Toward a further elucidation: role of vertebral artery hypoplasia in acute ischemic stroke

BACKGROUND AND PURPOSE: Congenital vertebral artery (VA) hypoplasia is an uncommon embryonic variation of posterior circulation. The frequency of this congenital variation was reported to be 2-6% from autopsy and angiograms. The aim of our study was to elucidate the role of VA hypoplasia in acute ischemic stroke. METHOD: We examined 191 acute ischemic stroke patients (age 55.8 +/- 14.0 years). TOAST subtypes were determined. A cervical magnetic resonance angiogram was performed in every patient. A duplex study of bilateral VA with flow velocities and vessel diameter recording in the intertransverse (V2) segment was performed within 72 h after onset of ischemic stroke. The net VA flow volume was measured in each subject. RESULT: The overall incidence of a unilateral congenital hypoplastic VA was 11.51%, which was statistically higher especially in cases of brainstem/cerebellar infarction. Of these, subjects with VA hypoplasia had an etiological preponderance of the 'large-artery atherosclerosis' subtype and a topographic preponderance of ipsilateral posterior circulation infarction. CONCLUSIONS: Based on our results, VA hypoplasia seemed a contributing factor of acute ischemic stroke, especially in posterior circulation territories.     

A thread of hope for successful revascularization for acute embolic basilar artery occlusion due to miserable vertebral artery stump syndrome. A technical report

Acute basilar artery occlusion (BAO) is associated with major morbidities and a high mortality rate. The prevalence of acute BAO is 10.4% among patients treated with thrombectomy for acute large vessel occlusion. Vertebral artery stump syndrome (VASS) reportedly causes ischemic stroke with tandem occlusions as vertebral artery (VA) origin occlusion and BAO. The pathogenesis of ischemic stroke due to VASS can be attributed to thrombi or emboli. Acute embolic BAO due to VASS accounted for 2 of 25 cases (8.0%) of BAO treated using thrombectomy between April 2014 and May 2019 in our registry. VASS must be considered as one cause of BAO. With the initial Magnetic resonance angiography on arrival, it is difficult to distinguish between BAO due to simple cardiogenic embolus and due to embolus caused by VASS rapidly. In patients suffering from acute embolic BAO due to VASS, the presence of VA origin occlusion makes endovascular therapy (EVT) difficult to perform. Here, we report consecutive cases of thrombectomy for acute embolic BAO due to VASS, showing markedly different outcomes. VA origin occlusion severely limits the technical options for EVT. Visualization or conjecture of the origin of both or dominant VAs conceivably offers the possibility of successful EVT and may allow good outcomes.     

椎动脉发育不全与卒中

目的 先天的椎动脉发育不全是一种后循环罕见的胚胎变异。从尸体解剖和血管造影中发现这种先天变异的频率为2%～6%。此研究的目的是阐明椎动脉发育不全在急性脑梗死中的作用。方法 我们收集了195位急性脑梗死患者(年龄57±13岁),并对每位受试者进行脑梗死类型（TOAST分型）的分类及磁共振血管造影（Magnetic Resonance Angiography,MRA）,并于卒中后72h内完成颈动脉超声及椎动脉血流量测量。结果 单侧的先天椎动脉发育不全总的发生率是11.79%;脑干、小脑梗死患者中发生率特别高。先天椎动脉发育不全与TOAST分类“大动脉粥样硬化”子类型相关。结论 基于我们的结果,先天椎动脉发育不全,特别在后循环上的先天椎动脉发育不全似乎是一种脑梗死的加重因素。     

Use of 3-Dimensional,Black-Blood,Contrast-Enhanced,T1-Weighted Magnetic Resonance Imaging to Identify Vascular Occlusion in the Posterior Circulation After Acute Ischemic Stroke

Background: Three-dimensional, black-blood, contrast-enhanced, T1-weighted magnetic resonance imaging (3D-BB-ceT1-MRI) could play a role in detection of thrombi and symptomatic intracranial atherosclerotic stenosis. We investigated the role of 3D-BB-ceT1-MRI in patients with acute ischemic stroke in the posterior circulation, and compared our findings with those from susceptibility-weighted imaging (SWI). Materials and Methods: We retrospectively reviewed 3D-BB-ceT1-MRI for patients between January 2017 and August 2018 with acute ischemic symptoms in the posterior circulation. During this period, 199 patients with acute infarction in the posterior circulation were enrolled. Time-of-flight-magnetic resonance angiography or cerebral angiography was used as the reference standard. Results: Of these 199 patients, 47 had vessel occlusion associated with acute infarction. The sensitivity of 3D-BB-ceT1-MRI for detection of vessel occlusion was significantly higher than that of SWI (95.7% versus 53.2%, P < .001). Twenty-one lesions with strong enhancement on 3D-BB-ceT1-MRI showed a negative susceptibility vessel sign (SVS) on SWI. Conclusions: 3D-BB-ceT1-MRI showed strong enhancement (due to contrast stagnation) in the intra-arterial thrombi of patients with acute infarction in the posterior circulation. 3D-BB-ceT1-MRI had higher sensitivity than that of an SVS on SWI for detection of intra-arterial thrombi.     

Association between pneumonia in acute stroke stage and 3-year mortality in patients with acute first-ever ischemic stroke

The influence of pneumonia in acute stroke stage on the clinical presentation and long-term outcomes of patients with acute ischemic stroke is still controversial. We investigate the influence of pneumonia in acute stroke stage on the 3-year outcomes of patients with acute first-ever ischemic stroke. Nine-hundred and thirty-four patients with acute first-ever ischemic stroke were enrolled and had been followed for 3 years. Patients were divided into two groups according to whether pneumonia occurred during acute stroke stage or not. Clinical presentations, risk factors for stroke, laboratory data, co-morbidities, and outcomes were recorded. The result showed that a total of 100 patients (10.7%) had pneumonia in acute stroke stage. The prevalence of older age, atrial fibrillation was significantly higher in patients with pneumonia in acute stroke stage. Total anterior circulation syndrome and posterior circulation syndrome occurred more frequently among patients with pneumonia in acute stroke stage (P < 0.001 and P = 0.009, respectively). Multivariate Cox regression revealed that pneumonia in acute stroke stage is a significant predictor of 3-year mortality (hazard ratio = 6.39, 95% confidence interval = 4.03–10.11, P < 0.001). In conclusion, pneumonia during the acute stroke stage is associated with increased risk of 3-year mortality. Interventions to prevent pneumonia in acute stroke stage might improve ischemic stroke outcome.     

Vertebral artery pseudoaneurysms secondary to blunt trauma: Endovascular management by means of neurostents and flow diverters

Extracranial vertebral pseudoaneurysms that develop following blunt trauma to the cervical area may have a benign course; however, embolic or ischemic stroke and progressive pseudoaneurysm enlargement may occur. We review the presentation and endovascular management of pseudoaneurysms of the cervical vertebral artery (VA) due to blunt trauma in nine patients (eight male, mean age 27 years). Pseudoaneurysms occurred in dominant vessels in seven patients and coexisted with segmental narrowing in six. We favored endovascular intervention during the acute phase only in cases with significant narrowing of a dominant VA, especially when anticoagulation was contraindicated. Four patients were treated during the acute stage (contraindication to anticoagulation, mass effect, severely injured dominant VA/impending stroke); five during the chronic phase (pseudoaneurysm growth, ischemic stroke on aspirin prophylaxis, patient preference). Reconstructive techniques were favored over deliberate endovascular occlusion when dominant vessels were involved. Arterial reconstruction was performed in eight of nine patients using a flow-diverter implant (5 patients), stent-assisted coiling (1), overlapping stent implant (1), or implantation of a balloon-expandable stent (1). Deliberate VA occlusion with coils was performed in one of nine patients due to suboptimal expansion of the stented artery after flow-diverter implant. No neurological complications occurred during follow-up. All cases treated by reconstructive techniques showed complete, persistent pseudoaneurysm occlusion and full arterial patency. Endovascular therapy of traumatic VA pseudoaneurysms using neurostents and flow-diverters resulted in occlusion of the pseudoaneurysms, preservation of the parent vessel, and no periprocedural or delayed clinical complications, supporting the feasibility and safety of the approach.     

Multiple acute infarcts in the posterior circulation.

OBJECTIVE--to evaluate clinical, radiological, and prognostic features of patients with multiple acute infarcts in remote arterial territories of the posterior circulation. DESIGN--Data analysis from a prospective acute stroke registry in a community based primary care centre using a standard protocol including MRI and MRA. RESULTS--In three and a half years, 27 of the 236 patients (11%) with posterior circulation stroke had multiple acute infarcts in the posterior circulation as shown by gadolinium enhancement on MRI. Eighteen patients had multiple infratentorial and supratentorial infarcts including the cerebellum and posterior cerebral artery territory, with coexisting brainstem involvement in seven patients. Fourteen patients had a rostral basilar artery syndrome and cerebellar signs; four patients had a visual field defect with cerebellar signs. Causes were vertebral (six) or basilar (four) artery atheromatosis, and cardioembolism (four). Seven patients had multiple acute infarcts in the posterior circulation of the cerebellum and lower brainstem. Brainstem and cerebellar signs were found in most patients (five); aetiologies were small vessel disease (four), cardioembolism (one), and vertebral artery dissection (one). Two patients with large artery atheromatosis had multiple acute infarcts in the posterior circulation in the brainstem and posterior cerebral artery territory. One month after stroke more than 25% of the patients were dependent or had died. There was no difference in the outcome between the three groups, and recovery was linked to the size of infarcts rather than to a high number of infarcts. CONCLUSIONS--multiple acute infarcts in the posterior circulation usually involve the cerebellum. Simultaneous brainstem and posterior cerebral artery territory infarcts sparing the cerebellum are uncommon. They can be suspected clinically before neuroimaging, mainly when supratentorial and infratentorial infarcts coexist. This may be important, because different patterns of infarction are associated with different causes of stroke.     

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.     

Rate of arterial occlusion in patients with acute ischemic stroke

OBJECTIVE: Computed tomographic angiography (CTA) was invented more than 20 years ago, but only gained acceptance recently, thanks to advancements in the computer technology. It can demonstrate areas of arterial stenosis or occlusion with accuracy nearly that of digital subtraction angiography (DSA). It is also able to clearly illustrate calcification, which is more difficult to define on magnetic resonance angiography and is not clearly depicted on DSA. METHODS: Our retrospective study attempted to clarify the rate of occlusion or stenosis in the patients with acute ischemic stroke. RESULTS: Over the period of 7 months, 93 consecutive patients were admitted with acute ischemic stroke. Fifty-six patients underwent CTA and were included in this study. Most of the patients were admitted after 6 hours following onset of symptoms. There were 28 men and 28 women, and 80.4% of the cohort was of African-American origin. The majority of strokes were attributed to small-vessel disease (25/56). The rest of the cases were deemed secondary to atheroembolism (15/56), cardioembolism (9/56) or of unclear etiology (7/56). In 24 (42.9%) patients, CTA failed to reveal any abnormalities of the cerebrovascular tree. CTA demonstrated arterial occlusion in ten (17.9%) patients and stenosis of extracranial or intracranial arteries on the symptomatic side in 22 (39.2%) patients. There was very good correlation between CTA and ultrasound techniques (carotid duplex and transcranial Doppler). CTA was superior in demonstrating distal intracranial stenosis. CONCLUSION: Overall, CTA is an extremely valuable and fast way to emergently evaluate the cerebrovascular anatomy, making it very useful for pre-thrombolysis evaluation of patients with ischemic stroke.     

Outcomes in Acute Ischemic Stroke Patients Without Angiographically Documented Arterial Occlusion

BACKGROUND AND PURPOSE: Patients with acute ischemic stroke who undergo emergent cerebral angiography for consideration of intra-arterial treatment and do not have an angiographically demonstrable occlusion pose a management dilemma. The authors reviewed their experience to determine the clinical out comes of patients with ischemic stroke evaluated within 6 hours of symptom onset in whom negative angiograms were obtained. METHODS: A prospective registry was maintained for all patients (N = 56) who were considered for intra-arterial thrombolysis. Patients without angiographic arterial occlusion were not treated with thrombolytics, and data pertaining to clinical characteristics and neuroimaging findings was collected. Follow-up data were acquired through clinic visits or telephone interviews at 5.5 +/- 5.0 months (mean +/- SD), range 1 to 15 months, after onset of stroke. RESULTS: Of the 56 patients, no arterial occlusion was observed in 17 (30%) patients (mean age 65.8 +/- 13.0 years; 7 were men). The mean (+/- SD) baseline National Institute of Health stroke scale score was 10.2 +/- 7.1. Symptoms were referable to the anterior or posterior circulation in 76% and 18% of the patients, respectively; they could not be localized to either circulation in 6%. Follow-up neuroimaging studies demonstrated cerebral infarction in 12 of 14 patients. Eleven of the 17 had a favorable long-term recovery as assessed by the modified Rankin Scale (score 0 or 1). Five other patients had modified Rankin Scale scores of 3 (n = 1), 4 (n = 2), or 5 (n = 2). One patient died during the follow-up period. With regard to location of ischemic deficits, the highest rate of death or dependency was observed in patients with pontine infarction (three of four patients). CONCLUSION: Although the outcome following ischemic stroke in patients without angiographically documented occlusion appears to be better than that reported for patients with angiographically documented occlusion, death or disability is observed in at least one third of the patients. There fore, acute ischemic stroke in the absence of angiographic occlusion is not entirely a "benign" entity and can be particularly devastating when the brainstem is involved.     

Brain CT perfusion improves intracranial vessel occlusion detection on CT angiography

Background and purpose

To evaluate whether brain CT perfusion (CTP) aids in the detection of intracranial vessel occlusion on CT angiography (CTA) in acute ischemic stroke.

Combined carotid and transcranial ultrasound findings compared with clinical classification and stroke severity in acute ischemic stroke

BACKGROUND: The aim of this study was to assess the association between cerebral hemodynamics and the clinical picture as defined by the Oxfordshire Community Stroke Project (OCSP) classification, as well as the clinical severity as defined by the National Institute of Health Stroke Scale (NIHSS) within the first 6 h of an acute middle cerebral artery (MCA) stroke onset. METHODS: 70 unselected patients were grouped according to the OCSP classification and NIHSS. All patients immediately had extracranial and transcranial Doppler (TCD) ultrasound examinations. RESULTS: In the study population as a whole, there was a significant association between intracranial vascular pathology and the OCSP classification (p<0.001) as well as the NIHSS score (p<0.001). In patients with severe stroke, however, TCD demonstrated the hypothesized proximal MCA(1) occlusion in only 34% of patients with an OCSP-defined total anterior circulation syndrome and in 42% of patients with an NIHSS score of >or=15. In moderate stroke, the OCSP classification was misleading in almost half of the patients with a partial anterior circulation syndrome, i.e. a hypothesized distal MCA(2) occlusion suitable for thrombolysis. CONCLUSIONS: Neither the OCSP classification nor the NIHSS grading provided reliable information about the site or presence of intracranial arterial occlusion in acute stroke within the first 6 h after stroke onset in the individual patient. The results of this study strongly suggest that selection of acute ischemic stroke patients for thrombolysis should also include an assessment of cerebral hemodynamics.     

11例颈动脉盗血综合征临床分析

目的分析11例颈动脉盗血综合征(CSS)的临床表现和影像学特点,评估其侧支循环建立与代偿方式及不同治疗方式的预后,为CSS的诊治提供依据。方法纳入2016年1月~2016年5月住院治疗的CSS患者11例。所有患者均进行颈部血管彩超、头颅CT血管造影(CTA)或磁共振血管成像(MRA)、数字剪影血管造影(DSA)等检查明确CSS诊断,进行侧支循环代偿评估。11例CSS患者中,4例患者行颈动脉内膜剥除术(CEA),5例行颈动脉内支架植入术(CAS),2例颈动脉闭塞患者药物保守治疗。对11例患者在治疗3个月、6个月和1年后进行随访,并评估缺血性脑血管事件及改良RANKIN量表评分(mRs)。结果 11例CSS患者中,单侧颈内动脉病变7例,双侧颈内动脉病变4例。临床表现为短暂性脑缺血发作7例,分水岭梗死3例,腔隙性脑梗死1例;其中后循环缺血7例,前循环缺血4例。DSA评估侧支循环建立单以一级侧支循环(11例)和二级侧支循环(4例)开放为主。ASITN评分大部分为3~4级。治疗后随访,有2例行CAS的患者出院后出现不同时期卒中样症状,4例行CEA的患者随访期内均未发生卒中。CAS和CEA术后3个月、6个月和1年的mRs评分均有不同程度改善。结论 CSS患者多发生于颈动脉狭窄严重患者,其侧支循环开放良好,以一、二级侧支循环开放为主,临床表现以后循环缺血症状多见。CAS及CEA能改善颈动脉狭窄,可能成为CSS的治疗手段。     

Absent collateral function of the circle of Willis as risk factor for ischemic stroke

BACKGROUND: Autopsy studies show a higher prevalence of circle of Willis anomalies in brains with signs of ischemic infarction. Our goal was to examine the collateral function of the circle of Willis in ischemic stroke patients and to assess in a case-control study if a collateral deficient circle of Willis is a risk factor for ischemic stroke in patients with severe internal carotid artery (ICA) occlusive disease. METHODS: Our case-control study included 109 patients with an acute ischemic stroke in the anterior circulation and 113 patients with peripheral arterial disease and no known history of cerebral ischemia. The collateral function of the anterior and posterior communicating arteries of the circle of Willis was assessed by means of transcranial color-coded duplex ultrasonography (TCCD) and carotid compression tests. RESULTS: TCCD was successfully performed in 75 case patients (mean age 64 years, range 41-91 years) and in 100 control patients (mean age 61 years, range 35-89 years). In 26 cases and 19 controls, a >/=70% stenosis or occlusion of the ICA was found. A nonfunctional anterior collateral pathway in the circle of Willis was found in 33% of the cases and in 6% of the controls (p < 0.001). The posterior collateral pathway was nonfunctional in 57% of the cases and in 43% of the controls (p = 0.02). In patients with severe ICA occlusive disease, the odds ratios of a nonfunctional anterior and a nonfunctional posterior collateral pathway were 7.33 (95% confidence interval, CI, = 1.19-76.52) and 3.00 (95% CI = 0.77-12.04), respectively. CONCLUSIONS: Patients who suffer ischemic stroke in the anterior circulation have a higher incidence of collateral deficient circles of Willis than those with atherosclerotic vascular disease without ischemic cerebrovascular disease. The presence of a nonfunctional anterior collateral pathway in the circle of Willis in patients with severe ICA occlusive disease is strongly associated with ischemic stroke.     

Characteristics of vascular lesions in patients with posterior circulation infarction according to age and region of infarct

Patients with posterior circulation infarction underwent CT angiography and magnetic resonance angiography. Intracranial and extracranial vasculopathy was evaluated according to age group and location of stroke. Patients aged > 60 years and < 60 years had similar rates of vertebral artery dominance and vertebrobasilar artery developmental or origin anomalies. Vertebrobasilar artery stenosis or occlusion and tortuosity occurred more frequently in patients aged > 60 years than < 60 years. The rates of vertebrobasilar artery anomalies and tortuosity were high in patients with posterior circulation infarction. Vertebrobasilar artery tortuosity occurred more frequently in patients aged > 60 years, whereas vertebrobasilar artery developmental anomalies occurred with similar frequency in patients aged < 60 years and > 60 years. Patients with infarction of the brainstem or cerebellum were more likely to have vertebral artery stenosis or occlusion, basilar artery stenosis or occlusion, vertebral artery dominance or tortuosity, and basilar artery tortuosity, and patients with infarction of the thalamus, medial temporal, or occipital lobes were more likely to have stenosis or occlusion of the vertebral or basilar arteries. Vertebrobasilar artery tortuosity, vertebral artery dominance (hypoplasia), and congenital variations of the vertebrobasilar system may lead to posterior circulation infarction at different locations in different age groups.     

Acute Ischemic Stroke Involving Both Anterior and Posterior Circulation Treated by Endovascular Revascularization for Acute Basilar Artery Occlusion via Persistent Primitive Trigeminal Artery

We report a case of acute ischemic stroke involving both the anterior and posterior circulation associated with a persistent primitive trigeminal artery (PPTA), treated by endovascular revascularization for acute basilar artery (BA) occlusion via the PPTA. An otherwise healthy 67-year-old man experienced sudden loss of consciousness and quadriplegia. Magnetic resonance imaging showed an extensive acute infarction in the right cerebral hemisphere, and magnetic resonance angiography showed occlusion of the right middle cerebral artery (MCA) and BA. Because the volume of infarction in the territory of the right MCA was extensive, we judged the use of intravenous tissue plasminogen activator to be contraindicated. Cerebral angiography revealed hypoplasia of both vertebral arteries and the presence of a PPTA from the right internal carotid artery. A microcatheter was introduced into the BA via the PPTA and revascularization was successfully performed using a Merci Retriever with adjuvant low-dose intraarterial urokinase. After treatment, his consciousness level and right motor weakness improved. Although persistent carotid-vertebrobasilar anastomoses such as a PPTA are relatively rare vascular anomalies, if the persistent primitive artery is present, it can be an access route for mechanical thrombectomy for acute ischemic stroke.     

Acute stroke with major intracranial vessel occlusion: Characteristics of cardioembolism and atherosclerosis-related in situ stenosis/occlusion

Acute ischemic stroke with major intracranial vessel occlusion is commonly due to cardioembolic or atherosclerosis-related in situ stenosis/occlusion, and immediate identification of these subtypes is important to establish the optimal treatment strategy. The aim of this study was to clarify the differences in clinical presentation, radiological findings, neurological temporal courses, and outcomes between these etiologies, which have not been fully evaluated. Consecutive emergency patients with acute ischemic stroke were retrospectively reviewed. Among them, patients with stroke with major intracranial vessel occlusion were analyzed with a focus on clinical and radiological findings, and a comparison was performed for those with cardioembolic or atherosclerosis-related in situ stenosis/occlusion. Of 1053 patients, 80 had stroke with acute major intracranial vessel occlusion (45 with cardioembolic and 35 with atherosclerosis-related in situ stenosis/occlusion). Interestingly, the susceptibility vessel sign (SVS) on T2-weighted MR angiography was more frequently detected in cardioembolic stroke (80.0%) than in atherosclerosis (in situ stenosis: 5.9%, chronic occlusion: 14.3%). Moreover, the proximal intra-arterial signal (IAS) on arterial spin labeling MRI and the distal IAS on fluid attenuated inversion recovery MRI was less frequently detected in chronic occlusion (27.3% and 50.0%, respectively) than in acute occlusion due to cardioembolic or in situ stenosis. Multivariate regression analysis showed that the SVS was significantly related to cardioembolism (adjusted odds ratio (OR): 21.68, P = 0.004). Clinical characteristics of acute stroke with major intracranial vessel occlusion differ depending on the etiology. The SVS and proximal/distal IAS on MRI are useful to distinguish between cardioembolic and atherosclerotic-related in situ stenosis/occlusion.     

椎-基底动脉狭窄和闭塞的超声影像学进展

椎-基底动脉狭窄和闭塞常常引起后循环缺血性病变,并可增加卒中再发的几率。数字减影血管造影（digital subtraction angiography,DSA）是诊断椎-基底动脉狭窄和闭塞的金标准,但其为有创性检查。近年来,随着与超声相关的新技术的快速发展,使其能够早期、准确的诊断椎-基底动脉狭窄或闭塞。本文旨在对椎-基底动脉狭窄和闭塞的超声影像学进展进行综述,以增加医生对超声影像检查在椎-基底动脉狭窄和闭塞方面的认识。     

Association of ischemic lesion patterns on early diffusion-weighted imaging with TOAST stroke subtypes

BACKGROUND: Different topographic patterns in patients who experience an acute ischemic stroke may be related to specific stroke causes. OBJECTIVE: To determine if lesion patterns on early diffusion-weighted imaging (DWI) are associated with stroke subtypes determined by the TOAST (Trial of ORG 10172 in Acute Stroke Treatment) classification. DESIGN: Cross-sectional study. SETTING: General community hospital.Patients We studied 172 consecutive ischemic stroke patients with a symptomatic lesion on DWI performed within 24 hours of stroke onset. MAIN OUTCOME MEASURES: Lesion patterns on DWI were classified into single lesions (corticosubcortical, cortical, subcortical > or =15 mm, or subcortical <15 mm), scattered lesions in one vascular territory (small scattered lesions or confluent with additional lesions), and multiple lesions in multiple vascular territories (in the unilateral anterior circulation, in the posterior circulation, in bilateral anterior circulations, or in anterior and posterior circulations). RESULTS: We found an overall significant relationship between DWI lesion patterns and TOAST stroke subtypes (P<.001). Corticosubcortical single lesions (P =.01), multiple lesions in anterior and posterior circulations (P =.03), and multiple lesions in multiple cerebral circulations (P =.008) were associated with cardioembolism. Multiple lesions in the unilateral anterior circulation (P =.04) and small scattered lesions in one vascular territory (P =.06) were related to large-artery atherosclerosis. Nearly half (11/23) of the patients with a single subcortical lesion that was 15 mm or larger were classified as having cryptogenic strokes (P =.001), although 9 of these patients had a classic lacunar syndrome without cortical hypoperfusion. CONCLUSIONS: Early DWI lesion patterns are associated with specific stroke causes. Conventional 15-mm criteria for lacunes, however, may underestimate the diagnosis of small-vessel occlusion with DWI.     

A Case of Posterior Circulation Embolism Due to a Subtype of Bow Hunter's Syndrome Diagnosed by Non-Invasive Examination

Bow hunter's syndrome is the mechanical compression of the vertebral artery due to cervical rotation, resulting in ischemic symptoms in the vertebrobasilar artery territory. However, some cases present without typical symptoms and exhibit compression of the non-dominant side of the vertebral artery. We encountered a case of posterior circulation embolism due to a subtype of bow hunter's syndrome in a 74-year-old man. Although the right vertebral artery was not visualized on time-of-flight magnetic resonance angiography in the neutral position, duplex ultrasonography and time-of-flight magnetic resonance angiography in the left cervical rotation position showed blood flow in the right vertebral artery. In this case, blood flow in the contralateral vertebral artery was normal, and typical bow hunter's syndrome symptoms did not occur. In a case of posterior circulation embolism with undetermined etiology, wherein the routine duplex ultrasonography and time-of-flight magnetic resonance angiography results were inconclusive, additional testing with head positioning led to the diagnosis of a subtype of bow hunter's syndrome.