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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enhancement of the brain substance for CT evaluation using inhaled Xenon is confirmed. This technique was applied to the study of the normal and the embolized adolescent baboon. Healthy cerebral tissue enhances symmetrically, while abnormal areas show significantly diminished enhancement. At maximal enhancement, an indication of gross comparative cerebral perfusion to obtained. By obtaining serial CT scans over a 10 minute time interval, the clearance rate of Xenon (cerebral blood flow) may be evaluated. Xenon-enhanced CT enables a visual and numerical analysis of both brain morphology and physiology.
Stroke
PMID:Xenon enhanced CT for analysis of cerebral integrity, perfusion, and blood flow. 41 27

Regional cerebral blood flow (rCBF) was determined in man by Xenon-133 intravenous bolus injection technique. This method is of value especially for patients with stroke. The measuring system constituted of a 16 channel cerebrograph (rCBF 1656, Meditronic, Denmark) and a minicomputer (AI Electronics, Japan). Then, for an estimation of rCBF, two compartment analysis was applied in which a special computer program was used for this purpose. Amount of Xenon-133 in expired air was used for calculation, since we confirmed that Xenon-133 clearance in expired air was similar to that in arterial blood except for those patients with obstructive lung disease and so on. In normal adults, rCBF of the gray matter was 67 +/- 13 ml/100 g brain/min. (95% confidence limits). Patients who had been TIA or RIND, revealed a decrease of rCBF of 33--49 ml/100 g brain/min. bilaterally, although they did not show any clinical signs at the time of measurement. Contrariwise, two cases of Moya-moya disease showed a normal value of rCBF at their silent periods.
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PMID:[A study of regional cerebral blood flow by intravenous injection method of Xenon-133 (author's transl)]. 52 61

The effect of intravenous infusion of 10 per cent glycerol on regional cerebral blood flow (using hydrogen bolus and Xenon-133 (133Xe) clearance methods) and metabolism was investigated in 57 patients with recent cerebral infarction. Hemispheric blood flow (HBF) increased, together with increase in regional cerebral blood flow (rCBF) and cerebral blood volume (rCBV), in foci of brain ischemia. Hemispheric oxygen consumption (HMIO2) decreased together with hemispheric respiratory quotient. Systemic blood levels of glucose, lactate, pyruvate, and triglycerides also increased after glycerol while free fatty acids (FFA) and inorganic phosphate (Pi) decreased. Hemispheric glucose consumption was unaltered after glycerol so that hemispheric glucose to oxygen ratio tended to rise. Pyruvate and lactate production by brain was unchanged. Glycerol moved across the blood brain barrier into brain and cerebrospinal fluid (CSF). Release of FFA and Pi from infarcted brain was reversed by glycerol. Total phosphate balance was maintained actoss brain both before and after glycerol infusion. Triglycerides increased in CSF after glycerol, originating either from cerebral blood or as a result of lipogenesis in cerebral tissue. The EEG Recording and neurological status of the patients improved despite decreased brain oxygen consumption. Results of this study suggest that after intravenous infusion of 10 per cent glycerol in patients with recent cerebral infarction, glycerol rapidly enters the CSF and brain compartments and favorably affects the stroke process in two ways: first, by redistribution of cerebral blood flow with increase in rCBF and rCBV in ischemic brain secondary to reduction in focal cerebral edema; and second glycerol may become an alternative source of energy either by being directly metabolized by the brain, or indirectly, by enhancing lipogenesis, or by both processes. Involvement of glycerol in lipogenesis with esterification to accumulated FFA might lead to improved coupling of oxidative phosphorylation, a hypothesis that fits the finding of improved neuronal function despite further decrease in cerebral hemispheric oxygen consumption.
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PMID:Circulatory and metabolic effects of glycerol infusion in patients with recent cerebral infarction. 109 Mar 93

In order to investigate functional cortical reorganization during recovery from conduction aphasia, regional cerebral blood flows (rCBF) were measured by the two-dimensional 133 Xenon inhalation method in ten stroke patients. rCBF measurements were performed at rest and during the performance of a linguistic task, one month and three months after onset. The analysis of flow changes from rest to test condition indicates an increasing contribution of the right hemisphere as time goes on. The absence of flow increase in Broca's region suggests that this region is definitively disconnected from posterior language "centers" by the arcuate fasciculus lesion.
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PMID:Brain activation during a linguistic task in conduction aphasia. 187 57

Cerebral blood flow and cerebral blood volume were measured and quantified using single photon emission computed tomography before and after unilateral endarterectomy in 3 patients with bilateral severe lesions of the internal carotid artery. These parameters were measured using an intravenous injection of 133 Xenon and 99m Technetium respectively. Before endarterectomy cerebral blood volume was high in all patients suggesting a focal vasodilatation in response to a reduced cerebral perfusion pressure. After endarterectomy a decrease of cerebral blood volume and an increase of cerebral blood flow were observed. These preliminary results confirm that the hemodynamic adaptative mechanisms secondary to carotid occlusion are reversible when the stenosis is removed and demonstrate that these changes can be accurately measured using single photon emission computed tomography. Positron emission tomography was previously considered to be the only method able to quantify cerebral blood volume in man. Single photon emission computed tomography can also be considered a reliable technique to measure both cerebral blood flow and cerebral blood volume. This technique can then be used to assess individual cerebral vascular adaptative states and to evaluate the influence of cerebral hemodynamic changes on stroke occurrence in large longitudinal studies.
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PMID:[Cerebral blood volume, endarterectomy and SPECT]. 202 51

The effect of acetyl-L-carnitine on cerebral blood flow was evaluated in ten patients with cerebrovascular disease, who suffered an ischaemic stroke at least six months before the study. All patients performed a computerized tomograph scan and were investigated by Xenon 133 using a brain dedicated Single Photon Emission Computerized Tomography. Acetyl-L-carnitine was administered intravenously (i.v.) at a dosage of 1.5 g. Cerebral blood flow (ml/min. 100 g) was evaluated before and 45 min after the injection. Cerebral blood flow improved in both the ispilateral and controlateral hemisphere of the ischaemic area, but not in the stroke corresponding zone. It is concluded that acetyl-L-carnitine at a dosage of 1.5 g i.v. improves cerebral blood flow in patients with cerebrovascular disease.
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PMID:Cerebral blood flow in patients with chronic cerebrovascular disease: effect of acetyl L-carnitine. 238 59

In 43 patients suffering from unilateral supratentorial ischaemia the changes over an interval of 3 years in clinical score, quantified EEG (using the neurometric method) and CBF (Xenon inhalation method) were studied. The patients were examined 3 times: shortly after the onset of ischaemia and respectively 3 and 36 months after this first measurement. Three patients died from causes not related to cerebral ischaemia. In the surviving patients the EEG and clinical score improved, often dramatically; the CBF values did not change significantly. Most of the changes occurred in the first 3 months after the stroke. For the evaluation of the prognostic value of the various parameters, 2 sub-groups of patients with different outcome but comparable initial clinical scores were studied. A persistent neurological deficit was predicted by a low CBF at the first measurement. The neurometric parameters obtained from the initial EEG had no value in this respect.
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PMID:Recovery from cerebral ischaemia. EEG, cerebral blood flow and clinical symptomatology in the first three years after a stroke. 245 26

Regional cerebral blood flow was simultaneously determined using the stable xenon computed tomographic and the radioactive microsphere techniques over a wide range of blood flow rates (less than 10-greater than 300 ml/100 g/min) in 12 baboons under conditions of normocapnia, hypocapnia, and hypercapnia. A total of 31 pairs of determinations were made. After anesthetic and surgical preparation of the baboons, cerebral blood flow was repeatedly determined using the stable xenon technique during saturation with 50% xenon in oxygen. Concurrently, cerebral blood flow was determined before and during xenon administration using 15-microns microspheres. In Group 1 (n = 7), xenon and microsphere determinations were made repeatedly during normocapnia. In Group 2 (n = 5), cerebral blood flow was determined using both techniques in each baboon during hypocapnia (PaCO2 = 20 mm Hg), normocapnia (PaCO2 = 40 mm Hg), and hypercapnia (PaCO2 = 60 mm Hg). Xenon and microsphere values in Group 1 were significantly correlated (r = 0.69, p less than 0.01). In Group 2, values from both techniques also correlated closely across all levels of PaCO2 (r = 0.92, p less than 0.001). No significant differences existed between the slopes or y intercepts of the regression lines for either group and the line of identity. Our data indicate that the stable xenon technique yields cerebral blood flow values that correlate well with values determined using radioactive microspheres across a wide range of cerebral blood flow rates.
Stroke 1989 Dec
PMID:Stable xenon versus radiolabeled microsphere cerebral blood flow measurements in baboons. 251 92

In eight patients undergoing carotid endarterectomy, the mean velocity and an index of pulse amplitude in the middle cerebral artery were monitored continuously by transcranial doppler ultrasound. rCBF was measured by intracarotid injection of 133 Xenon shortly before and at the time of the carotid artery occlusion, and again a few minutes after carotid flow was reestablished. Comparison of the mean velocity in the MCA and the cortical convexity rCBF revealed relatively little hysteresis in their relationship from prior to after the occlusion. There was however, considerable variability in this relationship among patients. Both the rCBF and the velocity decreased substantially at occlusion in three cases, neither changed very much in three. While in two, though the rCBF decreased significantly, the velocity did not change. The index of pulse amplitude was somewhat more sensitive to the occlusion, decreasing in the seven cases in which it was recorded, including one in which the rCBF did not change.
Stroke
PMID:Transcranial Doppler and rCBF compared in carotid endarterectomy. 294 97

Intervillous placental blood flow responses to standardized exercise during late pregnancy were studied using a Xenon technique in 25 healthy women. Thirteen of them were studied twice between the 32nd and 38th weeks of pregnancy, with mean 32 (range 22 to 40) days between the studies. At the end of a 6-min exercise, mean maternal heart rate had risen from 77 +/- 10 (SD) to 154 +/- 11 beats/min, amounting to 63% of maximal oxygen uptake. Stroke volume rose by 9%, cardiac output by 65% and cardiac index by 71% as a consequence of exercise, but peripheral vascular resistance declined by 41%. The placental blood flow was at a similar level after the exercise as before the exercise, being 95 +/- 19 (mean +/- SD) ml/min/100 ml of intervillous space before, 98 +/- 24 one min after, and 93 +/- 16 30 min after the cessation of exercise. No change was found in the level of placental blood flow between the 32-34th and 37-38th weeks of pregnancy. The placental blood flow had a positive correlation with maternal weight, mean arterial blood pressure and with diastolic blood pressure. Maternal heart rate, cardiac output, cardiac index, placental weight and the birth weight of the infant was not correlated with placental blood flow. It is concluded that in normal pregnancy a short submaximal exercise has little effect on placental blood flow measured after exercise.
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PMID:Effect of exercise on maternal hemodynamics and placental blood flow in healthy women. 317 9


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