The Prevalence of Asymptomatic Intracranial Large-Vessel Occlusive Disease: The Role of Diabetes

OBJECTIVE: To investigate the prevalence of asymptomatic intracranial stenosis using transcranial Doppler ultrasonography in patients with evidence of asymptomatic carotid stenosis. BACKGROUND: Symptomatic atherosclerotic intracranial largeartery stenosis accounts for approximately 10% of ischemic strokes annually. It is unknown whether a significant risk for stroke is associated with asymptomatic intracranial stenosis, especially in patients with known asymptomatic carotid disease. DESIGN AND METHODS: Transcutaneous real-time B-mode Doppler ultrasonography was performed on 510 patients referred for the evaluation of asymptomatic carotid bruits. A peak systolic flow velocity > 1.40 m/s indicated carotid stenosis. Transcranial Doppler ultrasound was performed to identify intracranial large-artery disease. The peak systolic flow velocity indicating stenosis was > 120 cm/s for anterior circulation and > 100 cm/s for posterior circulation. Demographic and cerebrovascular risk factor information was recorded at the time of examination. Chi-square analysis with Pearson correction was performed to examine the significance of the findings. RESULTS: Five hundred ten patients (252 male, 258 female) aged 71.4 +/- 10.45 years were studied. The laboratory's accuracy was previously established as 93% for each technique for laboratory certification. Two hundred patients (39.2%) were found to have extracranial carotid stenosis, and 66 (12.9%) were found to have intracranial stenosis. Thirty-seven patients (56%, P < .01) were found to have concurrent stenosis. In patients with intracranial stenosis, 19 (28.8%, P < .03) had diabetes, and 26 (39.4%, p < .03) had coronary disease. There was no corresponding correlation with extracranial carotid disease and diabetes or coronary artery disease. CONCLUSIONS: The prevalence of patients with asymptomatic intracranial stenosis with concurrent carotid stenosis was greater than expected. Coexisting diabetes and coronary disease were significant risk factors in this population. Doppler ultrasonography may be a useful technique in delineating asymptomatic intracranial stenosis in those patients with existing carotid stenosis. Further studies are needed to clarify the risk of this population for stroke from asymptomatic intracranial stenosis and to determine optimal therapy.     

Noninvasive imaging of atherosclerotic plaque in the arch of the aorta with transcutaneous B-mode ultrasonography

Atherosclerotic plaque at the arch of the aorta has been identified as a potential source for atheroembolic stroke. Imaging of aortic arch plaque can be performed with transesophageal echocardiography (TEE), but TEE is an invasive procedure. A new noninvasive method has been developed to image aortic arch plaque employing transcutaneous real time B-mode ultrasonography with color flow duplex Doppler. B-mode imaging has an 86% accuracy for identifying complex aortic arch plaques as compared with TEE. Noninvasive imaging of the aortic arch can be employed in diagnosing the etiology of cerebrovascular disease in patients with stroke or transient ischemic attack in conjunction with duplex B-mode sonography of the extracranial carotid arteries. It also provides a noninvasive method for studying atherosclerotic plaque in the aortic arch which is applicable for investigational studies of the mechanisms of atherosclerosis and evaluation of pharmacological agents designed to treat atherosclerotic disease.     

Risk factors for atherosclerosis of cervicocerebral arteries: intracranial versus extracranial

OBJECTIVES: To search for factors determining the site of atherosclerosis of the cervicocerebral arteries in patients from Bangkok (Thailand) with ischemic stroke in the carotid territory. MATERIAL AND METHODS: Patients with the clinical syndrome of stroke or transient ischemic attack in the carotid territory or with ocular stroke were retrospectively studied. They were divided into an intracranial and an extracranial carotid stenosis group based on their vascular imaging. The stroke risk factors were then compared. RESULTS: There were 49 cases with extracranial carotid stenosis and 51 with intracranial stenosis. Among the patients with extracranial stenosis, 98% had associated intracranial disease, whereas none of those with intracranial stenosis had more than 50% of extracranial carotid stenosis. The presence of diabetes mellitus and a history of ischemic heart disease were found to be significantly more prevalent among patients with extracranial internal carotid artery stenosis. CONCLUSION: Diabetes mellitus as well as a history of ischemic heart disease were found to be more significantly prevalent in patients with combined extracranial internal carotid artery and intracranial stenosis. Extracranial carotid stenosis might represent a more severe atherosclerotic process of the cervicocerebral circulation when compared with intracranial stenosis.     

缺血性脑卒中患者动脉粥样硬化分布的临床研究

目的探讨急性缺血性脑卒中不同亚型与颈动脉粥样硬化分布的相关性。方法通过经颅多普勒超声(TCD)和颈动脉彩色多普勒血流成像(CDFI)方法检测颅内、外动脉粥样硬化程度,并结合病史、生化指标及影像学提示的病变部位进行综合分析。结果411例急性缺血性脑卒中患者,颅内动脉狭窄率为38.93%(160/411),颈动脉颅外段狭窄率24.09%(99/411)。颈动脉颅外段狭窄者年龄大、吸烟比例高,与无狭窄者比较差异有统计学意义(P=0.020,0.013);而颅内动脉狭窄者糖尿病发病率明显高于无狭窄者(P=0.005)。411例中皮质梗死49例、皮质下梗死108例、腔隙性梗死72例和短暂性脑缺血发作30例,颈动脉颅外段狭窄者以皮质梗死为主(P=0.001),并且动脉内-中膜层厚度明显增加(P=0.020);而颅内动脉狭窄者以腔隙性梗死更多见(P=0.016)。颅内、外动脉狭窄者的年龄、性别、血糖及血脂之间差异无统计学意义(均P>0.05)。结论临床和影像学检查所确定的急性缺血性脑卒中亚型与颅内、外动脉粥样硬化的病变部位相关,提示发病的原因可能不同。糖尿病与吸烟是引起颅内、外动脉病变的重要原因。     

闭塞性脑血管病经颅多谱勒超声和脑血管造影的比较

观察经颅多谱勒超声对颈部和颅内血管狭窄诊断的可靠性。方法收集患者１１０例，分为非脑血管病，非闭塞性脑血管病、闭塞性脑血管病三组。分别用２Ｈｚ和４Ｈｚ多谱勒探头检查颅脑和颈部大动脉的血流速度，然后做数字减影血管造影。结果在闭塞性脑血管病驵菘检查血管７７１条，多谱勒超声发现狭窄血管１２４条，６４７条正常，其中１１３第与ＤＳＡ所见一致，ＤＳＡ发现另外１８条狭窄的智力 。     

Cerebrovascular ultrasound

Rapid progress in noninvasive ultrasound techniques has resulted in a wide variety of clinical applications for assessment of both extracranial and intracranial arterial diseases. Recent highlights in cerebrovascular ultrasound research include imaging methods for characterization of intracranial aneurysms, use of echocontrast agents for improved evaluation of acute stroke patients and transient response harmonic imaging for depiction of brain perfusion. The important role of transcranial Doppler microembolism detection in carotid endarterectomy has been defined, new approaches to noninvasive Doppler measurement of intracranial pressure are progressing, and the clinical indications for transcranial Doppler monitoring of intracranial vasospasm to prevent secondary stroke have expanded. New functional transcranial Doppler applications, which are complementary to positron emission tomography and functional magnetic resonance imaging studies, are evolving for evaluation of functional recovery after stroke; investigation of perfusion asymmetries during complex spatial tasks; assessment of hemispheric dominance in surgical candidates for epilepsy surgery; and elucidation of temporal patterns of regional neuronal activity. With increasing sophistication of cerebrovascular ultrasound methodology, it is essential that standards for data acquisition and interpretation be established. Three recent consensus meetings have provided detailed recommendations on quantification of carotid artery stenosis, on characterization of carotid artery plaques and on microembolism detection by transcranial Doppler.     

Ultrasonography for Diagnosis and Management of Carotid Artery Atherosclerosis; A Position Paper of the American Society of Neuroimaging

The importance of identifying patients with carotid artery stenoSIS has attained greater significance in light of recent treatment tnals of the efficacy of medical and surgical treatment of both symptomatic and asymptomatic carotid stenosis. Doppler and B-mode ultrasonography can accurately diagnose and quantify stenosis at the cervical carotid artery bifurcation. The development of duplex color-flow instruments has enhanced the sensitivity and specificity of this examination. Ultrasonography should be employed as an mitial examination to identify patients with carotid artery stenosis and determine whether further evaluation or treatment is necessary.     

Can simple clinical features be used to identify patients with severe carotid stenosis on Doppler ultrasound?

OBJECTIVES—Carotidendarterectomy reduces the risk of stroke in symptomatic patients withsevere ipsilateral carotid stenosis. Symptomatic patients shouldtherefore undergo carotid Doppler imaging, but in some centres accessto imaging is limited. It was therefore investigated whether simpleclinical features alone or in combination could be used to identifypatients with severe carotid stenosis, so that they could be referredpreferentially for carotid imaging.
METHODS—1041 patientswith acute stroke, cerebral or retinal transient ischaemic attacks, andretinal strokes admitted to Western General Hospital or seen inneurovascular clinics were assessed by a stroke physician. Theircarotid arteries were investigated using colour Doppler imaging by aconsultant neuroradiologist. Patients with primary intracerebralhaemorrhage, total anterior circulation strokes, posterior circulationstrokes, or posterior circulation transient ischaemic attacks wereexcluded because carotid surgery would be inappropriate.
RESULTS—726 patientswere used in the analysis. Stepwise logistic regression showed thatthere were significant positive associations between severe carotidstenosis and an ipsilateral bruit, diabetes mellitus, and previoustransient ischaemic attacks; and a negative association with lacunarevents. The strategy with the highest specificity (97%) was "anythree of these four features" but sensitivity was only 17%. Thestrategy with the highest sensitivity (99%) was to use one or more ofthe four features, but specificity was only 22%.
CONCLUSION—None of thestrategies identified all patients with severe carotid stenosis with areasonable specificity. When access to carotid imaging is severelylimited, simple clinical features are of some use in prioritisingpatients for imaging, but access to carotid imaging should be improved.

     

压力导丝在颈动脉支架成形术中的应用

研究背景目前对于颈动脉狭窄临界性病变尚缺乏相应的治疗标准,颈动脉支架成形术需要更加直观的参考标准,本研究旨在探讨压力导丝用于颈动脉支架成形术的可能性,以及压力阶差对颈动脉支架成形术适应证选择的指导作用。方法选择2012年5-10月施行颈动脉狭窄支架成形术治疗的患者共32例,分别于手术前后根据颈动脉彩色超声、CT灌注成像及术中支架植入前后颈动脉血管内压力阶差变化,评价颅内血流代偿情况。结果术前颈动脉超声检查显示32例患者颈动脉狭窄率均≥70%或接近闭塞,狭窄血管收缩期峰值流速为184～718cm/s;术中全脑血管造影狭窄率达50%～70%者7例、>70%～90%者16例、>90%者9例,颈动脉超声与脑血管造影符合率约为84.38%(27/32)。术中颈动脉压力阶差获取率为100%,术前压力阶差为10～92mmHg、平均(41.45±25.50)mmHg,术后为0～15mmHg、平均(3.44±3.47)mmHg。根据全脑血管造影检查,颅内血供代偿良好者4例、不良者28例。结论压力导丝可以安全有效的获得颈动脉狭窄两端的压力阶差,对于缺乏颅内代偿的颈动脉狭窄患者,随着狭窄程度的加重,在一定范围内其颈动脉压力阶差亦随之增加。因此对于压力阶差较低的颈动脉狭窄患者施行支架成形术治疗时需综合考虑。     

Intracranial dissection mimicking transient cerebral arteriopathy in childhood arterial ischemic stroke

Transient cerebral arteriopathy is a frequent cause of childhood arterial ischemic stroke. Differentiating this condition from intracranial carotid artery dissection is challenging but important for initial treatment. We describe 4 cases from the International Pediatric Stroke Study of intracranial carotid artery dissection, initially misdiagnosed as transient cerebral arteriopathy. Presentations were abrupt, with focal neurological deficits in 4, preceding headache in 3, and minor trauma in 1. Infarcts involved the anterior circulation, and magnetic resonance angiography showed unilateral arterial stenosis/occlusion. None had evidence of dissection. All received anticoagulation or thrombolysis. Three died from refractory intracranial hypertension. Intracranial carotid artery dissection was confirmed postmortem (n = 3) and on dedicated MR wall imaging showing intramural hematoma (n = 1). In differentiating transient cerebral arteriopathy from intracranial carotid artery dissection, routine magnetic resonance angiography is unreliable and adjunctive conventional angiography, gadolinium magnetic resonance angiography, or dedicated MRI wall imaging should be considered.     

64排螺旋CT血管成像诊断前循环颅内段血管狭窄的应用价值

目的 探讨64排螺旋CT血管成像评价前循环颅内段血管狭窄的临床价值.方法 选取80例前循环缺血性卒中患者为实验组,同期60例非缺血性卒中患者为对照组,入院1周内行头颈联合扫描CTA,检测双侧颈动脉（颈总动脉、颈内动脉、大脑中动脉、大脑前动脉）血管狭窄程度.结果 实验组血管狭窄的检出率（91%）明显大于对照组（73%）,且实验组中各段血管狭窄的检出率明显高于对照组,差异有统计学意义（P=0.005）,颈动脉颅内段中重度狭窄比颅外段明显增高,差异有统计学意义（P=0.038）.结论 64排螺旋CT血管成像对前循环颅内段血管狭窄的评价有较高的临床应用价值.     

Comparison of ultrasound and IV-DSA for carotid evaluation

Sixty carotid bifurcations in 34 symptomatic patients were examined prospectively with ultrasound (continuous wave Doppler and high resolution, B-mode imaging) and intravenous digital subtraction angiography (IV-DSA). The overall quality of examination was better with DSA than with ultrasound. Imaging of the external carotid artery was particularly difficult with sonography. For evaluation of the common and internal carotid arteries, eight percent of IV-DSA studies were poor or inadequate as compared with 12% for B-mode imaging. Overall for detection of atherosclerotic plaque, high resolution B-mode sonography was 84% sensitive and DSA 81% sensitive. When only the common and internal carotid arteries were considered, the sensitivity of high resolution sonography improved to 93% and the sensitivity of IV-DSA increased to 86%. Ultrasound (combined high resolution, B-mode sonography and CW Doppler) correctly identified all six internal carotid occlusions in the series. While IV-DSA correctly identified five of the six occlusions, the sensitivity for detection of lesions causing 70% or more stenosis was 95% for both ultrasound and IV-DSA. Sensitivity for 50% or greater obstruction was 79% for ultrasound and 85% for IV-DSA. Ultrasound sensitivity for greater than 50.9% stenoses rose to 87% when only the common and internal carotid were considered while IV-DSA sensitivity remained at 85%. Specificity was good at all levels of obstruction. It may be concluded from this study that the accuracy of ultrasound and IV-DSA are quite similar for evaluation of the carotid bifurcation and that either test is a satisfactory screening method for carotid bifurcation atheromatous disease.     

颈动脉粥样硬化斑块无创性高分辨力磁共振成像研究进展

颈动脉粥样硬化性狭窄与脑卒中复发密切相关。目前颈动脉狭窄的治疗方法主要包括药物治疗和外科手术(颈动脉支架成形术和颈动脉内膜切除术)。脑卒中预防在于识别颈动脉狭窄危险因素,筛查脑卒中复发高危患者,从而使其从药物治疗或外科手术中获益,然而目前仅根据颈动脉狭窄程度制定治疗方案,缺乏个体化治疗。近年来,新型影像学技术如无创性高分辨力磁共振成像(HRMRI)等,可以检测出颈动脉易损斑块。与传统数字减影血管造影术测量的颈动脉狭窄程度相比,无创性HRMRI可以根据颈动脉斑块特征准确预测同侧脑卒中风险,从而指导个体化治疗。     

Is Doppler ultrasound sufficient as the sole investigation before carotid endarterectomy?

BACKGROUND AND AIMS: Doppler ultrasound (DU) of the extracranial carotid arteries has been advocated as the sole imaging modality in carotid endarterectomy (CE) candidates. However this approach fails to identify patients with potentially significant intracranial disease, at high risk of stroke and death. Therefore, many stroke clinicians recommend angiography after screening DU. We aimed to identify the proportion of cases referred for CE in whom the identification of intracranial disease could have altered management. METHODS: Two neuroradiologists, blinded to the clinical history, reviewed the films of 111 CE candidates, predominantly of Caucasian background, who had undergone carotid angiography after screening DU. Intracranial stenoses >50% luminal diameter, incidental aneurysms and non-atherosclerotic lesions were documented. Demographic and epidemiological data were collected. RESULTS: Of the 111 patients, 87 had >50% extracranial stenoses although two thirds were asymptomatic. Intracranial stenotic lesions were recorded in 29% of patients. Over half of these were tandem lesions, distal to an extracranial stenosis. Aneurysms were found in 4.5% of patients. CONCLUSIONS: DU alone would have failed to detect significant intracranial disease in nearly a third of cases. These patients are at high risk of stroke. The identification of this group allows more aggressive stroke prevention therapy.     

Color velocity imaging: introduction to a new ultrasound technology.

Noninvasive ultrasound is the preferred methodology for the initial evaluation of carotid atherosclerosis. Since the early use of continuous-wave Doppler to assess carotid artery flow velocity blindly, neurosonology has progressed through crude B-mode imaging, spectral analysis of the Doppler signal, and gray-scale duplex Doppler/B-mode imaging, to color-flow Doppler duplex imaging. The latter allows color coding of Doppler data based on the velocity of blood flow. The combination of color-flow Doppler with gray-scale B-mode imaging allows simultaneous visual display of anatomical and hemodynamic information. Physical limitations of color-flow duplex Doppler imaging may affect the clinical utility of these techniques. Problems with pulse repetition frequency, aliasing, resolution capability of the color data, and interpolation of data make some applications difficult. Color velocity imaging uses the data contained in the gray-scale B-mode image scan lines to determine velocity of blood flow, and it offers potential advantages over conventional color-flow duplex Doppler for the assessment of carotid atherosclerosis and hemodynamics. Initial comparison of spectral Doppler and color velocity imaging data suggests that the latter is an accurate method to assess blood flow velocity. Understanding of the validity, utility, and prognostic advantages offered by color velocity imaging awaits careful prospective clinical trials.     

Transcranial Doppler in Asymptomatic Carotid Stenosis Representing Hemodynamic Impairment: Correlation Study with Magnetic Resonance Imaging

BACKGROUND AND PURPOSE: Since the benefit of an endarterectomy in an asymptomatic carotid stenosis is not as clear as that in symptomatic stenosis, identifying patients with a high risk of stroke will allow the improved selection of surgical candidates. To evaluate the role of transcranial Doppler (TCD) in assessing an asymptomatic stenosis, this study examined the association of a TCD-detected hemodynamic change with a stenosis-related abnormality on magnetic resonance imaging (MRI). METHODS: Asymptomatic patients with a more than 60% internal carotid artery stenosis were enrolled in this study. The hemodynamic change in the TCD was analyzed in terms of the demographic characteristics, the stroke risk factors, and the stenosis-related MRI abnormalities that are a proven risk factor of a further stroke. RESULTS: Fifty-three patients were retrospectively recruited. While there were no differences in the demographic characteristics or frequency of the stroke risk factors, the proportion of patients with stenosis-related MRI abnormality was significantly higher in patients with a hemodynamic change on TCD (13/19 vs 6/34, P < .01; odds ratio = 10.11; 95% confidence interval = 2.73-37.4). CONCLUSIONS: The TCD-detected hemodynamic changes may provide useful information for assessing the frequency of silent stroke in patients with an asymptomatic carotid stenosis.     

经颅彩色双功能超声在成人中的临床应用

经颅彩色双功能超声（transcranial color-coded duplex sonography,TCCS）将二维灰阶实时显像、彩色多普勒血流显像和多普勒频谱分析技术结合在一起,非侵入性观察脑实质和颅内血管的解剖结构和毗邻关系,以色彩显示血管的部位、形态、走行和血流方向,同时探测其多普勒频谱信号。本文综述了其在成人疾病中的临床应用,包括卒中、动静脉畸形、动静脉瘘、颅内动脉瘤、脑静脉血栓形成及其他疾病。并讨论了TCCS优势和局限性。     

Advances in transcranial doppler ultrasonography

Transcranial Doppler ultrasonography (TCD) is the only noninvasive real-time neuroimaging modality for the evaluation of characteristics of blood flow in basal intracerebral vessels that adds physiologic information to structural imaging. TCD has been rapidly evolving from a simple noninvasive diagnostic tool to an imaging modality with a broad spectrum of clinical applications. In acute stroke, TCD can provide rapid information about vascular stenosis and occlusion, the hemodynamic status of the cerebral circulation, and real-time monitoring of recanalization. Extended applications such as vasomotor reactivity testing, emboli monitoring, and right-to-left shunt detection help clinicians ascertain stroke mechanisms at the bedside, plan and monitor treatment, and determine prognosis. In the neurointensive care unit, TCD is useful for detecting increased intracranial pressure and confirming cerebral circulatory arrest. TCD is of established value for screening children with sickle cell disease and detecting and monitoring vasospasm after spontaneous subarachnoid hemorrhage.     

Endothelial dysfunction and systemic inflammation in persons with echolucent carotid plaques

Echolucent carotid plaques are associated with high risk for future ischemic cerebrovascular events independent of the degree of stenosis. Elevated levels of markers of systemic inflammation and endothelial dysfunction are predictors for future myocardial infarction and stroke. The present study was undertaken to investigate the relations between plaque morphology, endothelial dysfunction assessed by tissue-plasminogen activator antigen (t-PA ag) and vonWillebrand factor (vWF), and systemic inflammation in persons with carotid stenosis. We conducted a crosssectional study including 133 persons with carotid stenosis and 138 controls without stenosis recruited from the populationbased Troms? Study. High-resolution B-mode and colour Doppler/pulsed-wave Doppler ultrasonography of both carotid arteries was performed, and plaque morphology in terms of echogenicity was assessed. Persons with carotid stenosis had significantly higher plasma t-PA and vWF concentrations than controls. There was a significant inverse relationship between t-PA ag and plaque echogenicity (p = 0.034). The increased plasma t-PA ag in persons with carotid stenosis was not associated with increased plasminogen activator inhibitor-I (PAI-1). Persons with echolucent carotid plaques had higher degree of systemic inflammation, and plasma t-PA and vWF concentration increased significantly across quartiles of WBC, fibrinogen, and hs-CRP. Our findings may suggest that plasma t-PA may be superior to vWF as a marker for endothelial dysfunction due to its ability to discriminate between various plaque echogenicity, and that the predictive role of t-PA ag in cardiovascular disease is independent of inhibited fibrinolysis.