bluuebunny/crossref_metadata_2025 huggingface dataset:
Increased vulnerability of the blood-brain barrier to experimental subarachnoid hemorrhage in spontaneously hypertensive rats.
Authors: Dóczi T , Joó F , Sonkodi S , Adám G
Published: June 2011

The influence of chronic arterial hypertension upon the permeability to albumin of the cerebral capillaries, i.e. the blood-brain barrier, was studied in normotensive Wistar and spontaneously hypertensive Wistar rats with experimental subarachnoid hemorrhage. The blood-brain barrier permeability to albumin was assessed quantitatively by spectrophotometric determination of Evans blue extravasation. Subarachnoid hemorrhage was produced by injecting autologous blood into the cortical subarachnoid space. A significant increase of Evans blue albumin extravasation was found in the spontaneously hypertensive rats with subarachnoid hemorrhage as compared with normotensive animals suffering from subarachnoid hemorrhage. Subarachnoid hemorrhage in this model alone caused a significant Evans blue extravasation, whereas sham-operation did not. These findings emphasize the necessity for effective attempts to reduce the leakage of the capillary system in the early stage of subarachnoid hemorrhage.
Effect of nimodipine on cerebral functional and metabolic recovery following ischemia in the rat brain.
Authors: Mabe H , Nagai H , Takagi T , Umemura S , Ohno M
Published: June 2011

Whether the calcium entry blocker, nimodipine, prevents the increase in the concentration of free fatty acids and metabolic disturbances during ischemia and promotes functional and metabolic recovery after recirculation were examined. Severe forebrain ischemia in rats was induced by four-vessel occlusion with mild hypotension. After 30 minutes of ischemia, recirculation was started by removal of the arterial clamps and by increasing blood pressure to the preischemic level. Recovery of EEG activity following recirculation was better in the nimodipine-treated group than in the control group. During the ischemic period, there were no significant differences in accumulation of free fatty acids or in depletion of ATP between treated and control groups. At 120 minutes following recirculation, recovery of the ATP level was significantly better in the treated group than in the control group. Therefore, the promotion of functional and metabolic recovery by nimodipine-treatment is suggested to be not due to the prevention of an accumulation of free fatty acids nor to the depletion of ATP during the ischemic period, but to either improvement of postischemic hypoperfusion or a direct action on metabolic processes during reperfusion period.
Different susceptibilities to cerebral infarction in spontaneously hypertensive (SHR) and normotensive Sprague-Dawley rats.
Authors: Coyle P
Published: June 2011

Rapid occlusion of the middle cerebral artery (MCA) was undertaken in 5-6 week old rats to determine whether or not the young spontaneously hypertensive rat (SHR) or the normotensive Sprague-Dawley rat (SD) is protected against cerebral infarction by collateral circulation. Rats were killed 3 days after MCA occlusion and administration of Evans blue. As compared to SD, the SHR had elevated blood pressure prior to MCA occlusion, large cortical infarcts marked with Evans blue, and motor deficits contralateral to the occluded MCA. SHR did not develop an adequate collateral circulation, but SD were protected from infarction by it. Because the cerebral lesions were in young spontaneously hypertensive rats living prior to the established form of hypertension, the increased susceptibility to infarction was not secondary to it. Since normotensive rats usually do not infarct after sudden MCA occlusion, the infarction trait may be linked to the mechanism causing elevated blood pressure in spontaneously hypertensive rats.
Central nervous system complications of percutaneous transluminal coronary angioplasty.
Authors: Galbreath C , Salgado E D , Furlan A J , Hollman J
Published: June 2011

During 1968 consecutive percutaneous transluminal coronary angioplasty (PTCA) procedures, 4 patients (0.2%) suffered a focal central nervous system complication. Two patients had a hemisphere infarct, one a brainstem infarct and one a hemisphere transient ischemic attack. Embolism was the likely mechanism in 3 cases; in 1 air was injected through the guiding catheter, and in 2 post-coronary bypass cases the ascending aorta was "scraped" with the guiding catheter while searching for a graft ostium. In 1 case the event occurred after a successful PTCA during a period of hypotension. Neurologic complications are rare during PTCA but will occasionally occur as the procedure is performed more frequently.
Embolic complications in paroxysmal atrial fibrillation.
Authors: Petersen P , Godtfredsen J
Published: June 2011

The incidence of embolic complications among 426 patients with initial paroxysmal atrial fibrillation (PAF) was analysed. A distinct clustering of emboli was seen at the time of onset of PAF. After transition to chronic atrial fibrillation (CAF), which developed in 141 patients (33.1%), the incidence of emboli was seen to rise to a new level several times higher than the incidence level for patients with PAF. Also in this group a distinct clustering of emboli was seen during the first year after transition to CAF. On this background it is suggested that patients with PAF may benefit from treatment with anti-arrhythmic agents in order to prevent the development of CAF and that anticoagulants for stroke prevention seems especially desirable in atrial fibrillation (AF) of recent onset.
The beneficial effect of intracarotid urokinase on acute stroke in a baboon model.
Authors: Del Zoppo G J , Copeland B R , Waltz T A , Zyroff J , Plow E F , Harker L A
Published: June 2011

The capacity of intracarotid infusion of urokinase to salvage neurologic function in a baboon model of acute thrombotic stroke has been studied. The model consists of reversible eccentric balloon compression (3 hours) of the right middle cerebral artery (MCA) proximal to the take-off of the lenticulostriate arteries (LSA), resulting in in situ thrombosis of perforating branches supplying the right corpus striatum. Neurologic endpoints included quantitative assessment of neurologic function (NE), estimation of cerebral infarction volume by computerized tomographic (CT) scan, and carotid angiography. In untreated acute stroke control animals (n = 6), a persistent decrease in functional score (from 100 to 36 +/- 11) at 14 days and a defined region of cerebral infarction (volume = 3.2 +/- 1.5) were detected at 10 days. Intracarotid urokinase administered to five animals (1.2 X 10(6) IU over 60 min) following the 3 hour period of MCA occlusion improved neurologic function (NE = 50, 55, 85, 100, 100) and reduced infarction size (0.3, 0.5, 0.8, 0.7, 1.1 cm3, respectively) without evidence of intracranial hemorrhage. Systemic fibrinogenolysis was produced in all five treated animals. We conclude that thrombolytic therapy given within 3 hours of experimental thrombotic occlusion may salvage neurologic function and reduce cerebral infarction volume without CT scan detectable intracranial bleeding.
The Canadian Neurological Scale: a preliminary study in acute stroke.
Authors: Côté R , Hachinski V C , Shurvell B L , Norris J W , Wolfson C
Published: June 2011

Acute central nervous system dysfunction resulting in coma can be measured simply and reliably by the Glasgow scale. However, when the injury does not impair consciousness and the patient has aphasia, no comparable scale exists. A complementary scale to assess conscious and aphasic patients is proposed. Preliminary validation has been carried out in acute stroke patients, who commonly suffer neurological deficits without loss of consciousness. A simple standardized scale aids in the monitoring of neurological status, and may help in the assessment of prognosis and therapy.
The effect of the calcium antagonist nimodipine on the gerbil model of experimental cerebral ischemia.
Authors: Fujisawa A , Matsumoto M , Matsuyama T , Ueda H , Wanaka A , Yoneda S , Kimura K , Kamada T
Published: June 2011

The gerbil model was used to assess the therapeutic effects of the calcium antagonist nimodipine on cerebral ischemia. Transient cerebral ischemia was produced in each gerbil by bilateral common carotid occlusion of 10-, 15- or 20-min duration. Nimodipine (0.01 or 0.1 mg/kg) was administered intraperitoneally just before the carotid occlusion or 10-30 min after the removal of the arterial clips. Morbidity of each animal was evaluated using the stroke index, and the sum of stroke indices was calculated for evaluating the overall morbidity during a particular period of reperfusion. Mortality was observed for 24 hours after clip removal. Although, depending on the timing of the drug administration, the low-dose (0.01 mg/kg) nimodipine worsened the morbidity in the gerbils with 10-min ischemia, the high-dose (0.1 mg/kg) of the drug had a clear beneficial effect on the mortality associated with cerebral ischemia. These results are considered worthwhile for further trials to assess the usefulness of nimodipine as a therapeutic agent in the management of the acute ischemic stroke.
Ataxic hemiparesis with reductions of ipsilateral cerebellar blood flow.
Authors: Sakai F , Aoki S , Kan S , Igarashi H , Kanda T , Tazaki Y
Published: June 2011

Regional cerebellar blood flow was measured in a patient with left-sided ataxic hemiparesis, using single-photon emission computed tomography and N-isopropyl-p-[123I]Iodoamphetamine. X-ray computed tomography revealed a small infarct in the paramedian portion of the right upper basis pontis. Blood flow was markedly reduced in the contralateral cerebellar hemisphere corresponding to the side of ataxia. The present study emphasizes the value of the three-dimensional functional imaging of the cerebellum to investigate the responsible lesion for ataxia and to study function of the cerebro-cerebellar circuits.
Cigarette smoking, hypertension and the risk of subarachnoid hemorrhage: a population-based case-control study.
Authors: Bonita R
Published: June 2011

A case-control analysis is used to examine the relation of cigarette smoking, hypertension and the risk of subarachnoid hemorrhage in men and women aged 35-64 years. 45 men and 70 women with subarachnoid hemorrhage were identified as part of a large community based study of stroke, and the controls, 1017 men and 569 women, came from a survey of cardiovascular risk factors conducted in the same community. Cigarette smokers, after adjusting for age, had a significantly increased risk of subarachnoid hemorrhage compared with nonsmokers with relative risks of 3.0 for men and 4.7 for women. The strength of the risk increased with the amount smoked. The association remained significant for each sex after adjusting for hypertension. Those who both smoked and had a history of hypertension had an increased risk of subarachnoid hemorrhage of almost 15 fold compared to those who neither smoked nor had been treated for hypertension. The estimated population attributable risk of subarachnoid hemorrhage associated with cigarette smoking (43%) was greater than that of hypertension (28%) in this population.
Italian multicenter study on reversible cerebral ischemic attacks: VI--Prognostic factors and follow-up results.
Authors: Candelise L , Vigotti M , Fieschi C , Brambilla G L , Bono G , Conforti P , De Zanche L , Inzitari D , Mariani F , Prencipe M
Published: June 2011

A total of 462 patients (mean age 52 years) affected by reversible focal ischemic attacks (RIAs) were followed prospectively in 8 neurologic institutions in Italy for 4 years. All cases were evaluated with a cerebral angiography and 21% of angiograms were normal. At the end of the follow-up period the cumulated probability for death, stroke, cardiac event and new RIA was respectively 7%, 8%, 3% and 36%. The predictive value of the baseline characteristics of this series was evaluated by a multifactorial analysis which showed that RIA and stroke (specific cerebrovascular risk) were more likely to develop in patients with a history of more than one RIA and in those in whom multiple vascular territories were involved. Moreover, previous myocardial infarction, intermittent claudication, angina pectoris, time elapsed since the first attack, and duration and severity of the attack itself were independently associated with general cardiovascular risk (death, stroke and myocardial infarction). We conclude that predictive factors, and thus also pathogenetic mechanisms, may be different for general cardiovascular risk and specific cerebrovascular risk in RIA patients.
No evidence for transhemispheric diaschisis after human cerebral infarction.
Authors: Wise R , Gibbs J , Frackowiak R , Marshall J , Jones T
Published: June 2011

Forty-four studies of regional cerebral blood flow (rCBF), fractional oxygen extraction (rOER) and oxygen consumption (rCMRO2) were made on twenty-five patients with recent internal carotid artery territory infarcts. The purpose was to study flow-metabolism relationships in the contralateral hemispheres, and to investigate whether contralateral rCMRO2 was depressed as a result of the recent infarcts. Two groups of controls were included for comparison--seventeen normal volunteers, and ten patients with proven extracranial cerebrovascular disease but without evidence of cerebral infarction. The results demonstrated that: contralateral hemispheric rCMRO2 was less variable than regional oxygen availability (the product of rCBF and arterial oxygen content). This was due, in part, to the effect of individual variations in PaCO2 on rCBF, but other uncontrolled factors, such as intracranial pressure, may have had influences. As a result, rCMRO2 did not correlate with rCBF; mean rCMRO2 in the contralateral hemispheres was 12% lower than normal (a significant difference), but was not different from the value found in patients with extracranial vascular disease in whom there was no evidence of infarction or ischemia; contralateral rCMRO2 did not correlate with the size of the infarct in the opposite hemisphere. It is concluded that rCMRO2 cannot be inferred from rCBF measurements in uncontrolled human studies (as frequently done in the past), and that depression of contralateral rCMRO2 may have preceded infarction in the opposite hemisphere, a consequence of the previous influences of diseases that predispose to stroke.
The association of hyperglycemia with cerebral edema in stroke.
Authors: Berger L , Hakim A M
Published: June 2011

A retrospective review of stroke patients admitted to our hospital revealed 39 patients diagnosed as suffering an acute completed ischemic stroke who also had had fasting (AC) serum glucose determinations and sequential computer tomography (CT) studies. The patients were divided into three groups on the basis of mean AC serum glucose: Group 1 (n = 12) mean serum AC glucose greater than 150 mg/dl; Group 2 (n = 13) mean serum AC glucose 100-150 mg/dl; and Group 3 (n = 14) mean serum AC glucose less than 100 mg/dl. CT scans performed on each patient were studied for the presence of midline shift and/or ventricular compression, which were interpreted as evidence of cerebral edema. The three groups were comparable with respect to mean age, average mean arterial blood pressure and initial infarct size. Our results show that in Group 1, 42% of the patients died within the first week following their CVA with clinical evidence of transtentorial herniation confirmed by CT or autopsy. In contrast, none of the Group 3 patients died and only one showed radiological evidence for cerebral edema. Group 2 patients showed intermediate mortality and evidence of cerebral edema. These trends were statistically significant at p less than 0.005. In addition, the combined hyperglycemic group (1 and 2) had a significantly higher rate of development of hypodensity on CT (p less than 0.05) than the normoglycemic group. Our findings suggest that patients with hyperglycemia in association with their CVA develop more pronounced cerebral edema and have a worse clinical outcome. Possible pathophysiological mechanisms that may underlie this observation are discussed.
The predicted value of arteriography in nontraumatic intracerebral hemorrhage.
Authors: Toffol G J , Biller J , Adams H P , Smoker W R
Published: June 2011

We retrospectively assessed the diagnostic value of cerebral arteriography for the search of an etiology in 102 patients with nontraumatic intracerebral hemorrhages evaluated between 1980 and 1985. Arteriography was diagnostic in 22 of 50 non-hypertensive patients and in only 6 of 47 hypertensive patients. Five patients with a bleeding diathesis had normal arteriography. From the total group, we found 12 saccular aneurysms, 9 arteriovenous malformations, 3 cases of moya-moya and 3 instances of superior sagittal sinus thrombosis. One patient had metastatic choriocarcinoma. Sites of hemorrhage among all patients with diagnostic arteriograms were: lobar 19, intraventricular 5, thalamic 2, caudate 1, and corpus callosum 1. Lobar hemorrhages in the non-hypertensive group and intraventricular hemorrhages in hypertensive individuals had the highest yield of arteriographic abnormalities. We believe cerebral arteriography is indicated in non-hypertensive patients with lobar hemorrhages. Most hypertensive patients, in particular those with putaminal hemorrhages, do not require arteriography.
Duplex scanning of normal vertebral arteries.
Authors: Touboul P J , Bousser M G , LaPlane D , Castaigne P
Published: June 2011

Vertebral arteries were studied by Duplex scanning in 50 normal subjects. Pretransverse and C6-C5, C5-C4 intertransverse segments were visualized in all cases on both sides; segment C4-C3 was visualized in 100% of the cases on the right side and in 90% on the left; ostium was obtained in 94% of the cases on the right and in 60% on the left. The left vertebral artery was dominant in 48% of the cases while the right vertebral artery was dominant in 14%. Three vertebral arteries were hypoplasic. Duplex scanning was thus found to be an easily performed noninvasive method to study morphological and hemodynamic characteristics of vertebral arteries from their origin to the C4-C3 level.
Time-related asymmetric changes of brain microvessel beta-adrenergic receptors in the two hemispheres after carotid occlusion.
Authors: Magnoni M S , Frattola L , Pasinetti G , Govoni S , Battaini F , Trabucchi M
Published: June 2011

The effect of short term and long term ischemia induced by right carotid occlusion was studied on beta-adrenergic receptor function in rat cerebral microvessels. The results show a different time-dependent responsiveness of the two hemispheres to ischemia, with a pronounced and more persistent decrease in the number of capillary beta-receptors in the left side of the brain. The data suggest the existence of asymmetries in the control of brain microvasculature which may mediate the different time-course of beta-receptor changes in response to ischemia.
Incidental subcortical lesions identified on magnetic resonance imaging in the elderly. I. Correlation with age and cerebrovascular risk factors.
Authors: Awad I A , Spetzler R F , Hodak J A , Awad C A , Carey R
Published: June 2011

Patchy subcortical foci of increased signal intensity are frequently identified on magnetic resonance imaging (MRI) in the elderly. The incidence and clinical correlates of these lesions remain unknown. In this report, 240 consecutive MRI scans performed over a 6-month period were reviewed (excluding patients with recent brain trauma or known demyelinating disease). Subcortical incidental lesions (ILs) were identified, which could not be accounted for by the patient's current clinical diagnosis, neurological status, or CT scan. The ILs were graded according to size, multiplicity, and location. The incidence and severity of ILs increased with advancing age (p less than 0.0005). Among patients over 50 years of age, the incidence and severity of ILs were correlated with a previous history of history of ischemic cerebrovascular disease (p less than 0.05) and with hypertension (p less than 0.05). Multivariable regression analysis identified age, prior brain ischemia, and hypertension as the major predictors of ILs in the elderly. Diabetes, coronary artery diseases, and sex did not play a significant role. With the exception of cerebrovascular disease, there was no association between ILs and any particular clinical entity, including dementia. It is concluded that subcortical parenchymal lesions are frequent incidental findings on MRI in the elderly, and may represent an index of chronic cerebrovascular diseases in such patients.
Protection from cerebral air emboli with perfluorocarbons in rabbits.
Authors: Spiess B D , Braverman B , Woronowicz A W , Ivankovich A D
Published: June 2011

Cerebral air emboli have been implicated in the transient neurological deficits seen in patients after cardiovascular surgery. Since perfluorocarbon emulsions such as FC-43 have greater solubilities for gases compared to plasma, it was decided to investigate their potential in providing protection against transient ischemia produced by such emboli. Forty rabbits were divided into three groups of ten, twenty, and ten. They were anesthetized with acepromazine and ketamine and were given an infusion of either hetastarch or FC-43, 10 ml/kg i.v. In Group I, which received a bolus air injection into the internal carotid artery, survival rates were: 2/5 for the hetastarch group and 5/5 for the FC-43 group (p less than .05). In Group 2, which received an air infusion until the EEG was flat bilaterally, 3/10 hetastarch-treated rabbits survived while 10/10 FC-43-treated rabbits survived for 24 hours (p = .035). In Group 3, analysis of blood viscosity and osmolality over a four hour period following either hetastarch or FC-43 infusion resulted in no significant differences between the two treatments but a significant decrease in both variables after 30 minutes which returned to baseline values at 60 minutes. The results of the study demonstrate a protective effect from cerebral air emboli delivered into the internal carotid artery as either a bolus or slow infusion in rabbits pretreated with a perfluorocarbon emulsion in terms of survivability and recovery from transient neurological deficits.
Influence of anatomic origin on intracranial distribution of micro-emboli in the baboon.
Authors: Svensson L G , Robinson M F , Esser J , Fritz V U , Levien L J
Published: June 2011

The purpose of this study was to investigate whether the anatomic origin of micro-emboli influences their intracranial distribution. In twenty-two baboons, we examined the distribution of 99-Technetium labelled albumin aggregates (5 to 40 microns in size) after injection into the circulation at the left atrium (LA), carotid trifurcation (CA), and anterior and posterior common carotid artery (CCI). In a further subgroup, the emboli were introduced at the carotid trifurcation with the contralateral carotid artery ligated (CA + L). The results of this study demonstrated that aggregates introduced at the carotid artery lodged preferentially in the ophthalmic (p = 0.032) and middle cerebral artery territories (p = 0.016). If the contralateral common carotid artery was ligated, however, more aggregates were found in the ipsi- and contralateral anterior cerebral artery territories (p = 0.01, p = 0.003). Aggregates introduced into the cardiac circulation were equally distributed throughout the brain. This experimental model determined patterns of flow that might be analogous to the human situation where unilateral or bilateral carotid stenosis or stenosis with contralateral occlusion has occurred or embolus from cardiac source has occurred. The results do not imply that the 40 micron microaggregates do cause TIA. These experimental findings support clinical observations that cardiac lesions may cause transient ischemic attacks (TIA) anywhere in the brain. In contrast, those of carotid artery origin cause predominantly middle cerebral or ophthalmic artery territory TIAs unless the contralateral carotid artery is severely stenosed or occluded.
Effects of atherosclerosis on cerebral vessels: hemodynamic and morphometric studies.
Authors: Tamaki K , Armstrong M , Heistad D
Published: June 2011

In this study hemodynamic and morphometric consequences of atherosclerosis were examined in cynomolgus monkeys. We tested the hypothesis that atherosclerosis augments cerebral vasoconstrictor responses to serotonin. We studied 8 normal and 8 atherosclerotic monkeys, which were fed an atherogenic diet for 17 months. Morphometric studies indicated marked intimal proliferation of extracranial carotid arteries, with only modest reduction in the vascular lumen, as atherosclerotic lesions were displaced outward. Cerebral blood flow was measured with microspheres and microvascular pressure was measured with a micropipette in pial arteries approximately 350 microns diameter. Intracarotid infusion of serotonin reduced microvascular pressure, which indicates constriction of large arteries upstream, but cerebral blood flow did not decrease. Serotonin produced a 2-fold greater reduction in cerebral microvascular pressure in atherosclerotic monkeys than in normal monkeys. Intracarotid histamine increased flow and hypocapnia reduced flow in both normal and atherosclerotic monkeys, without altering cerebral microvascular pressure. We conclude: First, atherosclerosis potentiates constrictor responses to serotonin in large cerebral arteries. Because platelets release serotonin when they aggregate, augmentation of responses by atherosclerosis may have implications for cerebral vascular responses during aggregation of platelets at carotid lesions. Second, despite marked proliferation of intima, atherosclerotic lesions are displaced outward during a prestenotic phase of the disease, so that the lumen is relatively well preserved.
Effect of aspirin and ticlopidine on platelet deposition in carotid atherosclerosis: assessment by indium-111 platelet scintigraphy.
Authors: Isaka Y , Kimura K , Etani H , Uehara A , Uyama O , Yoneda S , Kamada T , Kusunoki M
Published: June 2011

The antiplatelet effects of aspirin and ticlopidine were studied by a dual-tracer method, using indium-111 labeled platelets and technetium-99m human serum albumin, in a group of 12 patients with suspected ischemic cerebrovascular disease. The magnitude of platelet accumulation at the carotid bifurcation was expressed as the ratio of radioactivity of indium-111 platelets deposited on the vascular wall to those circulating in the blood-pool (PAI, platelet accumulation index), 48 hr after injection of labeled platelets. PAI values were measured before (baseline studies) and after the antithrombotic therapies (aspirin studies: 325 mg bid for 22.3 +/- 1.3 days, ticlopidine studies: 100 mg tid for 21.8 +/- 2.1 days). At the baseline, the mean PAI value at 24 carotid bifurcations in the patient group was 15.7 +/- 15.3% (mean +/- S.D.) compared to -4.3 +/- 9.1 at 24 carotid bifurcations in 12 normal subjects (p less than 0.01). We defined the upper limit for a normal PAI (%) value to be +13.9, namely the mean PAI plus 2 SD for the carotid bifurcation in normal subjects and used this value for semiquantitative analysis. At the baseline, significant elevation of PAI (more than 13.9%; positive scintigram) was observed at 12 of 24 vessels, while 12 other regions were negative (less than 13.9%). In the lesions with positive scintigraphic results at the baseline, the mean PAI (%) value from the baseline, aspirin and ticlopidine studies was 29.5 +/- 7.0, 11.2 +/- 8.5 (p less than 0.01 versus baseline) and 21.4 +/- 21.3 (not significant from baseline), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Reduction in regional cerebral metabolic rate of oxygen during human aging.
Authors: Yamaguchi T , Kanno I , Uemura K , Shishido F , Inugami A , Ogawa T , Murakami M , Suzuki K
Published: June 2011

To investigate changes in cerebral circulation and oxygen metabolism during aging, regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rOEF), regional cerebral metabolic rate of oxygen (rCMRO2) and regional cerebral blood volume (rCBV) were measured using the 15O labelled gas inhalation technique and a multi-slice positron emission tomograph (PET) in 22 healthy volunteers, aged from 26 to 64 years old. The measurements were performed with subjects at rest, without sensory deprivation. The values of rCBF, rOEF, rCMRO2 and rCBV in more than 40 anatomical structures of the brain were evaluated by studying a large series of scans in each region of interest after the functional PET image had been anatomically identified using x-ray computed tomographic images corresponding to the PET. In mean gray values, only CMRO2 showed significant reduction with age. rCMRO2 significantly decreased with age only in the supratentrium, and much more in the left hemisphere. Especially remarkable was rCMRO2 reduction in the left caudate region. Both CBF and OEF were variable and less age-dependent. It was concluded that CMRO2 could be reflecting healthy brain aging most properly.
Aggregation of multiple risk factors for stroke in siblings of patients with brain infarction and transient ischemic attacks.
Authors: Diaz J F , Hachinski V C , Pederson L L , Donald A
Published: June 2011

Hypertension, heart disease, and diabetes are not only the major risk factors for stroke, but they tend to cluster in families. It is unknown, however, whether these conditions occur more frequently among relatives of patients with specific types of stroke as compared to non-relatives. The frequencies of stroke and its major risk factors in two groups of subjects were compared. One group consisted of 76 siblings of 41 patients hospitalized with cerebral infarction and transient ischemic attacks in an investigative stroke unit; the other consisted of 55 siblings of the patients' spouses. The occurrence of these conditions in the relatives was determined from a questionnaire completed by the relatives and supported by information from the relatives' family physicians. When considered separately, hypertension, heart disease, and stroke occurred in a small but not statistically significant excess among the relatives in-law. However, various combinations of two or three diseases, (including diabetes), occurred in 20.9% of the patients' siblings as compared to only 3.6% of the relatives in-law (p less than 0.001). These results suggest that living siblings of patients with cerebral infarction and transient ischemic attacks may have an increased risk of stroke and cardiovascular disease as a result of multiple risk factors operating simultaneously. Prevention programs among this high risk population may be particularly worthwhile.
Effect of carotid artery ligation and infusion of fluosol FC-43 emulsion on brain surface oxygen tensions.
Authors: Laycock J R , Coakham H B , Silver I A , Walters F J
Published: June 2011

In eight rabbits, the common carotid artery was ligated and multiple estimations of brain surface oxygen tension performed using a seven barrelled mini-electrode. In five rabbits ligation of the carotid artery resulted in impairment of cortical oxygenation. The remaining three rabbits showed no impairment in the supply of oxygen to the cerebral cortex after carotid occlusion. In the five rabbits who displayed a reduction in oxygen supply after carotid ligation, ventilation with 33% oxygen after the infusion of 15 ml/kg of Fluosol FC-43 produced an improvement in cortical oxygenation in only three of the five rabbits. When these animals were ventilated with 100% oxygen after carotid ligation and Fluosol infusion, oxygen supply in all five was commensurate with or greater than that during control conditions.
Superoxide anion radical does not mediate vasodilation of cerebral arterioles by vasoactive intestinal polypeptide.
Authors: Ballon B J , Wei E P , Kontos H A
Published: June 2011

We examined the hypothesis that oxygen radicals may mediate the vasodilator effect of VIP on cerebral arterioles in cats equipped with cranial windows. The appearance of superoxide anion radical in cerebral extracellular space during VIP application was examined by measuring the rate of superoxide dismutase (SOD)-inhibitable reduction of nitroblue tetrazolium (NBT). Although VIP (1 and 10 micrograms/ml) caused substantial reduction of NBT, the rate of the SOD-inhibitable portion was not significantly different from zero. We also examined the effect of scavenging of superoxide and hydrogen peroxide by topical application of SOD plus catalase on the vasodilator effect of VIP (0.05-1.0 microgram/ml). The dilation in response to VIP was not significantly affected in either large or small arterioles by scavenging of superoxide and hydrogen peroxide. We conclude that VIP does not cause generation of superoxide and that superoxide or other reactive oxygen species derived from it, such as hydrogen peroxide and hydroxyl radical, are not mediators of the cerebral vasodilation caused by VIP.
Ophthalmoplegia with contralateral hemiplegia. Occlusion of the internal carotid artery due to thrombosis of an intracavernous aneurysm.
Authors: Gautier J C , Awada A , Majdalani A
Published: June 2011

A left ophthalmoplegia and right hemiplegia were due to thrombosis of an intracavernous aneurysm with occlusion of the left internal carotid artery. Ophthalmoplegia with contralateral hemiplegia is probably a rare syndrome. Thrombosis of an intracavernous aneurysm is probably a rare cause of occlusion of the internal carotid artery.
IMPS (intact months of patient survival): an analysis of the results of carotid endarterectomy.
Authors: Jonas S
Published: June 2011

The literature on carotid surgery for lesions appropriate to prior episodes of ischemia has been reviewed. Only one randomized study and six non-controlled reports give useful data (this despite more than thirty years of surgical activity in this field). When analyzed by the IMPS (intact months of patient survival) criterion, the randomized study failed to show benefit from surgery. This failure can be attributed to a high (35%) operative stroke and death rate. That sufficiently low operative stroke and death rates are readily achievable is not clear, however, only two of six relevant non-controlled series reported in the literature had operative stroke and death rates below the 10.4% level calculated as necessary for a "break-even" situation. Three of the six non-controlled series contain sufficient follow-up data to permit IMPS comparison against the "standard" of the control group of the randomized study. Against this "standard" only one of the three non-controlled studies would have "shown benefit" from surgery. Barnett, Plum, and Walton have called for audits of endarterectomy results in institutions in which such surgery is performed. It is suggested that such audits be done by the IMPS method, which gives appropriate weight to the effects of operative, as well as of long-term follow-up, strokes and deaths.
Directional C-W Doppler sonography in the diagnosis of basilar artery disease.
Authors: Biedert S , Betz H , Reuther R
Published: June 2011

Using directional continuous-wave Doppler sonography of the vertebral arteries, we have investigated 1,540 patients during the past 5 years. On the basis of unilateral and bilateral retrograde brachial angiograms in the same patients (a total of 1,989 angiograms) we have developed sonographic criteria for demonstrating a significant increase in the peripheral resistance of both distal vertebral arteries and/or the basilar artery. All 11 cases of basilar artery stenosis of at least 60% reduction in lumen diameter (as shown by angiography) exhibited an approximately 40% or higher reduction in the sum of the modified Pourcelot indices of both vertebral arteries with respect to age-matched controls. All 3 stenoses of less than 60% reduction in lumen diameter were not detected by sonography. Even a good collateral circulation through rete mirabile anastomoses did not normalize the modified Pourcelot indices. One case of a persistent primitive trigeminal artery with thin-calibered vertebral arteries was also detected by sonography. The high percent of patients with one hypoplastic vertebral artery in the group with basilar artery stenoses indicates an increased risk for atherosclerosis of the basilar and/or distal vertebral artery in these patients. All 14 angiographically verified occlusions of the basilar artery were detected by sonographic criteria independent of the occlusion localization. Thus, we believe that directional continuous-wave Doppler sonography is a reliable technique for detecting basilar artery stenoses of at least 60% reduction in lumen diameter and basilar artery occlusions.
PET studies of changes in cerebral blood flow and oxygen metabolism after unilateral microembolization of the brain in anesthetized dogs.
Authors: Weyne J , De Ley G , Demeester G , Vandecasteele C , Vermeulen F L , Donche H , Deman J
Published: June 2011

Cerebral blood flow and oxygen metabolism have been measured with the steady-state oxygen-15 technique and positron emission tomography in anesthetized dogs. Regional microembolization was induced by infusing Sephadex particles (diameter, 40 micron) into one of the common carotid arteries. In the first series of experiments, 2.5 mg Sephadex was infused, and the dogs were examined within 3-4 hours after embolization. In a second series 0.55 mg Sephadex was infused, and the dogs were examined either in the first 3-4 hours or 24-48 hours after embolization. Cerebral blood flow, oxygen extraction ratio, and cerebral oxygen utilization were measured at 3 PCO2 levels. In the acute experiments, cerebral oxygen utilization in the embolized hemisphere was 6 (0.55 mg Sephadex) and 25% (2.5 mg Sephadex) lower than on the contralateral side. While cerebral blood flow was symmetrically distributed in normocapnia and hypocapnia, it was 9 (0.55 mg Sephadex) and 35% (2.5 mg Sephadex) lower in the embolized hemisphere during hypercapnia. In normocapnia and hypocapnia the lower oxygen utilization in the embolized hemisphere was characterized by a lower oxygen extraction ratio, and in hypercapnia by an unchanged (0.55 mg Sephadex) or by a higher (2.5 mg Sephadex) extraction ratio. The different effect on oxygen extraction ratio in the control and embolized hemispheres resulted in images of uncoupling between perfusion and oxygen demand that varied according to the PCO2. The experiments also showed a fall in cerebral blood flow in the embolized hemisphere after 3-4 hours, indicating delayed hypoperfusion. After 24-48 hours, blood flow was about 10% higher in the embolized hemisphere, and this was observed at the 3 PCO2 levels, while the oxygen extraction ratio was systematically lower. Oxygen utilization in the embolized hemisphere was depressed to practically the same extent as in acute experiments. It can be concluded that between 4 and 24 hours after microembolization the cerebral microcirculation shows important changes, with installation of luxury perfusion in the face of an unchanging decreased oxygen metabolism.
Regional cerebral blood flow in essential hypertension: data evaluation by a mapping system.
Authors: Rodriguez G , Arvigo F , Marenco S , Nobili F , Romano P , Sandini G , Rosadini G
Published: June 2011

Regional cerebral blood flow was studied by means of the 133Xe inhalation method in 26 untreated and 10 treated patients with essential hypertension. The untreated subjects were divided into newly and previously diagnosed groups to assess the relation between regional cerebral blood flow and the duration of hypertension. The overall flow reduction was more marked in the frontal and temporal regions in the previously diagnosed group, and this was attributed to pathological changes in the district served by the middle cerebral artery. Regional temporal lobe impairment was also noted in the newly diagnosed and treated subjects. A significant correlation was found between regional cerebral blood flow and mean arterial blood pressure.
Transport of sodium from blood to brain in ischemic brain edema.
Authors: Lo W D , Betz A L , Schielke G P , Hoff J T
Published: June 2011

Brain water and sodium increase during ischemia, suggesting that the blood-brain barrier permeability to sodium is increased. To test this hypothesis we measured the permeability-surface area products of 22Na and [3H]sucrose in gerbils following 3 hours of unilateral ischemia. In animals with neurologic symptoms, unilateral carotid occlusion reduced the cerebral blood flow in the ipsilateral cerebral hemisphere to 13 +/- 4 ml/100 g/min (n = 6). The water content of the ischemic hemisphere increased from 79.0 +/- 0.6 to 80.8 +/- 0.2% (n = 7, p less than 0.001) and tissue sodium content increased from 231 +/- 17 to 359 +/- 23 mEq/kg (p less than 0.0001). However, there was a 40% reduction in the sodium permeability-surface area product of the ischemic hemisphere compared with the control side (1.65 +/- 0.44 vs 2.79 +/- 0.29 microliter/g/min, n = 6, p less than 0.001). The sucrose permeability-surface area product, a measure of blood-brain barrier integrity, was unchanged. Although ischemia was less severe in the diencephalon, the tissue water and sodium contents increased significantly on the ischemic side. In contrast to the cerebral hemisphere, however, the permeability-surface area products for both sodium and sucrose were unchanged in the ischemic diencephalon. These results suggest that the increase in tissue sodium seen in ischemic edema is not due to enhanced sodium uptake; we speculate that it results, in part, from a reduction in sodium and water clearance from the tissue.
Experimental focal ischemia in cats: changes in multimodality evoked potentials as related to local cerebral blood flow and ischemic brain edema.
Authors: Kataoka K , Graf R , Rosner G , Heiss W D
Published: June 2011

Somatosensory and auditory evoked cortical potentials (SEP's and AEP's), regional cerebral blood flow, regional brain water content, and alteration of the blood-brain barrier were investigated in 3 cortical areas during permanent and 1- and 2-hour transient occlusion of the left middle cerebral artery and after restoration of blood flow in cats. During occlusion, blood flow in the auditory cortex was severely suppressed. In the fore limb projection area of the somatosensory cortex, blood flow was moderately reduced while it was nearly unaffected in the hind limb projection area. Despite different degrees of ischemia in the 3 cortical areas, all evoked responses were completely abolished within 10 minutes after occlusion. During permanent occlusion, the pattern of blood flow reduction persisted, and all evoked potentials stayed abolished. Recirculation after occlusion restored blood flow rapidly. AEP's recovered poorly after both 1 and 2 hours of ischemia. SEP's regained normal amplitudes soon after recirculation in the group with 1-hour occlusion. After 2 hours of ischemia, the recovery of SEP's was variable but better than that of the AEP's. Remarkable water accumulation was observed in the auditory cortex of all 3 groups and was accompanied in the 2-hour ischemia group by a disruption of the blood-brain barrier. In the 2-hour group, water accumulation was also found in the subcortical white matter radiation, whereas significant changes in regional water content were not observed in the somatosensory areas. The present study indicates that abolition of SEP's during middle cerebral artery occlusion in cats is caused by lesions in the afferent pathway leading to cortical deafferentation rather than by cortical ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)
Hemodynamic effect of carotid endarterectomy.
Authors: Schroeder T , Sillesen H , Engell H C
Published: June 2011

Cerebral blood flow was measured by the intravenous xenon-133 technique at rest and during cerebral vasodilation with acetazolamide in 32 patients before and after uncomplicated carotid endarterectomy. The results were compared with the internal carotid artery perfusion pressure measured during surgery. A significant improvement in side-to-side cerebral blood flow asymmetry occurred in 6 patients studied at baseline and in 11 patients during provoked cerebral vasodilation. These patients all belonged to a group of 14 patients who, in addition to a severe stenosis of the internal carotid artery, presented a reduction in cerebral perfusion pressure of at least 20%. No improvements occurred in 18 patients with no or only minor reduction in perfusion pressure, irrespective of the degree of stenosis. These findings indicate an improved perfusion reserve following carotid endarterectomy in most patients with marked reduction in perfusion pressure, whereas only some of these patients will experience an improvement in baseline cerebral blood flow.
Failure of nimodipine to prevent ischemic neuronal damage in rats.
Authors: Vibulsresth S , Dietrich W D , Busto R , Ginsberg M D
Published: June 2011

The efficacy of nimodipine in preventing ischemic brain injury was tested in rats subjected to a 20-minute period of high-grade forebrain ischemia by 4-vessel occlusion. Three minutes after restoration of circulation to the brain, an intravenous bolus of 5 micrograms/kg nimodipine or an equivalent amount of vehicle or saline was given, followed by continuous intravenous infusion of the respective solution at 1 microgram/kg/min for 2 hours. In a second series, a larger bolus (20 micrograms/kg of nimodipine) and longer infusion period (6 hours) were employed. Histopathology of the brain was evaluated blindly 72 hours later and graded on a conventional 3-point scale. There was no significant effect of treatment in either series. In the 6-hour series, the percent of cerebral hemispheres showing damage of Grades 2 or 3 in zone CA1 of the hippocampus and in the striatum, respectively, was 100 and 40% for the nimodipine-treated rats, 100 and 42% for rats receiving vehicle, and 75 and 25% for animals receiving saline. Thus, this study revealed no beneficial effect of nimodipine when given following a 20-minute period of severe forebrain ischemia.
Pulsatile tinnitus.
Authors: Sila C A , Furlan A J , Little J R
Published: June 2011

Pulse-synchronous tinnitus suggests a vascular etiology and is deemed rare by the otologic literature. During the period 1978-1985 we evaluated 20 patients with the sole or initial complaint of pulsatile tinnitus. Fourteen patients had objective pulsatile tinnitus, perceived by the patient and the examiner alike, and 6 had subjective pulsatile tinnitus, perceived by the patient only. Angiographic findings in patients with objective pulsatile tinnitus included dural or pial arteriovenous malformations, occlusive disease of the intra- or extracranial carotid arteries from atherosclerosis or dissection, panarterial ectasia, and venous sinus thrombosis. Most of the patients with subjective pulsatile tinnitus had normal evaluations, but other possible causes of subjective pulsatile tinnitus included a carotid occlusion and pseudotumor cerebri. Pulsatile tinnitus is an uncommon symptom produced by a variety of causes. Given the abnormalities present in our series, we would recommend intraarterial digital subtraction angiography or conventional angiography in the evaluation of objective pulsatile tinnitus and intravenous digital subtraction angiography for subjective pulsatile tinnitus. Increased intracranial pressure must also be considered.