Lesion development and reperfusion benefit in relation to vascular occlusion patterns after embolic stroke in rats

Vascular occlusion sites largely determine the pattern of cerebral tissue damage and likelihood of subsequent reperfusion after acute ischemic stroke. We aimed to elucidate relationships between flow obstruction in segments of the internal carotid artery (ICA) and middle cerebral artery (MCA), and (1) profiles of acute ischemic lesions and (2) probability of subsequent beneficial reperfusion. Embolic stroke was induced by unilateral intracarotid blood clot injection in normotensive (n=53) or spontaneously hypertensive (n=20) rats, followed within 2 hours by magnetic resonance (MR) angiography (MRA), diffusion- (DWI) and perfusion-weighted magnetic resonance imaging (MRI) (PWI). In a subset of animals (n=9), MRI was repeated after 24 and 168 hours to determine the predictive value of the occlusion pattern on benefit of reperfusion. The extent of cerebral perfusion and diffusion abnormality was related to the pattern of flow obstruction in ICA and MCA segments. Hypertensive animals displayed significantly larger cortical perfusion lesions. Acute perfusion-diffusion lesion mismatches were detected in all animals that subsequently benefitted from reperfusion. Yet, the presence of an angiography-diffusion mismatch was more specific in predicting reperfusion benefit. Combination of DWI, PWI, and MRA exclusively informs on the impact of arterial occlusion profiles after acute ischemic stroke, which may improve prognostication and subsequent treatment decisions.     

急性脑梗死散在和单一弥散加权成像病损与其供血动脉狭窄的关系

目的 探讨急性脑梗死弥散加权磁共振成像(DWI)上大脑中动脉(MCA)供血区散在性或单一性缺血性病损与其脑供血动脉狭窄或闭塞的关系.方法 回顾性分析73例连续积累的DWI显示一侧MCA供血区脑梗死的病例,入组病例均排除心源性栓塞性脑梗死,所有患者均在发病24 h内进行MRI和MRA等检查,7例患者并进行DSA.采用DWI急性缺血性病损分类方法 分为散在病损组和单一病损组,比较两组的病灶同侧MCA、颈内动脉(ICA)颅内段和颅外段狭窄或闭塞的发生率.结果 散在病损组42例,单一病损组31例.在病损同侧ICA颅外段和MCA闭塞或重度狭窄方面两组差异有统计学意义(28.6%与0,x2=10.6,P=0.001).在病损同侧ICA颅内段并MCA轻中度狭窄方面,两组间差异具有统计学意义(31.0%与9.7%,x2=4.717,P=0.03).散在病损与MCA和(或)ICA严重或多发狭窄呈正相关(OR值为13.7,95%CI:3.6～52.5).在MRA或DSA未发现颅内外大血管狭窄方面,两组间差异具有统计学意义(11.9%与32.3%,x2=4.526,P=0.033).散在病损组与无明显血管狭窄呈负相关(OR值为0.284,95%CI:0.09～0.94).结论 (1)脑梗死急性期DWI显示的MCA区散在性病损患者,MCA和ICA狭窄、甚至闭塞的可能性较大,以ICA颅外段闭塞较为常见;(2)DWI显示单一病损时提示脑供血动脉狭窄程度较轻,范围较局限,小血管病变的可能性相对较高,很少为严重的ICA颅外段狭窄或闭塞.

Abstract：

Objective To investigate the relationship between scattered or single lesion of acute cerebral infarction in middle cerebral artery territory on diffusion-weighted imaging (DWI) and stenosis of middle cerebral artery (MCA) or internal carotid artery (ICA). Methods With exclusion of cardioembolism, 73 consecutive patients with acute cerebral infarction of the unilateral MCA territory on DWI were analyzed. All patients got magnetic resonance imaging (MRI) and angiography (MRA) within 24 hours after onset, and 7 patients also had digital subtraction angiography (DSA). The patients were classified into single lesion group or scattered lesions group according to the DWI findings. The incidence of stenosis or occlusion of ipsolateral MCA, intracranial and extracranial ICA were compared between the two groups. Results 42 patients had scattered lesions and 31 patients had single lesion. The scattered-lesions group had a high incidence of ipsilateral extracranial ICA or MCA occlusion or severe stenosis ( 25.6%versus 0, x2 = 10.6, P = 0.001 ) and a high incidence of ipsilateral intracranial ICA or MCA moderate or mild stenosis (31.0% versus 9.7% ,x2 =4.717, P =0.03 ). A positive correlation was found between the scattered lesions and severe or multifocal stenosis of ipsilateral ICA and MCA ( OR: 13.7, 95% CI: 3.6 to 52.5). There was a low incidence of absence of extra- and intracranial stenosis on MRA or DSA in the scattered-lesions group ( 11.9% versus 32.3%, x2= 4.526, P = 0.033 ). A negative correlation was found between the scattered lesions and absence of large-artery stenosis ( OR: 0.284, 95% CI: 0.09 to 0.94).Conclusions ( 1 ) Patients with acute cerebral infarction and scattered lesions on DWI were more likely to suffer from stenosis or occlusion of ICA or MCA, especially over the extracranial ICA. (2) Patients with single lesion were less likely to have severe or multiple stenosis of MCA and ICA, indicating the relevance of small-vessel pathogenesis.     

Susceptibility weighted magnetic resonance imaging of brain: A multifaceted powerful sequence that adds to understanding of acute stroke

Context:

To evaluate the additional information that susceptibility weighted sequences and datasets would provide in acute stroke.

Aims:

The aim of this study were to assess the value addition of susceptibility weighted magnetic resonance imaging (SWI) of brain in patients with acute arterial infarct.

Materials and Methods:

All patients referred for a complete brain magnetic resonance imaging (MRI) between March 2010 and March 2011 at our institution had SWI as part of routine MRI (T1, T2, and diffusion imaging). Retrospective study of 62 consecutive patients with acute arterial infarct was evaluated for the presence of macroscopic hemorrhage, petechial micro-bleeds, dark middle cerebral artery (MCA) sign and prominent vessels in the vicinity of infarct.

Results:

SWI was found to detect hemorrhage not seen on other routine MRI sequences in 22 patients. Out of 62 patients, 17 (10 petechial) had hemorrhage less than 50% and 5 patients had greater than 50% area of hemorrhage. A “dark artery sign” due to thrombus within the artery was seen in 8 out of 62 patients. Prominent cortical and intraparenchymal veins were seen in 14 out of 62 patients.

Conclusions:

SWI has been previously shown to be sensitive in detecting hemorrhage; however is not routinely used in stroke evaluation. Our study shows that SWI, by virtue of identifying unsuspected hemorrhage, central occluded vessel, and venous congestion is additive in value to the routine MR exam and should be part of a routine MR brain in patients suspected of having an acute infarct.     

高分辨率磁共振对大脑中动脉斑块与梗死灶类型关系的研究

目的 本研究主要应用高分辨率磁共振成像（high-resolution magnetic resonance imaging,HRMRI）探索 大脑中动脉（middle cerebral artery,MCA）粥样硬化所致狭窄与梗死灶分布类型的相关性,并进一步探 索不同脑梗死类型与斑块性质、重塑率及患者发生卒中的可能机制。 方法 回顾性分析2012-2016年于南京鼓楼医院就诊的14 d内发生MCA供血区缺血性卒中并进行 HRMRI扫描的患者临床资料。在弥散加权成像（diffusion weighted imaging,DWI）上将梗死类型分为 穿支动脉梗死（perforating artery infarct,PAI）、皮质支供血区梗死（pial infarct,PI）、分水岭梗死 （border zone infarct,BZI）和混合型梗死（PAI+PI,PAI+BZI,PI+BZI,PAI+PI+BZI）。在矢状位HRMRI上测 量MCA M1段狭窄率及重构率,并收集斑块位置、长度、厚度等形态学指标。正性重构＞1.05,负性重 构＜0.95。将PAI、PI、BZI的患者分入单型梗死组,将PAI+PI、PAI+BZI、PI+BZI、PAI+PI+BZI的患者归入 混合型梗死组。 结果 共纳入51例MCA狭窄程度≤50%的患者,其中单型组32例,混合组19例。单型组中,PAI 2 2 例（68.8%）,PI 6例（18.7%）,BZI 4例（12.5%）,正性重构22例（68.8%）。混合组中PAI+BZI 7 例（36.8%）,PAI+PI 2例（10.6%）,PI+BZI 5例（26.3%）,PAI+PI+BZI 5例（26.3%）,正性重构17例 （89.5%）。混合型组的狭窄程度较单型组重（P =0.01）,斑块厚度较单型组大（P =0.001）,比较差异 有统计学意义。 结论 不同程度的MCA狭窄,其梗死灶分布有所不同,单型梗死主要为PAI,混合型梗死主要以 PAI+BZI多见。同时HRMRI发现对于轻型MCA狭窄的患者,血管的狭窄程度和斑块厚度增加可能与混合 型梗死有关。     

建立基于临床和磁共振表观弥散系数的急性前循环缺血性卒中预后评估系统

目的 探讨影响急性缺血性卒中预后的因素,建立一种基于临床和多模式磁共振成像（magneticresonance imaging,MRI）的急性前循环缺血性卒中预后评估系统。方法 选择发病9小时内完成多模式MRI的前循环急性缺血性卒中患者40例。按照改良的Ranking量表（modified Ranking Scale,mRS）分为预后良好组（0～1分）和预后不良组（2～6分）。评价两组年龄、基线美国国立卫生研究院卒中量表评分（national institutes of health stroke scale,NIHSS）、基线弥散加权像（diffusion-weighted imaging,DWI）体积、基线灌注加权像（perfusion-weighted imaging,PWI）体积以及由基于表观弥散系数（apparent diffusion coefficient,ADC）的图像分析方法获得的预测梗死核心体积、预测可挽救脑组织体积等临床/影像信息对预后的影响;采用多因素分析筛查出单因素分析中具有统计学意义的变量作为预后评估系统的组成部分,应用受试者工作特征曲线（receiver operatorcharacteristic curve,ROC）分析获得各变量的阈值评分,整合后获得临床/ADC评分,应用ROC曲线下面积（area under curve,AUC）分析各评分模式判断预后的效能。结果 预后良好组与预后不良组在年龄、基线NIHSS、预测梗死核心体积、预测可挽救脑组织体积、预测最终梗死体积、实际最终梗死体积和基线DWI异常区域体积的差异均具有统计学意义。多因素分析显示年龄、预测梗死核心体积、预测最终梗死体积和基线NI HSS能作为判断预后的风险因素,构成临床/ADC预后评分系统的四个因素。应用ROC分析获得以上四个变量判断预后不良的阈值分别为＞58岁、＞5.84 ml 、＞10.6 ml 和＞12分。该评分系统的AUC最大（AUC=0.878,P＜0.01）,其判断急性缺血性卒中患者90 d预后的效能最高,其次是实际最终梗死体积（AUC=0.802,P =0.001）、预测最终梗死体积（AUC=0.797,P =0.001）、预测梗死核心体积（AUC=0.739,P =0.01）、基线NIHSS（AUC=0.759,P =0.005）、预测可挽救脑组织体积（AUC=0.719,P =0.018）和基线DWI异常区域体积（AUC=0.693,P =0.037）。其中,临床/ADC预后评分系统与预测梗死核心体积、预测可挽救脑组织体积、基线DWI异常区域体积AUC之间的差异具有统计学意义（P分别为0.043,0.035和0.01）。结论 临床/ADC预后评分系统比基线NIHSS评分和各影像参数判断90 d急性缺血性卒中患者预后的效能高;制定急性缺血性卒中患者治疗方案时,应结合患者临床和影像信息综合考虑。     

大脑中动脉供血区梗死灶形态与可能发病机制的回顾性研究

目的 探索大脑中动脉(MCA)供血区的梗死灶形态与脑卒中可能发病机制之间的关系.方法 回顾性分析了148例连续的急性缺血性脑卒中患者,所有患者均为颈内动脉(ICA)系统脑梗死,DWI显示相应MCA供血区责任病灶,根据血管及心脏检查将患者分为ICA病变组、MCA病变组、ICA+MCA病变组、心源性栓塞组(CE组)及检查结果阴性组(NR组).将梗死灶形态分为单发和多发,前者按部位分为:穿动脉梗死灶(PAI)、皮质支梗死灶(PI)、分水岭梗死灶(BZ)、大面积梗死灶.结果 MCA供血区的梗死灶形态可分为12种;不同病变所致脑卒中的梗死灶形态存在差异(χ2=55.88,P=0.004).但在MCA组、ICA组、MCA+ICA组及CE组中,未发现各自特异的梗死灶形态,仅PAI更多见于MCA组;与NR组相比,ICA组患者中更多出现PAI伴PI(7/27,χ2=6.61,P<0.05),而MCA组和CE组均未见特征性的梗死灶形态.动脉狭窄的程度与梗死灶形态亦存在一定关联,重度ICA病变更多地表现为PAl伴PI(5/16,χ2=7.32,P<0.05);而重度MCA病变则好发PAI伴BZ(4/30,χ2=5.59,P<0.05)及PAI伴PI和BZ(6/30,χ2=6.41,P<0.05).结论 MCA供血区内的梗死灶形态与其颅内动脉病变之间存在一定的关系,揭示脑卒中发生的不同机制,可能与动脉-动脉栓塞、灌注不良有关;我们以检查结果阴性患者为对照比较,尚不能完全揭示MCA供血区内的梗死灶形态和与脑卒中的不同机制之间的相关性.     

Leptomeningeal anastomosis and early ischemic lesions on diffusion-weighted imaging in male murine focal cerebral ischemia

Leptomeningeal anastomosis is a key factor for determining early ischemic lesions on diffusion-weighted imaging (DWI) in human stroke. However, few studies have validated this relationship in an experimental model. This study sought to clarify the involvement of leptomeningeal anastomosis in early ischemic lesions using a murine model. Adult male C57BL/6 mice were subjected to unilateral common carotid artery (CCA) occlusion or sham surgery. Seven or 14 days later, the middle cerebral artery (MCA) was occluded for 45 min. In the first experiment, the leptomeningeal collaterals were visualized using magnetic resonance imaging (MRI) DWI. In the second experiment, DWI was performed immediately after MCA occlusion, and the infarct sizes were determined 24 hr after recirculation. Unilateral CCA occlusion reduced the size of early ischemic lesions, enlarged the pial vessel diameter, and mitigated infarct size. The relationship between the DWI lesion size and pial vessel diameter was significant (r = 0.84, p < 0.01). The association between infarct size and DWI lesion size was also significant (r = 0.96, p < 0.01). In conclusion, involvement of the collateral circulation in early ischemic lesions was evident in the murine model. Both MRI and evaluation of leptomeningeal anastomosis could be used to develop a novel strategy targeting enhancement of the collateral circulation.     

Neuroprotective role of ornithine decarboxylase activation in transient focal cerebral ischaemia: a study using ornithine decarboxylase‐overexpressing transgenic rats

Nuclear magnetic resonance imaging (MRI) was used to study dynamics of maturation and the size of ischaemic stroke lesions in rats with greatly increased activity of ornithine decarboxylase (ODC). Syngenic rats, either with or without chronic pre-ischaemic treatment with an ODC inhibitor, α-difluoromethylornithine (DFMO), as well as ODC-overexpressing transgenic rats were subjected either to transient middle cerebral artery (MCA) occlusion or permanent occlusion of the cortical branch of MCA. The two models were chosen to assess the role of ODC activity in damage caused by ischaemia and reperfusion, respectively. Diffusion of water was quantified by means of the trace of the diffusion tensor (D_av = Trace=D) to assess the extent of energy failure and cytotoxic oedema, whereas the spin–spin relaxation time (T₂) was used as a quantitative indicator of irreversible damage by MRI. Exposure to transient MCA occlusion resulted in significantly smaller stroke lesions in the ODC-overexpressing transgenic (246 ± 14 mm³) than in syngenic (320 ± 9 mm³) or DFMO-treated (442 ± 63 mm³) rats as determined 48 h after the occlusion. The differences in sizes were due to smaller lesions in the cortical tissue (transgenic vs. syngenic) or both in cortical and striatal regions (transgenic vs. DFMO-treated animals). The degree of irreversible oedema was greater in DFMO-treated rats than in syngenic or transgenic animals indicating accelerated development of a permanent damage in the absence of ODC induction. Cortical infarct following permanent MCA occlusion developed faster in the DFMO-treated than in syngenic or transgenic rats as the lesion sizes at 10 h were 26.2 ± 4.3 mm³, 14.2 ± 2.3 mm³ and 12.3 ± 1.9 mm³, respectively. However, the stroke volumes by 48 h were not statistically different in the three animal groups. The present data demonstrate that ODC activation is an endogenous neuroprotective measure in transient cerebral ischaemia.     

大脑中动脉粥样硬化的狭窄度与卒中机制——一项高分辨磁共振研究

目的本研究旨在探索大脑中脉(middle cerebral artery,MCA)狭窄率与MCA斑块形态学及梗死类型的相关性,并探索不同狭窄率患者卒中的发生机制。方法连续收集2009-2014年于北京协和医院就诊的2周内发生MCA供血区缺血性卒中并进行高分辨磁共振(high-resolution magnetic resonance imaging,HRMRI)扫描的患者。纳入MCA M1段存在斑块的患者,排除心源性、颅外大动脉粥样硬化及其他病因的卒中患者。在弥散加权成像(diffusion weighted imaging,DWI)上将梗死类型分为穿支、皮层、分水岭和混合型梗死,并测量梗死体积。在矢状位HRMRI上测量MCA M1段狭窄率,并收集斑块位置、长度、厚度、信号和斑块连续性等形态学指标。将狭窄率50%的患者分入重度狭窄组,将狭窄率≤50%的患者归入轻度狭窄组。结果研究共纳入102例患者,其中重度狭窄组39例,轻度狭窄组63例。重度狭窄组患者卒中,穿支梗死14例(35.9%),皮层梗死9例(23.1%),分水岭梗死4例(10.3%),混合型梗死12例(30.8%);轻度狭窄组患者中,穿支梗死44例(69.8%),皮层梗死8例(12.7%),分水岭梗死3例(5.8%),混合型梗死8例(12.7%),两组构成类型比较,差异有显著性(P=0.014)。与轻度狭窄组比较,重度狭窄组患者斑块更长(P0.001)、更厚(P0.001)、更多混合信号斑块(P0.001)。斑块厚度(P0.001,OR 87.792,95%CI 13.120~587.453)和斑块混合信号(P=0.007,OR 7.358,95%CI 1.725~31.382)是MCA狭窄率50%的独立预测因子。重度狭窄组中,梗死体积与斑块表面不连续(P=0.004)相关。轻度狭窄组中,梗死类型与斑块表面不连续(P=0.002)及斑块厚度(P=0.032)相关。且斑块表面不连续是发生栓塞性梗死的独立预测因子(P=0.003,OR 5.778,95%CI 1.788~18.672)。结论 MCA狭窄率50%和≤50%的患者具有不同的卒中分型比例和斑块形态学;狭窄率≤50%的斑块表面不连续是栓塞性梗死独立预测因子,提示轻度狭窄MCA斑块破裂可能是引起栓塞性病灶的机制。     

Rapamycin protects against middle cerebral artery occlusion induced focal cerebral ischemia in rats

Stroke is a major cause of mortality and disability. The management with thrombolytic therapy has to be initiated within 3-4 h and is associated with limitations like increased risk of intracranial hemorrhage and progression of cerebral injury. Immunophilin inhibitors such as cyclosporine A and tacrolimus have been shown to afford neuroprotection by improving neurological functions and infarct volume in models of ischemic stroke. In the present study, the effect of rapamycin in middle cerebral artery occlusion (MCAo) model of ischemic stroke was evaluated.Ischemic stroke was induced in rats by occluding the MCA using the intraluminal thread. After 1 h of MCAo, animals were administered rapamycin (50, 150, 250 μg/kg, i.p.). After 2 h of occlusion, reperfusion was done. Thirty minutes after reperfusion, animals were subjected to diffusion-weighted magnetic resonance imaging for assessment of protective effect of rapamycin. Twenty-four hours after MCAo, motor performance was assessed, the animals were euthanized and the brains were removed for estimation of malondialdehyde, glutathione, nitric oxide and myeloperoxidase.Significant improvement was observed with rapamycin 150 and 250 μg/kg in percent infarct area, apparent diffusion coefficient and signal intensity as compared to vehicle treated group. Rapamycin treatment ameliorated motor impairment associated with MCAo and significantly reversed the changes in levels of malondialdehyde, glutathione, nitric oxide and myeloperoxidase.The results of the present study indicate neuroprotective effect of rapamycin in MCAo model of stroke. Therefore, rapamycin might be considered as a therapeutic strategy for stroke management.     

Massive haemorrhagic transformation in cardioembolic stroke: the role of arterial wall trauma and dissection

The pathogenesis of massive haemorrhagic transformation is not well established. Fatal haemorrhagic transformation associated with in situ dissection after acute middle cerebral artery (MCA) occlusion in a patient with atrial fibrillation is reported. An 80 year old woman with atrial fibrillation developed mild hemiparesis and aphasia. Brain CT and MRI at 4 and 5 hours, respectively, of symptom onset showed proximal MCA trunk occlusion with developing striatocapsular infarct and hypoperfusion in the superficial MCA territory. A few hours later, she developed massive bleeding into the ischaemic area and died. Pathological examination showed MCA trunk dissection, surrounded by a subarachnoid clot which communicated with the cerebral haematoma. It is suggested that direct arterial wall trauma as a result of cardioembolic MCA occlusion caused bleeding into the infarct. Secondary in situ dissection may be an overlooked mechanism of haemorrhagic transformation.     

Type and extent of hemispheric brain infarctions and clinical outcome in early and delayed middle cerebral artery recanalization.

We evaluated the influence of time of recanalization or degree of initial leptomeningeal collateral blood flow in cardioembolic or arterio-arterial middle cerebral artery (MCA) occlusion on infarct size and clinical outcome in a series of 34 consecutive acute stroke patients with main stem (N = 31) or major branch (N = 3) occlusions using CT, initial cerebral arteriography (N = 21), repetitive close-meshed transcranial Doppler ultrasonography, and a neurologic stroke scale. We treated 15 patients with tissue plasminogen activator intravenously within the first 6 hours. The type and size of infarction depended on the location of the occluding lesions within the MCA trunk. Proximal MCA occlusion always led to infarction involving the striatum and internal capsule. Sixty-five percent of patients showed recanalization of the occluded MCA within 1 week. Following MCA recanalization, hyperperfusion was present in 38 to 44% of cases. There was a marginally significant relation between size of infarction on CT and recanalization time within the first 24 hours. The more rapidly recanalization occurred, the smaller the size of the infarct. When recanalization time was greater than 8 hours, the lesions always extended to the cortex. An additional good leptomeningeal collateral blood flow significantly reduced the size of the infarct and improved clinical outcome after 17 days and after 10 months. Early recanalization of embolic MCA occlusions within up to 8 hours, in conjunction with good transcortical collateralization, has a favorable impact on infarct size and outcome and may constitute the therapeutic window of opportunity.     

磁敏感成像对急性期大脑中动脉闭塞的显示作用

目的评价急性期脑梗死时磁敏感成像(susceptibility weighted imaging,SWI)对大脑中动脉(middlecerebral artery,MCA)闭塞显示的准确性。方法回顾性分析56例急性期大脑中动脉供血区脑梗死患者的临床资料,SWI、MRI和MRA结果,探讨SWI对急性期MCA闭塞显示的敏感性。结果急性期MCA闭塞可在SWI检查中显示为沿血管走行的低信号影,称为MCA磁敏感征。MCA磁敏感征对MCA起始段至豆纹动脉段闭塞的敏感性、特异性和准确性均为100%,对MCA豆纹动脉段后至皮层支闭塞则分别为32%、100%和77%。MCA磁敏感征阳性患者起病时NIHSS评分和梗死体积明显高于MCA磁敏感征阴性患者。结论急性期SWI检查能够很好地显示MCA近端闭塞,有助于脑梗死患者分型治疗。     

无症状大脑中动脉闭塞的临床研究

目的 探讨无症状大脑中动脉闭塞患者的临床和影像学特点。 方法 回顾性分析2016年1月-2019年1月连续住院并行头颅MRA检查患者的临床及影像学资料,选 择无症状性大脑中动脉主干闭塞患者作为研究对象,分析其临床和影像学特点。 结果 研究共筛查3967例行头颅MRA检查的患者,其中无症状大脑中动脉闭塞者23例（0.58%）,年 龄34～80岁,平均61.2±11.2岁;男性14例（60.87%）,女性9例（39.13%）;既往高血压14例（60.87%）、 高脂血症12例（52.17%）、脑梗死病史6例（26.09%）、高同型半胱氨酸血症8例（34.78%）、糖尿病6例 （26.09%）、吸烟4例（17.39%）。头颅MRA检查显示左侧大脑中动脉闭塞10例（43.48%）,右侧大脑中 动脉闭塞10例（43.48%）,双侧大脑中动脉均闭塞3例（13.04%）。随访3个月～3年,患者均无新发脑 梗死症状。 结论 大脑中动脉闭塞可以无相应临床症状和脑梗死病灶而孤立存在,是一种值得进一步研究的 脑血管病状态。     

Reversible uncal herniation in a neonate with a large MCA infarct

Uncal herniation due to a large cerebral infarct is well-described in adults, with high rates of morbidity and mortality. This phenomenon, however, has not been previously reported in neonates. We present a newborn male delivered via cesarean section with difficult extraction who presented with frequent seizures. He was found to have an acute left MCA territory infarct secondary to an M1 occlusion detected on MRI/MRA. He became lethargic and developed a left uncal herniation on CT at 72 h of life. He was treated medically with osmolar agents and hemodynamic support, and had resolution of the herniation on CT at 120 h of life. At 19 months he had residual moderate right hemiparesis with only mild gait disturbance and mild speech delay. As seen in this case, uncal herniation, though rare, may occur in neonates. Also, the outcome for this neonate was much better than for typical adults with a similar disease course.     

Serial magnetic resonance imaging in a rat pup filament stroke model

Neonatal stroke is increasingly recognized in preterm and term infants but the ability to study this condition has been limited by the technical challenges in developing suitable animal models. In the current study we report the use of transient filament middle cerebral artery occlusion for 1.5 h in 10-day-old rat pups in which we were able to perform serial magnetic resonance imaging (MRI) studies. Serial MRI was performed immediately after the onset of stroke until 28 days after injury in an 11.7 T scanner using diffusion weighted and T2-weighted images. At 28 days the rat pups were sacrificed and standard histological stains were performed to validate stroke area. Serial behavioral assessments were also performed on the day of each imaging study. The anatomical distribution of stroke was similar to that expected from occlusion of the middle cerebral artery in adult models and represents a specific model of neonatal stroke in contrast to the commonly used model of carotid artery occlusion with 8% hypoxia. The initial stroke volume from MR measurements was 39% of the ipsilateral hemisphere at 0 h post-occlusion, reached a maximum at 24 h (44%) and then decreased in size (17%) with subsequent cavitation by 28 days. Infarction was more visible early with diffusion weighted imaging whereas T2-mapping provided more accurate infarct volumes at later time points. Despite the relatively large infarct volume, we saw little evidence of behavioral neurological deficit suggesting that this may also serve as a model of developmental plasticity and recovery.     

Visual evaluation of perfusion computed tomography in acute stroke accurately estimates infarct volume and tissue viability

OBJECTIVE: To establish the validity of visual interpretation of immediately processed perfusion computed tomography (CT) maps in acute stroke for prediction of final infarction. METHODS: Perfusion CT studies acquired prospectively were reprocessed within six hours of stroke onset using standard CT console software. Four contiguous 5 mm thick images were obtained and maps of time to peak (TTP) and cerebral blood volume (CBV) generated. Volumes of lesions identified only by visual inspection were measured from manually drawn regions of interest. Volumes of tissue with prolonged TTP or reduced CBV were compared with independently calculated volume of infarction on non-contrast CT (NCCT) at 24-48 hours, and with clinical severity using the NIHSS score. Arterial patency at 24-48 h was included in analyses. RESULTS: Studies were analysed from 17 patients 150 minutes (median) after stroke onset. Volume of tissue with prolonged TTP correlated with initial NIHSS (r = 0.62, p = 0.009), and with NCCT final infarct volume when arterial occlusion persisted (r = 0.953, p = 0.012). Volume of tissue with reduced CBV correlated with final infarct volume if recanalisation occurred (r = 0.835, p = 0.001). Recanalisation was associated with lower 24 h NIHSS score (6 (IQR, 5 to 9.5) v 19 (18 to 26), p = 0.027), and in 10 patients given rtPA for MCA M1 occlusion, with lower infarct volume (73 v 431 ml, p = 0.002). CONCLUSIONS: Visual evaluation of TTP and CBV maps generated by standard perfusion CT software correlated with 24-48 hour CT infarct volumes. Comparison of TTP and CBV maps yields information on tissue viability. Perfusion CT represents a practical technique to aid acute clinical decision making. Recanalisation was a crucial determinant of clinical and radiological outcome.     

脑梗死磁共振弥散加权成像信号改变和近似弥散系数的时间演变规律

目的 :确定脑梗死磁共振弥散加权成像 (DWI)信号改变和近似弥散系数 (ADC)的时间演变规律。方法 :分析 10 1例脑梗死患者的 13 5次DWI资料。结果 :超急性、急性和亚急性期脑梗死DWI为高信号 ,慢性早期多数病灶仍为高信号 ,慢性晚期绝大部分病灶为等或低信号。超急性期、急性期和亚急性期脑梗死ADC下降 ,慢性早期多数病灶接近或高于正常 ,慢性晚期明显升高。结论 :脑梗死的DWI信号和ADC变化具有特征性的时间演变规律 ,结合常规MRI ,DWI可以推断脑梗死所处的时期     

Outcome of acutely ischemic brain tissue in prolonged middle cerebral artery occlusion: a serial positron emission tomography investigation in the baboon.

Thrombolysis within 3 to 6 hours of symptom onset is recommended therapy for acute middle cerebral artery (MCA) stroke, but recent imaging studies in humans suggest that the penumbra may last much longer in some patients. It is therefore important to study the events that take place with occlusions that last longer than 6 hours. Based upon positron emission tomography (PET), the tissue with high oxygen extraction fraction (OEF) is at risk of infarction. In a previous sequential PET study in anesthetized baboons, we documented that when reperfusion was initiated at 6 hours after MCA occlusion, the region with the acutely highest OEF was not incorporated within the final magnetic resonance imaging (MRI)-defined infarct, suggesting reperfusion prevented such demise. In agreement with this hypothesis, we report here using the same sequential PET paradigm with final chronic-stage volume MRI that a 20-hour MCA occlusion resulted in, on average, 36% of the highest OEF area being recruited into the final infarct. We also found that the portion of the highest OEF area that went on to infarct had at the earliest time-point significantly lower cerebral blood flow and cerebral oxygen metabolism (mean reductions relative to unoccluded side, 56% and 32%, respectively) than the portion that did not (41% and 11%, respectively) and that some reperfusion occurred in the latter at second time-point, that is, before recanalization. Thus, apart from duration of occlusion, the fate of the at-risk tissue is predicated by the initial severity of the ischemia as well as by early secondary events such as partial spontaneous reperfusion.     

磁共振对颈内动脉狭窄与闭塞患者卒中解剖模式诊断价值的初步探讨

摘要】 目的 研究单侧动脉粥样硬化性颈内动脉狭窄与闭塞的急性缺血性卒中患者在磁共振上的病灶模式,探讨颈内动脉病变引起卒中的发病机制。 方法 利用数字减影脑血管造影定位动脉粥样硬化性颈内动脉重度狭窄（≥70%）或闭塞而无同侧大脑中动脉闭塞性病变。利用常规磁共振成像（magnetic resonance imaging,MRI）和液体衰减翻转恢复（fluid-attenuated inversion recovery,FLAIR）序列研究颈内动脉闭塞性病变引起缺血性卒中的形态学表现。有潜在心源性栓子患者除外。 结果 94例患者中,颈内动脉重度狭窄（≥70%）45例,颈内动脉闭塞49例。磁共振上缺血病灶的局部解剖模式分为4种：区域梗死、皮质下梗死、边缘带梗死、弥散小梗死。颈内动脉闭塞组中区域梗死的发生率较颈内动脉狭窄组高（47% vs 22%;P<0.05）;颈内动脉狭窄组中边缘带梗死的发生率较颈内动脉闭塞组高（42% vs 22%;P<0.05)。 结论 动脉粥样硬化性颈内动脉闭塞患者多见于区域梗死,而颈内动脉重度狭窄（≥70%）患者多见于边缘带梗死。