bluuebunny/crossref_metadata_2025 huggingface dataset:
Incidence of stroke in an African City: results from the Stroke Registry at Ibadan, Nigeria, 1973-1975.
Authors: Osuntokun B O , Bademosi O , Akinkugbe O O , Oyediran A B , Carlisle R
Published: June 2011

Studies based on hospital populations reported from negro communities in several countries in Africa suggest that cerebrovascular disease (CBVD) shows increasing mortality and morbidity in Africans although 2 decades ago CBVD was believed to be uncommon. We report the first study in the African to determine the incidence of stroke in an urban area, Ibadan, Nigeria.
Occlusion of the vertebral or basilar artery. Follow up analysis of some patients with benign outcome.
Authors: Caplan L R
Published: June 2011

Ten patients with angiographically verified occlusion of the basilar or vertebral artery have been followed for an average of 2.75 years. None has developed further ischemia after the initial stroke, and 4 patients survived without any clinical deficit. In occlusive disease of the posterior circulation, the critical period for deficit acquisition is at the time of occlusion. Extent of the deficit depends on the rapidity of development of adequate collateral circulation, and the presence of distal embolization at the time of occlusion. Some patients survive basilar occlusion without permanent deficit.
Isoproterenol treatment of visual symptoms in migraine.
Authors: Kupersmith M J , Hass W K , Chase N E
Published: June 2011

Six patients with transient or permanent visual loss associated with migraine are presented. In 3 patients with monocular and one patient with binocular episodes of transient visual loss subsequent visual episodes were relieved by prompt inhalation of isoproterenol. The authors review the possible mechanisms of action of isoproterenol in migraine and present evidence to support the prophylactic use of isoproterenol to prevent transient and possible persistent visual loss in patients with migraine.
Changes in internal carotid artery flow velocities with cerebral vasodilation and constriction.
Authors: Beasley M G , Blau J N , Gosling R G
Published: June 2011

Non-invasive Doppler-shift ultrasound, together with spectral analysis, have been used to study the changes in internal carotid artery flow velocity patterns that occur with cerebral vasoconstriction and vasodilation provoked by over-breathing and breath-holding. Significantly different waveform shapes, characteristic for each vessel, were demonstrated from the internal and external carotid arteries, making identification of the internal carotid certain. In 5 healthy subjects over-breathing for 3 minutes significantly lowered the mean height of the internal carotid waveform by an average of 32% (p less than 0.001). Breath-holding for 40-60 seconds raised the mean height by an average of 31% (p less than 0.001). The pulsatility index of the waveforms varied inversely to mean height. These results show that the effects of cerebral dilation or constriction are easily detected by flow-velocity changes in the internal carotid artery.
Ineffectiveness of the Doppler Ophthalmic Test (DOT) in post-endarterectomy evaluation.
Authors: Otis S M , Smith R A , Dalessio D J , Kroll A D , Rush M , Dilley R B
Published: June 2011

In an effort to evaluate the effectiveness of the Doppler Ophthalmic Test (DOT) following carotid endarterectomy, a large group of patients was examined both pre- and postoperatively with non-invasive techniques. The DOT, which has proven to be a useful non-invasive diagnostic test for the determination of significant carotid artery stenosis, was found to be persistently abnormal in 46% of patients with a preoperative positive test. This occurred in spite of the fact that operative arteriography, direct ultrasonic auscultation, and Doppler imaging studies were all within normal limits. It is suggested from this study that the Doppler Ophthalmic Test alone is not adequate to follow patients postoperatively, especially if an abnormal study persists following a satisfactory endarterectomy. Other non-invasive techniques, which employ direct ultrasonic imaging of the carotid flow, may be more accurate in determining vessel patency.
Cerebral artery thrombosis and intramural hemorrhage.
Authors: Sadoshima S , Fukushima T , Tanaka K
Published: June 2011

Thirty-nine thrombosed arterial segments of the branches of the circle of Willis were studied by a complete serial section technique. Twenty-two patients had been hypertensive and 8 had hypercholesterolemia before the onset of cerebral artery thrombosis. The histological characteristics of the thrombosed arterial segments were intramural hemorrhage in 28 segments, superficial edema of the fibrous cap of the atheroma of fibrous plaque in 4, rupture of the atheromatous plaque in 1, superficial accumulation of foam cells in the atheroma in 1 and an atheroma or fibrous plaque without any other changes in 5. They were many intramural small blood vessels in the atheroma or fibrous plaques of 22 segments with intramural hemorrhage. Fibrinoid degeneration of these small blood vessels was noted in 5. These findings suggested that intramural hemorrhage from the intramural small blood vessels was the major cause of cerebral artery thrombosis and that persistent hypertension not only promoted cerebral atherosclerosis but also induced hemorrhage from the intramural small blood vessels.
Small animal model for investigation of subarachnoid hemorrhage and cerebral vasospasm.
Authors: Barry K J , Gogjian M A , Stein B M
Published: June 2011

A method for induction of subarachnoid hemorrhage (SAH) in a rat model is described. Resolution of the hemorrhage was documented photographically and microscopically at intervals from 1 hr to 8 days. Photographs indicated that most of the hemorrhage was resorbed within 3 days, an observation confirmed microscopically by the amount of red blood cells in the subarachnoid space. Significant cerebral vasospasm was documented within the first 2 days after the induction of hemorrhage with the basilar artery returning to baseline values at an average of 3 days followed by moderate dilatation at 5 to 8 days. The suitability of the rat as an animal model for further investigation of subarachnoid hemorrhage is discussed.
Correlated electrical and mechanical responses of isolated rabbit pial arteries to some vasoactive drugs.
Authors: Lusamvuku N A , Sercombe R , Aubineau P , Seylaz J
Published: June 2011

Simultaneous measurements were made of spike activity and perfusion pressure (PA) in intact segments of rabbit middle cerebral artery in vitro. The segments were mounted on a Teflon tube designed so that the perfusing solution flowed in the annular space between the tube and the artery wall, thus magnifying the PA changes occurring when the artery constricted or dilated. A widened portion of the Teflon tube immobilized 1--2 mm of the artery segment for electrical recording with fine glass microelectrodes. Spontaneous spike activity (extra- and intracellular) was regularly observed. When a steady PA and spike discharge was obtained, tests were performed by substituting for the normal perfusion liquid, solutions containing 5 microgram/ml norepinephrine, 5 microgram/ml angiotensin II or 7.5 microgram/ml isoproterenol. Norepinephrine and angiotensin each increased spike frequency (+ 293 and + 126%) and PA (+ 6.6 and + 7.9 mm Hg) whereas isoproterenol decreased spike frequency (-89%) and PA (-22.9 mm Hg). These results a) confirm the presence of receptors to these agents in pial arteries, and b) demonstrate a high degree of correlation between membrane electrical events and mechanical activity of these spontaneously-active myovascular cells.
Incidence of transient cerebral ischemic attack in Hawaii Japanese men. The Honolulu Heart Study.
Authors: Rhoads G G , Popper J S , Kagan A , Yano K
Published: June 2011

At the Honolulu Heart Study 7,895 men of Japanese ancestry, 45--68 year-old, who were free of previous stroke at the baseline examination (1965--1968) were followed 6 years for the development of transient cerebral ischemic attacks (TIA). Fifty-one men developed probable or possible episodes. In multivariate analysis TIA was associated with preceding hypertension, cigarette smoking and coronary heart disease. It was less common in men who were facile with written Japanese language, in those who consumed alcohol, and in those who were physically active. During an average follow up of 3 years after these TIA events 2 strokes occurred, vs 0.7 expected. This prognosis is more favorable than that reported by other studies.
Regional cerebral blood flow in the rat as determined by particle distribution and by diffusible tracer.
Authors: Horton R W , Pedley T A , Meldrum B S
Published: June 2011

Measurements of total and regional cerebral blood flow in paralyzed rats maintained on 70% N2O/30% O2 obtained by a diffusible tracer technique, iodoantipyrine, and by a particle distribution method, microspheres, have been compared. Total CBF values were in good agreement, 0.86 +/- 0.07 ml/g/min (PaCO2 37.3 +/- 1.5, iodoantipyrine method) and 0.88 +/- 0.02 (PaCO2 36.2 +/- 0.8, microsphere method). Regional cerebral blood flows showed good agreement with the 2 methods, with highest flow in the colliculi, striatum and cerebral cortex and lowest flows in the hypothalamus, pons medulla and cerebellum. The iodoantipyrine method is technically easier to perform and had a higher precision.
Anticoagulant vs anti-platelet therapy as prophylactic against cerebral infarction in transient ischemic attacks.
Authors: Olsson J E , Brechter C , Bäcklund H , Krook H , Müller R , Nitelius E , Olsson O , Tornberg A
Published: June 2011

156 patients with transient ischemic attacks (TIA) or reversible ischemic neurological deficit (RIND) were given prophylactic anticoagulant (AC) treatment against cerebral infarction in a prospective multicenter study from 5 hospitals in southern Sweden. After 2 months of AC treatment, 135 patients remained in the study and were randomized into 2 groups; one continued with AC treatment and one changed to anti-platelet therapy. The patients were followed for 12 months. No significant difference was seen between the 2 groups but 3 completed cerebral infarctions occurred during anti-platelet therapy against one during AC treatment. One cerebral hemorrhage was seen during AC treatment. All completed strokes occurred in men who initially had carotid symptoms. The number of patients with TIA/RIND was somewhat higher in the anti-platelet group whereas myocardial infarctions occurred more often during AC treatment. Compared to the natural history of untreated TIA/RIND both treatments were found to have a prophylactic effect against cerebral infarction.
Plasma acetylsalicylate and salicylate and platelet cyclooxygenase activity following plain and enteric-coated aspirin.
Authors: Ali M , McDonald J W , Thiessen J J , Coates P E
Published: June 2011

Compressed and enteric-coated acetylsalicylate (ASA) tablets have been compared in normal healthy subjects. Plasma ASA and salicylate (SA) were measured by high pressure liquid chromatography (HPLC). Platelet cyclooxygenase activity in vitro was studied by a radiometric technique. Following ingestion of 650 mg of ASA in the form of compressed tablets, cyclooxygenase activity was inhibited 95% within 45 min. Enzyme activity was observed to increase within 8 h and reached 10% of control level by 24 h. The pattern suggests that only circulating platelets are affected by ASA ingestion. Following the administration of 650 mg of ASA as enteric-coated tablets comparable inhibition of cyclooxygenase activity was observed, although the effect was delayed, reflecting the delayed appearance of ASA in the plasma. Return to control levels followed a pattern similar to that observed with the compressed tablet.
Effects of formaldehyde fixation on basilar artery caliber.
Authors: Hart M N , O'Donnell S L
Published: June 2011

The external diameters of rat and rabbit basilar arteries were determined before and after formaldehyde fixation in relaxed and drug constricted vessels. Fixation usually resulted in an immediate vessel constriction followed by partial relaxation after several hours. However, the results were inconstant from vessel to vessel and from area to area of the same vessel. It is concluded that morphologic as well as morphometric assessment of formaldehyde-fixed basilar arteries is unreliable.
Effect of steroid on ischemic brain edema. Analysis of cytotoxic and vasogenic edema occurring during ischemia and after restoration of blood flow.
Authors: Ito U , Ohno K , Suganuma Y , Suzuki K , Inaba Y
Published: June 2011

Mongolian gerbils were observed for the effects of beta-methasone on ischemic brain edema which developed during ischemia or after blood flow restoration. The severity of brain edema was determined by measuring water content of the ischemic cerebral hemisphere, using the wet and dry methods. Sodium and potassium ions were extracted from homogenized brains with 0.75N HNO2 and ion concentration measured by flame photometry. Passage of RISA from blood into the cerebral parenchyma, as an indicator of blood-brain barrier change, was determined with a gamma-scintillation counter. In the cytotoxic edema model, animals were killed after 9 h permanent ischemia or 3 h after 1 h ischemia. In the simultaneous cytotoxic and vasogenic edema model, the animals were killed either 20 h or 3 days following 1 h ischemia, or 3 h after blood flow restoration following 6 h ischemia. Steroid treatment was ineffective in ischemic brain edema of the cytotoxic or vasogenic type.
Cerebral venous pressure during actively induced hypertension and hypercapnia in cats.
Authors: Auer L , Johansson B , MacKenzie E T
Published: June 2011

Superior sagittal sinus pressure, intracranial pressure and arterial pressure were recorded in an experimental series on 10 cats. During drug-induced, severe, acute arterial hypertension and parallel hypercapnia, venous pressure could exceed intracranial pressure in both the supra- and infratentorial compartment. From these data it is concluded that cerebral venous pressure during acute arterial hypertension may contribute to protein extravasation at the postcapillary-venular level.
Resolving siphon stenosis following endarterectomy.
Authors: Day A L , Rhoton A L , Quisling R G
Published: June 2011

Tandem arteriosclerotic lesions of the carotid sinus and siphon increase the risks of carotid endarterectomy; when the siphon is severely stenotic, a microvascular bypass may be the preferable procedure. Two patients, each with severe siphon stenosis and significant sinus lesions, however, were subjected to carotid endarterectomy as their initial surgical procedure. The postoperative arteriogram showed resolution of the siphon stenosis in both patients. The identification of an associated extracranial lesion, or the presence of a lesion located more distal in the siphon than atheroma usually occur, should alert the surgeon that the intracranial obstruction may be due to embolism. In patients with these tandem lesions, therefore, a repeat arteriogram, performed several weeks after endarterectomy of sufficient medial treatment interval, may show resolution of the intracranial lesion, and may avoid an unnecessary bypass procedure.
Enhancement of cerebrovascular effect of CO2 by hypoxia.
Authors: Quint S R , Scremin O U , Sonnenschein R R , Rubinstein E H
Published: June 2011

Internal carotid blood flow, taken as an index of cerebral blood flow (CBF); arterial pressure; and respiratory O2 and CO2 concentrations, were measured in halothane (1%)-anesthetized, paralyzed and mechanically ventilated rabbits. CBF was determined at end-tidal CO2 of 4% (normocapnia) and 8%, as inspired O2 [O2]I) was varied stepwise over the range of 6.5 to 92%. Normocapnic CBF was constant over the range of 15 to 92% [O2]I, but it increased significantly to 240% and 380% of control when [O2]I was at 10% and 6.5%, respectively. Cerebrovascular response to CO2 was constant over the range of [O2]I tested, except for a significant elevation to 180% of control at [O2]I of 10%.
Superior sagittal sinus thrombosis 10 years after surgery for ulcerative colitis.
Authors: Yerby M S , Bailey G M
Published: June 2011

Cerebral vein thrombosis is a known complication of active ulcerative colitis. It is generally believed that panproctocolectomy ameliorates the thromboembolic and other systemic complications of ulcerative colitis. We report an unusual patient, 10 years post-panproctocolectomy for ulcerative colitis, who developed a cerebral sinus thrombosis. Physicians should be aware of the possibility of thromboembolic complications of ulcerative colitis long after definitive surgery has been performed.
Elastic elements in the media and adventitia of human intracranial extracerebral arteries.
Authors: Mérei F T , Gallyas F , Horváth Z
Published: June 2011

We find that the media and adventitia of adult human cerebral arteries contain elastic fibers forming a dense, coherent network, similar to that found in muscular arteries of the same size in other organs. The external elastic layer in the adult human is masked for the currently employed staining methods. By treatment with 90% formic acid before fixation, the original staining character of elastic tissue can be restored. The light microscopic and scanning electron microscopic features of this network of elastic fibers are presented.
Cerebral protective, metabolic, and vascular effects of phenytoin.
Authors: Artru A A , Michenfelder J D
Published: June 2011

In mice breathing 5% oxygen, pretreatment with the optimal dose of 200 mg/kg of phenytoin increased survival time 123%. This increase was somewhat less than that observed with certain barbiturates using the same model but significantly greater than that observed with diazepam which is more effective than phenytoin in suppressing hypoxemic convulsions in this model. In dogs maintained at an expired halothane concentration of either 0.87% or < 0.1%, phenytoin tended to decrease cerebral blood flow and had no effect on the cerebral metabolic rate for oxygen at 3 different doses. Assuming a similar effect in mice, there cerebral protection during hypoxemia observed with phenytoin cannot be explained by a reduction in metabolic rate, an increase in oxygen delivery, or by an anticonvulsant effect per se. In additional dog studies, pretreatment with phenytoin decreased the rate of potassium accumulation in cisternal cerebrospinal fluid following 20 minutes of anoxia. We speculate that phenytoin protection may be linked to this effect.
Cerebral fat embolism: a neuropathological study of a microembolic state.
Authors: Kamenar E , Burger P C
Published: June 2011

Multiple cerebral petechiae associated with intravascular globules of neutral fat and localized primarily within the white matter are distinctive lesions which secure the pathologic diagnosis of cerebral fat embolism. The abundance of these lesions in an unknown, but presumably small, percentage of cases of fat embolism, along with the even more widespread distribution of embolic fat droplets throughout both white and gray matter, suggest that these lesions and emboli must have a profound effect on neurologic function. Nevertheless, respiratory insufficiency is by far a more common clinical manifestation of the fat embolism syndrome and the neurologic involvement of such patients is often attributed to the secondary effects of generalized hypoxia. The following patient with overt respiratory and neurologic symptoms re-emphasizes the direct primary effect of fat emboli within the central nervous system as a cause of white matter hemorrhages and neurologic deterioration. Explantations for the selectivity of the lesions for the cerebral white matter are explored.
Correlation between rCBF and histological changes following temporary middle cerebral artery occlusion.
Authors: Tamura A , Asano T , Sano K
Published: June 2011

Correlations between changes in regional, cortical, cerebral blood flow (rCBF) and histological changes in the corresponding brain regions were examined following middle cerebral arterial occlusion in 24 cats. In all animals, the duration of arterial occlusion was 2 hours followed by 2 hours of recirculation. The animals were divided into 2 groups according to the severity of the observed histological damage. Severe cortical damage was observed in 8 cats (Group A), and, in the remaining 16 cats, little or no cortical damage was seen (Group B). There was a statistically significant difference between these 2 groups in the average rCBF values during ischemia. During recirculation, there was a prompt and uniform recovery of rCBF in animals in group B but a marked diversity; of rCBF ranging from hyperemia to oligemia in animals in group A. This diversity of rCBF reflects inhomogenous blood flow. This study indicates potential hazards for surgical revascularization in the aute stage of stroke when brain damage has progressed beyond a certain level.
Local cerebral blood flow following transient cerebral ischemia. I. Onset of impaired reperfusion within the first hour following global ischemia.
Authors: Miller C L , Lampard D G , Alexander K , Brown W A
Published: June 2011

Using the hydrogen clearance technique, local cerebral blood flow (LCBF) in 22 dogs was estimated at 6 parietal sites prior to and following 5 min of total global ischemia. Ischemia was immediately followed by an initial reactive hyperemia during which the electrocorticogram (ECoG) usually began to recover, and within the first 30 min, most of the LCBF's decreased to subnormal values. This onset of hypoperfusion was accompanied by a concomitant decrease in ECoG activity. Two animals that maintained normal local perfusion after the initial hyperemia recovered ECoG activity quickly. These results suggest that the subsequent poor reperfusion was caused by an increased microvascular resistance rather than by blood aggregates, increased blood viscosity, or a variety of other mechanism which have been proposed. Increased vascular tonus was, at least, partly responsible for the increased vascular resistance. This report supports the hypothesis that impaired reperfusion (which occurs some time after an initial hyperemia) may be responsible for ultimate neuronal death, rather than the period of global ischemic hypoxia per se.
Intra-arterial nitroprusside treatment of acute experimental vasospasm.
Authors: Hirsh L F
Published: June 2011

The effect of intra-arterial sodium nitroprusside infusions on acute experimental basilar artery spasm was studied in dogs. Vasospasm produced by subarachnoid hemorrhage at normal intracranial pressure was partially relieved by nitroprusside. When given by the intra-arterial route, 15 times the recommended maximum intravenous does can be infused without significant hypotension or elevation in intracranial pressure.
Experimental cerebral ischemia in spontaneously hypertensive rats (SHR): Importance of degree of hypertension.
Authors: Fujishima M , Tamaki K , Nakatomi Y , Ishitsuka T , Nakagawara K , Omae T
Published: June 2011

To study the relationship between the degree of hypertension and experimentally-induced cerebral ischemia, brain metabolites, including lactate, pyruvate and adenosine triphosphate (ATP) were determined one hour after bilateral carotid occlusion in 119 spontaneously hypertensive rats (SHR) with a variety of mean arterial pressures (MAP). Of these, 36 SHR were given antihypertensive agents for 10 weeks to reduce blood pressure prior to the experiment. There was a significant linear correlation between MAP before and either supratentorial lactate (r = 0.482, p less than 0.001) or the lactate/pyruvate ratio (r = 0.388, p less than 0.001) in the brain after carotid occlusion. An inverse correlation was observed between supratentorial lactate and either ATP (r = -0.627, p less than 0.001) or arterial PCO2 (r = -0.477, p less than 0.001) after carotid occlusion. The changes suggest that the animals with a higher MAP had a greater increase in ischemic metabolites with a decrease in ATP and a more pronounced hypocapnia after carotid occlusion. This hypocapnia is believed to be due to hyperventilation induced by cerebral ischemia. It is concluded that hypertensive rats are more susceptible to cerebral ischemia and the susceptibility is related to the degree of hypertension. By long-term lowering of the blood pressure prior to carotid occlusion, the ischemic changes are lessened in this experimental model.
Morphometry of brain parenchymal vessels following subarachnoid hemorrhage.
Authors: Hart M N
Published: June 2011

This study was performed to test the hypothesis that vascular spasm can occur in brain parenchymal vessels following subarachnoid hemorrhage (SAH). Five cc of autologous blood was injected into the cisterna magna of test cats and 5 cc of saline into control cats. After 2 hours, a cranial window was created and cortical tissue frozen in situ with liquid nitrogen. Statistical analysis of 124 test and 93 control arteries and arterioles showed a significantly greater mean wall to lumen ratio in the test vessels but with almost identical mean cross sectional areas for both groups of vessels. This finding provides evidence for at least vasoconstriction, if not frank spasm, in parenchymal vessels in conjunction with SAH.
Progressive vascular changes in Moyamoya syndrome.
Authors: Murphy M J
Published: June 2011

Progressive vascular changes are described in an adult with moyamoya syndrome and similar cases are reviewed. Angiographic findings support the concept of a progressive acquired stenosis of the internal carotid artery as the primary abnormality in this syndrome.
A computerized technique for the display and comparison of regional cerebral blood flow data.
Authors: Farrar J K
Published: June 2011

A technique is described by which the sizes, shape and orientation of the brain with respect to detector positioning can be reproduced by computerized simulation. Head size is estimated from the distance between the external acoustic meatus (EAM) and the outer canthus and head shape is determined from the length and height of the skull. These values are used to magnify and alter the shape of a standard brain outline to comply with individual patient measurements. The location of the EAM and nasion are used to establish the displacement and rotation of the orbito-meatal base line with respect to the detector holding assembly. The corrected brain outline is then rotated, centered and displayed superimposed on the regional flow data. Comparison of flow data from 2 studies is accomplished by mapping each probe location onto the standard brain and projecting these brain coordinates onto the second study. Flow data from the nearest detectors are averaged to obtain the interpolated flow value for that brain region. This method corrects for differences in head size and shape between patients and for changes in head positioning and rotation between studies. Computer simulation studies demonstrated that this correction procedure can significantly reduce the variance of flow measurements for expected ranges of head size and orientation.
Limitations of quantitative oculoplethysmography and of directional Doppler ultrasonography in cerebrovascular diagnosis: assessment of an air-filled OPG system.
Authors: Ginsberg M D , Greenwood S A , Goldberg H I
Published: June 2011

500 consecutive patients were evaluated for extracranial disease of the internal carotid arteries by an automated, air-filled, digital oculoplethysmographic system (OPG) of the Kartchner type (Zira) and by supraorbital (SO) and supratrochlear (ST) directional Doppler ultrasonography. Cerebral arteriograms were performed in 58 patients (110 vessels), and OPG timing criteria for detecting hemodynamically significant carotid artery stenosis (60% or greater diameter reduction) were ascertained. Optimal criteria were a delay of one ocular pulse, relative to the other, of greater than 12 msec; and a delay of an ocular pulse, relative to the earlier ear (external carotid) pulse, of greater than 36 msec. These criteria correctly identified 73% of vessels with 0 to 59% stenosis and 76% of vessels with 60 to 100% stenosis. However, in 26% of the vessels, OPG was either inconclusive or inaccurate. Correct diagnosis of bilateral hemodynamically significant carotid artery stenoses was made by OPG in 6 of 9 affected patients. SO Doppler was normal in 70% of vessels with 0-59% stenosis, and abnormal in 75% of vessels with 60-100% stenosis. Corresponding percentages for ST Doppler were 95% and 44%. Abnormal Doppler responses to compression of contralateral facial branches were predictive of intracranial cross-collateralization in only 25% of patients. These results suggest that both quantitative OPG in its present form and directional Doppler studies have serious limitations as non-invasive diagnostic methods.
Effects of hypercapnia on enhancement of decreased perfusion flow in non-infarcted brain tissues.
Authors: Nakagawa Y , Yamamoto Y L , Meyer E , Hodge C P , Feindel W
Published: June 2011

The effects of hypercapnia on enhancement of reduced cerebral perfusion were re-evaluated in areas of ischemia produced by occlusion of the canine middle cerebral artery. Perfusion was measured by 85Kr (beta-ray) and 133Xe (gamma-ray) clearances, fluorescein angiography and diameter measurement of arteries. Between 45 and 55 mm Hg of PaCO2 rCBF measured with both isotopes increased significantly. When PaCO2 was elevated above 55 mm Hg, there was a remarkable dissociation in the rCBF measured by both isotopes. Cortical blood flow measured by 85Kr clearance decreased and, conversely, rCBF measured by 133Xe continued to increase. Arteries of less than 50 mu in diameter in areas of ischemia dilated significantly during hypercapnia. At PaCO2 above 65 mm Hg, progressive sub-pial hemorrhage and extravasation of dye were observed as side effects of hypercapnia. The use of mannitol combined with hypercapnia appeared to be harmful. A PaCO2 level between 45 and 55 mm Hg increases perfusion in areas of mildly reduced rCBF.
In vivo and In vitro studies on the cerebrovascular dilatation induced by diazoxide in normotensive and renal hypertensive goats.
Authors: Estrada C , Dieguez G , Conde M V , Gómez B , Lluch S
Published: June 2011

We studied the in vivo and in vitro effects of diazoxide on the cerebral circulation of 8 normotensive (mean arterial pressure = 100 mm Hg) and 5 renal hypertensive (mean arterial pressure = 146 mm Hg) goats. Injections of diazoxide (0.3-27 mg) into the internal maxillary artery of unanesthetized goats produced dose-dependent increases in cerebral blood flow (electromagnetic flowmeter), this effect being significantly higher in hypertensive goats. Intravenous injection of 5 mg/kg of diazoxide into normotensive goats increased cerebral blood flow 40 ml/min/100 g and mean arterial pressure dropped 22 mm Hg whereas in hypertensive goats cerebral blood flow was unchanged and mean arterial pressure decreased 50 mm Hg. The increase in heart rate due to intravenous diazoxide was similar in normotensive and hypertensive goats (35 beats/min). Cumulative applications of diazoxide (10(-5) to 10(-3)M) on isolated middle cerebral arteries produced dilatory responses both under resting conditions and after previous tonic contraction by serotonin. This relaxation was significantly greater in arterial segments from hypertensive goats. The results indicate that diazoxide exerts powerful dilatatory effects on cerebral vessels, both in vivo and in vitro, and that these effects are particularly evident in hypertensive animals.
Blood flow and regulation of blood flow in experimental peritumoral edema.
Authors: Hossman K A , Blöink M
Published: June 2011

In 27 pentobarbital-anesthetized cats cerebral blood flow and regulation of cerebral blood flow was measured one to 3 weeks following stereotactical xenotransplantation of a rat glioma clone into the internal capsula. Tumor growth was accompanied by severe vasogenic peritumoral edema in the white matter of the tumor-bearing hemisphere. White matter water content in the vicinity of the tumor increased from 69.1 +/- 0.9 to 0.5 +/- 0.7 ml/100 g wet weight (means +/- SE) which corresponds to an increase in tissue volume of about 60%. Intracranial pressure after 3 weeks was 12 +/- 2.6 mm Hg. Blood flow in the peritumoral white matter decreased from 32.2 +/- 5.6 to 18.6 +/- 1.9 ml/100/g/min but it did not change in the peritumoral grey matter or the opposite hemisphere. The decrease in blood flow was due to the volume expansion of the swollen edematous tissue and not to a compression of the microcirculation because neither flow nor vascular resistance changed when referred to dry rather than to wet weight of the edematous tissue. Flow regulation in the peritumoral edematous white matter was disturbed. CO2 reactivity of blood flow was 5.4% mm Hg change in aPCO2 (non-edematous contralateral white matter 6.4%/mm Hg), and the autoregulatory capacity between 40 and 170 mm Hg was 0.7%/mm Hg (non-edematous white matter 1.0% mm Hg). It is concluded that in the absence of significant intracranial hypertension, even severe degrees of vasogenic peritumoral edema do not interfere with blood flow and flow regulation. This is in contrast to the cytotoxic type of edema, and indicates that microcirculatory compression by edema, when present, is the consequence of pericapillary glial hydrops and not of an accumulation of extravasated edema fluid.
Embolism distal to stenosis of the middle cerebral artery.
Authors: Adams H P , Gross C E
Published: June 2011

Fibrin-platelet microembolism in cortical branches distal to stenosis of the middle cerebral artery was directly visualized in a patient with transient ischemic attacks (TIA) and was histopathologically confirmed. Cerebral microembolism may produce TIA in patients with stenosis of the middle cerebral artery and may influence the success of the extracranial-intracranial bypass operation in treatment of these patients.
Effects of arterial hypotension on brain metabolism in normotensive and spontaneously hypertensive rats.
Authors: Nakatomi Y , Fujishima M , Ishitsuka T , Tamaki K , Omae T
Published: June 2011

The effects of graded systemic hypotension induced by the combination of bleeding and trimethaphan camsylate infusion on brain metabolism were studied in normotensive rats (NTR) and spontaneously hypertensive rats (SHR). Metabolites such as lactate, pyruvate and adenosine triphosphate (ATP) of the brain frozen in situ were measured at the end of 1 hour of hypotension. In SHR, either cerebral lactate or the lactate/pyruvate (L/P) ratio increased rapidly and progressively with a concomitant decrease in ATP, when mean arterial blood pressure (MAP) fell below about 50 mm Hg. In NTR, on the other hand, the metabolites changed little until MAP fell to about 40 mm Hg. Metabolic derangements of the brain during profound hypotension were more marked and severe in SHR than in NTR. These results suggest that the SHR is more vulnerable to severe hypotension than NTR, probably due to hemodynamic difference of the cerebral circulation between the 2 groups. The increased cerebral vascular resistance and upward shift of cerebral autoregulation in hypertension might be responsible for this vulnerability.
Evaluation of cross-circulation through circle of Willis using an ultrasonic Doppler technique. Part II. Comparison between blood flow velocity by ultrasonic Doppler flowmetry and cerebrovascular resistance.
Authors: Yoneda S , Nukada T , Kimura K , Tanaka K , Ashida K , Asai T , Etani H , Imaizumi M , Abe H
Published: June 2011

The correlation between the increase in velocity of blood flow in both the internal carotid and vertebral arteries during a carotid compression and the cerebrovascular resistance (CVR) was investigated in 11 patients with chronic ischemic cerebrovascular disease and 4 without organic brain lesions. The velocity of blood flow was measured by an ultrasonic Doppler flowmeter. CVR was calculated from cerebral blood flow and arterial blood pressure. There was no correlation between the increased velocity of blood flow in the internal carotid and vertebral arteries and CVR. The increased velocity of blood flow in patients with low CVR was, however, significantly higher than that of patients with high CVR. The investigation of cross-circulation by ultrasonic Doppler flowmetry is a useful non-invasive method for the detection of changes in cerebral vascular resistance.
Asymptomatic carotid disease in the cardiovascular surgical patient: is prophylactic endarterectomy necessary?
Authors: Barnes R W , Marszalek P B
Published: June 2011

This prospective study used non-invasive techniques to screen for asymptomatic carotid occlusive disease in 314 patients who were to have coronary or peripheral arterial reconstruction. Hemodynamically significant carotid obstruction (greater than or equal to 50% stenosis or occlusion) was present in 54 arteries of 41 patients (13.1%), but only one-third of these lesions were accompanied by a cervical bruit. Among 48 carotid arteries where a bruit was heard, only 18 (37.5%) were associated with significant obstruction demonstrated by non-invasive screening. No prophylactic carotid endarterectomies were performed. There was only one perioperative TIA and one non-fatal stroke, neither of which was related to detectable carotid obstruction. In patients with peripheral vascular disease and detectable carotid obstruction or bruit, the perioperative mortality was higher than in patients without carotid obstruction or bruit (15.0% and 18.2 vs 3.1% and 2.1%, respectively). The deaths were primarily due to myocardial infarction. This study suggests that asymptomatic carotid occlusive disease, while common in patients with other cardiovascular disease, does not necessarily predispose to perioperative stroke and thus does not necessitate prophylactic carotid endarterectomy prior to indicated coronary or peripheral vascular reconstruction.
Bilateral deafness of vascular origin.
Authors: Khurana R K , O'Donnell P P , Suter C M , Inayatullah M
Published: June 2011

Two patients with reversible bilateral deafness of vascular etiology are reported. Serial audiometric studies in the first patient before and after a brainstem stroke indicated retrocochlear auditory dysfunction. The second patient showed bitemporal infarction on cranial CT scan which was subsequently confirmed postmortem.
Marantic endocarditis in children and young adults: clinical and pathological findings.
Authors: Young R S , Zalneraitis E L
Published: June 2011

The clinical and pathologic findings of 7 children and young adults with marantic endocarditis are reviewed. Cerebral embolic infarction attributable to the marantic vegetations occurred in 3 patients. The most common neurologic findings were altered mental status, seizures, and hemiplegia. Five of the 7 patients had had cardiac catheterization. Sepsis, pneumonia, hypoxia, disorders of coagulation, and renal failure were frequently present in these seriously ill patients. In each instance, the diagnosis of marantic endocarditis was unsuspected and established only at autopsy.
Effect of flow split on separation and stagnation in a model vascular bifurcation.
Authors: LoGerfo F W , Crawshaw H M , Nowak M , Serrallach E , Quist W C , Valeri C R
Published: June 2011

This is a study of the flow disturbance in a plastic model of an asymmetric vascular bifurcation. A sidearm was attached to the mainlimb at an angle of 15 degrees to the inlet flow axis. Water at steady flow was used and flow patterns were demonstrated by a dye injection technique. The proportion of inlet flow (Qi) exiting from the sidearm (Qs) was varied and flow patterns were recorded photographically. A laser Doppler anemometer (LDA) was used to measure near-wall velocity. At a physiologic Reynolds' number of 500, no flow disturbance occurred in the mainlimb when the sidearm was completely occluded. When the fraction of flow exiting from the sidearm (Qs/Qi) reached 0.19, a region of boundary layer separation developed along the wall of the mainlimb opposite the flow divider. This region of nearly static fluid spread circumferentially around the mainlimb as Qs/Qi increased. Near-wall velocity within the separation decreased and became negative when Qs/Qi = 0.31. When Qs/Qi reached 0.38, the separation enveloped the wall of the entire bifurcation with a shell of slowly moving fluid. At the same time, the rapidly moving mainstream impinged directly on the flow divider. There is a similarity between the region of separation seen in this model and the site of formation of atherosclerotic plaque at the carotid bifurcation. Separation may contribute to atherogenesis by creating a region of low wall shear at bifurcations.
Effect of acute and chronic reduction of cerebral blood flow on glucose metabolite levels in SHRSP.
Authors: Nara Y , Horie R , Yamori Y
Published: June 2011

Glucose metabolites in the rat brain were measured under various stages of ischemia. In acute ischemia induced by bilateral carotid artery ligation, phosphocreatine and ATP levels were significantly decreased and lactate levels were significantly increased in stroke-prone spontaneously hypertensive rats (SHRSP). These extreme changes were not observed in normotensive Wistar-Kyoto rats (WKY) and stroke-resistant spontaneously hypertensive rats (SHRSR), under the same conditions. In chronic ischemia induced by long-lasting regional cerebral blood flow reduction due to severe hypertension, similar changes were observed only in SHRSP at the advanced stage. The levels of glucose metabolites in the brain were confirmed to be well maintained within control ranges even though the cerebral tissues were subjected to the chronic ischemia related to severe hypertension.
Focal cerebral ischemia measured by the intra-arterial 133xenon method. Limitations of 2-dimensional blood flow measurements.
Authors: Skyhøj Olsen T , Larsen B , Bech Skriver E , Enevoldsen E , Lassen N A
Published: June 2011

The limitations of 2-dimensional isotope techniques in the study of focal cerebral ischemia were investigated using the intra-carotid 133 xenon injection method and a 254 multidetector scintillation camera. To make sure that the detectors "look" directly on infarcted areas, only patients with infarcts involving cortical surface structures were included in the study. Eleven such patients were found among 43 consecutive patients with completed stroke, all investigated with CT-scan. The blood supply to the infarcted areas was evaluated using 3 different approaches: 1) The first minute washout of 133 xenon (rCBF), 2) the initial distribution of isotope during the first 5 sec and 3) the cumulated counts recorded during 15 min. Compton scatter and the "look through phenomenon" were responsible for the majority of counts recorded from the infarcted areas and the blood flow recorded was found to be grossly overestimated and much more influenced by the blood flow in the surroundings than in the ischemic area itself. However, using the 3 approaches, infarcted areas were always disclosed by our equipment. It is concluded that 2-dimensional isotope technique is not reliable for quantifying focal ischemic lesions. The method should be limited to the qualitative demonstration of the ischemic lesions for which it is fully reliable.
Quantitative carotid phonoangiography.
Authors: Knox R , Breslau P , Strandness D E
Published: June 2011

One hundred and sixteen carotid artery bruits were assessed using quantitative phonoangiography (spectral bruit analysis - SBA). This technique uses the averaged break frequency of the bruit to calculate the diameter of he residual lumen at the site of stenosis. Biplanar contrast arteriography was performed on 43 (37%) of the sides. All 116 sides were also evaluated with an ultrasonic Duplex scanner. Ten (8.6%) bruits could not be analyzed by the SBA, leaving 106 sides in which the residual lumen diameter could be estimated. The diameter of the vessel at the site of stenosis estimated by SBA and arteriography were compared and found to agree within 1 mm of each other in 85% of patients. A linear relationship was demonstrated between absolute lumen diameter and percent stenosis as measured from the arteriograms, but we were unable to correlate the absolute diameter of hte residual lumen as assessed by arteriography or SBA with the assessment of the degree of the stenosis derived from spectral analysis of the pulsed Doppler signal. The significance of these findings is discussed with relevance to the clinical application of spectral bruit analysis.
Ultrasonic evaluation of superficial temporal artery-middle cerebral artery anastomosis.
Authors: Tanaka K , Nukada T , Yoneda S , Kimura K , Abe H , Iwata Y
Published: June 2011

Ultrasonic Doppler studies were made pre- and postoperatively in 22 patients undergoing STA-MCA anastomosis. A quantitative evaluation of the bypass was attempted by determining the STA blood flow velocity and pattern. The STA velocity on the Doppler sonogram was compared with the degree of intracranial vascular filling via anastomotic channels and the STA diameter on angiogram. The STA velocity was increased and the blood flow pattern of STA altered from an external carotid pattern to an internal carotid pattern in a patent bypass. The results were in good agreement with angiographic findings. The are of intracranial vascular filling via a vewly formed bypass on angiogram was proportional to the increase in STA velocity. As the STA diameter enlarged, the STA velocity increased progressively. It is suggested the Doppler flowmetry is reliable as a semi-quantitative means of evaluationg the STA-MCA anastomosis.
Internal carotid occlusion: volume of cerebral infarction, clinical findings, and prognosis.
Authors: Takagi S , Shinohara Y
Published: June 2011

Clinical, angiographic and computed tomographic (CT) findings, and the volume of an infarcted area as estimated from tomograms, were evaluated in 26 patients with proven, unilateral, internal carotid artery (ICA) occlusion. The volume of cerebral infarction (CI) ranged from 0 cm3 to 200 cm3. It was shown that the CI volume in the group of patients with good collateral flow was smaller than that in the group with poor or no collaterals (p less than 0.05). It was also found that the smaller the volume of infarcted area, the better the patient's ability to carry out activities of daily living (ADL). The volume of infarction in patients without disturbance of consciousness was smaller than in patients with such disturbance. Thirteen of 15 patients with infarction of less than 50 cm3 eventually showed good ADL. The patients with a deeply located infarction had a good prognosis and no disturbance of consciousness. In patients with superficial infarction there were relationship between the volume of infarction and prognosis, and between the volume and disturbance of consciousness. It is concluded that estimation of the volume of an infarcted area is important in assessing the clinical state and prognosis in patients with ICA occlusion.
Alpha-adrenoreceptor antagonists and pial vessel diameter during hypercapnia and hemorrhagic hypotension in the cat.
Authors: Auer L M , Trummer U G , Johansson B B
Published: June 2011

It has been proposed that sympathetic activation may prevent maximum dilatation of extra-parenchymal cerebral vessels during hemorrhagic hypotension and hypercapnia. In the present study, the effect of alpha-adrenoreceptor antagonists (phenoxybenzamine 1.5 mg kg-1 or phentolamine 8 mg kg-1) on pial vessel diameter was studied in the cat during hypotension and hypercapnia alone or in combination. Two levels of hypercapnia were used (mean PaCO2 74 and 122 mm Hg respectively). Pial arterial vessels (resting diameter 40--184 micrometers) were observed by means of a closed cranial window technique using a Leitz intravital microscope, an image splitting eyepiece, and a videoangiometer, the latter giving continuous data on changes of the inspected vessel diameters. Alpha-adrenoreceptor antagonists did not further increase the arterial diameter in any of the situations studied.