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Intracranial Arterial Stenosis (intracranial + arterial_stenosis)
Selected AbstractsNatural History of Asymptomatic Intracranial Arterial StenosisJOURNAL OF NEUROIMAGING, Issue S1 2009Robert A. Taylor MD ABSTRACT The prevalence and natural history of asymptomatic intracranial arterial stenosis are not very well characterized. Existing data suggest that incidentally discovered asymptomatic intracranial stenosis presents a fairly low risk of stroke, though substantial uncertainty remains. Patients may be at greater risk if there are tandem stenoses. Methods to stratify the risk of stroke with asymptomatic intracranial atherosclerotic lesions have yet to be established and validated. In general, aggressive intervention for an asymptomatic intracranial stenosis is not currently recommended. [source] Screening for Intracranial Stenosis With Transcranial Doppler: The Accuracy of Mean Flow Velocity ThresholdsJOURNAL OF NEUROIMAGING, Issue 1 2002Robert A. Felberg MD ABSTRACT Background. Patients with 50% intracranial arterial stenosis may require more intensive therapies for stroke prevention. Transcranial Doppler (TCD) is a convenient noninvasive screen for intracranial stenosis. The accuracy of different mean flow velocity (MFV) thresholds for determining the degree of stenosis remains uncertain. Methods. The authors prospectively compared the accuracy of TCD criteria and MFV thresholds to magnetic resonance, computed tomography, and digital subtraction angiography in patients with symptoms of recent or remote stroke or transient ischemic attack. Stenosis on angiography was measured as 0%, <50%, or ,50% diameter reduction. Results. Of 136 consecutive patients, 33 (24%) had distal internal carotid artery (ICA), middle cerebral artery (MCA), posterior cerebral artery, or basilar artery stenosis on angiography (14 patients [10%] were excluded due to incomplete TCD examinations, mainly from a lack of temporal windows). TCD showed 31 true-positive, 9 false-positive, 2 false-negative, and 94 true-negative studies. For all vessels, TCD had a sensitivity of 93.9% (confidence interval [CI] = 89%-98%), a specificity of 91.2% (CI = 87%-96%), a positive predictive value (PPV) of 77.5%, and a negative predictive value (NPV) of 97.9%. The trade-off in sensitivity and specificity for MCA MFV thresholds was as follows: MFV ,80 cm/s had a sensitivity of 100%, a specificity of 96.9% (CI = 94%-99%), a PPV of 84%, and an NPV of 100%. MFV,100 cm/s had a sensitivity of 100%, a specificity of 97.9% (CI = 96%-99%), a PPV of 88.8%, and an NPV of 94.9%. MFV,120 cm/s had a sensitivity of 68.7% (CI = 61%-78%), a specificity of 100%, a PPV of 100%, and an NPV of 94.9%. Reasons for false-positive findings include collateralization of flow in the presence of proximal ICA stenosis and prestenotic to stenotic MCA velocity ratios of 1:,2. Conclusion. TCD is both sensitive and specific in identifying ,50% intracranial arterial stenosis. A MFV threshold cutoff of 100 cm/s has an optimal sensitivity and specificity trade-off for ,50% MCA stenosis. To help avoid false-positive results, a prestenotic to stenotic MCA velocity ratio of 1:,2 should be used in addition to the MFV threshold. [source] Comparison of Transcranial Color-Coded Sonography and Magnetic Resonance Angiography in Acute Ischemic StrokeJOURNAL OF NEUROIMAGING, Issue 4 2001Li-Ming Lien MD ABSTRACT Background and Purpose. This study was designed to assess the accuracy of transcranial color-coded sonography (TCCS) as compared to magnetic resonance angiography (MRA) for detecting intracranial arterial stenosis in patients with acute cerebral ischemia. Methods. The authors prospectively identified 120 consecutive patients admitted with acute ischemic stroke and performed both TCCS and MRA with a mean interval of 1 day. TCCS data (sampling depth, peak systolic and end diastolic angle-corrected velocity, mean angle-corrected velocity, and pulsatility index) for middle cerebral arteries (MCAs) were compared to MRA data and classified into 4 grades: normal (grade 1): normal caliber and signal; mild stenosis (grade 2): irregular lumen with reduced signal; severe stenosis (grade 3): absent signal in the stenotic segment (flow gap) and reconstituted distal signal; and possible occlusion (grade 4): absent signal. The cutoffs were chosen to maximize diagnostic accuracy. Results. Interobserver agreement for MRA grading resulted in a weighted-kappa value of 0.776. The rate of poor temporal window was 37% (89/240). Doppler signals were obtained in 135 vessels, and the angle-corrected velocities (peak systolic, end diastolic, mean) were significantly different (P= .001, P= .006, P < .001) among the MRA grades: grade 1 (100, 47, 68 cm/s), grade 2 (171, 72, 110 cm/s), grade 3 (226, 79, 134 cm/s), grade 4 (61, 26, 39 cm/s). Additionally, an angle-corrected MCA peak systolic velocity ,120 cm/s correlates with intracranial stenosis on MRA (grade 2 or worse) with high specificity (90.5%; 95% confidence interval = 78.5%,96.8%) and positive predictive value (93.9%) but relatively low sensitivity (66.7%; 95% confidence interval = 61.2%,69.5%) and negative predictive value (55.1%). Conclusion. Elevated MCA velocities on TCCS correlate with intracranial stenosis detected on MRA. An angle-corrected peak systolic velocity ,120 cm/s is highly specific for detecting intracranial stenosis as defined by significant MRA abnormality. [source] Circulating endothelial microparticles as a marker of cerebrovascular disease,ANNALS OF NEUROLOGY, Issue 2 2009Keun-Hwa Jung MD Objective Circulating endothelial microparticles (EMPs) have been reported to reflect vascular damage. Detailed profiling of these blood endothelial markers may adumbrate the pathogenesis of stroke or enable determination of the risk for stroke. We investigated EMP profiles in patients at risk for cerebrovascular disease. Methods We prospectively examined 348 consecutive patients: 73 patients with acute stroke and 275 patients with vascular risk factors but no stroke events. We quantified various types of EMPs by flow cytometry using CD31, CD42b, annexin V (AV), and CD62E antibodies in the peripheral blood of patients. This method allowed fractionation of CD31+/CD42b,, CD31+/AV+, and CD62E+ EMPs. Clinical and laboratory factors associated with EMPs were assessed. Results Recent ischemic episodes were found to be more strongly associated with greater CD62E+ EMP levels than with levels of other phenotypes. Increased National Institutes of Health Stroke Scale scores and infarct volumes in acute stroke patients were significantly associated with greater CD62E+ EMP levels. In the risk factor group, patients with extracranial arterial stenosis had greater CD62E+ EMP levels, whereas those with intracranial arterial stenosis had greater CD31+/CD42b, and CD31+/AV+ EMP levels. The ratio of CD62E+ to CD31+/CD42b, or CD31+/AV+ EMP level significantly discriminated extracranial and intracranial arterial stenosis. Interpretation Circulating EMP phenotypic profiles reflect distinct phenotypes of cerebrovascular disease and are markers of vascular pathology and an increased risk for ischemic stroke. Ann Neurol 2009;66:191,199 [source] | ||||||||||