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

The developments concern methods of application and therapeutic agents. Regarding drug aplication Ocusert has to be mentioned: inserted in the cul de sac of the eye once a week it releases a low concentration of a substance continuously and with a constant rate. For acetazolamid (Diamox) it has been shown, that in long term treatment much lower concentrations than usual are effective. Efforts regarding new local agents reducing intraocular pressure are stimulating as well as inhibiting the sympathetic tone. The practically most important discovery so far is Clonidine, whose pressure lowering mechanism is not quite clarified yet and which, due to other problems, demands a very critical indication. Beta-receptor-blocking agents, such as Propranolol could become somewhat important, as well as for some special indications the chemical sympathectomy by 6-Hydroxydopamine. The sympatholytic agent Guanethidine proves to be very valuable in special cases. Besides the pressure reducing treatment medicamentally achieved increase of the blood supply to the optic nerve becomes more important. It becomes more and more evident that the elevation of the stroke volume--thus heart output--by cardiac therapy is important what demands collaboration with colleagues of other disciplines.
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PMID:[Approaches in medical treatment in glaucoma (author's transl)]. 85 80

The correlation between the drug-induced hypotension somatosensory evoked potential (SEP) test and regional cerebral blood flow changes after acetazolamide administration was studied. Fourteen patients presenting with transient ischemic attack, reversible ischemic neurological deficits, or minor completed stroke were evaluated. All patients had no or only localized low-density areas on computed tomographic scans, and unilateral occlusion or severe stenosis of the internal carotid or middle cerebral artery on cerebral angiograms. The Diamox asymmetry enhancement (DAE) was studied to detect reduced cerebral perfusion reserve in the affected hemispheres. The DAE was 7.9 +/- 5.8% in seven patients positive in the SEP test, significantly higher than -1.5 +/- 2.9% in patients negative in the SEP test. Postoperative SEP tests were negative in all five patients who underwent extracranial-intracranial (EC-IC) bypass surgery, suggesting that the EC-IC bypass improved the cerebral perfusion reserve in the affected hemispheres. The DAE decreased significantly in four of these patients. This study disclosed a significant correlation between the drug-induced hypotension SEP test and DAE. These parameters are considered important for evaluating patients with hemodynamic compromise and/or suitable candidates for EC-IC bypass.
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PMID:Drug-induced hypotension SEP test and acetazolamide test using 133Xe SPECT in patients with occlusive carotid disease--selection of candidates for extracranial-intracranial bypass. 171 25

We implemented a technique for measuring regional cerebral blood volume using single-photon emission computed tomography and in vivo technetium-99m-labeled red blood cells and then evaluated it in nine normal human volunteers (controls) and seven patients with bilateral occlusion or severe stenosis of the internal carotid artery. We also measured regional cerebral blood flow using single-photon emission computed tomography and intravenous xenon-133 in the same subjects. We studied regional cerebral blood flow, regional cerebral blood volume, and their ratio before and after the intravenous injection of 1 g acetazolamide. Mean +/- SD baseline regional cerebral blood volume was higher in the patients than in the controls (4.1 +/- 0.6 versus 3.2 +/- 0.3 ml/100 g, p less than 0.01), and mean +/- SD baseline regional cerebral blood flow was lower in the patients than in the controls (40.5 +/- 11 versus 55.6 +/- 11 ml/100 g/min, p less than 0.05). Acetazolamide induced similar mean +/- SD increases in regional cerebral blood volume in both the controls and the patients (0.3 +/- 0.1 and 0.3 +/- 0.2 ml/100 g), while the mean +/- SD regional cerebral blood flow reactivity was significantly less in the patients than in the controls (12.6 +/- 7.6 versus 24.5 +/- 9.6 ml/100 g/min, p less than 0.05). Our study shows that single-photon emission computed tomography can provide quantitative estimates of both regional cerebral blood volume and regional cerebral blood flow in humans.
Stroke 1991 Mar
PMID:Quantitative assessment of cerebral blood volume by single-photon emission computed tomography. 184 74

Cerebral blood flow (CBF) and cerebrovascular reserve capacity (CRC) were measured by stable xenon computerized tomography (Xe-CT) and acetazolamide test in 15 patients with cerebrovascular disease before and after extracranial-intracranial (EC-IC) bypass surgery for minor stroke, reversible ischemic neurological deficit or transient ischemic attack. All had angiographically shown occlusive lesions of the major arterial trunk. In the present series, global analysis showed that the bypass did not increase the resting rCBF, but did increase the rCRC. We divided the patients into four groups according to the preoperative resting rCBF and rCRC. All 3 patients with normal resting rCBF and reduced rCRC showed postoperative improvement of rCRC. Of 6 patients with reduced CBF and reduced CRC, three had postoperative increase in resting CBF and four had increased CRC. One of two patients with reduced CBF and normal CRC showed only an increase in CRC. We propose that reduced CRC or reduced CBF with reduced CRC are criteria for selection of candidates for bypass surgery. We conclude that Xe-CT with the Diamox test is a useful and simple method for evaluating cerebral hemodynamics. Preoperative grouping with a combination of preoperative resting rCBF and preoperative rCRC is useful for predicting the effect of EC-IC bypass surgery.
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PMID:The effect of EC-IC bypass surgery on resting cerebral blood flow and cerebrovascular reserve capacity studied with stable XE-CT and acetazolamide test. 188 38

Acetazolamide (ACZ), a potent carbonic anhydrase inhibitor, is known to decrease submaximal exercise tolerance under normoxic and hypoxic conditions. These decrements in performance occur despite the maintenance of O2 consumption and CO2 removal. Because ACZ is a diuretic, it induces a moderate hypohydration that may have a role in reducing the ability to sustain exercise through cardiovascular and thermoregulatory impairment. To investigate this potential impairment, seven healthy males between 21 and 35 yr of age were studied in a double-blind crossover design (placebo vs. ACZ). ACZ was administered in three 250-mg oral doses 14, 8, and 2 h before exercise. Subjects exercised at 70% peak O2 uptake for 30 min on a cycle ergometer in a normoxic thermoneutral environment (25 degrees C, 40% relative humidity). Results indicate that exercise minute ventilation was greater but O2 uptake, CO2 output, and respiratory exchange ratio did not differ with ACZ. ACZ led to lower mean skin (0.7 degrees C), higher rectal (0.6 degrees C), and higher mean body temperatures (0.4 degrees C) after 30 min of exercise. Whole-body sweat loss was reduced 23%, and heat storage during the exercise bout was increased 55%. Stroke volume decreased 25%, and arteriovenous O2 difference increased 15%. A significant inverse relationship (r = -0.63) between heart rate and stroke volume was observed. It is concluded that previously reported decreases in the ability to sustain submaximal exercise with ACZ may be related to hypohydration-induced impairment of the cardiovascular and thermoregulatory systems.
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PMID:Acetazolamide alters temperature regulation during submaximal exercise. 226 61

To evaluate the efficacy of 133Xe SPECT and Diamox test, for selecting patients with hemodynamic compromise, tests using 133Xe inhalation method and single photon emission computed tomography (SPECT) with acetazolamide (Diamox) were performed in twenty-three patients with chronic cerebral ischemia, before and after extracranial-intracranial bypass surgery or carotid-endarterectomy. All patients complained of TIA, RIND, or minor completed stroke, and cerebral angiography of all patients demonstrated severe stenosis or occlusion in the ipsilateral internal carotid artery or middle cerebral artery. Cerebral blood flow (CBF) was also measured 15 minutes after intravenous administration of 10-12 mg/kg Diamox, which is known as a cerebral vasodilatory agent (Diamox test). Our results revealed that all patients could be divided into four types according to the findings of their resting rCBF and Diamox reactivity. The patients who had normal resting rCBF and normal Diamox reactivity (type 1) were considered to have well-developed collateral circulation and normal cerebral perfusion pressure (CPP) in spite of severe occlusive lesions in the carotid system. Moderate vasodilatation due to reduced CPP was considered to occur in patients who had normal resting rCBF and decreased Diamox reactivity (type 2). The resting rCBF remained unchanged, but Diamox reactivity improved to the normal range after surgery in the patients of type 2 (p less than 0.01), which indicated the improvement of CPP and the resolution of the autoregulatory vasodilatation. Maximum vasodilatation or dysautoregulation was considered to occur due to the inadequate collateral flow and the severely reduced CPP in patients whose findings revealed decrease in the resting rCBF and impaired Diamox reactivity (type 3).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Diagnosis of hemodynamic compromise in patients with chronic cerebral ischemia; the detection of impaired vasodilatory capacity with 133Xe SPECT and acetazolamide (Diamox) test]. 233 45

Increases in regional cerebral blood flow have been described in a variety of cerebral pathologic states, including stroke and seizure disorders. The usefulness of technetium-99m-labeled cysteinate dimer as a marker in the measurement of regional cerebral blood flow was tested in five cynomolgus monkeys. To expand the range of blood flow to beyond the normal limits, 40 mg/kg i.v. of the carbonic anhydrase inhibitor acetazolamide was administered. Regional cerebral blood flow in all five monkeys was measured using radiolabeled microspheres (before and after acetazolamide) and the marker (after acetazolamide) in 60-70 samples from 12 brain regions. Acetazolamide significantly increased the mean +/- SEM regional cerebral blood flow measured using microspheres from 0.56 +/- 0.21 to 1.71 +/- 0.9 ml/min/g (p less than 0.01 for each region). A significant positive correlation was found between regional cerebral blood flow values calculated using microspheres and the marker after normalizing the values to those in the cerebellum (r = 0.773, p less than 0.0001). The mean +/- SEM regional cerebral blood flow determined using the marker in a single monkey (1.21 +/- 0.04 ml/min/g) did not differ significantly from that determined in the same monkey using microspheres (1.13 +/- 0.04 ml/min/g). These data support the potential use of this new brain perfusion imaging agent to assess regional cerebral blood flow over a clinically relevant range of blood flows.
Stroke 1990 Jul
PMID:Regional cerebral blood flow and distribution of [99mTc]ethyl cysteinate dimer in nonhuman primates. 236 7

Cerebral blood flow (CBF) was measured with 133xenon inhalation and single photon emission computed tomography in 33 cases of internal carotid artery occlusion, in the resting state and 25 minutes after acetazolamide (Diamox) administration. The patient population consisted of 24 males and nine females with a mean age of 57 years, who presented with transient ischemic attacks or stroke. Acetazolamide inhibits carbonic anhydrase, and CBF increases as a result of dilatation of cerebral arteries due to CO2 accumulation. The mean CBF was 46 ml/100/g/min on the affected hemisphere and 56 ml/100/g/min on the unaffected hemisphere. The mean CBF value obtained by the same method in 10 normal volunteers was 55 ml/100/g/min. Thus, in the patients, CBF decreased on the affected side. The average increase in CBF after acetazolamide administration was 9% on the affected side and 17% on the unaffected side. The average increase in 10 normal volunteers was 32%. The reduced cerebral arterial reactivity to acetazolamide administration was bilateral in the patient group, which suggests that the cerebral arteries were dilated in order to maintain normal CBF. Extra-intracranial (EC-IC) bypass surgery was performed in nine patients. Preoperatively, the mean CBF was 48 ml/100 g/min on the affected side and 57 ml/100 g/min on the unaffected side; the postoperative CBF was 48 ml/100 g/min on the affected side and 56 ml/100 g/min on the unaffected side. Thus, there was no notable change in CBF on either side after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Measurement of cerebral blood flow by single photon emission computed tomography in cases of internal carotid artery occlusion]. 247 52

Cerebral blood flow (CBF) was measured in a series of patients with ischemic cerebrovascular disease using xenon-133 inhalation and single photon emission computer tomography. The spontaneous course of CBF changes in a consecutive series of stroke patients was evaluated. A quite heterogeneous pattern of flow changes was observed: In patients with large cortical/subcortical infarcts, extensive hypoperfused areas were observed, often significantly larger than the corresponding hypodense lesion on the CT scan. Smaller CT lesions caused relatively smaller flow changes. Patients with lacunar infarcts showed only a discrete reduction of CBF, but comprising most of the ipsilateral hemisphere. Repeated CBF studies in the chronic phase showed, that the clinical improvement commonly noted in stroke patients is not related to a CBF increase. On the contrary, the CBF lesions tended to become somewhat larger and more demarcated even in cases where the finding of a normal angiogram and a transient state of hyperemia suggested a dissolution of the intracerebral embolus. The pathogenetic mechanisms for these persisting low flow areas in CT intact structures was discussed. One possibility was a selective neuronal cell damage in the peri-infarct areas caused by the ischemic insult. Such lesions would leave the structures macroscopically intact, but decrease both the metabolic demands and CBF. However, this interpretation finds little support in recent microscopic neuropathological studies in man. A more likely possibility was then considered to be disconnection (diaschisis) where the reduced flow is due to a decreased neuronal function caused by undercutting of afferent or efferent nervefibers. A crossed cerebellar diaschisis was observed in all patients with major infarcts in the forebrain. These findings were observed already in the acute phase, but persisted quite unchanged throughout the subacute and chronic phases. The patients with lacunar infarcts showed cerebellar diaschisis in the acute phase only, suggesting that a transient suppression of remote areas is possible too. In order to differentiate between permanent flow changes caused by a functional impairment and a possible hemodynamic component, CBF was measured before and after administration of a potent cerebral vasodilator, acetazolamide (Diamox). In normal cases tested with Diamox, an even CBF increase is noted throughout the hemispheres, while the cerebral metabolic rate for oxygen remains stable. In patients having a severe stenosis or occlusion of the internal carotid artery, this vasodilatory stress test will identify the patients having poor collateral capacity via the circle of Willis.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Tomographic cerebral blood flow measurements in patients with ischemic cerebrovascular disease and evaluation of the vasodilatory capacity by the acetazolamide test. 325 61

Cerebral blood flow (CBF) was measured by xenon-133 inhalation tomography in 18 patients with cerebrovascular disease before and 4 months after extracranial-intracranial bypass surgery. Only patients who showed a reduced CBF in areas that were intact on the CT scan and relevant to the clinical and angiographical findings were operated. The majority of the patients had suffered a minor stroke with or without subsequent transient ischemic attacks. They were studied at least 6 weeks following the stroke. All patients had an occlusion of the relevant internal carotid artery. To identify preoperatively the patients with a compromised collateral circulation and hence reduced CBF due to reduced perfusion pressure, a cerebral vasodilatory stress test was performed using acetazolamide (Diamox). In normal subjects, Diamox has been shown to increase tomographic CBF without change of the flow distribution. In the present series 9 patients showed a significant redistribution of flow in favor of the non-occluded side ("positive" Diamox test). Two of these 9 patients showed even a paradoxical decrease in focal CBF preoperatively, i.e., a "steal" effect. These 2 patients were the only patients who improved in focal CBF after shunting. The remaining 9 patients all showed uniform flow responses ("negative" Diamox test), and none of these increased in focal CBF postoperatively. The finding of an unchanged flow map postoperatively confirmed that the low flow areas were not due to restricted flow via collateral pathways. However, an increase in the regional vasodilatory capacity was observed postoperatively in the majority of patients.
Stroke
PMID:Evaluation of the cerebral vasodilatory capacity by the acetazolamide test before EC-IC bypass surgery in patients with occlusion of the internal carotid artery. 349 87


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