. Further questions remain concerning the incidence of pseudohypertension and the potentially harmful effects of its treatment on the brain, and the possibility that fluctuations in blood pressure may be worse than elevation alone. A pragmatic approach would be to treat hypertension with vigor in the young, with caution in the mature, and with reluctance in the old.

Aging↗

PubMed1991

Multi-infarct dementia: a reappraisal.

Multi-infarct dementia (MID) may not be the only or even the most important form of vascular dementia. Vascular factors probably contribute to dementia through cerebral infarcts and white matter changes more often than they cause it. More subtle ischemic insults affecting synapses, cells, or protein synthesis without causing frank infarction remain plausible but unproven postulates. Lest we regress to vague and comforting notions of silting blood vessels and ailing neurons, let us recognize that although MID may not explain all of vascular dementia, it has the virtue of being a firm, testable concept. As such it has not been overthrown or even seriously challenged. But it is time for a reappraisal.

Aged↗

PubMed1991

Assessment of therapeutic effects in ischemic stroke.

The three fundamental methods of assessing the therapeutic effects in ischemic stroke are measurements of mortality, morbidity and quality of life. Increasingly more sophisticated cerebral blood flow and metabolism determinations are allowing insights into pathophysiology and giving guidance to the most promising therapeutic approaches. Experimental work and pathophysiological studies provide the scientific basis for therapy, but the assessments that ultimately matter to the patient are clinical, and preferably ones derived from controlled clinical trials.

Animals↗

PubMed1990

The decline and resurgence of vascular dementia.

Arteriosclerotic narrowing of cerebral arteries was once viewed as the key to mental decline. As Alzheimer's disease gained recognition and the concept of multi-infarct dementia achieved acceptance, vascular dementia came to be regarded as uncommon. The changing nature of cerebral vascular disease, the aging of the population and the widespread use of brain imaging techniques have brought new prominence to vascular dementia, chiefly in the form of an epidemic of "Binswanger's disease". Growing evidence suggests that not only grey matter lesions but also white matter lesions contribute to dementia, that vascular factors commonly coexist and interact with Alzheimer changes and that Alzheimer's disease has a vascular and potentially treatable component. Vascular dementia needs to be redefined, reappraised and reinvestigated.

Aged↗