Journal of neuroimaging : official journal of the American Society of Neuroimaging
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The authors attempt to determine whether hemodynamically significant extracranial internal carotid artery (ICA) lesions correlate with the severity of first-ever hemispheric ischemic stroke. ⋯ There is no positive correlation of stroke severity with the severity of duplex findings, which may be due to low prevalence of significant ICA lesions or other stroke mechanisms. Most of the patients had mild stroke, and the majority had ICA stenosis < 50%. Small-vessel occlusion tended to have mild severity of stroke. Intracranial artery lesions or other factors causing stroke in Taiwanese should be investigated. Given the low incidence of significant extracranial carotid disease in symptomatic Taiwanese stroke patients, routine screening of symptomatic Taiwanese for extracranial carotid artery disease does not provide enough information to determine stroke mechanism, and transcranial Doppler should be added to the screening tests.
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Cerebral vasoreactivity can be studied with transcranial Doppler (TCD) by monitoring CO2-induced middle cerebral artery (MCA) velocity changes. Expected MCA mean velocity (Vm) changes due to changes in end-expiratory CO2 (EE-CO2) are established, but reactivity of common carotid artery (CCA) volume flow rate (VFR) has not been extensively reported. The authors assess the relationship between MCA Vm, CCA VFR, and EE-CO2. ⋯ MCA Vm increased 0.3 cm/s for each ml/min increase in CCA VFR. In normal individuals, there is a direct correlation between MCA Vm, CCA VFR, and EE-CO2. Measurement of CCA VFR changes during CO2 inhalation may be an alternative method to estimate cerebral vasoreactivity when the MCA velocity cannot be obtained because of inadequate acoustic temporal windows.
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Stroke patients with paradoxical embolus mandate a search for deep venous thrombosis (DVT) in the lower extremities. Iliac vein compression, or May-Thumer syndrome, places certain patients at risk for development of DVT. The authors present 3 stroke patients with patient foramen ovale and paradoxical cerebral embolism, with demonstrated iliac vein compression as the presumed source of their embolus. May-Thumer syndrome should be considered a potential source of clot, as definitive therapy of this disorder can be curative.
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High-resolution magnetic resonance images obtained in a patient several months after carbon monoxide (CO) intoxication revealed nearly symmetric regional atrophy of both lateral temporal lobes. This pattern of cortical lesions after CO exposure has not been reported before. The patient suffered from severe cognitive deficits including a transient Klüver-Bucy-like behavior. This report underlines the value of high-resolution magnetic resonance imaging in chronic stages of CO intoxication in the attempt to understand the neuroanatomical bases of the observed behavior.
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The authors establish accuracy parameters of a broad diagnostic battery for bedside transcranial Doppler (TCD) to detect flow changes due to internal carotid artery (ICA) stenosis or occlusion. ⋯ In symptomatic patients, bedside TCD can accurately detect flow changes consistent with hemodynamically significant ICA obstruction; however, TCD should not be a substitute for direct carotid evaluation. Because TCD is sensitive and specific for a > or = 70% carotid stenosis or occlusion in both extracranial and intracranial carotid segments, it can be used as a complementary test to refine other imaging findings and detect tandem lesions.