Biomedical subjects

A Y Gur

Publications and source records attributed to A Y Gur.

11 recordsLinked to original sources

PubMed2006

Cerebral vasomotor reactivity of bilateral severe carotid stenosis: is stroke unavoidable?

We evaluated the cerebral hemodynamic features of severe bilateral carotid stenosis by assessing and comparing cerebral vasomotor reactivity (VMR) in the middle cerebral (MCA) and vertebral arteries (VA) by transcranial Doppler and the Diamox (1 g acetazolamide i.v.) test. VMR was evaluated by recording the percentage differences in peak systolic blood flow velocity in each MCA and VA at baseline and by the Diamox test. Twenty-eight symptomatic (SCAS) and 31 asymptomatic (ACAS) patients with bilateral severe (>70%) internal carotid artery stenosis were studied. The mean MCA VMR% was 29 +/- 26.9% in SCAS and 43.2 +/- 26.8% in ACAS patients (P < 0.01). Their respective mean VA VMR% was 30.2 +/- 36.5% and 39.6 +/- 24.4% (P = NS). VMR% of the symptomatic MCA side in SCAS patients was significantly lower than the opposite side (20.5 +/- 31.1% and 39.2 +/- 37.9% respectively; P < 0.03). In contrast, the VA VMR% of both sides in SCAS patients remained similar (28.1 +/- 39.3% and 34.6 +/- 47.9% respectively; P = NS). VMR% of the MCA and VA in ACAS patients was also similar for both sides of bilateral carotid stenosis. The cerebral hemodynamic features differ between SCAS and ACAS patients with bilateral carotid occlusive disease in the anterior part of the circle of Willis. An independent cerebral vascular reserve capacity of the posterior circulation is proposed.

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PubMed2003

Cerebral vasomotor reactivity of the posterior circulation in patients with carotid occlusive disease.

We evaluated the hemodynamic features of the posterior circulation in patients with severe carotid stenosis by assessing and comparing cerebral vasomotor reactivity (VMR) in the middle cerebral (MCA) and vertebral arteries (VA) by transcranial Doppler and the Diamox (1 g acetazolamide i.v.) test. Sixty symptomatic and 111 asymptomatic patients with unilateral severe (>70%) internal carotid artery stenosis were studied. The VMR was 19.2 +/- 18.9% for the MCA ipsilateral to the stenosis and 27.3 +/- 17.4% on the contralateral side (P < 0.0001) for all patients. It was 18.2 +/- 23.2% for the VA ipsilateral to the stenosis and 19.7 +/- 21% on the contralateral side (P = NS). The symptomatic patients' VMR of the MCA on the side of stenosis and the opposite side were 19.2 +/- 17.6 and 29 +/- 17.2%, respectively (P < 0.03). The VMR of the VA remained similar (15.1 +/- 21 and 21.6 +/- 6%, respectively, P = NS). The asymptomatic patients' VMR of the MCA on the side of the stenosis was also lower (19.2 +/- 19.7 vs. 26.5 +/- 17.5% on the opposite side, P < 0.001). In contrast, the VMR in the VA was similar (19.8 +/- 21.4 and 18.7 +/- 19.5%, respectively, P < 0.6, NS). Thus, the VMR of the posterior circulation remained similar regardless of carotid stenosis and a symptomatic/asymptomatic course of carotid occlusive disease, suggesting an independent cerebral vascular reserve capacity of the posterior circulation.

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PubMed2002

Stroke in hospitalized patients: are there special risk factors?

BACKGROUND AND PURPOSE: The occurrence of stroke in patients hospitalized for various illnesses remains a particular challenge for neurologists. Determining the potential causes for these particular cerebrovascular events may help to define the population at risk and to take measures in order to prevent stroke during hospitalization. The aim of our study was to evaluate the potential risk factors associated with stroke, which occurred in patients hospitalized for other illnesses. METHODS: This retrospective case-control study based on data of patients who underwent an ischemic stroke while being hospitalized not because of stroke and a control group of patients admitted during the same period who were matched for age and sex to the study patients. Common vascular risk factors, e.g. fever, leukocytosis, blood pressure, hemoglobin, cardiac arrhythmia and dehydration, were compared between the study and control groups. RESULTS: Of 2,247 consecutive patients with ischemic stroke, the stroke had occurred during hospitalization not related to any surgical procedure in 80 (3.5%). Six parameters were found as being significant independent risk factors for in-hospital stroke: fever and leukocytosis during hospitalization, elevated diastolic and unstable blood pressure, dehydration and past history of myocardial infarction. CONCLUSION: Careful monitoring of temperature, blood count, blood pressure, and clinical and laboratory signs of dehydration is needed to prevent in-hospital stroke.

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PubMed2001

TCD and the Diamox test for testing vasomotor reactivity: clinical significance.

Transcranial Doppler sonography has become widely used in assessing cerebral vasomotor reactivity which provides information regarding cerebral autoregulation and collateral circulation. Cerebral vasomotor reactivity is defined as a shift between cerebral blood flow or cerebral blood velocity before and after administration of a potent vasodilatory stimulus test. Three such tests are currently used for this purpose: the apnea test, CO2 inhalation and the Diamox test (i.v. acetazolamide), all of which are based on the dilatatory response of cerebral blood flow to hypercapnia. Certain advantages of the Diamox test were described, but each of the three tests has its strong and weak points, and this will be the topic under discussion. There are several practical applications of the combined TCD and the vasodilatory tests in assessing of cerebral vasomotor reactivity: 1. To evaluate the intracranial hemodynamic status in patients with carotid occlusive disease with the intent of predicting the occurrence of ischemic brain events. 2. To compare intracranial hemodynamics before and after carotid endarterectomy. 3. To compare autoregulation and collateral circulation in the different parts of the circle of Willis. 4. To predict dementia after stroke. In summary, the potential clinical usefulness of combined TCD and provocative vasodilatory tests has been clearly shown. Further large scale studies are needed in order to augment the applications of cerebral vasomotor reactivity assessment in the clinical setting.

Acetazolamide↗

PubMed2000

Vasomotor reactivity in the ophthalmic artery: different from or similar to intracerebral vessels?

OBJECTIVE: In order to evaluate hemodynamic features of ophthalmic arteries in patients with severe carotid artery stenosis, we assessed and compared vasomotor reactivity in the middle cerebral and ophthalmic arteries. METHODS: Sixty-five patients (25 symptomatic, 40 asymptomatic) with severe (70-99%) internal carotid artery stenosis were studied using transcranial Doppler and the Diamox test. RESULTS: Vasomotor reactivity was found to be similar in the middle cerebral and ophthalmic arteries on the side of severe carotid stenosis in both symptomatic and asymptomatic patients. In contrast, the vasomotor reactivity of the ophthalmic arteries was significantly different from that of the middle cerebral arteries on the side of the normal or the non-significantly stenotic side of the internal carotid artery. CONCLUSIONS: These data suggest a specific autoregulative response of the ophthalmic artery compared to that of the middle cerebral artery and may shed light on the role of the ophthalmic artery in oculovascular hemodynamics.

Acetazolamide↗

PubMed2000

Are there any unique epidemiological and vascular risk factors for ischaemic strokes that occur in the morning hours?

It is now accepted that the incidence of ischaemic stroke is significantly increased in the morning. Any attempts to prevent its occurrence must be based on determining the mechanisms, special risk factors and appropriate protective measures needed during this vulnerable period. We studied the epidemiological features of morning stroke and reviewed the records of 2312 consecutive patients recorded prospectively in the Tel Aviv Stroke Register. Information about time of stroke onset was obtained from the patient, family members or other observers. The study parameters of age, sex, vascular distribution (carotid versus vertebrobasilar), ischaemic heart disease, myocardial infarction, diabetes mellitus, arterial hypertension, smoking, hyperlipidaemia, stroke severity and recurrence were compared between patients with morning stroke and those with stroke occurring at other times. In 599 patients (34%) stroke occurred between 06:00 and 10:00 h. No evaluated parameter was found to be statistically different among the morning stroke patients compared with stroke occurring at other times (P < 0.2). Patients with arterial hypertension and ischaemic heart disease and male patients had a greater likelihood of stroke occurrence between 22:00 and 02:00 h (P < 0.05). Our data suggest that none of the common vascular risk factors could explain the morning peak of stroke occurrence. The next step in the quest for understanding the phenomenon of circadian variation is to identify other physiological factors and the effects of pharmacological agents in morning stroke protection.

Brain Ischemia↗

PubMed1996

The Tel Aviv Stroke Registry. 3600 consecutive patients.

BACKGROUND AND PURPOSE: We undertook to estimate the frequency of various risk factors and the type and severity of stroke in different ethnic groups documented in a large hospital-based stroke registry. Tel Aviv is a metropolis with about 400000 inhabitants and about 600000 daily visitors and workers. The Tel Aviv Medical Center (TAMC) is the only tertiary medical care facility to which all patients with acute stroke are referred. Israel is a country with a heterogeneous population, of which a significant proportion was born abroad. The people differ in their genetic background, as well as in their early environmental conditions, lifelong diet, and other habits. This variety has proved to be a fertile ground for the study of different neurological diseases, including stroke. METHODS: A prospective hospital-based registry using systematic computer coding of data of all consecutive stroke patients admitted to the TAMC has been conducted since May 1988. Different aspects of the amassed data were analyzed statistically. RESULTS: From May 1988 until April 1994, 3600 stroke patients were admitted to the TAMC. The mean age was 73.2 years, and 58.2% were males. Cerebral infarctions were diagnosed in 80.9%, primary intracerebral hemorrhages in 8.0%, and transient ischemic attacks in 11.1%. There were 861 patients (24%) who were admitted with recurrent strokes. Past medical history of hypertension was the major risk factor (occurring in 52.2% of the patients), followed by ischemic heart disease (29.7%), diabetes mellitus (25.2%), smoking (17.0%), atrial fibrillation (14.3%), and hyperlipidemia (8.4%). Ischemic heart disease and atrial fibrillation were more frequent in patients from Europe and America (Ashkenazi group), whereas diabetes mellitus and smoking were more prominent in the other groups. The in-hospital mortality rate was 13.8% and was similar in both ethnic groups. CONCLUSIONS: This registry allows the study of the risk factors, natural history, and clinical manifestations of stroke in different ethnic groups.

Africa↗

PubMed1996

Is impaired cerebral vasomotor reactivity a predictive factor of stroke in asymptomatic patients?

BACKGROUND AND PURPOSE: Identification of the subgroup of asymptomatic patients with severe internal carotid artery stenosis and high risk of stroke has important clinical implications. Cerebral vasomotor reactivity provides information regarding intracranial hemodynamic features and might have a prognostic value in predicting cerebrovascular ischemic events, especially in patients with carotid stenosis. The aim of our study was to assess the cerebral vasomotor reactivity in asymptomatic patients with carotid stenosis and evaluate its role in stroke occurrence. METHODS: Cerebral vasomotor reactivity was assessed using transcranial Doppler ultrasonology and the Diamox test (intravenous administration of 1.0 g acetazolamide) in 44 asymptomatic patients with severe (> 70%) internal carotid artery stenosis. Patients were followed up prospectively (mean, 2 years). RESULTS: Cerebral vasomotor reactivity was estimated as good (> 40% increase of blood flow velocity in the middle cerebral artery ipsilateral to the carotid stenosis after undergoing the Diamox test) in 23 patients; it was impaired in the other 21. During the follow-up period, the overall annual rate for ipsilateral stokes was 2.3%; it was 7.9% for all ischemic cerebral events. No strokes or transient ischemic attacks occurred in the former group, but there were 7 cerebral ischemic events (2 strokes [1 fatal] and 5 transient ischemic attacks) in the latter group. There was a statistically significant correlation between cerebral ischemic events and impaired cerebral vasomotor reactivity (P = .009). CONCLUSIONS: The data of this preliminary study suggest an important role of impaired cerebral vasomotor reactivity in predicting ischemic cerebral events. Preventive vascular surgery might be considered in this high-risk subgroup of asymptomatic patients with severe carotid stenosis.

Acetazolamide↗

PubMed1996

Do silent brain infarctions predict the development of dementia after first ischemic stroke?

BACKGROUND AND PURPOSE: Silent brain infarctions (SBI) are common findings in advanced age, but their relationship to dementia is still uncertain. The present study was designed to evaluate whether SBI predict the development of dementia after first clinical ischemic stroke. METHODS: We blindly studied admission CT scans of 175 consecutive nondemented patients presenting with ischemic stroke that clinically was their first stroke episode. SBI were defined as CT evidence of infarcts not compatible with the acute event. The patients were subsequently followed for their mental state for 5 years. Survival analysis, wherein onset of dementia was the end point, was performed on the total sample population and conducted separately on those with and without SBI at admission. RESULTS: Dementia developed in 56 patients (32%), including 22 of the 63 (35%) with SBI and 34 of the 112 (30%) without SBI. Thus, dementia was not related to SBI. CONCLUSIONS: Our data indicate that SBI do not predict the development of dementia after stroke.

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PubMed1994

EEG as predictor of dementia following first ischemic stroke.

INTRODUCTION: Predictive factors for occurrence of vascular dementia may help identify patients at increased risk of developing this condition. Our purpose was to evaluate the prognostic value of early EEG findings in patients after first ischemic cerebral stroke on the development of dementia. MATERIAL AND METHODS: We performed routine EEG recordings in 199 consecutive non-demented patients with first-ever ischemic stroke, within 48 h of the event. The patients were subsequently followed for their mental state for 2 years. Survival analysis, wherein onset of dementia was the end-point, was performed on the total sample population and conducted separately on those who had normal EEG at time of the event and on those who had abnormal EEG findings (focal or diffuse slowing). RESULTS: Patients with abnormal EEG at baseline had 2.6 times the risk of developing dementia than those who had normal EEG; this odds ratio was statistical significant (CL: 1.3-5.1, p = 0.003). Development of dementia was not related to any specific EEG abnormal pattern. CONCLUSIONS: Abnormal EEG performed close to the first ischemic stroke appears to be an indicator of subsequent cognitive decline, probably because it indicates cortical involvement by the stroke or an underlying indolent cerebral degeneration.

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PubMedDate not supplied

Stroke during sleep: epidemiological and clinical features.

Stroke during sleep is an unexplored area of vascular neurology and its pathogenesis; clinical significance and prevention still remain uncertain. The aim of our study was to determine the epidemiological and clinical patterns of ischemic stroke occurring during sleep. Consecutive patients (n = 1822) with acute ischemic stroke recorded in the Tel Aviv Stroke Register were studied. Stroke during sleep was determined whenever focal neurological deficit was verified to have occurred while the patient had been asleep. The comparisons between patients with stroke during sleep and while awake were performed using the t test with Bonferroni correction and the chi(2) test for age, sex, vascular risk factors (i.e. ischemic heart disease, myocardial infarction, atrial fibrillation, arterial hypertension, hyperlipidemia, diabetes mellitus, peripheral vascular disease, smoking), vascular distribution (carotid versus vertebrobasilar) and severity of stroke (mild, moderate or severe). Data regarding the onset of stroke (during sleep or while awake) were available for 1,671 patients. A minority of strokes occurred during sleep (n = 311, 18.6%), and stroke during sleep was severer (chi(2) = 11.9, p < 0.002). No significant differences were found in terms of age, sex and vascular distribution between the two groups. None of the vascular risk factors was found to be more frequent in stroke during sleep. Strokes occurring during sleep were found to be severer than those with onset while awake. However, no specific clinical patterns of risk factor profiles could be identified in these patients. Hemodynamic factors may play an important role in the occurrence of stroke during sleep, and this issue should be further investigated.

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