Cerebral cortical microinfarcts in patients with internal carotid artery occlusion

Cerebral cortical microinfarcts (CMI) are small ischemic lesions that are associated with cognitive impairment and probably have multiple etiologies. Cerebral hypoperfusion has been proposed as a causal factor. We studied CMI in patients with internal carotid artery (ICA) occlusion, as a model for cerebral hemodynamic compromise. We included 95 patients with a complete ICA occlusion (age 66.2 ± 8.3, 22% female) and 125 reference participants (age 65.5 ± 7.4, 47% female). Participants underwent clinical, neuropsychological, and 3 T brain MRI assessment. CMI were more common in patients with an ICA occlusion (54%, median 2, range 1–33) than in the reference group (6%, median 0; range 1–7; OR 14.3; 95% CI 6.2–33.1; p<.001). CMI were more common ipsilateral to the occlusion than in the contralateral hemisphere (median 2 and 0 respectively; p<.001). In patients with CMI compared to patients without CMI, the number of additional occluded or stenosed cervical arteries was higher (p=.038), and cerebral blood flow was lower (B −6.2 ml/min/100 ml; 95% CI −12.0:–0.41; p=.036). In conclusion, CMI are common in patients with an ICA occlusion, particularly in the hemisphere of the occluded ICA. CMI burden was related to the severity of cervical arterial compromise, supporting a role of hemodynamics in CMI etiology.     

Clinical implications of collateral middle cerebral artery flow in acute ischaemic stroke with internal carotid artery occlusion

Background and purpose: The presence of collateral middle cerebral artery (MCA) flow via the primary collateral pathway is thought to protect against the progression of cerebral ischaemia. However, there have been few reports on early clinical outcomes according to the presence of collateral MCA flow in acute ischaemic stroke (AIS) with internal carotid artery (ICA) occlusion. Therefore, we sought to investigate the early clinical outcomes and lesion patterns according to the presence of collateral MCA flows in AIS with ICA occlusion. Methods: This is a retrospective study of patients with AIS with ICA occlusion consecutively admitted to our stroke center between October 2008 and March 2010. Patients were included if they were admitted within 12 h of symptom onset with AIS and symptomatic ICA occlusion. Collateral MCA flow was defined as the presence of MCA signals from proximal M1 to distal MCA branches ipsilateral to the ICA occlusion by magnetic resonance angiography. Early neurological deterioration (END) was defined as a 4‐point increase in the National Institutes of Health Stroke Scale (NIHSS) score and persistent neurological deterioration for at least 24 h or newly developed neurological symptoms within 7 days. Results: Sixty‐five patients (42 men, 23 women) were finally included. Initial NIHSS scores were significantly lower, and favorable outcomes at 3 months were better in patients with collateral MCA flow than in those without (P < 0.001). Initial lesion patterns were different according to the collateral MCA flow. However, patients with mild AIS might more frequently deteriorate than those with moderate to severe AIS. Conclusions: In our study, collateral MCA flow reduced initial stroke severity and was associated with favorable outcomes at 3 months but did not seem to protect against END in mild AIS patients with ICA occlusion. Therefore, the results of this study suggest that mild AIS patients with ICA occlusion should be carefully managed because their conditions may deteriorate.     

Chronic remote ischemic conditioning for symptomatic internal carotid or middle cerebral artery occlusion: A prospective cohort study

AimsRemote ischemic conditioning (RIC) has been demonstrated to reduce recurrent stroke in patients with intracranial artery stenosis. This study aimed to evaluate the effects of RIC in patients with the symptomatic internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion.MethodsThis study is based on a high‐volume single‐center prospective cohort study in China, which included patients with symptomatic ICA or MCA occlusion with impaired hemodynamics and receiving chronic RIC. Clinical follow‐up visits were performed regularly, and cardio‐cerebrovascular events were assessed.ResultsIn total, 131 patients (68 with ICA occlusion and 63 with MCA occlusion; mean age, 52.6 ± 13.7 years; stroke, 73.5%; transient ischemic attack TIA, 26.5%) qualified for the analysis; the mean follow‐up period was 8.8 years (range, 3–14 years). The compliance of RIC was 95.6 ± 3.7%, and no associated severe adverse events happened. The annual risk of ischemic stroke and ischemic cerebrovascular events was 2.4% and 3.3%, respectively. The cumulative probabilities of ischemic cerebrovascular events and major adverse cardiovascular and cerebrovascular events were 32.8% and 44.8% at 14 years, respectively.ConclusionIn patients with symptomatic ICA or MCA occlusion with impaired hemodynamics, chronic RIC is well‐tolerated, and it appears to be associated with a low annual risk of ischemic stroke and cardio‐cerebrovascular events.     

颈内动脉扭曲的特点及其脑血流动力学变化

目的 研究颈内动脉(ICA)扭曲的特点及其脑血流动力学变化.方法 对223例缺血性脑血管病患者进行全脑血管造影和经颅多普勒超声检查.观察ICA扭曲的形态,将患者分为ICA扭曲组及正常组.比较两组的脑血流动力学参数.结果 全脑血管造影示ICA扭曲159例(ICA扭曲组),其中双侧扭曲127例(79.9％),单侧扭曲32例(20.1％);无扭曲64例(正常组).扭曲的类型以迂曲型最多(47.8％),折曲型次之(36.8％),盘曲型最少(5.3％);其中ICA左侧迂曲率(56.7％)显著高于右侧(43.3％)(P＜0.05).与正常组比较,ICA扭曲组及双侧折曲患者的大脑中动脉的收缩期峰速、舒张末期血流速度、平均血流速度、搏动指数及阻力指数明显降低(均P＜0.05);双侧迂曲患者各血流动力学参数的差异无统计学意义.结论 ICA扭曲以迂曲型和折曲型为主.ICA扭曲及其折曲型可引起脑血流动力明显降低,迂曲型则无显著改变.     

Cerebrovascular reactivity in carotid artery occlusion: possible implications for surgical management of selected groups of patients

OBJECTIVES: The aim of this study was to use transcranial Doppler ultrasonography to investigate cerebrovascular reactivity to hypercapnia in the middle cerebral arteries of patients with carotid occlusion with different outcomes. PATIENTS AND METHODS: Cerebrovascular reactivity to hypercapnia was calculated with the breath-holding index (BHI). Patients with unilateral carotid occlusion were divided as follows: asymptomatic (20 patients), transient ischemic attack (TIA) (20 patients), minor (20 patients) and major stroke (14 patients). Values of BHI homolateral to the carotid occlusion were compared with those of 25 healthy subjects and 34 stroke patients without significant carotid stenosis. RESULTS: BHI values were comparable in healthy controls, non stenotic stroke patients and asymptomatic occluded patients. BHI values of patients with symptomatic occlusion were significantly lower than those of the above-mentioned groups (P<0.0001). Moreover, the reduction of BHI was significantly associated with the extent of the neurological impairment. In fact, BHI values were significantly higher in TIA than in minor and major stroke (P<0.0001) and in minor than in major stroke patients (P<0.02). Finally, we found that a BHI value homolateral to carotid occlusion of 0.69 can be considered the cut-point for distinguishing between symptomatic and asymptomatic patients. CONCLUSION: Prospective studies are needed to demonstrate if the presence of this threshold value may help in selecting a subset of patients with asymptomatic carotid occlusion or with transient or mild neurological deficit with the highest probability of benefiting from surgical therapy.     

Cerebral arterial compliance in patients with internal carotid artery disease

Background: A decrease in arterial compliance of the internal carotid artery has been associated with an increased risk in ipsilateral ischaemic stroke. However, so far, no technique has been validated to monitor the compliance of intracerebral arteries (Ca) in patients with carotid artery disease. In this study, we sought to monitor Ca in patients with unilateral symptomatic disease and to determine its variations during changes in PaCO₂. Methods: We studied 18 patients with unilateral symptomatic internal carotid artery stenosis >50% or occlusion. Patients underwent monitoring of arterial blood pressure (ABP) and middle cerebral artery cerebral blood flow velocities (CBFV) during baseline, hyperventilation and 5%CO₂ inhalation. Ca was calculated from pulsatile amplitudes of ABP and Cerebral arterial blood volume, extracted from the CBFV waveform using a new mathematical model. Results: At baseline, the decrease in Ca on the diseased side was correlated with the degree of stenosis (r = −0.35; P = 0.01). During hypocapnia, Ca was lower compared to baseline on the normal side (P = 0.004) and on the diseased side (P = 0.04). Ca reactivity, reflecting the changes in Ca per changes in 1 mmHg PaCO₂, was lower on the diseased side between baseline and hypocapnia (3.4 vs. 2.6%; P = 0.04). During hypercapnia, no changes in Ca on the diseased (P = 0.8) nor on the normal sides (P = 0.2) were observed. Conclusions: The decrease in cerebral arterial compliance the side of stenosis/occlusion was correlated with the severity of the internal carotid artery disease. Further studies are needed to determine whether Ca may improve the prediction of ischaemic events in symptomatic and asymptomatic patients.     

颈内动脉急性闭塞致大面积脑梗死侧支循环建立及影响因素

目的评估颈内动脉急性闭塞致大面积脑梗死侧枝循环建立情况及影响因素。方法纳入29例经诊断为颈内动脉急性闭塞致大面积脑梗死的患者,所有患者均行颈动脉超声、经颅多普勒超声(TCD)、头颅CT、头颅磁共振血管造影(MRA)、心电图检查,同时收集患者基本信息。结果一级侧枝循环建立与糖尿病显著相关(P 0. 05),与房颤、高血压、吸烟、NIHSS评分无关(P 0. 05)。二级侧枝循环建立与房颤、高血压、糖尿病、吸烟、NIHSS评分均无关(P 0. 05)。心源性脑栓塞导致的急性大面积脑梗死与脑疝显著相关(P 0. 05)。TCD评估一级侧枝循环的建立与MRA具有高度一致性(Kappa值=0. 656,P 0. 05)。结论糖尿病可促进颈内动脉急性闭塞导致的大面积脑梗死一级侧枝开放。心源性脑栓塞导致的大面积脑梗死易发生脑疝。TCD可以较好评估颈内动脉急性闭塞导致的大面积脑梗死的一级侧枝循环建立。     

Long‐term follow‐up of patients with asymptomatic occlusion of the internal carotid artery with good and impaired cerebral vasomotor reactivity

Background: Cerebral hemodynamic status might be prognostic for either the symptomatic or asymptomatic course of carotid occlusive disease. It is determined by evaluating cerebral vasomotor reactivity (VMR). We assessed VMR in asymptomatic patients with total occlusion of the internal carotid artery (ICA) and followed them to evaluate the role of impaired VMR in predicting ischaemic stroke (IS). Methods: Thirty‐five patients (21 men, mean age ± SD 68 ± 7.5 years) with unilateral asymptomatic ICA occlusion were studied by transcranial Doppler and the Diamox test (intravenous 1.0 g acetazolamide) and followed for 48 months or until reaching the end‐points of IS, transient ischaemic attack, or vascular death. VMR% was evaluated by recording the percent differences in peak systolic blood flow velocities in each middle cerebral artery at baseline and after Diamox administration. Results: Based on VMR% calculations, 14 (40%) patients had good VMRs and 21 (60%) had impaired VMRs. The global annual risk of ipsilateral ischaemic events was 5.7%. The annual ipsilateral ischaemic event risk was 1.8% in patients with good VMRs, whilst it was 7.1% in patients with impaired VMRs. An impaired VMR was significantly correlated with ipsilateral IS (Kaplan–Meier log rank statistic, P = 0.04). Conclusions: Our results support the value of VMR assessment for identifying asymptomatic patients with carotid occlusion who belong to a high‐risk subgroup for IS. New trials using extracranial‐to‐intracranial bypass surgery in patients with asymptomatic ICA occlusion and impaired VMRs are warranted.     

慢性颈内动脉闭塞导致认知功能障碍的研究进展

慢性颈内动脉闭塞(CICAO)是认知功能障碍的独立危险因素,可通过多种机制影响脑部结构及血流动力学情况(包括淀粉样蛋白沉积、炎症介质形成、脑灌注不足等),导致非心脑血管事件风险增加。颈动脉系统重度狭窄或闭塞部位不同所致认知功能减退的表现形式可能存在差异,控制高血压等高危因素可降低其发生风险。临床上对于CICAO患者脑血流动力学情况常用的评估手段为CT灌注成像检查(CTP),其可能通过间接评估侧支循环及其他血流动力学指标来预测患者出现认知功能减退的风险,但准确性仍有争议。目前临床上常用药物可在一定程度上改善患者的认知功能,尚无根治药物,血管内介入治疗可能通过降低脑梗死再发及改善脑灌注而改善认知功能,但对于纳入患者的标准仍需严格评估,其安全性及有效性仍需进一步探索。该文基于该类疾病的研究现状,对其发病机制、影响因素、评估手段及治疗方案进行综述,以期为临床诊疗及后续研究提供参考。     

颈内动脉重度狭窄或闭塞患者的侧支循环与神经功能的单因素分析

目的 探讨颈内动脉重度狭窄或闭塞患者侧支循环的代偿作用与临床神经功能缺损程度的关系. 方法对52例连续颈内动脉狭窄或闭塞所致的脑梗死患者入院时行神经功能缺损评分(NIHSS)评分,利用数字减影脑血管造影技术(DSA)评估颅内动脉的侧支循环代偿情况.应用统计学方法探讨两者之间的关系.结果 DSA发现52例患者18例出现颈内动脉闭塞,单侧颈内动脉重度狭窄28例,6例双侧重度狭窄.52例患者中出现前交通动脉代偿18例,后交通动脉代偿8例,前后交通动脉同时代偿12例,14例患者未出现Willis环血管的代偿.无Willis环代偿组与Willis环代偿组NIHSS评分平均秩次分别为35.75和23.09,两组差异有统计学意义(P<0.05).前交通代偿组与后交通代偿组NIHSS评分平均秩次分别为12.42和15.94,两组差异无统计学意义(P<0.05).结论颈内动脉狭窄或闭塞时可通过多种方式进行有效的代偿.NIHSS评分与血管代偿及阻塞位置显著有关.DSA对侧支循环的判定在治疗干预中显得尤为重要.     

颈内动脉狭窄相关性脑缺血病变的临床分析

目的 探讨颈内动脉狭窄致脑缺血病变的临床特点及发生机制,为临床指导治疗及判断预后提供依据.方法 回顾分析111 例经CT 血管造影(CTA)证实的颈内动脉狭窄患者的颅内Willis 环形态、TCD 资料及临床表现.结果 颈内动脉轻、中、重度狭窄组脑梗死发生率分别为14.7% 、30.6% 、46.3%,三组间差异具有显...     

Angiographic circulation time and cerebral blood flow during balloon test occlusion of the internal carotid artery

Angiography-based balloon test occlusion (BTO) has been empirically used to predict tolerance to permanent carotid artery occlusion. We tested the hypothesis that the laterality of the hemispheric circulation time (HCT) of the contrast medium at cerebral angiography would reflect bilateral asymmetry of the cerebral blood flow (CBF) during BTO. Thirty-one consecutive patients who underwent BTO of the internal carotid artery were retrospectively analyzed. HCT was defined as the interval between the time-to-peak in the middle cerebral artery and the cortical veins calculated using time-density curve. The difference in HCT between the occluded and nonoccluded side was calculated at the carotid or dominant vertebral angiograms obtained during BTO. We estimated the correlation between the difference in HCT and bilateral asymmetry of the CBF, which was quantitatively determined by single-photon emission computed tomography. The HCT was 5.3±1.5 seconds and regional CBF was 41.3±11.3 mL/100 g per minute in the occluded side, compared with 3.6±0.9 seconds and 48.4±14.9 mL/100 g per minute in the nonoccluded side, respectively. The difference in HCT was strongly correlated with the asymmetry ratio of the CBF (r²=0.89, P<0.0001). Angiographically based measurement of the cerebral circulation time can provide valuable information concerning cerebral hemodynamics.     

颈内动脉闭塞患者危险因素的Logistic回归分析

目的探讨颈内动脉闭塞的相关危险因素。方法回顾性分析2003年1月～2008年3月北京友谊医院收治的94例颈内动脉闭塞患者的危险因素,并与2007年1月～2007年6月收治的105例（无颈内动脉闭塞）缺血性脑血管病患者（对照组）的危险因素进行比较,并进行多因素Logistic回归分析。结果2组间缺血性脑血管病常见的危险因素如高血压病、高脂血症、糖尿病、高龄和饮酒史,无统计学差异（P〉0．05）,而性别、脑卒中病史及吸烟史3个因素在2组间具有统计学意义（P〈0．05）。将男性、脑卒中病史及吸烟史3个变量代入Logistic回归方程行多因素分析显示,3种相关危险因素中性别与颈内动脉闭塞相关性最高（P=0．041）,吸烟史和脑卒中病史为仅次于性别的危险因素。结论性别、脑卒中病史及吸烟史是颈内动脉闭塞的重要相关危险因素,临床应加强脑卒中的二级预防,并加强戒烟宣传等工作。     

The course of dynamic cerebral autoregulation during cervical internal carotid artery occlusion

Abstract

Objectives: The selection of patients with cervical internal carotid artery occlusion (ICAO) for extracranial-intracranial bypass surgery is based on exhausted cerebrovascular reactivity to vasodilatory stimuli. However, a spontaneous increase in this reactivity can occur with time, questioning the ideal time for bypass surgery. In contrast, the natural course of dynamic cerebral autoregulation is not known in these patients.

Methods: Patients with cervical ICAO were examined at baseline and after a mean interval of 15 months. Dynamic autoregulation was determined by transcranial Doppler sonography in both middle cerebral arteries via respiratory-induced 0·1-Hz oscillations (phase, available for n=47 patients) and correlation analysis between diastolic blood pressure and Doppler signal (index Dx, n=55 patients). Pre-defined cut-off values and repeatability measures of healthy controls were used to define significant individual changes in autoregulation.

Results: Group mean comparisons between studies were not significant for any autoregulation parameter. The intraclass correlation coefficient between studies was high for phase (ipsilateral: 0·83; contralateral: 0·74), and moderate for Dx (ipsilateral: 0·63; contralateral: 0·35). There was no clear trend for an improvement across cut-off values. A significant individual improvement/deterioration in autoregulation occurred in 6%/6% for phase and 13%/9% for Dx.

Discussion: Dynamic autoregulation only rarely improves during the course of ICAO. This finding should be considered when deciding for or against a policy of delaying extracranial-intracranial bypass surgery for reasons of a potentially improving hemodynamic status.     

Prediction of delayed ischemic injury with diffusion-weighted MRI following temporary middle cerebral artery occlusion in rats

Early reductions in the apparent diffusion coefficient of water (ADC) during focal cerebral ischemia are often reversible with reperfusion. With sustained ischemia, the magnitude of the ADC reduction generally increases with time, which could reflect increased severity of ischemic damage. Thus, a threshold in ADC reduction may exist beyond which damage can not be reversed with reperfusion. The goal of this study was to determine if such a threshold exists that is independent of the duration of ischemia in a rat model. Rats were subjected to either 30, 60, or 90 min of temporary middle cerebral artery occlusion. ADC maps acquired just before and 30 min after reperfusion were compared to histology performed after a 72 h survival period to determine the relationship between ADC reduction and final ischemic injury. Significant variability in tissue recovery was observed for the 30 min group. Regions with ADC reductions of up to 45% often recovered, while some regions not exhibiting any change in ADC during occlusion showed ischemic injury at 72 h. Similar observations were made in cortical regions of the 60 min group. In the caudate-putamen, reduced ADC was often associated with ischemic injury. For the 90 min group, results for the caudate-putamen were similar to those for the 60 min group, while reduced ADC was a much better predictor of final ischemic injury in cortical regions than it was in both the 30 and 60 min groups. Thus, no single threshold of ADC reduction that was independent of the duration of ischemia was associated with irreversible injury.     

颈总动脉闭塞患者的临床特点分析

目的分析颈总动脉患者临床特点,以加深对该病变的认识。方法对14例颈总动脉患者的临床资料、影像及超声进行分析。结果14例颈总动脉闭塞患者中,表现为病变对侧的肢体无力7例（50%）,病变同侧一过性黑朦发作5例（35.7％）,晕厥发作5例（35.7％）;MRI显示新发梗死7例;TCD显示眼动脉血流正常6例,眼动脉侧支开放（颈内外侧枝开放）4例,眼动脉闭塞4例。结论颈动脉闭塞除了表现为肢体无力外,还可以一过性黑朦及晕厥为主要表现。     

Ischaemia-induced vascular vulnerability resulting in intracerebral haemorrhage with ipsilateral internal carotid artery occlusion

Intracerebral haemorrhage accompanied with cervical internal carotid artery (ICA) occlusion on the same side without moyamoya-like vessels is rare. A 73-year-old man with left ICA occlusion and no presence of moyamoya disease criteria underwent xenon-enhanced computed tomography with acetazolamide challenge test. The findings showed hypoperfusion and no vasoreactivity in the territory of the left middle cerebral artery. During follow-up he suffered bleeding in the left frontoparietal lobe. Cerebral angiography showed left ICA occlusion and cross flow via the anterior communicating artery without moyamoya vessels. Long-term ischaemia would make perforating or anastomotic arteries vulnerable. These arteries were easily ruptured by hypertension, resulting in intracerebral haemorrhage.