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type=\u0022text\/css\u0022 rel=\u0022stylesheet\u0022 href=\u0022\/\/d282kpwvnogo5m.cloudfront.net\/sites\/default\/files\/cdn\/css\/http\/css_Xg7z6oCTVgud_Q0huYz9x9iiD5H_2YPSJ5z2ZViSWdY.css\u0022 media=\u0022all\u0022 \/\u003E\n\u003Clink rel=\u0027stylesheet\u0027 type=\u0027text\/css\u0027 href=\u0027\/sites\/all\/modules\/contrib\/panels\/plugins\/layouts\/onecol\/onecol.css\u0027 \/\u003E\u003C\/head\u003E\u003Cbody\u003E\u003Cdiv class=\u0022panels-ajax-tab-panel panels-ajax-tab-panel-sageoa-tab-art\u0022\u003E\u003Cdiv class=\u0022panel-display panel-1col clearfix\u0022 \u003E\n  \u003Cdiv class=\u0022panel-panel panel-col\u0022\u003E\n    \u003Cdiv\u003E\u003Cdiv class=\u0022panel-pane pane-highwire-markup\u0022 \u003E\n  \n      \n  \n  \u003Cdiv class=\u0022pane-content\u0022\u003E\n    \u003Cdiv class=\u0022highwire-markup\u0022\u003E\u003Cdiv xmlns=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022 id=\u0022content-block-markup\u0022 xmlns:xhtml=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022\u003E\u003Cdiv class=\u0022article fulltext-view \u0022\u003E\u003Cspan class=\u0022highwire-journal-article-marker-start\u0022\u003E\u003C\/span\u003E\u003Cdiv class=\u0022section abstract\u0022 id=\u0022abstract-1\u0022\u003E\u003Ch2\u003ESummary\u003C\/h2\u003E\u003Cp id=\u0022p-1\u0022\u003EHigh oxygen extraction fraction (OEF) is detectable by positron emission tomography (PET), and superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery can be used to improve cerebral hemodynamics in stroke risk patients [Zipfel et al. \u003Cem\u003ESkull Base\u003C\/em\u003E 2005]. This article discusses some of the studies that have used PET to detect OEF, including the COSS Study, WASID Trial, SAMMPRIS Study.\u003C\/p\u003E\u003C\/div\u003E\u003Cul class=\u0022kwd-group\u0022\u003E\u003Cli class=\u0022kwd\u0022\u003Eneurology\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003Ecerebrovascular disease\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003Einterventional techniques \u0026amp; devices\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003Eneuroimaging\u003C\/li\u003E\u003C\/ul\u003E\u003Cdiv class=\u0022section\u0022 id=\u0022sec-1\u0022\u003E\u003Cp id=\u0022p-2\u0022\u003EWhen cerebral blood flow falls due to reduced cerebral perfusion pressure and the brain is unable to compensate through normal autoregulatory vasodilation, it can increase oxygen extraction fraction (OEF) to support normal oxygen metabolism. However, at least 2 studies have shown that a high OEF significantly increases the risk for stroke recurrence [Grubb RI et al. \u003Cem\u003EJAMA\u003C\/em\u003E 1998; Yamauchi H et al. \u003Cem\u003EJ Nucl Med\u003C\/em\u003E 1999]. High OEF is detectable by positron emission tomography (PET), and superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery can be used to improve cerebral hemodynamics in stroke risk patients [Zipfel et al. \u003Cem\u003ESkull Base\u003C\/em\u003E 2005].\u003C\/p\u003E\u003Cp id=\u0022p-3\u0022\u003EGregory J. Zipfel, MD, Washington University School of Medicine, St. Louis, MO, discussed some of the studies that have used PET to detect OEF.\u003C\/p\u003E\u003Cp id=\u0022p-4\u0022\u003EThe Carotid Occlusion Surgery Study (COSS) study is a randomized trial to determine if STA-MCA bypass surgery can reduce stroke risk in patients with recent symptomatic carotid occlusion and high OEF, as measured by PET. To date, 660 patients have been enrolled. The study is expected to be completed by May 2013. Moyamoya is an inherited disease that is associated with a high risk of recurrent stroke, particularly in individuals with bilateral involvement and ischemic symptoms that may be augmented with surgical revascularization [Hallemeir CL et al. \u003Cem\u003EStroke\u003C\/em\u003E 2006]. The North American Moyamoya study is an ongoing study that is attempting to identify high-risk moyamoya patients using PET-detected increased OEF to guide clinical management.\u003C\/p\u003E\u003Cp id=\u0022p-5\u0022\u003EFelipe C. Albuquerque, MD, Barrow Neurological Institute, Phoenix, AZ, reviewed surgical approaches for basilar artery reconstruction. Patients with basilar occlusion are 2.5 times more likely to have a poor outcome compared with those who have basilar stenosis. Conventional treatment (eg, antiplatelets, anticoagulation, or both) of symptomatic basilar artery occlusion is associated with a poor outcome in almost 80% of patients [Schoneville WJ et al. \u003Cem\u003EJ Neurol Neurosurg Psychiatry\u003C\/em\u003E 2005]. Neither a local intra-arterial thrombolysis (IAT) nor intravenous thrombolysis (IVT) approach seems to improve mortality or morbidity. Death and dependency are equally common (78% [59 of 76] and 76% [260 of 344], respectively; p=0.82). Only 24% of patients who were treated with IAT and 22% who were treated with IVT reached good outcomes [Lindsberg P \u0026amp; Mattle HP. \u003Cem\u003EStroke\u003C\/em\u003E 2006].\u003C\/p\u003E\u003Cp id=\u0022p-6\u0022\u003ERecanalization may be an option. In data that were presented by Dr. Albuquerque from his own clinic, of 10 patients who were treated with angioplasty and\/or stenting, 7 improved or were stable and 3 died.\u003C\/p\u003E\u003Cp id=\u0022p-7\u0022\u003EIn another study, despite a significant incidence of ischemic and nonischemic complications after basilar artery stent placement, most patients achieved freedom from vertebrobasilar ischemia and good-to-excellent clinical outcomes (9 of 10 patients) at late midterm follow-up (12 to 46 months) [Abruzzo TA et al. \u003Cem\u003EAm J Neuroradiol\u003C\/em\u003E 2007].\u003C\/p\u003E\u003Cp id=\u0022p-8\u0022\u003EThe complete occlusion of the basilar artery has a poor natural history despite the best medical management. It is a different disease state than acute occlusion in that it has a longer course to presentation due to the presence of some collateral flow around the occlusion. Recanalization may improve outcomes in certain individuals if a steady state of patency can be achieved. However, Dr. Albuquerque believes that it is imperative that the patient and family understand the high-risk nature of this procedure.\u003C\/p\u003E\u003Cp id=\u0022p-9\u0022\u003EMarc I. Chimowitz, MBChB, Medical University of South Carolina, Charleston, SC, discussed the lessons that were learned from the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial and how the trial impacted the design of the Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis (SAMMPRIS) study.\u003C\/p\u003E\u003Cp id=\u0022p-10\u0022\u003EIn the WASID study, warfarin was associated with a high rate of death (9.7% in the warfarin group vs 4.3% in the aspirin group; p=0.02) and major hemorrhage (8.3% in the warfarin group vs 3.2% in the aspirin group; p=0.01). However, the probability of stroke\/vascular death (about 22%) at 4.5 years was the same for both warfarin and aspirin (p=0.83; \u003Ca id=\u0022xref-fig-1-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F1\u0022\u003EFigure 1\u003C\/a\u003E) [Chimowitz MI et al. \u003Cem\u003EN Engl J Med\u003C\/em\u003E 2005].\u003C\/p\u003E\u003Cdiv id=\u0022F1\u0022 class=\u0022fig pos-float  odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/d282kpwvnogo5m.cloudfront.net\/content\/spmdc\/10\/1\/27\/F1.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022Primary Endpoint: Stroke and Vascular Death.\u0022 class=\u0022fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-2053813821\u0022 data-figure-caption=\u0022Primary Endpoint: Stroke and Vascular Death.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cimg class=\u0022fragment-image\u0022 alt=\u0022Figure 1.\u0022 src=\u0022http:\/\/d282kpwvnogo5m.cloudfront.net\/content\/spmdc\/10\/1\/27\/F1.medium.gif\u0022\/\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u00220 first\u0022\u003E\u003Ca href=\u0022http:\/\/d282kpwvnogo5m.cloudfront.net\/content\/spmdc\/10\/1\/27\/F1.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Figure 1.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u00221\u0022\u003E\u003Ca href=\u0022http:\/\/d282kpwvnogo5m.cloudfront.net\/content\/spmdc\/10\/1\/27\/F1.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u00222 last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/11244\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption attrib\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFigure 1.\u003C\/span\u003E \u003Cp id=\u0022p-11\u0022 class=\u0022first-child\u0022\u003EPrimary Endpoint: Stroke and Vascular Death.\u003C\/p\u003E\u003Cq class=\u0022attrib\u0022 id=\u0022attrib-1\u0022\u003ECopyright \u00a9 2005 Massachusetts Medical Society. All rights reserved.\u003C\/q\u003E\u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cp id=\u0022p-12\u0022\u003EIt was also noted that elevating blood pressure to protect against hypoperfusion in symptomatic patients with intracranial stenosis is associated with an increased (not decreased, as originally thought) risk of stroke [Chaturvedi S et al. \u003Cem\u003ENeurology\u003C\/em\u003E 2007; Turan TN et al. \u003Cem\u003ECirculation\u003C\/em\u003E 2007]. The WASID study also identified subgroups (patients with stenosis \u226570% after recent symptoms and women) who were at very high risk of stroke in the first year in the territory of the stenotic artery [Kasner SE et al. \u003Cem\u003ECirculation\u003C\/em\u003E 2006].\u003C\/p\u003E\u003Cp id=\u0022p-13\u0022\u003EWith these findings in mind, the SAMMPRIS study was designed to compare aggressive medical therapy alone with intracranial stenting (Wingspan stent system) plus aggressive medical therapy in high-risk patients with symptomatic stenosis of a major intracranial artery. The primary endpoint in SAMMPRIS is any stroke or death within 30 days of enrollment or revascularization done during follow-up or stroke in the territory of the stenotic\/ stented artery beyond 30 days of enrollment. The mean follow-up is expected to be 2 years. Aggressive medical management includes daily administration of aspirin and clopidogrel for 90 days followed by aspirin alone, blood pressure and low-density lipoprotein reduction, and a lifestyle modification program.\u003C\/p\u003E\u003Cp id=\u0022p-14\u0022\u003ESAMMPRIS enrollment is proceeding well, and the trial is scheduled to be completed in 2013\u20132014. Regardless of outcome, this study will provide future standard of care for treating intracranial arterial stenosis.\u003C\/p\u003E\u003Cp id=\u0022p-15\u0022\u003EIntracranial stenosis from atherosclerosis accounts for approximately 10% to 15% of all ischemic strokes. Ajay K. Wakhloo, MD, University of Massachusetts, Boston, MA, discussed the challenges of treating intracranial stenosis, starting with early developmental changes of the carotid bulb.\u003C\/p\u003E\u003Cp id=\u0022p-16\u0022\u003EThe tortuous morphology that leads to changes in flow dynamics as the carotid bulb develops increases the risk for atherosclerotic plaque and intracranial stenosis later in life [Peterson RE et al. \u003Cem\u003ENeurology\u003C\/em\u003E 1960]. Carotid bulb stenosis is localized and progresses circumferentially from the outer wall toward the carina affecting interstitial flow through the intraepithelial layer (IEL) and in turn affecting shear stress on arterial smooth muscle cells. There is a decrease in shear stress after IEL injury.\u003C\/p\u003E\u003Cp id=\u0022p-17\u0022\u003EKnowledge of cerebral vascular hemodynamics can be used in the assessment of stroke risk and best treatment course for patients with symptomatic vertebrobasilar disease. Using quantitative magnetic resonance angiography to stratify patients on the basis of the presence or absence of distal flow compromise, patients with normal distal flow had an event-free survival (stroke and combined stroke\/TIA) of 100% and 96%, respectively. Comparatively, patients with low distal flow experienced a 71% and 53% event-free survival, demonstrating a significantly higher risk of recurrent ischemia (p=0.003). Patients with low flow who subsequently underwent treatment (n=12) had an 82% event-free survival [Amin-Hanjani S et al. \u003Cem\u003EStroke\u003C\/em\u003E 2005].\u003C\/p\u003E\u003Cp id=\u0022p-18\u0022\u003EDr. Wakhloo is awaiting results from the Vitesse Intracranial Stent Study for Ischemic Therapy (VISSIT), which is a randomized investigational device exemption (IDE) trial that is comparing medical therapy with stenting for symptomatic stenosis of 70% to 99% of the vessel.\u003C\/p\u003E\u003C\/div\u003E\u003Cul class=\u0022copyright-statement\u0022\u003E\u003Cli class=\u0022fn\u0022 id=\u0022copyright-statement-1\u0022\u003E\u00a9 2010 MD Conference Express\u003C\/li\u003E\u003C\/ul\u003E\u003Cspan class=\u0022highwire-journal-article-marker-end\u0022\u003E\u003C\/span\u003E\u003C\/div\u003E\u003Cspan id=\u0022related-urls\u0022\u003E\u003C\/span\u003E\u003C\/div\u003E\u003Ca href=\u0022http:\/\/mdc.sagepub.com\/content\/10\/1\/27.abstract\u0022 class=\u0022hw-link hw-link-article-abstract\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EView Summary\u003C\/a\u003E\u003C\/div\u003E  \u003C\/div\u003E\n\n  \n  \u003C\/div\u003E\n\u003C\/div\u003E\n  \u003C\/div\u003E\n\u003C\/div\u003E\n\u003C\/div\u003E\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022http:\/\/mdc.sagepub.com\/sites\/all\/modules\/highwire\/highwire\/plugins\/highwire_markup_process\/js\/highwire_figures.js?nzmulq\u0022\u003E\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022http:\/\/mdc.sagepub.com\/sites\/all\/modules\/highwire\/highwire\/plugins\/highwire_markup_process\/js\/highwire_openurl.js?nzmulq\u0022\u003E\u003C\/script\u003E\n\u003C\/body\u003E\u003C\/html\u003E"}