大脑中动脉狭窄程度与不同急性脑梗死模式的相关性研究

目的探讨大脑中动脉(MCA)狭窄程度与不同急性脑梗死病变模式的关系。方法回顾性分析324例急性脑梗死患者,根据头颅磁共振弥散加权成像(DWI)和磁共振血管成像(MRA),MCA狭窄程度分为轻、中、重度,患者梗死模式分为:单发性梗死(包括小的穿支动脉供血区梗死、大的穿支动脉供血区梗死、皮质分支动脉供血区梗死和大面积梗死)、分水岭梗死(CWI)和多发性梗死。比较不同模式的急性脑梗死患者的MCA病变情况。结果 324例急性脑梗死患者中,MCA狭窄致穿支动脉(PAI)梗死最为多见,占137例(42.28%);PAI患者MCA重度狭窄率与其他单发性梗死、多发性梗死和内分水岭梗死(IWI)患者相比较,差异具有统计学意义(P0.01)。内分水岭梗死、多发性梗死和大面积梗死的MCA重度狭窄率高于小穿支动脉梗死、大穿支动脉梗死、皮质穿支动脉梗死和外分水岭梗死(P0.05),而内分水岭梗死、多发性梗死和大面积梗死之间的MCA重度狭窄率相比差异无统计学意义(P0.05)。结论 MCA狭窄致PAI最为多见,但是MCA重度狭窄并非是PAI的重要原因;MCA重度狭窄易导致CWI(尤其是IWI)和多发性梗死;MCA重度狭窄也是导致LTI重要原因之一。     

颈内和大脑中动脉狭窄与闭塞的梗死类型及卒中机制的研究

目的 研究单侧动脉粥样硬化性MCA/ICA狭窄与闭塞的急性缺血性脑卒中患者在DWI上的梗死类型及发病机制.方法 起病48h内DWI诊断的急性脑梗死伴有动脉粥样硬化性MCA/ICA狭窄与闭塞的131例患者,有潜在心源性栓子患者除外.急性期DWI上梗死病灶分为：（1）单发病灶（小的穿动脉梗死灶;大的穿动脉梗死灶,皮层支梗死,大面积梗死,分水岭梗死）;（2）多发梗死病灶.结果 131例患者,ICA51例,MCA80例.ICA出现最多的梗死类型：穿支动脉伴分水岭梗死,但与MCA比较,皮层支伴分水岭梗死具有统计学意义（8/51,P=0.001）.MCA以穿支动脉伴皮层支梗死最多,且与ICA比较,具有统计学意义（12/80,P=0.003）.MCA中任何皮层支梗死与狭窄程度无关,ICA中任何分水岭梗死与狭窄程度相关.结论 颈内和大脑中动脉狭窄与闭塞在DWI上的梗死类型有明显的不同,提示有着不同的卒中发病机制.     

大脑中动脉狭窄与其深穿支供血区单发脑梗死的关系

目的 分析大脑中动脉(MCA)深穿支供血区单发脑梗死的形态学表现,进一步探讨其与MCA狭窄的关系.方法 连续入选2005年1月至2006年12月于北京协和医院神经科住院治疗急性脑梗死,并经头颅DWI检查明确急性梗死灶为单发,且位于MCA深穿支供血区域的55例患者;所有患者均行TCD和MRA检查,颅外颈内动脉狭窄>50%以及有可疑心源性栓子来源的患者从研究中排除.根据是否存在病灶同侧MCA狭窄将入选患者分为两组:MCA狭窄组(14例)与MCA正常组(41例).测量DWI上急性梗死灶的直径、面积和体积,并将直径≤2 cm归为经典腔隙性梗死,直径>2 cm归为纹状体内囊梗死.DWI上的梗死灶区分为基底节区、侧脑室体旁和同时累及上述2个部位,并判断MRI T2>像上皮质下多发陈旧性小梗死灶或白质疏松是否存在.结果 55例患者中,病灶侧MCA狭窄患者14例(25.5%),MCA正常患者41例(74.5%).MCA狭窄组中经典腔隙性梗死占71.4%,MCA正常组中经典腔隙性梗死占67.3%,差异无统计学意义(χ2=0.147,P=0.701).MCA狭窄组与正常组患者MCA深穿支梗死病灶的大小(包括直径、面积及体积)差异均无统计学意义.MCA正常组和MCA狭窄组病灶在基底节区、侧脑室体旁及基底节区+侧脑室体旁分布的比例依次为:正常组31.7%、17.1%和51.2%;狭窄组35.7%、28.6%和35.7%,两组间差异无统计学意义(χ2=1.272,P=0.529).同时存在皮质下多发陈旧性小梗死灶或白质疏松的患者在MCA正常组有23例(56.1%),在MCA狭窄组有3例(21.4%),二者差异有统计学意义(χ2=5.033,P=0.025).结论 MCA深穿支供血区梗死具有不同的发病机制,MCA狭窄和穿支动脉本身病变均可造成深穿支供血区单发脑梗死.梗死灶的大小、体积及梗死发生的部位与是否存在同侧大脑中动脉狭窄无明显相关性,而同时存在皮质下多发陈旧性小梗死灶或白质疏松对穿支动脉病变有提示作用.     

颈内和大脑中动脉重度狭窄或闭塞的分水岭梗死类型与机制的研究

目的研究单侧动脉粥样硬化性大脑中动脉(MCA)及颈内动脉(ICA)重度狭窄或闭塞所致急性缺血性脑卒中患者分水岭梗死(WI)类型及发病机制。方法起病48h内DWI诊断的急性分水岭梗死伴有动脉粥样硬化性MCA/ICA重度狭窄与闭塞的患者102例,其中MCA组38例,ICA组64例,有潜在心源性栓子患者除外。急性期DWI上分水岭梗死病灶分为:(1)单纯分水岭梗死病灶;(2)含分水岭梗死的多发梗死病灶。结果 ICA组单纯分水岭梗死病灶较多,其中前+内分水岭梗死的例数最多,与MCA组比较具差异有统计学意义(P<0.05);ICA组复合梗死病灶中,出现最多的梗死类型为穿支动脉伴分水岭梗死,与MCA组比较差异具有统计学意义。MCA组以穿支动脉伴皮层支梗死伴分水岭梗死最多,且与ICA组比较,差异具有统计学意义(P<0.05)。结论颈内和大脑中动脉重度狭窄与闭塞所致分水岭梗死的类型有明显的不同,提示有着不同的发病机制。     

大脑中动脉粥样硬化性狭窄患者卒中类型分析

目的研究大脑中动脉粥样硬化性狭窄或闭塞(MCAOD)患者的卒中类型及其发病机制。方法经TCD和(或)MRA确诊的症状性MCAOD的患者,依据头部弥散加权核磁成像(DWI)所示梗死灶的特点进行分类,并与MCA狭窄程度进行相关性分析。结果84例症状性MCAOD患者中,73.8%的患者表现为多发性脑梗死,主要累及内交界区(53.6%)、半卵圆中心(29.1%)和皮层(22.6%)。皮层区域内梗死、交界区梗死、深部小梗死灶的发生率分别为46.4%、56.0%和44.0%,以多发小灶性梗死为主,很少引起MCA主干支完全梗死。且皮层支完全梗死、半卵圆中心梗死与严重MCA狭窄有关,而腔隙样梗死多见于轻度MCAOD患者。结论MCAOD患者可表现为各种梗死类型,以交界区梗死最常见,且多发性脑梗死为MCAOD患者最常见的表现类型,主要累及皮层下白质等部位,病灶以链型或弧线型分布为特点,动脉-动脉栓塞为其发病机制之一;深部小梗死多为孤立病灶,与MCA主干粥样硬化斑继发的血栓堵塞豆纹动脉入口有关。     

烟雾病患者微栓子信号与临床表现及梗死灶关系的初步观察

目的 分析烟雾病患者的微栓子信号（microembolic signal,MES）与临床表现及梗死灶的关系。方法 总结了6例在常规经颅多普勒超声（transcranial Doppler,TCD）检查中出现MES的烟雾病患者的临床资料及弥散加权成像（diffusion-weighted imaging,DWI）影像资料,分析MES与患者临床表现及DWI上梗死灶之间的关系。结果 6例患者的MES均出现在大脑中动脉（middle cerebral artery,MCA）,3例（50%）闭塞,3例（50%）狭窄。6例中5例（83.33%）患者一个月内出现过缺血性症状,其中3例（50%）症状发生在无MES侧MCA供血区域;1例（16.67%）症状交替发生在MES同侧或对侧MCA供血区;1例（16.67%）为后循环缺血。5例（83.33%）患者DWI上出现梗死灶,在MES同侧MCA供血区内出现梗死灶的共有4（66.67%）例,无MES侧MCA供血区内出现梗死灶的共有5例（83.33%）。均为（100%）多发性梗死,皮层梗死为最常见梗死类型。结论 无论近期是否出现过缺血症状,烟雾病患者狭窄或闭塞的MCA均可发现MES。这些MES的存在与临床症状及梗死灶的相关性有待进一步研究。     

DWI对MCA狭窄患者卒中亚型的诊断

目的:评价弥散加权MRI(Diffusion-weighted imaging,DWl)对MCA狭窄患者急性梗死的诊断价值。方法:经TCD／MRA诊断的症状性大脑中动脉粥样硬化性狭窄(以下简称MCA闭塞性病变:middle cerebral artery occlesive disease MCAOD)患者,分别于病后1周内行头颅水抑制MRI成像(Fluid-attenuated inversion recovery,FLAIR)及DWI检查,比较FLAIR、DWI所示梗死灶的类型和数量。结果:238例症状性MCAOD患者的FLAIR结果表明,单发腑梗死137例(57.6％),多发性脑梗死101例(42.4％)。其中皮层区域内梗死82例(34.5％),深部小梗死120例(50.4％),变界区梗死143例(60.1％)。而内交界区梗死、半卵园中心梗死以及伴随的皮层小梗死的发生率分别为52.9％、22.7％、13.0％,84例MCAOD患者的DWl结果表明,73.8％患者呈多发性脑梗死表现,皮层区域内梗死、交界区梗死、深部小梗死的发生率分别为46.4％、56％和44.0％,而皮层播散性小梗死(22.6％)、半卵园中心梗死(29.1％)的诊断率高于FLAIR结果。结论:DWI对于微小梗死以及多发梗死的诊断明显优于FIAIR成像,尤其对于皮层播散性小梗死灶以及半卵园中心梗死的诊断更敏感,利于卒中亚型的诊断及卒中机制的判断。     

大脑中动脉区梗死的DWI特点及与其供血动脉狭窄的关系

目的 探讨大脑中动脉(MCA)区脑梗死磁共振扩散加权成像(DWI)成像病灶分布特点及与其供血动脉狭窄程度的关系.方法 回顾性的分析经颅脑磁共振成像(MRI)的DWI序列诊断的急性脑梗死,选择病灶位于MCA分布区,且完善其供血动脉检查,包括头颈部CTA,或颅脑MRA加颈部血管超声的患者108例,排除心源性栓塞、特殊血管病变导致的脑梗死.将梗死按照部位分为腔隙型梗死(SSSI)、皮层下梗死(SI)和混合型梗死(MI),供血动脉分为正常、轻度(50％)、重度(50％)和闭塞.比较不同类型梗死组的供血动脉狭窄的发生率.结果 各种梗死类型的发生率之间差异无统计学意义(x2=1.08,P＞0.05).单纯MCA病变者53例(53/108,49.1％),单纯ICA病变者28例(28/108,25.9％),单纯MCA病变高于单纯ICA病变(x2=12.35,P＜0.01).同侧血管正常者以LI类型的梗死多见,而单纯ICA病变者以MI类型的梗死多见(x2=10.22;10.54,P＜0.01);三种梗死类型在单纯MCA病变患者中差异无统计学意义(x2=0.25,P＞0.05);在单纯MCA病变者中,SI梗死类型多见于MCA闭塞患者(x2=7.45,P＜0.05).LI梗死类型多见于MCA轻度或重度狭窄患者(x2=6.39,P＜0.05).结论 结合DWI和相应血管检查对于明确MCA区动脉粥样硬化性脑梗死的病因和机制有一定帮助.基底节区的腔隙梗死,相应血管检查正常提示小血管病的可能大;MCA存在一定狭窄则可能是穿支受累造成;ICA病变多累及皮层,包括皮层型分水岭区梗死;而不同程度的MCA病变其梗死形态没有本质区别,皮层下梗死更多见MCA闭塞患者.     

基于MRI和DSA的ICA、MCA狭窄或闭塞患者发生不同供血区脑梗死的对比分析

目的 探讨颈内动脉(ICA)、大脑中动脉(MCA)狭窄或闭塞引发脑梗死的部位及特点。方法 选取2013年1月～2016年2月本院诊治的98例经头颅磁共振加权成像(DWI)和数字减影血管造影(DSA)确诊的ICA或MCA狭窄或闭塞引发脑梗死患者进行回顾性研究,根据患者起病1周内的DWI确诊梗死部位,对比ICA和MCA狭窄或闭塞引发脑梗死的部位和特点。结果 ICA组患者的完全性前循环脑梗死率(36.00%)显著高于MCA组的12.50%(P<0.05); ICA组的腔隙性脑梗死发生率(26.00%)显著低于MCA组的52.08%(P<0.05); ICA组和MCA组患者的PI、PAI、LTI供血区脑梗死发生率无明显差异(P>0.05); MCA组患者的BZI供血区脑梗死发生率(62.50%)显著高于ICA组的26.00%(P<0.05); ICA组患者的单发性脑梗死发生率(70.00%)显著高于MCA组患者的(47.92%)(P<0.05)。结论 ICA狭窄以单发性脑梗死多见,MCA以多发性脑梗死多见,MCA狭窄或闭塞患者的分水岭梗死发生率高于ICA狭窄或闭塞患者。     

颅内外动脉并发狭窄导致的脑梗死模式

目的 探讨颅内外动脉并发狭窄导致的脑梗死的模式.方法 用CT血管成像(CTA)检测185例急性脑梗死患者的颅内外动脉的狭窄情况;MR弥散加权成像(DWI)检查确定患者的脑梗死模式:单发或多发性脑梗死,穿动脉梗死(PAI)、皮质支梗死(PI)、分水岭梗死(BZI)、大面积脑梗死.比较并发狭窄与非并发狭窄患者的脑梗死模式.结果 CTA示颅内外动脉并发狭窄69例,其中串联狭窄49例、非串联狭窄20例;非并发狭窄99例;无狭窄17例.颅内外动脉并发狭窄组的多发性脑梗死、PAI+ PI+ BZI的比率(55.1％,20.3％)显著高于非并发狭窄组(34.3％,5.1％)(均P＜0.01);而单发小PAI的比率(24.6％)显著低于非并发狭窄组(48.5％)(P＜0.01).并发狭窄组中串联狭窄亚组的多发性脑梗死(65.3％)及PAI+ PI+ BZI(26.5％)的比率显著高于非串联狭窄亚组(30％,5％) (P＜0.05 ～0.01);而单发小PAI的比率(14.3％)显著低于非串联狭窄亚组(50.0％)(P＜0.01).结论 颅内外动脉并发狭窄导致的脑梗死以多发性梗死及PAI+PI+BZI的模式多见.     

Mechanisms of acute cerebral infarctions in patients with middle cerebral artery stenosis: a diffusion-weighted imaging and microemboli monitoring study

Although most therapeutic efforts and experimental stroke models focus on the concept of complete occlusion of the middle cerebral artery as a result of embolism from the carotid artery or cardiac chamber, relatively little is known about the stroke mechanism of intrinsic middle cerebral artery stenosis. Differences in stroke pathophysiology may require different strategies for prevention and treatment. We prospectively studied 30 consecutive acute ischemic stroke patients with middle cerebral artery stenosis detected by transcranial Doppler and magnetic resonance angiography. Patients underwent microembolic signal monitoring by transcranial Doppler and diffusion-weighted magnetic resonance imaging. Characteristics of acute infarct on diffusion-weighted magnetic resonance imaging were categorized according to the number (single or multiple infarcts) and the pattern of cerebral infarcts (cortical, border zone, or perforating artery territory infarcts). The data of microembolic signals and diffusion-weighted magnetic resonance imaging were assessed blindly and independently by separate observers. Diffusion-weighted magnetic resonance imaging showed that 15 patients (50%) had single acute cerebral infarcts and 15 patients had multiple acute cerebral infarcts. Among patients with multiple acute infarcts, unilateral, deep, chainlike border zone infarcts were the most common pattern (11 patients, 73%), and for single infarcts, penetrating artery infarcts were the most common (10 patients, 67%). Microembolic signals were detected in 10 patients (33%). The median number of microembolic signals per 30 minutes was 15 (range, 3-102). Microembolic signals were found in 9 patients with multiple infarcts and in 1 patient with a single infarct (p = 0.002, chi(2)). The number of microembolic signals predicted the number of acute infarcts on diffusion-weighted magnetic resonance imaging (linear regression, adjusted R(2) =0.475, p < 0.001). Common stroke mechanisms in patients with middle cerebral artery stenosis are the occlusion of a single penetrating artery to produce a small subcortical lacuna-like infarct and an artery-to-artery embolism with impaired clearance of emboli that produces multiple small cerebral infarcts, especially along the border zone region.     

Topographic Patterns of Small Subcortical Infarcts Associated with MCA Stenosis: A Diffusion-Weighted MRI Study

BACKGROUND AND PURPOSE: Small subcortical infarcts (SSI, maximum lesion diameter < or =2.0 cm) are usually considered as infarcts caused by small vessel disease. However, SSI can also be associated with large artery occlusive disease such as middle cerebral artery (MCA) stenosis. We performed a prospective study to investigate the relationship between MCA stenosis and SSI distribution and further to investigate the mechanism of SSI caused by MCA stenosis. METHODS: Magnetic resonance angiography (MRA) and diffusion-weighed MRI (DWI) of consecutive acute ischemic stroke patients with recent SSI were studied. The distribution of acute infarcts on DWI was categorized as cortical infarct (CI), border zone infarct (BI), or perforating artery infarct (PAI). RESULTS: Totally, 93 cases were recruited, among which 12 had single SSI with MCA stenosis (group 1) and 26 patients had multiple SSI with MCA stenosis (group 2), while 55 patients without MCA stenosis had single SSI (group 3). For patients with single SSI and MCA stenosis, 6 had BI and 6 had PAI; for patients with multiple SSI and MCA stenosis, 25 had BI, 4 had PAI and 9 had CI (compared with group 1: P= .001); for patients with single SSI but without MCA stenosis, 20 had BI and 35 had PAI (compared with group 1: P= .58). CONCLUSION: Multiple acute infarcts along the border zone are the commonest pattern in small infarcts with MCA stenosis, especially among those with multiple acute infarcts. Our data suggest that hemodynamic compromise and artery-to-artery embolism may be both important factors for infarcts in patients with MCA stenosis.     

Wall characteristics and mechanisms of ischaemic stroke in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study

Objective:: To evaluate the characteristics of atherosclerotic middle cerebral artery (MCA) stenosis by high-resolution magnetic resonance imaging (HR-MRI) and determine the relationship between wall characteristics and infarction patterns.

Methods:: Thirty-six patients with acute ischaemic stroke due to MCA stenosis underwent diffusion-weighted magnetic resonance imaging (DWI) and HR MRI. Wall characteristics of MCA, including irregular surface, superior location, T2-hyperintense of plaques and positive remodelling (PR), were analysed. Characteristics of acute infarct on DWI were categorised according to the number (single or multiple infarcts) and the pattern of cerebral infarcts (cortical, border zone or perforating artery territory infarcts). The relationship between wall characteristics and infarction patterns was evaluated.

Results:: PR was observed in 20 patients, irregular surface plaque in 18 patients, superior location of plaques in 14 patients and T2-hyperintense foci in 13 patients. Seventeen patients had multiple acute cerebral infarcts and 13 showed single acute cerebral infarcts. Border zone infarcts were the most common (76.5%) among multiple acute infarcts. Penetrating artery infarcts (PAI) accounted for 76.9% of all single infarcts. Multiple infarcts were more frequently observed in patients with PR (P = 0.007) or plaque surface irregularity (P = 0.035). Single infarcts, especially PAI, were more prevalent in patients with superior plaque (P = 0.030). No statistically significant differences were observed between multiple and single infarcts in patients with T2-hyperintense lesions (P?=?0.638).

Conclusions:: PR or irregular surface plaques were associated with artery-to-artery embolism. Superior location of plaques was associated with PAI. HR-MRI provides insights into intracranial atherosclerosis in vivo, predictive of infarction patterns.     

交界区脑梗死与脑动脉狭窄或闭塞的关系

目的　观察交界区脑梗死与颅内外主要动脉狭窄或闭塞的关系。方法　回顾性分析经磁共振(MRI)弥散加权成像 (DWI)检查证实的急性交界区脑梗死 4 5例患者的临床资料 ,将交界区梗死部位分为前交界区、后交界区及内交界区 ,利用磁共振血管成像 (MRA)和经颅超声多普勒 (TCD)检查判断颅内外主要动脉有无狭窄或闭塞 ,观察梗死部位与血管受累的情况。结果　 4 5例中共有 32例 (71 1% )存在相应血管狭窄或闭塞。大脑中动脉狭窄出现比例最高 (4 7 6 % ) ,其次为颈内动脉狭窄或闭塞 (31% ) ,大脑前或后动脉狭窄少(11 9% )。动脉异常情况在单交界区与多交界区梗死的患者间无差别 ,但内交界区受累更易合并大脑中动脉狭窄 (P <0 0 5 )。结论　交界区脑梗死患者常存在颅内外主要动脉狭窄或闭塞 ,大脑中动脉狭窄最常见 ,尤其在内交界区受累时。     

A Pilot Study of Microembolic Signals in Patients With Middle Cerebral Artery Stenosis

OBJECTIVE: There has been limited data on the frequency of microembolic signals in patients with middle cerebral artery (MCA) stenosis, especially during the acute phase of stroke. Using transcranial Doppler, the authors prospectively monitored the MCA segments distal to stenosis in 4 groups of patients for 30 minutes: (1) symptomatic patients with acute ischemic stroke and MCA stenosis, (2) asymptomatic group patients with asymptomatic MCA stenosis, (3) control patients with acute ischemic stroke of undetermined etiology, and (4) normal people. A total of 60 patients completed the study. There were no microembolic signals in the asymptomatic, control, and normal groups. Among 20 patients in the symptomatic group, microembolic signals were detected in 3 patients (15%). The number of emboli ranged from 1 to 6 per 30 minutes. This is the first report of the presence of microembolic signals in acute stroke patients with MCA stenosis.     

动脉硬化性大脑中动脉狭窄或闭塞所致脑梗死类型

目的探讨动脉硬化性大脑中动脉狭窄或闭塞性疾病(MCAOD)所致脑梗死的类型。方法对50例经颅脑MRA或DSA确诊的症状性MCAOD患者进行研究,依据其头部弥散加权成像(DWI)和T2W的改变对脑梗死分型。结果50例患者共发现57条动脉硬化性大脑中动脉狭窄或闭塞,未发现病灶的有6(占12．0%)个大脑半球,多发性脑梗死和单发脑梗死分别见于13(占22．8%)个和38(占66．7%)个大脑半球。脑分水岭梗死、流域性脑梗死、半卵圆区脑梗死、多发性散在点状脑梗死(MSSI)、腔隙性脑梗死分别见于18(占31．6%)个、12(占21．1%)个、6(占10．5%)个、2(占3．5%)个和1(占1．8%)个大脑半球。结论MCAOD可引起各种类型的脑梗死,脑分水岭梗死约占1/3,动脉粥样硬化性血栓形成约占1/5,纹状体内囊梗死约占1/5,主要发病机制与动脉-动脉栓塞和低灌注有关。     

Embolism in acute middle cerebral artery stenosis

OBJECTIVE: To investigate the frequency of middle cerebral artery (MCA) stenosis in a series of nonselected patients and the coexistence of microembolic signals with stenosis. METHODS: MCA stenosis was sought by transcranial Doppler (TCD) in 387 patients admitted consecutively with acute ischemic cerebrovascular disease within the first 48 hours of the onset of symptoms and again at 6 months. TCD monitoring for microembolic signals was performed on all patients with MCA stenosis. RESULTS: MCA stenoses were found in 29 patients (7%), although in only 20 patients (5%) was the stenosis symptomatic. Microembolic signals were detected in five of 14 symptomatic stenoses (36%) monitored at the acute phase, but none were found in the chronic phase or in asymptomatic stenosis. Despite one third of symptomatic patients having had a further source of emboli, microembolic signals were detected only distally to the MCA stenosis. In the symptomatic group, 25% of stenoses had completely disappeared 6 months after stroke. Microembolic signal detection at the acute phase was associated with the subsequent disappearance of the stenosis. CONCLUSIONS: The frequency of symptomatic MCA stenosis in acute ischemic stroke was 5% in the population studied. Many stenoses are transient, and microembolic signals are often detectable at the poststenotic segment in the acute phase. The origin of at least 25% of symptomatic acute MCA stenoses may be embolic rather than atherosclerotic.     

Clinically silent circulating microemboli in 20 patients with carotid or vertebral artery dissection

BACKGROUND AND PURPOSE: Carotid and vertebral artery dissections are frequently complicated by cerebral embolism. Detection of clinically silent circulating microemboli by transcranial Doppler sonography (TCD) is now widely investigated in patients with carotid artery disease in the hope to identify patients at increased risk for stroke. METHODS: In 20 patients with carotid (n = 17) or vertebral (n = 2) artery dissection, or both (n = 1), we performed a 1-hour microembolus detection downstream to the dissection in the middle or in the posterior cerebral artery, respectively. RESULTS: Five patients with a carotid artery stenosis of > or = 90% or with carotid artery occlusion showed microembolic signals at a rate of up to 15 events/h. In all these patients, the onset of the dissection was within the last 58 days. Patients with lower degrees of stenosis or onset of symptoms beyond 58 days did not show microembolic signals at all. Three patients who had presented with recurrent ischaemic events prior to TCD monitoring unexceptionally had microembolic signals. CONCLUSION: Microembolic signals occur in patients with high-grade stenosis or occlusion due to acute cervical artery dissection. Patients with microemboli seem to be at increased macroembolic risk, i.e. stroke recurrence, and may require close-meshed clinical follow-up and possibly stronger antithrombotic treatment.     

Circulating microemboli in 33 patients with intracranial arterial stenosis.

BACKGROUND: Intracranial arterial stenosis is a rare cause of stroke in Caucasians. Detection of clinically silent circulating microemboli by transcranial Doppler sonography is now widely investigated in patients with carotid artery disease in the hope to identify patients at increased risk for stroke. METHODS: In 33 patients with intracranial internal carotid (n = 12), middle cerebral (n = 18), posterior cerebral (n = 2), or basilar artery stenosis (n = 1), we performed a 1-hour microembolus detection downstream to the stenosis in the middle or in the posterior cerebral artery, respectively. The stenosis was assessed by transcranial Doppler and duplex ultrasound. 18 patients had been symptomatic in the dependent territory. RESULTS: Five patients with ischaemic symptoms within the last 8 days and with a peak systolic flow velocity of > or =210 cm/s in the stenosis showed microembolic signals at a rate of 3-25 events/h, despite effective anticoagulation. All these 5 patients had a lesion pattern on cranial CT or MRI scan suggesting embolic origin. All the asymptomatic patients (n = 15) and all the patients with a peak systolic intrastenostic velocity of 160 to <210 cm/s (n = 13) did not show microembolic signals at all. CONCLUSION: Microembolic signals occur in recently symptomatic patients with high-grade intracranial arterial stenosis indicated by a sonographically measured stenotic peak flow velocity of > or =210 cm/s. Therapeutic anticoagulation was not sufficient to suppress microemboli formation.     

Cerebral embolism in a patient with polycythemia rubra vera

Polycythemia rubra vera (PRV) is a rare haematological disorder that has a high risk of stroke, although the pathophysiological origin of the cerebral ischaemia in this disease is not well known. We report a case of a stroke patient with PRV in whom bilateral embolic signals were detected by transcranial Doppler (TCD). Cerebral computed tomography showed a cortical middle cerebral artery infarction, echocardiography was normal, duplex-scan showed moderate left carotid stenosis and digital angiography disclosed right siphon stenosis. TCD examinations in the acute phase repeatedly showed a great number of bilateral microembolic signals (MESs). Four months later magnetic resonance angiography showed no flow signal in the right siphon and a severe stenosis of the proximal right MCA. The detection of bilateral MESs in the absence of cardiac sources of embolism observed in this patient suggests that ischaemic cerebral events in PRV may have an embolic origin favoured by a prothrombotic state.