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

Regional cerebral blood flow and vasomotor reactivity were measured in 33 patients with surgically remediable hemispheric ischemia by the 133Xe inhalation method prior to superficial temporal to middle cerebral artery (STA-MCA) by-pass. Thirteen patients also underwent LCBF and L lambda measurements by the stable xenon CT method for comparison. Twenty-four had proximal occlusion of one or both internal carotid arteries, 9 had intracranial occlusive disease (4 internal carotid, 5 middle cerebral). Measurements were repeated at intervals up to 30 months following surgery and compared to measurements in a similar group (N = 13) treated medically. In the surgically treated group 22 patients had recurrent TIAs, of whom 12 also had minor residual neurological deficits from recent small cerebral infarctions with potential for recovery (RINDs) while the remaining 11 had RINDs without TIAs. After surgery 28 improved with cessation of TIAs and/or neurological recovery, 3 remained unchanged, 2 cases worsened. Compared to age-matched normal hemispheric F1 (gray matter) values, pre-operative F1 values in the STA-MCA group were reduced in both ischemic and opposite hemispheres. Ischemic regions showed imparied vasomotor reactivity to 5% CO2 or 100% O2 inhalation. After surgery, mean hemispheric F1 values increased + 12.8% on the by-pass side and + 10.5% on the contralateral side. Mean F1 increases reached a maximum 3 months after by-pass, most evident in ipsilateral frontal regions (+ 24.2%). Vasomotor reactivity did not significantly improve. Medically treated cases did not show similar F1 increases. Thirteen with carotid occlusive disease (8 with TIAs, 5 with small recent infarcts) underwent CT LCBF and L lambda measurements before and after STA-MCA by-pass. Cases with recent infarcts showed reduced LCBF and L lambda values which increased significantly after STA-MCA by-pass, however the total group operated upon showed only trends for CBF increases, probably due to large standard deviations encountered in serial measurements.
Stroke
PMID:Redistribution of cerebral blood flow following STA-MCA by-pass in patients with hemispheric ischemia. 714 91

Intravenous thrombolytic therapy using recombinant tissue plasminogen activator (rtpa) has been approved for the treatment of acute ischemic stroke in the USA, if treatment is initiated within 3-hours (NINDS tpa Stroke Study Group) but not 6 hours (ECASS II) after time of onset. Favorable outcome in the placebo arm was much higher than expected possibly because patients with TIA's are likely to be included as progressive ischemic stroke subjects when a brief 3-6 hours duration of stroke is defined as the therapeutic window. Yonas' group at the University of Pittsburg demonstrated that adding stable xenon inhalation to routine CT scanning performed during emergency screening of acute stroke, predicted which cases became irreversibly infarcted if thrombolytic therapy was not administered within a few hours of stroke onset, since non-contrasted CT scans are usually normal this early. Adding a few minutes for inhalation of 26% xenon is justified in order to measure LCBF values which predict size, severity and volumes of impending cerebral infarctions and rule out TIA's which have relatively normal CT-CBF values. CT-CBF measures provide positive indications for thrombolytic therapy. This is not possible by MRI and SPECT methods which are not sufficiently quantitative to discern LCBF values persistently below ischemic thresholds of 16 mls/100 gm/min, thereby predicting impending infarction.
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PMID:Why emergency XeCT-CBF should become routine in acute ischemic stroke before thrombolytic therapy. 1075 Mar 30