bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental brain infarcts in cats. II. Ischemic brain edema.
Authors: Schuier F J , Hossmann K A
Published: June 2011

In cats, the early development of ischemic brain edema was studied 1 to 4 hours after transorbital occlusion of the left middle cerebral artery (MCA). Two groups of animals were compared: those in which blood flow in the territory of the MCA decreased below the threshold of 10--15 ml/100 g/min (critical ischemia) and those in which it remained above this level (non-critical ischemia). In animals with critical ischemia, water content in the cortex of the MCA territory increased from 80.7 +/- 0.4 to 83.0 +/- 0.3 vol. % (means +/- SE) within 4 h. Edema was associated with an increase in tissue osmolality by 16--22 mosm/kg w.w., and a rise of sodium from 262 +/- 9 to 454 +/- 13 meq/kg d.w. and a decrease of potassium from 442 +/- 20 to 305 +/- 32 meq/kg d.w. The sodium/potassium ratio rose from 0.60 +/- 0.03 to 1.55 +/- 0.17. The water and electrolyte disturbances were accompanied by a major shift of extracellular fluid into the intracellular compartment, as evidenced by the increase in cortical impedance from 282 to 660 ohm/cm within 2 h. According to the Maxwell equation, this reflects a narrowing of the extracellular space from 19.8 to 11.4%. Brain volume was continuously monitored using an induction transducer; swelling began within a few minutes of vascular occlusion, and it continued throughout the 4 h observation period. During this time the blood-brain barrier remained intact as evidenced by the absence of Evans blue staining. Edema was associated with disturbances of the energy producing metabolism, but there was no strict correlation with either lactate or the concentration of high energy phosphates. In animals without critical ischemia, i.e. in which blood flow remained above 10--15 ml/100 g/min, edema was absent despite a distinct deterioration of the energy state of the brain. Edema was also absent in the border zone, in the territory of the posterior cerebral artery and in the contralateral hemisphere of animals with both critical and non-critical ischemia. It is concluded that the early ischemic brain edema following middle cerebral artery occlusion is of the cytotoxic type, that it develops at a flow rate below 10--15 ml/100 g/min, and that it is not strictly correlated with the energy state of the brain.
Effect of hypertension on blood-brain barrier. Change after restoration of blood flow in post-ischemic gerbil brains. An electronmicroscopic study.
Authors: Ito U , Ohno K , Yamaguchi T , Takei H , Tomita H , Inaba Y
Published: June 2011

The effect of induced hypertension on the blood-brain barrier (BBB) change in Mongolian gerbils exposed to various periods of ischemia was studied. Evans blue dye was used to determine the BBB change in animals subjected to different levels of hypertension after 3 h ischemia. Horseradish peroxidase (HRP) was used in electronmicroscopic studies of animals subjected to 30 min, 1, 3 or 6 h ischemia and subsequently exposed for 30 min to varying periods and sequences of normo- and hypertension. Furthermore, HRP-labeled vesicle counts were performed in animals from the 30-min ischemia group. Our findings revealed that hypertension, after blood flow restoration following ischemia, induces and/or accelerates BBB damage by enhancing endothelial vesicular and/or tubulo-channel transport.
"Low perfusion hyperemia" following middle cerebral arterial occlusion in cats of different age groups.
Authors: Tomita M , Gotoh F , Amano T , Tanahashi N , Tanaka K
Published: June 2011

Thirty-one cats were divided by age into 3 groups, young (Y), middle (M) and old (O). Continuous recordings of local cerebral blood volume (CBV) and frequent measurements of mean transit time of blood (t) were made from the Sylvian opercula after ischemia was produced by transorbital clipping of the middle cerebral artery at its origin (MCA occlusion). Control recordings were made simultaneously from the corresponding area of the contralateral cerebral hemisphere. MCA occlusion temporarily stopped cerebral blood flow (CBF) in the area supplied by the ipsilateral MCA, as indicated by a rapidly decreasing CBV and complete disappearance of hemodilution curves. Within 30 sec, CBF resumed with a dilatation of the vascular bed and reappearance of hemodilution curves through newly developed collateral channels. Despite a low CBF, below half the control, CBV recovered, overshooting the control level. The appearance of hyperemia in the ischemic area was statistically significant. Such "low perfusion hyperemia" was slower in appearance and of more diverse magnitude in group O than in group Y. This suggested that aging may lead to a decrease in rapidity of the vascular response to ischemia and impair the integrity of collateral vessels.
Continuous quantitative local cerebral blood flow measurement. Calibration of thermal conductivity measurements by the hydrogen clearance method.
Authors: Cusick J F , Myklebust J
Published: June 2011

The capability of a miniaturized probe to measure local cerebral blood flow in a continuous and quantitative manner is described. The incorporation of thermal conductivity measurements using the isothermal principle with the hydrogen clearance method allows calibration of the thermal conductivity component in absolute terms. Evaluation of this system in 14 cats showed a linear relationship between both measurement methods. The major limitation of this combination probe system is the need for routine intermittent recalibration in order that changes of tissues thermal conductivity induced by physiologic alterations during the experimental procedure may be recognized and resolved.
Cerebral ischemia in gerbils: polyribosomal function during progression and recovery.
Authors: Morimoto K , Yanagihara T
Published: June 2011

Cerebral ischemia was produced by clipping the right common carotid artery in Mongolian gerbils. Polyribosomal function in cerebral ischemia during progression and recovery was studied by investigation of morphology (electronmicroscopy), physical property (size distribution profiles) and biochemical property (polypeptide synthesis). Polyribosomes and their function were relatively well preserved during progression of ischemia. The most striking finding was an extensive disaggregation of polyribosomes and suppression of polypeptide synthesis immediately after re-establishment of cerebral circulation. These phenomena occurred not only with irreversible ischemia at 3 h but also with reversible ischemia at 30 min. In the latter, disaggregation of polyribosomes gradually recovered, but no tendency for recovery was observed after an ischemic period of 3 h. The disaggregation and delay in reaggregation of ribosomes after re-establishment of cerebral circulation may be a significant factor in the irreversibility of cerebral ischemia. The observed deterioration of cellular function during the recovery process may have an important implication not only for medical management of stroke but also for surgical recirculation during acute stroke.
Atraumatic CBF measurement with the scintillation camera. Comparison with intracarotid rCBF values.
Authors: Podreka I , Heiss W D , Brücke T
Published: June 2011

A scintillation camera connected to a dedicated computer system was employed for atraumatic CBF measurements in 43 patients after intravenous injection of 35 to 55 mCi 133Xe in saline solution. To validate this method results were compared to flow values in the same patients measured after intracarotid Xe injection. While the correlation between i.c. and i.v. values was not satisfactory when a high resolution collimator was used, a high sensitivity collimator improved count rates and yielded CBF values after i.v. in agreement with those from i.c. studies. For mean hemispheric flow, the correlation coefficient between the methods was 0.93 and the standard deviation of the i.v. value for a given i.c. value was 2.93. The correlation coefficients for 13 regions were between 0.55 and 0.85. These correlation coefficients are comparable to those obtained with multidetector equipment. Ischemic regions could be accurately detected, and the flow values in these areas were significantly related (r = 0.81). Values in 6 healthy volunteers were in the normal range reported by other investigators. One disadvantage of the camera is that measurements are restricted to one hemisphere, but selection of recording areas is not limited to the position of single probes and may be changed during analysis of the data permitting analysis of flow in irregularly-shaped, pathologically-perfused regions. The results indicate that the scintillation camera is a useful tool for clinical rCBF studies.
Brain tissue pH after global brain ischemia and barbiturate loading in rats.
Authors: Nemoto E M , Frinak S
Published: June 2011

Studies were done on rats to determine whether thiopental loading after complete, transient, global brain ischemia causes more rapid postischemic normalization of brain tissue pH. Fifteen halothane-anesthetized rats were subjected to 16 min of complete global brain ischemia by a combination of systemic arterial hypotension (40 torr) and a high pressure (1500 torr) neck cuff. Brain tissue pH was continuously monitored for up to 2 hour postischemia with microelectrodes (tip diameters of one to two micrometers) inserted about 500 micrometers into the parietal cortex. During ischemia, brain pH fell rapidly within the first 5 min from 7.0 to 6.2 and changed little thereafter. With restoration of arterial pressure and deflation of the neck cuff, pH did not immediately begin to rise back towards normal. Instead, after a few minutes, it transiently fell to even lower values before beginning to increase indicating increased tissue lactic acidosis when the brain is resaturated with glucose upon reperfusion. Beginning at 5 min postischemia, 7 of the 15 rats were infused with thiopental (90 mg/kg, IV over 60 min). At 30 min postischemia, brain tissue pH was similar in both groups and by 60 min, back to preischemic values. We conclude that thiopental loading postischemia does not improve normalization of brain pH. The transient decrease in brain pH with reperfusion is discussed.
Fibromuscular disease of carotid arteries: long term results of graduated internal dilatation.
Authors: Starr D S , Lawrie G M , Morris G C
Published: June 2011

From 1967 to 1979, 25 patients (pts) were operated on for fibromuscular disease (FMD) of the internal carotid artery (ICA). Eleven patients (44%) had transient weakness of an extremity, 4 had amaurosis fugax and 6 (24%) had an asymptomatic carotid bruit. Bilateral carotid arteriography showed significant stenotic lesions in 23 pts (92%) (bilateral in 10), arterial dissection in 1, and severe associated atherosclerosis with ICA endarterectomy and graduated internal dilatation (GID) (9 bilateral); 2 underwent GID with ICA endarterectomy and patch graft: 1 pt had tube graft replacement of the ICA. There was no operative mortality. One pt had a stroke during operation after tube graft replacement of the ICA. Of the 19 pts followed for 2 to 12 years (mean 7.3 years), 2 had late recurrence of mild symptoms. One pt required GID of the contralateral ICA recurrence of symptoms 4 years postoperatively. Graduated internal dilatation of fibromuscular disease of the internal carotid artery can produce long term relief of symptoms; recurrence is rare.
Plasma norepinephrine in stroke.
Authors: Myers M G , Norris J W , Hachniski V C , Sole M J
Published: June 2011

Cardiac arrhythmias, myocardial necrosis and ECG abnormalities in stroke may result from abnormally high levels of sympathetic activity. To examine this possibility, plasma norepinephrine, epinephrine and dopamine were measured in 74 patients with cerebral infarction, 18 with transient ischemic attacks and 33 non-stroke controls. Mean norepinephrine, epinephrine and dopamine values (pg/ml) in cerebral infarction (433.2, 81.6, 75.6 were higher (p less than 0.01) than in controls (281.1, 60.1, 40.5, respectively). Transient ischemic attacks produced values intermediate to these two groups (391.3, 80.9, 54.9). The elevated catecholamine concentrations in cerebral infarction could not be explained by differences in age, blood pressure, heart rate, stress, type or severity of stroke. The high plasma norepinephrine in the stroke group is consistent with an increase in peripheral sympathetic activity which could produce the cardiac abnormalities of cerebral infarction.
Brain extracellular ion composition and EEG activity following 10 minutes ischemia in normo- and hyperglycemic rats.
Authors: Siemkowicz E , Hansen A J
Published: June 2011

Hyperglycemia severely impairs the outcome from cerebral ischemia. In order to sort out whether impaired brain ion homeostasis contributes extracellular "K+], [Ca++], and [H+] concentrations, [K+]e, [Ca++]e and [H+]e, of the brain cortex, as well as the EEG, were monitored during and after 10 minutes of complete cerebral ischemia in normo- and hyperglycemic rats. In both groups, the EEG-activity disappeared in 10-20 seconds of ischemia, at a time when [K+]e, [Ca++]e and [H+]e started to increase. After about 1.5 min, [K+]e showed an abrupt increase and [Ca++]e a steep decrease in the normoglycemic group. In the hyperglycemic group the same event took place after about 3 min of ischemia. pHe decreased to 6.6 and 6.1 in the normoglycemic and hyperglycemic group, respectively. Following the ischemic episode [K+]e reached pre-ischemic level after 4 min, [Ca++]e after 13 min, and [H+]e after 30 min in both groups. Recovery of the EEG, however, was clearly different in the 2 groups. EEG-activity reappeared later in the hyperglycemic group and showed after one hour a pattern of burst-suppression activity while the normoglycemic group showed asynchronous activity resembling the control pattern. It is concluded that high glucose content in brain prior to ischemia - and hence lower brain pH during ischemia - does not interfere with the return of normal extracellular ion composition after cerebral ischemia, whereas the return and pattern of EEG activity is severely affected.
Are prostaglandins involved in experimental ischemic edema in gerbils?
Authors: Iannotti F , Crockard A , Ladds G , Symon L
Published: June 2011

Sixty-five male gerbils, divided into 3 groups, were used in this study, in which focal brain specific gravity, taken as a measure of edema, was compared to the corresponding focal cerebral blood flow using the hydrogen washout technique. Extracranial unilateral or bilateral carotid ligation was performed and one hour later the animal was sacrificed. When focal blood flow was less than 20 ml/100 g/min, edema developed and increased with progressive ischemia, reaching maximal values at 5-7 ml/100 g/min. In the zero flow situation there was no edema. Pretreatment of the other 2 groups with indomethacin or dexamethasone, did not prevent edema formation at flows of 20-12 ml/200 g/min, but considerably reduced the edema previously noted at low flows (5-7 ml/100 g/min). The drugs did not affect the decreased flow in the ischemic area. We conclude that prostaglandins, released by membrane disruption, are involved in the development of ischemic edema.
Cerebral blood flow in rats during physiological and humoral stimuli.
Authors: Gross P M , Harper A M , Graham D I
Published: June 2011

The technique for estimating cerebral blood flow (CBF) in anesthetized rats by injecting 133Xe into the internal carotid artery represents a potentially useful and inexpensive model for screening cerebral vascular responses to pathophysiological and pharmacological stimuli. We have examined associated neuropathology, the validity and the reproducibility of the method, and made comparisons of initial slope estimates of CBF with those obtained by stochastic analysis. Initial slope estimates (CBF = 1.62 +/- 0.04 ml min-1g-1, X +/- SE, N = 38) were linearly related to stochastic measurements (CBF = 1.42 +/- 0.09 ml min-1g-1, N = 6), and overestimated mean CBF by about 15%. A reactivity to CO2 of 0.05 ml min-1g-1 per mm Hg, and an auto-regulation range of 70 to 180 mm Hg were found. CBF responses to the intra-arterial infusion of aminergic drugs were determined before and after opening of the blood-brain barrier with hypertonic urea. Serotonin reduced CBF after, but not before, the administration of urea. Acetylcholine increased CBF when the barrier was intact, the effect being augmented when the barrier was disrupted; these responses were reduced by atropine. Histamine increased CBF only after barrier opening, and this response was attenuated by the H2-receptor antagonist, metiamide. These studies indicate that initial slope estimates of CBF derived in rats from intracarotid 133Xe injection, which represents an inexpensive and simplified approach for screening cerebral circulatory adjustments, may facilitate the characterization of stimuli affecting CBF.
Transient ischemic attacks associated with hypotension in hypertensive patients with carotid artery stenosis.
Authors: Ruff R L , Talman W T , Petito F
Published: June 2011

In a group of 132 patients with transient ischemic attacks ((TIAs) 7 patients (4 men, 3 women, ages 64 to 81) had TIAs preceded by hypotension. The average fall of mean blood pressure during an attack was 26.4 +/- 5.5 mm Hg (SD). Only one of these patients had a TIA which was not preceded by hypotension. This episode occurred during a paroxysm of coughing. All 7 of these patients had hypertension, and cerebral arteriography performed in 4 of the 7 revealed hemodynamically significant carotid artery stenosis. Each of the 4 patients developed hypotension and a TIA after the procedure. Twenty of the other patients had hypotensive episodes but did not develop focal neurological deficits. None of these patients had carotid artery stenosis. This study suggests that hypertensive patients with carotid artery stenosis may be at risk to develop focal cerebral ischemia during acute hypotensive episodes.
Stroke rehabilitation. Outcome studies and guidelines for alternative levels of care.
Authors: Feigenson J S
Published: June 2011

"Every year, nearly 400,000 people in the United States become stroke victims. Approximately 40% of these die within a month and at least two-thirds of those who survive have some degree of permanent disability. At the present time, the population of this country includes two and a half million disabled survivors of stroke. The economic toll of this disease, considering both the cost of care and the loss of earnings, is estimated to be nine and a half billion dollars annually."
Non-invasive external regional measurement of cerebral circulation time changes in supratentorial infarctions using pertechnetate.
Authors: Ahonen A , Tolonen U , Koskinen M , Kallanranta T , Hokkanen E
Published: June 2011

A method for measuring regional cerebral circulation time (rCCT) between the hemispheres using intravenous pertechnetate and a multidetector system is presented. Interhemispheric differences of rCCT instead of absolute values were selected because of the variation of pertechnetate bolus dispersion due to changes in the systemic circulation and injection technique inter-and intraindividually. Time activity curves over one minute were analyzed by a modified gamma function fitting method. The results are printed as a brain map which shows reference values and abnormal findings. Abnormal rCCT asymmetry was observed in 10 out of 77 controls (13%) and 58 out of 65 patients with cerebral infarction (89%). Within 2 weeks after a stroke shorter circulation time values on the side of the lesion than on the contralateral side were found in 5 patients. In the severe infarction cases and in the acute stages of infarction circulatory changes could be found in a great number of areas. In patients with manifest diabetes abnormal circulatory findings occurred in larger regions and in a greater number of the patients than in those without that disease. Although the luxury perfusion and diaschisis phenomena, as well as the influence of cross-over of the count rates between the hemispheres, reduce circulatory time differences, use of the present pertechnetate method allows detection of subtle regional circulatory changes in patients with brain infarction.
Stroke in Melbourne, Australia: an epidemiological study.
Authors: Christie D
Published: June 2011

A population-based stroke incidence study was carried out in Melbourne, Australia, between March 1978 and September 1979. Age-sex specific incidence rates were calculated and shown to be similar to those reported from the United States. At 18 months after the onset of stroke 55% of patients were alive and the probability of survival was shown to be related to the level of consciousness at time of maximum impairment. Seasonal variability of stroke incidence was demonstrated, as was an association between incidence rates and country of birth.
Reaction of pial arteries and veins to sympathetic stimulation in the cat.
Authors: Auer L M , Johansson B B , Lund S
Published: June 2011

The diameters of pial arteries and veins were continuously monitored by a multichannel videoangiometer through a closed cranial window in 13 cats. Seventy-two arterial portions (diameter 30-283 micrometer) and 103 venous segments (diameter 32-486 micrometer) were studied under resting conditions and during stimulation of the cervical sympathetic chain. Arteries with a diameter of less than or equal to 150 micrometer constricted 7.3 +/- 0.8%; those greater than 150 micrometer 13.1 +/- 1.4% (p less than or equal to 0.0005 for both groups). Veins constricted significantly more than arteries of corresponding size (p less than 0.005). Veins less than or equal to 150 micrometer constricted 11.5 +/- 0.9% and those greater than or equal to 150 micrometer constricted 19.9 +/- 1.9% (p less than 0.0005 for both groups compared to resting levels). Since the venous compartment contains about 70% of the regional blood volume the tone of the veins is of importance for intracranial pressure. Further studies on the role of sympathetic nervous activity in the regulation of cerebral venous tone under physiological and pathological conditions seem essential.
Microangioarchitecture of rat parietal cortex with special reference to vascular "sphincters". Scanning electron microscopic and dark field microscopic study.
Authors: Nakai K , Imai H , Kamei I , Itakura T , Komari N , Kimura H , Nagai T , Maeda T
Published: June 2011

Microangioarchitecture of the rat parietal cortex was studied by means of scanning electron microscopy and dark field microscopy. The richest supply of blood vessels in the parietal cortex was found in layer III + IV and layer V, where 2 isolated plexuses of microvessels were prominent. The appearance of the plexuses was quite different between motor and sensory areas. In the motor area the capillary plexuses were narrow and compact, while in sensory area the plexuses were wide and diffuse. Characteristic ring formations, called ring-shaped-compressions in the present study, were frequently observed at branching sites of arterioles. The ring-shaped-compression probably corresponds to the precapillary sphincter. A similar structure was also seen in capillaries and venules and, therefore, it is likely that not only arterioles, but also capillaries and even venules, can actively change diameter to control cerebral blood flow.
Disparate recovery of resting and stimulated oxidative metabolism following transient ischemia.
Authors: Duckrow R B , LaManna J S , Rosenthal M
Published: June 2011

To assess the residual effects of transient cerebral ischemia on mitochondrial oxidative metabolic function, changes in the reduction/oxidation state of cytochrome a,a3 and relative local blood volume were measured in situ from the exposed cerebral surface of rat brain before and after 10 minutes of carotid artery ligation. During the ischemic interval, cytochrome a,a3 became reduced and electrocortical activity was abolished. During the first 20 minutes of reperfusion cytochrome a,a3 was hyperoxidized beyond baseline with eventual recovery to the original steady state. Electrocortical activity returned more slowly. Increased energy demand induced by electrical stimulation of the cortex produced transient oxidation of cytochrome a,a3. The amplitude of this oxidative response was decreased during the first 30 minutes of reperfusion. During the first 2 hours of reperfusion the time required for re-reduction of the oxidative response was lengthened despite the recovery of baseline mitochondrial redox state. These data demonstrate residual metabolic dysfunction after transient ischemia not apparent under "resting" conditions but evident when the system is required to perform additional "work." We speculate this metabolic dysfunction could be due to relative substrate limitation.
Incidence of asymptomatic extracranial arterial disease.
Authors: Hennerici M , Aulich A , Sandmann W , Freund H J
Published: June 2011

Investigations of the incidence and the extent of the asymptomatic early stages of extracranial arterial disease (EAD) have been restricted for methodical reasons. Direct Continuous Wave-Doppler examination has given highly accurate results in the location and correct estimation of the degree of EAD both for the carotid (97%) and the vertebral arteries (90%), as shown from a detailed comparison with carotid (n = 604) and vertebral (n = 426) angiograms. Compared with this degree of reliability, the validity of normal auscultation for the diagnosis of EAD is shown to be poor: if bruits are taken as the only signs of associated EAD in patients with systemic atherosclerosis, only 27.6% in a group of 123 patients would have been correctly diagnosed. This parallels the number of false-positives (22.6%) in patients with normal results. The frequency and degree of EAD was studied by the use of direct Doppler examination in 2009 neurologically asymptomatic patients admitted either with severe vascular (n = 375) or coronary atherosclerosis (n = 262) or with high-risk factors (n = 1370). The frequency was significantly higher (32.8%) in patients with peripheral vascular disease than in those with coronary artery disease (6.8%) and in risk-factor patients (5.9%). The combination and degree of vessel involvement are presented in detail and their possible prognostic significance discussed.
Role of prostaglandin I2 and thromboxane A2 in recurring reduction of carotid and cerebral blood flow in dogs.
Authors: Uchida Y , Murao S
Published: June 2011

The roles of PGI2 and TXA2 in recurring reduction of carotid artery and cerebral blood flow induced by partial constriction of the common carotid artery and cerebral blood flow induced by partial constriction of the common carotid artery were examined in anesthetized dogs. The recurring reduction was eliminated by OKY 046 and 1580 which inhibit TX synthetase, acetylsalicylic acid which inhibits cyclo-oxygenase and lipoxygenase, PGI2 and by papaverine which enhances PGI synthesis. But the recurring reduction was not eliminated by phentolamine. The recurring reduction was induced by epinephrine which activates phospholipase A2 and cyclo-oxygenase and causes platelet aggregation. It was also induced by tranylcypromine which inhibits PGE2 synthetase and, although infrequently, by TXA2. The recurring reduction was also induced by indomethacin that inhibits cyclo-oxygenase. The indomethacin-induced recurring reduction, however, was eliminated not by OKY 046 and 1580 but by PGI2. It is suggested that TXA2 acted as an inducer and PGI2 as an inhibitor in the recurring reduction of carotid artery and cerebral blood flow.
Blood filtrability in cerebrovascular disorders, with special reference to erythrocyte deformability and ATP content.
Authors: Sakuta S
Published: June 2011

Erythrocyte deformability was determined in 48 patients with cerebrovascular disease and 116 healthy controls as an index of blood filtrability in microcirculation. Hemo-rheological and blood chemical changes were also studied to assess their effect on filtrability. Erythrocyte deformability, determined by Reid's method, was expressed as the deformability index (DI). DI and ATP levels decreased with advancing age in controls and patients; these levels were lower in patients. In the controls, DI was inversely proportional to hematocrit, hemoglobin, fibrinogen, and lactate; in patients, it was directly proportional to albumin. There were no significant differences in DI and ATP levels in patients with cerebral infarction and cerebral hemorrhage. The values for DI and ATP levels were the same in arterial and venous blood.
Fibromuscular dysplasia and the brain. II. Current concept of the disease.
Authors: Mettinger K L
Published: June 2011

Eleven hundred cases from the literature of fibromuscular dysplasia (FMD) are reviewed including 300 cases with aortocranial lesions. The male-female ratio is 1:2, and the prevalence seems increased among Caucasians. The clinical diagnosis of FMD is made by angiography, ten years earlier in patients with hypertension (mean age 39 years) than in those with cerebrovascular symptoms (mean age 50 years). Segmental dysplastic lesions are found mainly in primary aortic branches. All age groups may be affected and follow-up studies give evidence for stationary as well as slowly progressive lesions. A multifactorial hypothesis of etiology is presented: congenital minor lesions of tunica medial might predispose to aneurysms and to an abnormal fibroproliferative response to mechanical or circulatory stimuli. The association of FMD and intracranial aneurysmal disease in females is discussed. Inheritance as a dominant trait with reduced penetrance in males is suspected. Current aspects on morphology, symptomatology and clinical management are presented.
Risk factors for cerebral hemorrhage and cerebral infarction in a Japanese rural community.
Authors: Tanaka H , Ueda Y , Hayashi M , Date C , Baba T , Yamashita H , Shoji H , Tanaka Y , Owada K , Detels R
Published: June 2011

A ten-year follow-up study of stroke among residents 40 years and older in a rural community located on Shikoku Island, Japan, was completed in 1977. The response rate for the initial examinations was 85% of 920 males and 90% of 1,012 females. Seven hundred and seventy-two males and 901 females who were initially free of stroke were followed from July 1967 through June 1977. The incidence of all strokes was 10.47 per thousand person-years for males and 6.41 per thousand person-years for females. The statistically significant risk factors for stroke were age, male sex, elevated blood pressure, ECG abnormalities, and funduscopic abnormalities. Elevated blood pressure was the strongest risk factor and mean arterial pressure was the best predictive measure. Twice as high a proportion of strokes were subclassified as cerebral hemorrhage (26%) in this study as have been reported in comparable studies in the United States (12-15%). An inverse relationship between serum cholesterol levels and cerebral hemorrhage incidence, but not cerebral infarct, was observed. High alcohol intake was a risk factor for cerebral hemorrhage but not for cerebral infarct. No relationship between stroke and weight was observed despite the relationship of stroke to blood pressure and of weight to blood pressure.
rCBF in patients with carotid occlusion. Resting and hypercapnic flow related to collateral pattern.
Authors: Norrving B , Nilsson B , Risberg J
Published: June 2011

rCBF was measured by 133Xenon inhalation technique in 39 patients with unilateral carotid artery occlusion in a subacute-chronic stage. Resting flow values (ISI) varied between 23.7 and 52.4 ml/100 g/min. An almost constant finding was interhemispheric asymmetry, the degree of which was correlated with the severity of the initial symptoms. An ischemic focus was an insignificant finding. The CO2 response was normal in patients with angiographic signs of circle of Willis collateral flow and without significant contralateral carotid stenosis, whereas it was impaired in patients with a retrograde ophthalmic flow or collateral flow via the circle of Willis and contralateral carotid stenosis greater than or equal to 50%. It is concluded that the CO2 response in useful rCBF variable and may be applied for analysis of collateral flow capacity in patients with carotid artery occlusion considered for bypass surgery.
The effect of combined aspirin and dipyridamole therapy on thrombus formation in an arterial thrombogenic lesion in the dog.
Authors: Deen H G , Sundt T M
Published: June 2011

We investigated the potential of aspirin and dipyridamole in combination to inhibit thrombus formation by comparing endarterectomized segments of 20 dog carotid arteries in animals treated with pre- and post-operative aspirin and dipyridamole to 20 arteries from untreated animals and 20 arteries from animals receiving intra-operative heparin. The temporal profile of thrombus formation was assessed by means of angiography, light microscopy, and scanning electron microscopy at time intervals ranging from 30 minutes to three months from the time of surgery. All of the aspirin-dipyridamole vessels remained patent and only one had significant gross thrombus formation. This contrasted to six occlusions and six significant gross thrombi in the control group and one occlusion and six significant gross thrombi in the heparin group. The combination of oral aspirin and dipyridamole minimizes thrombus formation in the highly thrombogenic lesion created by carotid endarterectomy in the dog.
Transtentorial herniation with posterior cerebral artery territory infarction. A new mechanism of the syndrome of alexia without agraphia.
Authors: Kirshner H S , Staller J , Webb W , Sachs P
Published: June 2011

A 39-year-old male developed a right homonymous hemianopsia and alexia without agraphia following emergency surgery for hemorrhage into a left frontal tumor. A computerized tomographic (CT) scan demonstrated low density areas in the left frontal region and in the territory of the left posterior cerebral artery. The alexia without agraphia syndrome appeared to result from compression of the left posterior cerebral artery by a transtentorial pressure cone, a mechanism not previously reported in this syndrome. The behavioral investigation confirmed the diagnosis and replicated recent findings related to the syndrome of alexia without agraphia.
A review of cerebrovascular surgery in the People's Republic of China.
Authors: Cheng M K
Published: June 2011

Cerebrovascular disease (CBVD) is very common in the People's Republic of China (PRC). In 8 of 12 large cities in the PRC, CBVD ranked first in frequency as a cause of death. The ratio fo aneurysms to arteriovenous malformations (AVMs) was 0.84-2:1, much lower than in the United States (6.5:1). Hypertensive intracerebral hemorrhage (HIH) is the commonest cause of mortality in patients with CBVD; patients with ischemic stroke have been submitted to the extracranial-intracranial (EC-IC) arterial anastomosis since 1976. Moyamoya syndrome is not uncommon in the PRC; leptospiral arteritis was one of the major causes in the series that have been reported.
Whole blood viscosity parameters and cerebral blood flow.
Authors: Grotta J , Ackerman R , Correia J , Fallick G , Chang J
Published: June 2011

This report describes the statistical relationship of several whole blood viscosity parameters and cerebral blood flow (CBF) in 53 consecutive patients and normal controls. Significant correlations were present between CBF and serum fibrinogen (P = .05), hematocrit (P less than .05), and a relationship involving both fibrinogen and hematocrit (P less than .01). We conclude that heightened whole blood viscosity does correlate with decreased cerebral blood flow in the ranges measured in our patients, that both fibrinogen and hematocrit must be taken into consideration in viscosity determinations, and that changes in viscosity may have an important effect on CBF in regions of low flow.
Relation of blood pressure, serum lipids, and smoking to the risk of cerebral stroke. A longitudinal study in Eastern Finland.
Authors: Salonen J T , Puska P , Tuomilehto J , Homan K
Published: June 2011

The impact of blood pressure, serum cholesterol and triglycerides, and smoking on the risk of cerebral infarction and other stroke was studied by a longitudinal design. A random sample of the population aged 35-59 years in two counties of Eastern Finland was examined in 1972, with a participation rate of 92 per cent. In subjects (both sexes) standardized epidemiological measurements on blood pressure, height, weight, and serum lipids were made and questionnaire data were obtained on smoking. The cohort was followed for seven years by means of national hospital discharge and death certificate registers. During the follow-up 77 men and 65 women had a cerebral stroke. Based on multiple logistic risk function analysis, age, smoking, blood pressure, and history of previous stroke and diabetes turned out to be independent predictors of both cerebral infarction and other strokes in men. Diastolic blood pressure of 100 mm Hg or more was associated with a 1.9-fold (90% CI = 1.1-3.6) risk of cerebral infarction in men and 2.5-fold (90% CI = 1.1-5.6) risk in women with no previous stroke. In men 37% (90% CI = 21-53%) of all cerebral strokes were attributable to systolic blood pressure of 150 mm Hg or more and 27% (90% CI = 11-42%) to diastolic blood pressure of 95 mm Hg or more.
Correlation of peak Doppler frequency with lumen narrowing in carotid stenosis.
Authors: Zwiebel W J , Zagzebski J A , Crummy A B , Hirscher M
Published: June 2011

The peak Doppler-shifted frequency and degree of lumen narrowing were compared in 75 cervical carotid stenoses. Peak frequency was not found to precisely indicate severity of stenosis, but it was possible to divide stenoses into four ranges of severity on the basis of peak frequency. Peak frequencies of less than 5 KHz, in most instances, indicated stenoses of less than 50% decrease in lumen area. Frequencies from 5 to 8 KHz were generally associated with stenoses of 50-75% decrease in lumen area, and frequencies of 8-12 KHz were most often associated with stenoses of 75-90% decrease in area. Frequencies greater than 12 KHz almost invariably occurred in very severe lesions of greater than 90% decrease in lumen area (greater than 70% decrease in diameter). The use of peak frequency as an indicator of severity of stenosis, while not specific, is felt to be of considerable clinical benefit as it provides a more quantitative evaluation of stenosis than auditory assessment of Doppler frequencies.
Pure sensory stroke and allied conditions.
Authors: Fisher C M
Published: June 2011

This paper contains an analysis of 135 cases in which numbness, either episodic or persistent, involved one side of the body. In most cases, the patients were candidates for the diagnosis of pure sensory stroke which is usually the result of an occlusive cerebrovascular lesion involving the thalamus. The cases are divided into three main categories, pure sensory stroke, pure sensory TIAs, and atypical cases. The clinical features described in an earlier paper have been confirmed for the most part. A major limitation is the paucity of pathological studies. The lack of reliable criteria for the recognition of migrainous paresthesias has probably resulted in the inadvertent inclusion of some such cases. Some other conditions, hemidysesthesia and cervical disc, which have had to be considered in the differential diagnosis have been included. Cases of occlusive disease of the posterior cerebral internal carotid and middle cerebral arteries have been analyzed for patterns of paresthesias which may serve to distinguish cortical lesions from thalamic.
Cerebral ischemic events in patients with mitral valve prolapse.
Authors: Sandok B A , Giuliani E R
Published: June 2011

All patients 20 years old or older referred for echocardiographic examination and found to have mitral valve prolapse during the period January 1975 through December 1979 were included in the study. Of the 1,138 patients, two-thirds were women and one-third were men. Their average age was 48.4 years. Forty patients (3.5%) had histories of prior focal cerebrovascular ischemic events. In 26 of the 40 patients, no responsible mechanism other than mitra valve prolapse was identified, and in 4, the ischemic event occurred during an episode of bacterial endocarditis, a known complication of mitral valve prolapse. In 10 of the 26 patients, there was clinical information to suggest an embolic mechanism for the ischemic. A conservative estimate of the prevalence rate for cerebral infarction in this group of patients is four times greater than the rate expected in a normal population. This difference is likely due to the contribution of mitral valve prolapse in the pathogenesis of cerebral infarction.
Mitral valve prolapse and cerebral ischemic events. A comparison between a neurology population with stroke and a cardiology population with mitral valve prolapse observed for five years.
Authors: Jones H R , Naggar C Z , Seljan M P , Downing L L
Published: June 2011

Two populations of patients with mitral valve prolapse were analyzed to identify factors predisposing to the development of cerebral emboli. Of 760 patients followed for up to five years by our cardiologists with echocardiographically demonstrated mitral valve prolapse (MVP), only one, aged 82 years, has had a stroke. In contrast, of 43 patients admitted to our neurology service with a cerebral embolus and no evidence of carotid or other cardiac lesion and in whom echocardiography was performed, MVP was present in 9. No contributing etiologic mechanisms were uncovered to account for the disparity between the cardiology and neurology populations. However, with the apparent increased incidence of MVP in young patients with cerebral ischemia, both groups require longitudinal follow-up to understand better the factors that predispose a small percentage of patients with mitral valve prolapse to the development of cerebral ischemia.
Angiographic study of vasospasm following subarachnoid hemorrhage in monkeys.
Authors: Peerless S J , Fox A J , Komatsu K , Hunter I G
Published: June 2011

A model for producing chronic cerebral vasospasm in monkeys by injecting autologous blood into the basal cistern is described. Spasm/narrowing was observed by angiography one hour after SAH in 8 out of 10 monkeys and in 5 of these 8, spasm was observed both one and two weeks later. No narrowing of the vessels was observed in the control cases. In monkeys that showed spasm one week after SAH, narrowing of the extracranial vertebral arteries was also observed. Repeated injections of blood at intervals of one and two weeks caused intensification of spasm in the intracranial portion of vertebral arteries and the basilar arteries. It is suggested that cerebral vasospasm following SAH may in part be mediated by a central control mechanism acting through the sympathetic nervous system in that extracranial vessels remote from direct contact with blood showed reactive narrowing.
Reversal of experimental acute cerebral vasospasm by angiotensin converting enzyme inhibition.
Authors: Andrews P , Papadakis N , Gavras H
Published: June 2011

We tested the hypothesis that cerebral arteriospasm developing after rupture of a subarachnoid aneurysm may be due to the vasoconstrictor effect of locally generated angiotensin II. Ten dogs had subarachnoid hemorrhage simulated by intracisternal introduction of 2 ml autologous blood, and were followed by cineangiography. Thirty minutes later, when acute arteriospasm was established, seven dogs received injection of the angiotensin converting enzyme inhibitor teprotide and 3 control dogs received normal saline. Repeat angiography at 30 and 90 minutes after injection, showed total or partial release of spasm in the experimental dogs and no change or further intensification of spasm in the control animals. We concluded that angiotensin converting enzyme inhibition may be a potentially useful approach for the reversal or prevention of cerebral arteriospasm after subarachnoid hemorrhage.
Post-stroke depressive disorders: a follow-up study of 103 patients.
Authors: Robinson R G , Price T R
Published: June 2011

One hundred three patients attending a stroke clinic were evaluated for post-stroke depressive disorders using repeated quantitative assessment of psychopathology during a 12 month period. Almost one-third of these patients were depressed at the time of the initial assessment and two-thirds of these depressed patients who were re-evaluated remained depressed for 7 to 8 months. The prevalence and severity of depressive disorders was significantly elevated in those patients who were between 6 months and 2 years post-stroke. Demographic variables however did not distinguish depressed and non-depressed patients, nor did type of neurological symptoms, degree of impairment in activities of daily living or global cognitive impairment. However, patients with left hemisphere brain injury were significantly more depressed than patients with right hemisphere or brain stem infarctions. Based on this work and previous studies, we have suggested a profile for patients who are at high risk for developing post stroke depressive disorders: patients with left hemisphere frontal lobe infarctions who are within 2 years of the stroke. In spite of the fact that these depressions were clinically significant, none of the patients were presently receiving treatment. Effective treatment methods for these patients need to be developed.
Predicting functional outcome following acute stroke using a standard clinical examination.
Authors: Prescott R J , Garraway W M , Akhtar A J
Published: June 2011

In a series of 149 patients admitted to a stroke unit, the outcome of the acute phase of stroke rehabilitation, assessed by the patients' return to independence, was found to be related to the results of standardized weekly clinical examinations of mental, motor, sensory and communication function. The prediction of subsequent independence was estimated just as accurately using the results from three of these tests (upper limb motor function, postural function and proprioception) as when using the entire set of tests. A group of patients with little chance of responding to rehabilitation was identified.
Mathematical simulation of cerebral blood flow in focal ischemia.
Authors: Hudetz A G , Halsey J H , Horton C R , Conger K A , Reneau D D
Published: June 2011

A computer model was developed to describe regional cerebral blood flow and tissue oxygenation with autoregulation during focal ischemia produced by occlusion of th middle cerebral artery (MCA). This steady state model described the distribution of blood flow in the cerebral arterial system including the circle of Willis as well as the pial arterial anastomoses, and included a simplified form of autoregulation based on the local control of pressure and flow in the pial and intracerebral arteries, respectively. Preliminary simulation studies with the model yielded the following results. Less effective autoregulation was predicted by the model at low blood pressure in focal ischemia. Passive dilatation of the pial vasculature produced a leftward shift in the autoregulatory curve. Simulations with occlusion of the MCA revealed the ultimate importance of the pial anastomoses in providing adequate blood and oxygen supply in the ischemic territories including the specially vulnerable lenticulostriate area. The volume of the ischemic (pO2 less than 1 mmHg) brain tissue in the MCA-cortex estimated by using a concurrent Krogh cylinder model was 50% when the pial anastomoses were 80 micrometers in diameter and the ischemic area disappeared at 170 micrometers diameter. With relatively small anastomoses (less than 200 m) the model demonstrated intracerebral steal during intracerebral vasodilation. Passive dilation of the pial arteries including the pial anastomoses caused the steal to disappear and to reverse. These results suggest that both autoregulatory shift and steal reversal can be explained by passive dilatation of the pial vasculature.