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

To evaluate the cerebral distribution of 99mTc-ethyl cysteinate dimer (99mTc-ECD) at blood flow levels beyond the normal range, we investigated postischemic reperfusion and acetazolamide (Diamox) activation test in stroke patients. The postischemic reperfusion was studied in 10 patients who showed a postischemic hyperperfusion area on other single photon emission computed tomography (SPECT) studies using N-isopropyl-rho-[123I]iodoamphetamine ([123I]IMP), 99mTc-hexamethyl propyleneamine oxime (99mTc-HMPAO), or 133Xe. 99mTc-ECD SPECT demonstrated a hyperactive area in one case, an isoactive area in four, and a hypoactive area in five. Correlations with CT findings revealed hyperactive areas without any abnormality, isoactive areas with perifocal rim, perifocal edema, or diffuse cerebral edema, and hypoactive areas with an infarct core. The Diamox activation test was studied in eight other patients with atherothrombotic stroke, and a limitation in vasodilative capacity was classified into three grades: Gr. 0 (none to minimal), Gr. I (mild), and Gr. II (moderate). [123I]IMP SPECT showed Gr. II and limitation in all eight cases. However, 99mTc-ECD showed Gr. II in three cases and Gr. I in five, and 99mTc-HMPAO revealed Gr. II in two cases, Gr. I in three, and Gr. 0 in three. We suggest that a lack of retention of 99mTc-ECD in a postischemic reperfusion area indicates the severity of the initial brain damage. Although the limitation in vasodilative capacity under Diamox-activated conditions was underestimated using 99mTc-labeled CBF tracers as compared with [123I]IMP, a retention of 99mTc-ECD in the unaffected area with an increased CBF under Diamox activation could be relatively superior to 99mTc-HMPAO.
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PMID:Assessment of postischemic reperfusion and diamox activation test in stroke using 99mTc-ECD SPECT. 826 72

Cerebral infarction is the result of cerebrovascular insufficiency and itself creates complex changes in cerebral hemodynamics. To allow recognition of patterns of change in regional cerebral blood flow (r-CBF) caused by cerebral infarction, the authors present an atlas of Tc-99m hexamethylpropyleneamine oxime (Tc-99m HMPAO) SPECT brain scan sections for a variety of strokes demonstrating typical vascular territorial involvements and evolution of morphologic and r-CBF change. Sections from MRI or CT are shown with SPECT images of the stroke lesion for comparison of the complementary information provided by regional cerebroperfusion and by morphology. Examples of SPECT during acute, subacute, and chronic stages of stroke are provided. To illustrate the temporal evolution of stroke and accompanying changes in the "stroke penumbra," case examples of acute tissue necrosis, luxury perfusion, ischemia, and diaschisis are presented. Methods for semiquantitative analysis of morphologic versus r-CBF defect size after acute stroke are described. How brain SPECT scans conducted during Diamox initiated cerebrovascular stress tests can complement the information obtained from baseline studies and assist in the interpretation of r-CBF abnormalities is also demonstrated.
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PMID:Regional cerebral blood flow changes in stroke imaged by Tc-99m HMPAO SPECT with corresponding anatomic image comparison. 829 29

Although a sequential 99mTc-HMPAO SPECT technique with Diamox test (seq-SPECT) is a simple and time-saving procedure to assess brain perfusion reserve, the influence of the first dose of the tracer on the second one is not negligible. Therefore, a subtraction of the rest-SPECT from the 2nd SPECT is widely-used. However, subtracted SPECT images not only need to be corrected for the injected dose and the radiochemical purity due to inherent instability of HMPAO but also are usually degraded in quality. This study was undertaken to resolve these problems utilizing a change ratio (CR) map. The CR map was obtained by dividing 2nd SPECT by rest-SPECT. Prior to subtraction, the 2nd SPECT was normalized with the ratio of the mean whole brain counts between both SPECTs. To validate CR map, 7 patients were studied with both seq-SPECT and 133Xe inhalation CBF measurement (Xe-CBF). The right to left count ratio obtained from the ROIs placed on MCA territory of CR map correlated well with that from Xe-CBF (r = 0.89, p < 0.01). Fifty-three patients with stroke underwent the seq-SPECT which was compared with the cerebral angiography (CAG) and classified into 4 groups according to the CR map. In 25 patients, all of the rest-, the subtracted-SPECT and the CR map did not show any difference between the affected side and the contralateral normal side. Seven patients with normal rest-SPECT showed decreased subtracted-SPECT counts and CR on the affected side. Three of them showed more than 75% stenosis on CAG. Four patients with the decreased counts both at the rest- and the subtracted-SPECT revealed no difference on the CR map suggesting the matched decrease of both blood flow and metabolism in the affected side. In conclusion, the CR map was a simple and useful method to evaluate the brain perfusion reserve with the seq-SPECT.
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PMID:[Usefulness of change ratio map in 99mTc-HMPAO SPECT with acetazolamide enhancement]. 868 79

The EC-IC Bypass Study Group could not detect any benefit from surgery compared to medical management in the prevention of stroke in 1985 [15]. During the past years surgical revascularization was re-evaluated and considered as an appropriate treatment for a small subgroup of patients with recurrent focal cerebral ischaemia and impaired haemodynamics. This retrospective study examines the long-term benefit and patency rate of bypass. We present a follow-up of 5.6 years of 47 patients, all of whom underwent bypass surgery after 1985. Forty patients suffered recurring transient ischaemic attacks due to uni- or bilateral internal carotid artery occlusion. Examination included neurologic status, TCD with CO2 or Diamox challenge, angiography, CT and SPECT scans. Neurological improvement was seen in 23% of patients with better results after early surgery, a worsening in 22% suffering further ischaemic events on a postoperative average of 2.8 years. Patency rate for vein graft material was 50%, for the STA-MCA procedure 91%. Occlusion of the vein graft occurred on an average after 1.4 years, other anastomosis after 2.7 years. We conclude that only few patients derived long-term benefit from EC-IC bypasses. Functioning of the bypass worsens over time, suggesting a role for surgery predominantly in the first year of ischaemic events due to insufficient collateral supply. Actual indications for bypass surgery may be patients with failure of maximal medical therapy and progressive ischaemia and haemodynamic compromise.
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PMID:Long-term evaluation of EC-IC bypass patency. 889 Sep 90

Migraine headaches usually decrease in frequency and severity and often cease during advancing age. Occasionally, migraineurs report late-life migrainous accompaniments, i.e., auras without headache, particularly when typical migraine attacks terminate or diminish following major or minor strokes, at which time the auras may become atypical. Clinical observations such as these suggest that degenerative cerebrovascular changes accompanying aging may modify the course of migraine headaches particularly those with aura. To test this hypothesis, we quantitated age-related changes in cerebral vasodilator capacitance by measuring local cerebral blood flow utilizing xenon contrast computed tomography (CT) scanning before and after oral administration of the pharmacological cerebral vasodilator, acetazolamide (Diamox). Measurements were compared among 27 normal volunteers without headache (aged 24-94 years; mean age 61.1 +/- 17.6) and 37 carefully categorized groups of migraine patients (aged 27-83 years; mean age 59.4 +/- 12.4). The normals comprised Group A. Migraineurs were divided into two subgroups: Group B consisted of 27 migraineurs with and without aura who continued to suffer from incapacitating and frequent headaches and Group C consisted of 10 migraineurs who no longer suffered from severe and frequent headaches, two of whom still complained of atypical auras of the "late-life migrainous accompaniments" type. Cerebral vasodilator capacitance significantly declined with advancing age among normals and the two groups of migraineurs, confirming the development of age-related cerebrovascular diseases. Global CBF increases after Diamox in Group B (with persistent and severe migraine), were significantly greater compared with normals without headache, and with Group C consisting of migraineurs whose headaches had decreased, subsided, or become replaced by late-life migrainous accompaniments (Group C). Results establish that cerebrovasodilator capacitance declines with advancing age, probably due to progressive cerebral atherosclerosis, since these declines were accentuated by risk factors for stroke, particularly TIAs or documented lacunar infarcts by CT. Progressive impairments of cerebral vasodilator capacitance among migraineurs were associated with: (i) reductions in frequency and severity of migrainous cephalalgia and (ii) appearance of late-life migrainous accompaniments.
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PMID:Age-related cerebrovascular disease alters the symptomatic course of migraine. 964 95

In carotid artery disease (CAD) the basilar artery (BA) may act as an important intracranial collateral to supply hypoperfused middle cerebral artery (MCA) territories. Transcranial Doppler studies were performed to study the dependency between BA hemodynamics in relation to the MCA perfusion status. BA and MCA blood flow velocities (BFV), pulsatility indices (API) and cerebrovascular reactivity (CVR) were assessed in 40 patients with a progressive MCA hypoperfusion due to progressive CAD. All patients had patent cervical segments of their vertebral arteries with an antegrade vertebral flow profile. Duplex studies were performed to diagnose the severity of CAD. Hypoperfusion of the MCA was diagnosed by the degree of vasoparalysis assessed by a Diamox procedure. Analysis showed that the basilar BFV significantly increased in cases of progressive CAD, the basilar PI decreased but the basilar CVR remained unchanged. However, in cases of bilateral hemodynamic significant CAD and bilateral exhausted CVR in the MCA territory, the basilar artery did not exhibit an increase of BFVs or a decrease of the basilar PI, but the basilar CVR showed a significant decrease. Basilar artery CVR is not impaired if this artery has a function as intracranial collateral in CAD. However in cases of bilateral hypoperfused MCA territories the basilar artery does not function as a collateral pathway. The basilar CVR declines under these circumstances which merely reflects the exhausted hemodynamics in the anterior/posterior borderzones. This situation might lead to an increased stroke risk in the distal basilar supply zones.
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PMID:A transcranial Doppler study of basilar hemodynamics in progressive carotid artery disease. 971 38

In surgical treatment was performed of patients after cerebral ischaemic stroke and cerebral ischaemia. The authors applied the surgical technique of indirect anastomosis (EDAS-encephalo-duro-arterio synangiosis). The Japanese authors described this method first as a treatment for moya-moya disease. The acetazolamid (Diamox) test and clinical symptoms were the main criteria to perform this surgical procedure. All patient with abnormal Diamox test were treated surgically. After 6 months control angiography was performed to visualize a new network of vessels near the main vessel (superficial temporal artery).
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PMID:[Revascularisation after encephalo-duro-arterio-synangiosis. Case report]. 1198 11

Transcranial Doppler sonography has become widely used in assessing cerebral vasomotor reactivity which provides information regarding cerebral autoregulation and collateral circulation. Cerebral vasomotor reactivity is defined as a shift between cerebral blood flow or cerebral blood velocity before and after administration of a potent vasodilatory stimulus test. Three such tests are currently used for this purpose: the apnea test, CO2 inhalation and the Diamox test (i.v. acetazolamide), all of which are based on the dilatatory response of cerebral blood flow to hypercapnia. Certain advantages of the Diamox test were described, but each of the three tests has its strong and weak points, and this will be the topic under discussion. There are several practical applications of the combined TCD and the vasodilatory tests in assessing of cerebral vasomotor reactivity: 1. To evaluate the intracranial hemodynamic status in patients with carotid occlusive disease with the intent of predicting the occurrence of ischemic brain events. 2. To compare intracranial hemodynamics before and after carotid endarterectomy. 3. To compare autoregulation and collateral circulation in the different parts of the circle of Willis. 4. To predict dementia after stroke. In summary, the potential clinical usefulness of combined TCD and provocative vasodilatory tests has been clearly shown. Further large scale studies are needed in order to augment the applications of cerebral vasomotor reactivity assessment in the clinical setting.
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PMID:TCD and the Diamox test for testing vasomotor reactivity: clinical significance. 1200 54

The Japanese EC-IC bypass trial (JET study) was established to evaluate the validity of MCA-STA anastomosis in intracranial arterial occlusive disease aiming at stroke prevention. This study must use an objective method to reliably estimate hemodynamic brain ischemia. We devised a method of objectively classifying the severity of hemodynamic ischemia using quantitatively analytical and display software, stereotactic extraction estimation for stereotactic brain coordinates and three-dimensional stereotactic surface projections (3D-SSP). We analyzed data from 16 patients registered in the JET study. Our method offers quantitative information and 3-dimensional displays of the CBF at rest and after Diamox challenge, vascular reserve and the severity of the hemodynamic brain ischemia. We compared the maximal projection counts with ROI data from tomographic images in the anterior commissure-posterior commissure plane. The maximal counts data correlated closely with the ROI data of rest and with Diamox SPECT images (both p < 0.0001). The slopes of the linear regression line were 1.15 and 1.12, respectively. The results of this study indicated that our method could simply and objectively evaluate the severity of impaired brain circulation. This procedure should support the evaluation of hemodynamic ischemia in the JET study although validation is required by several institutions using more study subjects.
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PMID:Three-dimensional display in staging hemodynamic brain ischemia for JET study: objective evaluation using SEE analysis and 3D-SSP display. 1507 79

There has recently been a tremendous increase in imaging technology and imaging methodology enabling noninvasive exploration of brain function to such an intricate degree as to enable measurements of very small spatial and short temporal cerebral operations responsible for neurological and functional recovery after stroke. This has allowed conceptualization of rehabilitation strategies designed to maximally enhance rehabilitation protocols tailored to the individual patient's deficits. Rehabilitation strategies may now be designed and optimized by employing methods to synchronize functional training of brain regions ascribed to those areas innately undergoing neuronal plasticity change responsible for stroke recovery. In order to effectively apply these noninvasive imaging methods, one must have a clear understanding of the physics and technique of the imaging methodologies and how these are best applied to understand brain physiology during the stroke recovery process to provide a solid rationale for development of rehabilitation protocols. Nuclear medicine imaging is first presented as a diagnostic method to assess the stroke process. The initial brain damage and resulting neurological disability can be primarily assessed in terms of changes in the vascular and hemodynamic status of the cerebral circulation in addition to alterations in the metabolic status around the infarction region. Techniques for assessing perfusion and metabolism include regional cerebral blood flow (rCBF), single photon emission computed tomography (SPECT), and F-18 2-Fluoro-2-deoxy-D-glucose (F-18 FDG) positron emission tomography (PET). In addition, hemodynamic vascular insufficiency can be assessed using O-15 O2 oxygen extraction PET and rest and Diamox rCBF SPECT. The status of the peri-infarction region can be characterized in terms of components of diaschisis and ischemia using proton magnetic resonance spectroscopy imaging ((1)H MRSI) and rest/stress rCBF assessment of cerebral vascular reserve. As the brain recovers from cerebral infarction, areas of reorganization and energy utilization by the brain can be measured using oxygen extraction methods with PET, F-18 FDG glucose utilization by PET, and functional magnetic resonance imaging (fMRI) measures using the blood oxygenation level dependent (BOLD) technique. In addition, high field MRI imaging of the brain is now able to provide detailed fractional anisotropy (FA) maps to characterize changes in white matter by fiber tracking mapping using diffusion tensor imaging. Imaging of the stroke recovery process focuses on the physiologic model of stroke characterized by rCBF, metabolism, 1H spectroscopic measures of N-acetyl aspartate (NAA), choline (Ch) and creatine (Cr) in the peri-infarction zone as well as in the extended stroke penumbra including areas of distant ''pure'' diaschisis unencumbered with the confound of cerebral ischemia. Data is presented describing the results of application of imaging methodologies as the patient undergoes rehabilitation that demonstrates the importance of blood flow and metabolic changes in the contralesional frontal lobe both during the resting state and during motor and speech activation paradigms. The results of advanced imaging technologies on cerebral damage and cerebral reorganization during rehabilitation are presented in the context of furthering designs of rehabilitation strategies. Success can be monitored to assess the optimization of rehabilitation strategy design to maximize neurological recovery from stroke by employing facilitatory methods to maximally synchronize rehabilitation techniques with recovery of functionally counterpart areas of viable brain.
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PMID:Nuclear medicine in the rehabilitative treatment evaluation in stroke recovery. Role of diaschisis resolution and cerebral reorganization. 1726 87


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