Posterior circulation ischemia in patients with fetal-type circle of Willis and hypoplastic vertebrobasilar system

Little attention has been given to the fetal-type posterior circle of Willis (FTP) in the literature; also symptomatic basilar artery (BA) hypoplasia has been rarely reported. We aimed to illustrate that the association of a hypoplastic vertebrobasilar system (VBS) with the FTP may lead to posterior circulation ischemia. Magnetic resonance imaging and three-dimensional time-of-flight magnetic resonance angiography were performed in 88 consecutive patients with ischemic stroke or TIA in the VBS. Thirteen patients were identified with either stroke or TIA in the context of a hypoplastic VBS and a fetal origin of the posterior cerebral arteries. All patients had unilateral or bilateral FTP, hypoplastic BA and at least one hypoplastic vertebral artery. Transcranial color-coded duplex revealed decreased flow velocity and increased pulsatility index along the BA. A hypoplastic VBS may be accompanied by the FTP and its simultaneous occurrence can predispose to ischemic events in the posterior circulation.     

Basilar and distal vertebral artery stenosis: long-term follow-up

Forty-four patients with greater than or equal to 50% stenosis of a distal vertebral artery (VA) and/or basilar artery (BA) were followed up for an average of 6.1 years. Angiography was performed for definite vertebrobasilar (VB) transient ischemic attacks (TIA) in 19 (43%), for VB infarcts in 13 (30%) and for non localizing symptoms in 12 (27%). Stenosis in the BA with or without VA involvement was present in 28 patients (64%), while 16 patients (36%) had occlusive disease in one or both distal VA sparing the BA. In follow up, 7 patients (16%) had definite VB TIA and 3 patients had possible VB TIA. Eight patients (18%) sustained a stroke, 5 of which were in the VB territory. The observed stroke rate was 17 times the expected rate for a matched normal population. Eight patients died during follow up, three patients due to stroke (2 brainstem infarctions, one intraventricular hemorrhage). The observed 5 year survival rate was 78% compared to 90% in a matched normal population. In comparing this data with our previous study of 93 patients with proximal VA occlusive disease, distal VB occlusive disease appears to carry a higher risk for brainstem ischemia.     

转颈对眩晕患者基底动脉流速的影响

目的　采用TCD观测转颈对正常人及眩晕患者基底动脉流速的影响。方法　正常对照组 3 6例 ,眩晕患者 3 1例 ,TCD常规检查椎 -基底动脉及转颈时基底动脉流速的变化。结果　正常人随年龄增大 ,椎 -基底动脉流速下降 ,转颈前后基底动脉流速差异无显著性 ;眩晕患者椎 -基底动脉流速下降 ,转颈后基底动脉流速明显下降 ,较转颈前差异有显著性 (P <0 .0 5 )。结论　转颈后基底动脉流速下降≥ 2 0 % ,即为转颈试验阳性 ,提示患者椎—基底动脉系统代偿能力差 ,存在椎动脉狭窄等病变的可能 ,需进一步检查     

Vertebrobasilar artery territory infarction as an initial manifestation of systemic lupus erythematosus.

Cerebral infarction is a well-documented complication of systemic lupus erythematosus (SLE), that usually occurs several years after the diagnosis of SLE. To our knowledge, however, strokes associated with vertebrobasilar artery involvement were not reported to present as an initial manifestation of SLE. We report two patients, who presented with vertebrobasilar territory infarction as an initial manifestation of SLE. Patient 1 was a 16-year-old girl, who developed dysarthria and ataxia. MRI showed multiple infarcts in the pons, cerebellum and thalamus. Four-vessel cerebral angiography showed multifocal stenoses in the vertebral and basilar arteries with beaded appearance. Patient 2 was a 26-year-old woman, who developed headache associated with dysarthria, dizziness and ataxia. MRI showed multiple infarcts in the cerebellum, medulla, pons, midbrain and thalamus. Cerebral angiography revealed occlusion of both vertebral arteries at the first cervical vertebral level with non-visualization of the basilar artery. Both patients were diagnosed as having SLE supported by laboratory results. Although rare, posterior circulation stroke can present as an initial manifestation of SLE, which may be attributed to vasculitis or dissection in the vertebral/basilar artery.     

颅内椎基底动脉狭窄支架成形术后的远期疗效

目的 探讨症状性动脉粥样硬化性颅内椎基底动脉狭窄患者择期支架成形术治疗的远期疗效。方法 回顾性分析2001年9月至2007年9月在我院行择期支架成形术治疗的症状性动脉粥样硬化性颅内椎基底动脉狭窄（狭窄>50%）患者116例,其中基底动脉狭窄患者57例，狭窄57处；颅内椎动脉狭窄患者59例，狭窄60处。研究的主要终点事件是靶病变相关的缺血性卒中、症状性脑实质出血和蛛网膜下腔出血。结果 本组病例支架手术成功率为94%（110/117）。30 d内的卒中事件8例，30 d后（中位时间33.5个月）椎基底动脉供血区的卒中事件5例。椎基底动脉供血区年卒中率（包括30 d内的任何死亡和卒中）4.0%。结论 择期支架成形术治疗可减少症状性动脉粥样硬化性颅内椎基底动脉狭窄患者的年卒中风险、改善功能预后，效果优于药物治疗。远期疗效与支架是否成功置放以及狭窄部位有关。     

Dissection of the Extracranial Vertebral Artery: Clinical Findings and Early Noninvasive Diagnosis in 24 Patients

Dissection of cervical arteries causes ischemic stroke in young adults. This reports the clinical, ultrasonographic, and neuroradiological findings in 24 patients with 28 vertebral artery dissections in the neck (4 occurring bilaterally). In 20 patients (83%), the dissection was temporally related to trauma. No patients had an underlying vascular disease, for example, atherosclerosis or fibromuscular dysplasia. In all, the major initial manifestation was pain in the occipital or neck region. The next most common symptoms were vertigo and nausea (in 17 patients). Clinical manifestations were vertebrobasilar transient ischemic attack (TIA) (5 patients: in 2 patients vestibulocerebellar TIA, in 1 patient visual TIA, in 1 patient motor TIA, and in 1 patient brain stem TIA with perioral paresthesia), cerebellar infarction (10 patients, in 4 patients bilateral), brainstem infarction (5 patients), posterior cerebral artery territory infarction (1 patient), and multiple vertebrobasilar ischemic lesions (3 patients). Typical angiographic findings were irregular narrowing of the vessel lumen or a tapering stenosis with distal occlusion. Magnetic resonance imaging showed a thickened vessel wall with hematoma signal at the site of the dissection. Duplex color-flow imaging was valuable for the early diagnosis of extracranial vertebral artery dissection and for follow-up examinations. The distal V1- and the proximal V2-segment (at the level of C6 vertebra) was the most frequent localization of dissections (in 43%). The outcome was favorable except for 2 patients with basilar artery occlusion. Embolism to the basilar artery may be avoided by early administration of anticoagulants.     

频发短暂性脑缺血发作与颅内外血管病变的相关性

目的 探讨症状相关侧血管狭窄程度、颈动脉斑块性质与频发短暂性脑缺血发作(TIA)的相关性.方法 应用DSA和颈动脉超声、经颅彩色多普勒超声联合对79例急性期(7 d内)颈内动脉系统TIA患者进行检查,按照患者首次发作至入院当天(时间范围≤7 d)的TIA发作次数分为TIA缓解组(发作次数＜3次)和TIA频发组(发作次数≥3次),比较两组间症状相关侧血管狭窄程度、颈动脉斑块性质的差异.结果 颈内动脉系统TIA患者的血管病变以颅内病变为主,以大脑中动脉病变最为多见(51.2%),颈内动脉颅外段次之(37.2%).TIA频发组与TIA缓解组相比,发作时间短暂(≤10 min),两组差异有统计学意义(x2=5.343,P=0.021).TIA频发组症状相关侧血管≥50%狭窄比例(66.7%)明显高于TIA缓解组(35.3%,x2=7.655,P=0.006).症状相关侧颈动脉斑块性质与频发TIA无相关性(x2=0.939,P=0.332).结论 频发TIA发作时间短暂且与症状相关侧血管中重度狭窄(≥50%)相关,其发病机制可能主要与血流动力学因素有关.     

Distribution of artificial cerebral microemboli in stroke patients with patent foramen ovale

Abstract

Objectives: Patent foramen ovale (PFO) is considered as an important risk factor for cerebrovascular diseases. Nevertheless, the relationship between the distribution of highintensity transient signals (HITS), resulting from injection of air mixed with saline and detected by transcranial Doppler (TCD), and clinical cerebrovascular syndromes in these patients has not been investigated.

Methods: Using TCD, we screened 40 patients with stroke or transient ischemic attack (TIA), in whom PFO was proven by transesophageal echocariography (TEE). Of these, 30 patients (75%) with artificially produced HITS either in the middle cerebral artery (MCA) or the basilar artery (BA) were included in the analysis.

Results: Nineteen patients had a stroke or TIA in the carotid territory and 11 patients in the vertebro-basilar territory. HITS were found in the MCA in all 30 patients and in 21 of the 30 patients in the BA. Of the latter, ten patients were in the carotid group and 11 patients were in the veretebro-basilar group, p=0.011.

Conclusion: There is a significant association between the distribution of artificial HITS and the clinical cerebrovascular syndromes.     

Distribution of artificial cerebral microemboli in stroke patients with patent foramen ovale

OBJECTIVES: Patent foramen ovale (PFO) is considered as an important risk factor for cerebrovascular diseases. Nevertheless, the relationship between the distribution of high-intensity transient signals (HITS), resulting from injection of air mixed with saline and detected by transcranial Doppler (TCD), and clinical cerebrovascular syndromes in these patients has not been investigated. METHODS: Using TCD, we screened 40 patients with stroke or transient ischemic attack (TIA), in whom PFO was proven by transesophageal echocariography (TEE). Of these, 30 patients (75%) with artificially produced HITS either in the middle cerebral artery (MCA) or the basilar artery (BA) were included in the analysis. RESULTS: Nineteen patients had a stroke or TIA in the carotid territory and 11 patients in the vertebro-basilar territory. HITS were found in the MCA in all 30 patients and in 21 of the 30 patients in the BA. Of the latter, ten patients were in the carotid group and 11 patients were in the veretebro-basilar group, p = 0.011. CONCLUSION: There is a significant association between the distribution of artificial HITS and the clinical cerebrovascular syndromes.     

Basilar artery blood flow during head rotation in vertebrobasilar ischemia

Patients and methods – Forty-six patients with vertebrobasilar ischemia and 40 control subjects were examined during head rotation using transcranial Doppler ultrasonography. Results – In the control group, no difference in blood flow velocity through the BA was found between the neutral and rotated positions. Based on these data, a blood flow reduction in the BA of more than 20% was considered to be significantly abnormal (p < 0.01). In three of 46 patients no signal was detectable in the BA using TCD. The reduction in blood flow velocity through the BA during head rotation was strongly dependent on the condition of the VA; none of 23 patients without atherosclerotic lesions or hypoplasia of the VA developed a significant reduction in blood flow through the BA. Two of 11 patients with unilateral VA lesions had significantly reduced blood flow in the BA (27% and 31%), although both were asymptomatic. Five of nine patients with bilateral VA lesions showed a significant reduction in blood flow through the BA (mean = 52%, minimum = 30%), and four of these developed clinical symptoms such as vertigo or diplopia during the rotation maneuver. Conclusion – These data suggest that patients with uni- or bilateral lesions of the VA are at risk for developing clinically relevant reductions in blood flow through the BA during head rotation. Because not all patients with VA lesions developed reduced blood flow velocity, we conclude that individual vascular mechanisms must play an important compensatory role.     

Lesion patterns and etiology of ischemia in superior cerebellar artery territory infarcts

BACKGROUND AND PURPOSE: Infarcts in the territory of superior cerebellar artery (SCA) are uncommon. The clinical, and etiological mechanisms of different infarct patterns of SCA are not well known. Diffusion-weighted imaging (DWI) is superior to conventional magnetic resonance imaging for detecting acute small and multiple ischemic lesions. METHODS: We studied 60 patients with lesions involving SCA territory proved by DWI, which have been selected from 3,800 patients with first ischemic stroke consecutively admitted to our stroke unit over a period of 5 years. RESULTS: There are 7 distinctive SCA lesion patterns: (1) a lesion was found in the medial (m) branch territory of SCA (mSCA) in 14 patients; (2) a lesion in the lateral (l) branch territory of SCA (lSCA) was seen in 9 patients; (3) a coexisting lesion involving mSCA and lSCA was found in 9 patients; (4) a lesion in cortical borderzones between SCA and m/l branches of the posterior inferior cerebellar artery (PICA) was observed in 6 patients; (5) a lesion in deep borderzones between lSCA and mSCA, and lPICA and mPICA was present in 8 patients; (6) a lesion involving the medial rostral cerebellum between the right and left SCA was found in 4 patients; (7) multiple lesions involving SCA and other vertebrobasilar artery territories were present in 10 patients. The main cause was possible artery-to-artery embolism from atherosclerotic vertebrobasilar arteries to distal branches of SCA in 20 patients (33%). Fourteen patients had a source of cardioembolism (23%), and 6 patients (8%) had concomitant atherosclerotic vertebrobasilar artery disease and a source of cardioembolism. CONCLUSIONS: An acute ischemic lesion in the SCA territory is mainly multiple. The lSCA territory was the most involved area. Small territorial infarcts were frequently associated with large territorial SCA infarcts. Borderzone SCA infarcts occurred in one third of the patients with transient benign symptoms. Mass effects are unusual despite the large amount of SCA involvement. Our results supported the fact that embolism is the predominant stroke mechanism in the SCA territory infarction.     

Prognostic value of CT angiography in patients with suspected vertebrobasilar ischemia.

BACKGROUND: The outcome of vertebrobasilar ischemia depends on the clinical presentation and the presence or absence of vascular occlusion. The aim of our study was to analyze the CT angiography (CTA) predictors of outcome in patients with suspected vertebrobasilar ischemia. METHODS: We studied patients with suspected acute vertebrobasilar ischemia between April 2002 and January 2006 and had CTA done within 24 hours of symptom onset. We reviewed the final diagnosis and 3-month follow-up and analyzed the clinical and CTA predictors of outcome. RESULTS: Of the 133 patients, 21(15%), 18 (13%), and 16 (12%) had occlusion of basilar artery (BA), vertebral artery (VA), and posterior cerebral artery (PCA) respectively. The final diagnosis was stroke in 98 (73.6%), transient ischemic attack (TIA) in 10 (7.5%), and nonischemic in 25 (18.8%). No vascular occlusion was seen on CTA in patients with TIA and nonischemic diagnosis. At 3-month follow-up, we found a mortality rate of 10.6% and good functional outcome in 71.4%. The predictors of death in the multivariable analysis were the presence of BA occlusion (odds ratio[OR] 6.7, 95% CI, 1.4-30.6) and baseline National Institutes of Health Stroke Scale (NIHSS) (OR 1.14, 95% CI, 1.06-1.2). When patients with basilar occlusion were excluded, the presence of VA occlusion (OR 6.5, 95% CI, 1.34-31.4), age (OR 1.09, 95% CI, 1.03-1.14), and baseline NIHSS (OR 1.1, 95% CI, 1.03-1.18) predicted poorer outcome. CONCLUSIONS: The presence or absence of a vascular occlusion is a critical factor for prognosis in suspected acute vertebrobasilar ischemia and is correlated with the location of occlusion.     

A case of bow hunter's stroke caused by non-dominant vertebral artery

Rotational movements in the territory of vertebrobasilar artery of the head and neck can induce vertebrobasilar insufficiency (VBI) or infarction. The term "bow hunter's stroke" or "rotational VBI" has been used to describe this clinical syndrome. In most cases, symptoms were provoked because of involvement of a dominant vertebral artery (VA) with hypoplasia or occlusion of the contralateral VA. The author presented a case in which bow hunter's stroke was caused by occlusion of a non-dominant VA ending in the posterior inferior cerebellar artery (PICA). Diagnosis of rotational VBI was based on stereotypical clinical symptoms related to head rotation and hemodynamic study of the effects of head rotation. VA compression was documented in dynamic ultrasonography including the disappearance of end-diastolic flow in extracranial portion of VA and marked reduction in blood flow velocity (more than 50%) in the intracranial portion of VA upon head rotation. We emphasize that rotational occlusion of this anatomical variation is an important cause of VBI. This may cause permanent neurological deficits if left undiagnosed.     

L-arginine-mediated vasoreactivity in patients with a risk of stroke

OBJECTIVES:L-arginine is the substrate for nitric oxide (NO) production and has been shown to induce an endothelium-dependent increase in cerebral blood flow in humans. We studied the hypothesis that L-arginine-mediated vasoreactivity is impaired in patients with cardiovascular risk factors and a risk of stroke. METHODS: 55 patients with cardiovascular risk factors (mean age 63.0 +/- 8.5 years) were included in the study. 45 of them had a history of previous minor stroke or transient ischemic attack (TIA) while 10 patients had cardiovascular risk factors but no previous cerebral ischemic event. Endothelium-dependent changes in cerebral blood flow during the infusion of 30 g L-arginine were assessed by continuous transcranial Doppler sonography of both middle cerebral arteries, intima-media thickness (IMT) of the common carotid artery, by Duplex sonography. Associations between risk factors, IMT, L-arginine reactivity and previous cerebrovascular events were analyzed by stepwise multiple linear regression analysis and patient groups were compared. RESULTS: Normal young volunteers showed an L-arginine-mediated increase in mean flow velocity of 22 +/- 8%; L-arginine reactivity of the 55 patients was 28 +/- 10%. Patients with a history of stroke or TIA had significantly higher flow velocity responses to L-arginine (29 +/- 10%) than patients with cardiovascular risk factors but no previous cerebrovascular event (21 +/- 8%, p < 0.05). Stepwise multiple linear regression analysis showed a significant association of enhanced L-arginine reactivity with previous stroke/TIA (p < 0.001) and elevated fibrinogen levels (p < 0.05) but not with age, IMT, hypertension, cholesterol or other risk factors. The same regression model showed an association between IMT and previous stroke/TIA (p < 0.001) and serum cholesterol levels (p < 0.05) but not L-arginine reactivity. CONCLUSIONS: L-arginine reactivity of the cerebral vessels may be assessed by Doppler sonography and was enhanced in patients with a history of stroke or TIA. It was independent of IMT of the carotid arteries. We conclude that enhanced L-arginine reactivity is a potential marker for cerebral endothelial dysfunction and an independent indicator for an increased risk of stroke.     

Cerebral autoregulation in middle cerebral artery territory precedes that of posterior cerebral artery in human cortex.

OBJECTIVE: Cerebral autoregulation tends to compensate changes in arterial blood pressure. This mechanism of cerebral blood flow regulation appears to be insufficient in orthostatic dysregulation in which mainly vertebrobasilar symptoms occur. To investigate this hypothesis, we compared cerebral autoregulation in the vascular territory of the carotic and vertebrobasilar vessel system using a leg cuff test to induce a drop in cerebral perfusion pressure. METHODS: We measured blood flow velocity in 10 healthy young volunteers (aged 26.7 +/- 0.3 years, 7 male) simultaneously in the middle and posterior cerebral artery with transcranial Doppler sonography. A leg cuff test was used to induce a sudden decrease in arterial blood pressure. Arterial blood pressure was measured with a non-invasive photoplethysmographic method. The averaged relative blood flow velocity changes due to the pressure step were compared between both vessel territories. RESULTS: After cuff release systolic (diastolic) blood flow velocity increased with a latency of 1.1 +/- 0.3 s (1.8 +/- 0.4 s). Due to a smaller decrease and identical time courses cerebral blood flow velocity recovery in the posterior cerebral artery precedes blood flow recovery in the middle cerebral artery by 0.9 +/- 0.3 s. DISCUSSION: Cerebral autoregulation in the carotid and vertebrobasilar system does not differ in the time course of the blood flow velocity recovery. Due to a smaller decrease in blood flow velocity recovery in the posterior cerebral artery precedes recovery in the middle cerebral artery by nearly 1 s.     

Lesion patterns and etiology of ischemia in the anterior inferior cerebellar artery territory involvement: a clinical – diffusion weighted – MRI study

The topography and mechanism of stroke in the anterior inferior cerebellar artery (AICA) territory are delineated before, but the detailed clinical spectrum of lesions involving AICA territory was not studied by diffusion weighted imaging (DWI). We reviewed 1350 patients with posterior circulation ischemic stroke in our registry. We included patients if the diagnosis of AICA territory involvement was confirmed, and DWI, and magnetic resonance angiography were obtained in the 3 days of symptoms onset. The potential feeding arteries of the AICA territory were evaluated on magnetic resonance imaging (MRI) using a three-dimensional rotating cineoangiographic method. There were 23 consecutive patients with lesion involving AICA territory, six with isolated lesion in the AICA territory, six with posterior inferior cerebellar artery, 11 with multiple posterior circulation infarcts (MPCIs). The clinical feature of isolated AICA infarct was vertigo, tinnitus, dysmetria, ataxia, facial weakness, facial sensory deficits, lateral gaze palsy, and sensory-motor deficits in patients with pontine involvement. Patients with largest lesion extending to the anterior and inferolateral cerebellum showed mixed symptomatology of the lateral medullary (Wallenberg's syndrome) and AICA territory involvement. Patients with MPCIs presented various clinical pictures with consciousness disturbances and diverse clinical signs because of involvement of different anatomical structures. Large-artery atherosclerotic disease in the vertebrobasilar system was the main cause of stroke in 12 (52%) patients, cardioembolism (CE) in one (4%), and coexisting large-artery disease and a source of CE in four (17%). The main cause of stroke was atheromatous vertebrobasilar artery disease either in the distal vertebral or proximal basilar artery. The outcome was usually good except those with multiple lesions. The new MRI techniques and clinical correlations allow better definition of the diverse topographical and etiological spectrum of AICA territory involvement and associated infarcts which was previously based on pathological and conventional MRI studies.     

Long-term outcome of elective stenting for symptomatic intracranial vertebrobasilar stenosis

Seventy-nine consecutive patients with symptomatic atherosclerotic stenosis > or = 50% of intracranial vertebrobasilar artery (VBA) were treated by elective stenting. There were five strokes within 30 days, and three strokes in the VBA territory after 30 days (mean of 812 days). The annual stroke rate in the VBA territory (including any stroke and death within 30 days) was 4.6%. At the last follow-up time, 73 patients were independent (modified Rankin scale grade < or = 2). The outcome compares favorably with medical therapy.     

Pure midbrain ischemia and hypoplastic vertebrobasilar circulation

Isolated midbrain infarction is rare and little is known about etiology and patient’s long-term follow up. We aimed to describe the clinical features, the causative diseases and the outcome of patients with isolated midbrain infarction who were admitted to our center, focusing on vascular abnormalities of posterior circulation. All patients with first acute ischemic stroke limited to the midbrain were included and their demographic features, neurological symptoms, neuroimaging data, and cardiovascular risk factors were recorded. Functional outcome, using modified Rankin scale, was assessed at discharge and at the 3 month follow up evaluation. We found nine patients with acute isolated midbrain infarction, representing 0.61 % of all ischemic stroke admitted to our center. The most common cause of stroke was small-vessel disease (88.8 %). At stroke onset, none of the patients had consciousness disturbances, and four patients (44.4 %) had gait impairment, five patients (55.5 %) presented with diplopia due to involvement of the third nerve or fascicular type of third-nerve palsy, seven patients (77.7 %) had vascular anomalies of vertebrobasilar circulation: the most frequent was vertebral artery hypoplasia [four patients (44.4 %)]. At follow up evaluation, seven patients (77.7 %) had a good functional outcome and no patients experienced recurrence of cerebrovascular events. As isolated midbrain infarction is uncommon, specific ocular motor signs, mainly third-nerve palsy, may help to identify and localize the mesencephalic infarct. Abnormalities in vertebrobasilar circulation, such as hypoplastic basilar or vertebral artery, are frequently associated with isolated midbrain ischemia. The hypoplastic vertebrobasilar system may predispose to posterior ischemic stroke.     

Posterior cerebral artery territory infarcts: clinical features, infarct topography, causes and outcome. Multicenter results and a review of the literature

Only a few large series of posterior cerebral artery (PCA) stroke exist, and clinical features and causes have not been studied as extensively as in other vascular territories. The PCA syndrome includes more clinical signs than the well-known visual field deficits. Concomitant findings are frequently sensory, slight motor and neuropsychological deficits. Unilateral headaches are the common presenting symptom making complicated migraine an important differential diagnosis. Combined deep and superficial PCA territory infarcts involving the lateral thalamus are more frequent than commonly assumed and are mostly associated with sensory and reversible slight motor deficits. Occlusion of the precommunal PCA segment with associated paramedian midbrain infarction causes severe motor deficits, oculomotor signs, and decreased consciousness and has a poorer outcome than other PCA territory infarcts. Embolism from a cardiac or undetermined source is the leading mechanism accounting for up to half of the cases, whereas arterial embolism from significant proximal vertebrobasilar disease is less frequent. Local atherothrombotic stenosis or occlusion of the PCA is uncommon. In spite of thorough diagnostic evaluation, the etiology of PCA territory infarction cannot be determined in at least one quarter of patients. Among the rare causes of PCA territory infarction carotid artery disease is important while the significance of migraine remains controversial.     

支架成形术治疗椎—基底动脉狭窄

目的评价支架成形术治疗椎—基底动脉狭窄的临床疗效和安全性。方法对20例椎—基底动脉狭窄患者进行脑血管造影,行支架成形术,并进行随访。结果20例患者共植入支架22个,手术成功率为100%,狭窄从术前的75%～99%下降到术后的0%～10%。随访6～36个月均未再次发生脑卒中或TIA。结论支架成形术治疗椎—基底动脉狭窄是一种安全有效的方法。