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Query: UMLS:C0917798 (cerebral ischemia)
 17,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

Repeated cerebral blood flow (CBF) measurements with xenon-133 inhalation and single photon emission tomography were performed in a patient suffering a minor stroke with subsequent orthostatic-provoked transient ischemic attacks (TIA's). Angiography revealed a thread-like internal carotid artery and an occluded external carotid artery on the side of the ischemic neurological symptoms. Computerized tomography and technetium-99m-pertechnetate brain scintigraphy 2 weeks after stroke were both normal. Before reconstructive vascular surgery, resting CBF showed a hypoperfused area corresponding to the clinical symptoms. Diamox (acetazolamide, 1 gm) increased CBF by 24% in the unaffected hemisphere, whereas even a slight decrease in flow ("steal") was seen in the maximally affected region. In contrast, theophylline (220 mg) reduced CBF in the unaffected hemisphere and caused a slight increase in the previously maximally hypoperfused area ("inverse steal"). After surgery, the flow pattern practically normalized and the TIA's disappeared. The CBF measurements before surgery and also after the injection of the vasoactive drugs indicated that focal hemodynamic insufficiency elicited the TIA's, and pointed at a low mean arterial blood pressure of about 35 mm Hg in the affected hemisphere. The perioperative finding of a mean blood pressure in the internal carotid artery of 31 mm Hg on the symptomatic side confirmed that the brain tissue had a severely reduced perfusion pressure. On clamping the artery, a stump pressure of 22 mm Hg and electroencephalogram flattening was noted, so a temporary internal shunt was inserted. The findings demonstrate that preoperative CBF measurements, including studies of the regional vasoreactivity, may identify patients with hemodynamic TIA's. These patients are at particular risk of developing cerebral ischemia during carotid endarterectomy, as any further compromise of the inflow may precipitate frank ischemia.
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PMID:Hemodynamically significant stenosis of the internal carotid artery treated with endarterectomy. Case report. 660 27

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

The Japanese authors first described encephalo-duro-arterio-synangiosis, a new treatment for moya-moya disease, 17 years ago. The other authors used this method (EDAS, indirect anastomosis) in surgical treatment of patients suffered cerebral transient ischaemic attack and cerebral ischaemia. In our department this method was applied in 5 patients with cerebral ischaemia. All patients had internal carotid artery occlusion. After angiography, to localize carotid artery occlusion, acetazolamid (Diamox) test was performed. The patients with negative Diamox test were treated surgically (EDAS). The authors used the intraoperative microdoppler device to monitor blood flow velocity of the prepared vessel (temporal superficial artery) at every stage of surgery. The device was also useful in controlling the patency of encephalo-duro-arterio-synangiosis percutaneously after the surgery. The proximal and the distal part of the non-bypass anastomosis was examined in the follow up during 5-8 months before angiography.
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PMID:[The examination of the blood flow velocity in arterial vessel during and after encephalo-dura-arterio-synangiosis. Preliminary results]. 1046 33

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

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

It is considered controversial whether superficial temporal artery (STA)-middle cerebral artery (MCA) bypass affects the outcome of patients with ischemic stroke. This prospective study was undertaken to demonstrate the effect of STA-MCA bypass on the cerebral blood flow and neurological status of the patients with ischemic stroke. Seventy-five patients underwent unilateral or bilateral STA-MCA bypass surgery. The selection of the patients closely adhered to the criteria of the Japan EC-IC Bypass Trial (JET). Cerebral blood flow (CBF) before and after Diamox administration was measured by single photon emission computed tomography (SPECT) using iodine-123-N-isopropyl-p-iodoamphetamine (IMP). MRI, contrast-enhanced 3D CT scans, and angiography were performed on each patient pre- and postoperatively. Bypass surgery was successfully done in all patients. CBF was significantly increased after STA-MCA bypass (P < 0.05). In addition, reservation of CBF was significantly improved after STA-MCA bypass (P < 0.05). Patients with transient ischemic attack (TIA) did not experience recurrence of such episodes after STA-MCA bypass. The neurological deficit was unchanged in patients with complete stroke after bypass surgery. However, the NIH stroke scale was significantly improved after bypass surgery (P < 0.01). In addition, the satisfaction rate of treatment as assessed by the patients themselves was very high after STA-MCA bypass (>90%) compared to the conservative treatment group (<50%). STA-MCA bypass still plays a limited role in the treatment of ischemic stroke, but may become a bright hope in depressed patients after cerebral ischemia.
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PMID:STA-MCA bypass for the treatment of ischemic stroke. 2169 88