Significance of acute multiple brain infarction on diffusion-weighted imaging

Exploring the relationship between embolic acute stroke distribution and supra-aortic vessel patency: key findings from an in vitro model study

BACKGROUND

We investigated differences in intracranial embolus distribution through communicating arteries in relation to supra-aortic vessel (SAV) patency.

METHODS

For this experimental analysis, we created a silicone model of the extracranial and intracranial circulations using a blood-mimicking fluid under physiological pulsatile flow. We examined the sequence of embolus lodgment on injecting 104 frangible clot analogues (406 emboli) through the right internal carotid artery (CA) as SAV patency changed: (a) all SAV patent (baseline), (b) emboli from a CA occlusion, (c) emboli contralateral to a CA occlusion and (d) occlusion of the posterior circulation. The statistical analysis included a descriptive analysis of thrombi location after occlusion (absolute and relative frequencies). Sequences of occlusions were displayed in Sankey flow charts for the four SAV conditions. Associations between SAV conditions and occlusion location were tested by Fisher's exact test. Two-sided p values were compared with a significance level of 0.05.

RESULTS

The total number of emboli was 406 (median fragments/clot: 4 (IQR: 3-5)). Embolus lodgment was dependent on SAV patency (p<0.0001). In all scenarios, embolism lodging in the anterior cerebral artery (ACA) occurred after a previous middle cerebral artery (MCA) embolism (MCA first lodge: 96%, 100/104). The rate of ipsilateral ACA embolism was 28.9% (28/97) at baseline, decreasing significantly when emboli originated from an occluded CA (16%, 14/88). There were more bihemispheric embolisations in cases of contralateral CA occlusion (37%, 45/122), with bilateral ACA embolisms preceding contralateral MCA embolism in 56% of cases (14/25 opposite MCA and ACA embolism).

CONCLUSIONS

All emboli in the ACA occurred after a previous ipsilateral MCA embolism. Bihemispheric embolisms were rare, except when there was a coexisting occlusion in either CA, particularly in cases of a contralateral CA occlusion.

MRI in the Evaluation of Cryptogenic Stroke and Embolic Stroke of Undetermined Source

Cryptogenic stroke refers to a stroke of undetermined etiology. It accounts for approximately one-fifth of ischemic strokes and has a higher prevalence in younger patients. Embolic stroke of undetermined source (ESUS) refers to a subgroup of patients with nonlacunar cryptogenic strokes in whom embolism is the suspected stroke mechanism. Under the classifications of cryptogenic stroke or ESUS, there is wide heterogeneity in possible stroke mechanisms. In the absence of a confirmed stroke etiology, there is no established treatment for secondary prevention of stroke in patients experiencing cryptogenic stroke or ESUS, despite several clinical trials, leaving physicians with a clinical dilemma. Both conventional and advanced MRI techniques are available in clinical practice to identify differentiating features and stroke patterns and to determine or infer the underlying etiologic cause, such as atherosclerotic plaques and cardiogenic or paradoxical embolism due to occult pelvic venous thrombi. The aim of this review is to highlight the diagnostic utility of various MRI techniques in patients with cryptogenic stroke or ESUS. Future trends in technological advancement for promoting the adoption of MRI in such a special clinical application are also discussed.

MRI pattern characterization of cerebral cardioembolic lesions following atrial fibrillation ablation

Background

Recognizing etiology is essential for treatment and secondary prevention of cerebral ischemic events. A magnetic resonance imaging (MRI) pattern suggestive of an embolic etiology has been described but, to date, there are no uniformly accepted criteria.

Aim

The purpose of the study is to describe MRI features of ischemic cerebral lesions occurring after transcatheter ablation of atrial fibrillation (AF).

Methods

A systematic review and meta-analysis of studies performing brain imaging investigations before and after AF transcatheter ablation was performed. The incidence of cerebral ischemic lesions after AF transcatheter ablation was the primary endpoint. The co-primary endpoints were the prevalence of the different neuroimaging features regarding the embolic cerebral ischemic lesions.

Results

A total of 25 studies, encompassing 3,304 patients, were included in the final analysis. The incidence of ischemic cerebral lesions following AF transcatheter ablation was 17.2% [95% confidence interval (CI) 12.2%-23.8%], of which a minimal fraction was symptomatic [0.60% (95% CI 0.09%-3.9%)]. Only 1.6% of the lesions (95% CI 0.9%-3.0%) had a diameter >10 mm, and in 20.5% of the cases the lesions were multiple (95% CI 17.1%-24.4%). Brain lesions were equally distributed across the two hemispheres and the different lobes; cortical location was more frequent [64.0% (95% CI 42.9%-80.8%)] while the middle cerebral artery territory was the most involved 37.0% (95% CI 27.3-48.0).

Conclusions

The prevailing MRI pattern comprises a predominance of small (<10 mm) cortical lesions, more prevalent in the territory of the middle cerebral artery.

Acute bilateral multiple subcortical infarcts as manifestation in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is characterised by recurrent subcortical ischemic events, migraine with aura, dementia and mood disturbance. Strokes are typically lacunar infarcts; however, bilateral multiple subcortical lacunar infarcts have been described only sporadically.

METHOD

We described four CADASIL patients who presented with acute bilateral multiple subcortical infarcts as the first manifestation. We also briefly summarised the case reports detailing the bilateral multiple infarcts in CADASIL.

RESULTS

Patient 1 and patient 2 were family members, and they presented with cognitive impairment. Patient 3 and patient 4 presented with slurred speech and hemiparesis. Patients 1, 3 and 4 developed hemodynamic fluctuations before the occurrence of ischemic stroke. Laboratory tests revealed elevated fibrinogen levels in patients 3 and 4. The brain magnetic resonance imaging showed acute bilateral multiple subcortical infarcts on the periventricular white matter in all the patients.

CONCLUSION

CADASIL, with a poor brain hemodynamic reserve, is vulnerable to hemodynamic alterations (e.g. blood pressure fluctuation, dehydration, blood loss and anaemia) and intolerable to ischemia and hypoxia of the brain. Furthermore, blood hypercoagulation may contribute to acute multiple bilateral infarctions in CADASIL. Therefore, it is necessary to avert these predispositions in CADASIL patients in their daily life.

West Nile virus encephalomyelitis in an immunocompromised patient

We report a case of a 50-year-old immunocompromised woman who presented with acute encephalopathy and gait ataxia due to severe West Nile virus encephalomyelitis. The patient remarkably improved following early and sustained aggressive immunomodulation. Diagnosing West Nile neuroinvasive disease could be challenging without biochemical evidence of West Nile virus nucleic acid in the cerebrospinal fluid, a specific but not sensitive test. Although the neuroimaging findings in our patient could be considered "typical" for West Nile neuroinvasive disease, there is an overlap with the imaging abnormalities seen in other neuroinflammatory disorders presenting with acute leukoencephalopathy. Hence, we review West Nile neuroinvasive disease imaging characteristics and the differential diagnosis of acute leukoencephalopathy.

Distinct lesion features and underlying mechanisms in patients with acute multiple infarcts in multiple cerebral territories

Objective

To determine the etiology spectrum and lesion distribution patterns of patients with acute multiple infarcts in multiple cerebral territories (AMIMCT) and provide guidance for treatment and prevention strategies in these patients.

Methods

Patients with acute ischemic stroke diagnosed using diffusion-weighted imaging (DWI) were consecutively included in this study between June 2012 and Apr 2022. AMIMCT was defined as non-contiguous focal lesions located in more than one cerebral territory with acute neurological deficits. We retrospectively analyzed the clinical and imaging characteristics, etiology spectra and underlying mechanisms in patients with and without AMIMCT. Infarct lesion patterns on DWI and their relevance to etiology were further discussed.

Results

A total of 1,213 patients were enrolled, of whom 145 (12%) were diagnosed with AMIMCT. Patients with AMIMCT tended to be younger (P = 0.016), more often female (P = 0.001), and exhibited less common conventional vascular risk factors (P < 0.05) compared to those without AMIMCT. The constitution of the Trial of Org 10,172 in Acute Stroke Treatment classification was significantly different between patients with and without AMIMCT (P = 0.000), with a higher proportion of stroke of other determined causes (67.6% vs. 12.4%). For detailed etiologies, autoimmune or hematologic diseases were the most common (26.2%) etiologies of AMIMCT, followed by periprocedural infarcts (15.2%), cardioembolism (12.4%), tumor (12.4%), large artery atherosclerosis (10.3%), and sudden drop in blood pressure (8.3%). Hypercoagulability and systemic hypoperfusion are common underlying mechanisms of AMIMCT. Distinctive lesion distribution patterns were found associated with stroke etiologies and mechanisms in AMIMCT. Most of patients with large artery atherosclerosis (73.3%), autoimmune/hematologic diseases (57.9%) manifested the disease as multiple infarct lesions located in bilateral supratentorial regions. However, 66.7% of cardioembolism and 83.8% of cardiovascular surgery related stroke presented with both supratentorial and infratentorial infarct lesions.

Conclusion

The etiologies and mechanisms of patients with AMIMCT were more complex than those without AMIMCT. The distribution characteristics of infarct lesions might have important implications for the identification of etiology and mechanism in the future, which could further guide and optimize clinical diagnostic strategies.

Embolic infarct topology differs between atrial fibrillation subtypes and embolic stroke of undetermined source

BACKGROUND

The lack of superiority of anticoagulation over antiplatelet therapy in embolic stroke of undetermined source (ESUS) may be in part due to the misclassification of radiographic ESUS patterns as cardioembolic. In this imaging analysis, we sought to differentiate clinical and radiographic patterns of ESUS patients from patterns in patients with a highly probable cardioembolic source.

MATERIALS & METHODS

A prospective registry of consecutive adults with acute infarction on diffusion-weighted magnetic resonance imaging was queried. Patients with infarctions due to small vessel disease, large vessel disease, and other causes were excluded. Multivariable logistic regression was used to identify independent predictors of two potentially embolic patterns: (1) multifocal and (2) cortical lesions, comparing patients with ESUS against those with atrial fibrillation (AF).

RESULTS

Among 1243 screened patients, 343 (27.6%) experienced strokes due to ESUS or AF. Prior to the index stroke, patients with AF as compared to ESUS were older (median 75 vs. 65, p<0.01) and had more heart failure (25.9% vs. 8.4%, p<0.01). The odds of multifocal infarction were the same between patients with ESUS and both AF subtypes (p>0.05), however, cortical involvement was more associated with both AF versus ESUS (77.7% vs. 65.7%, P=0.02). A higher Fazekas grade of white matter disease was inversely associated with cortical infarction among included patients (aOR 0.77, 95% CI 0.62-0.96).

CONCLUSION

Cortical infarctions were twice as common among patients with AF versus ESUS. Subcortical infarct topography was strongly associated with chronic microvascular ischemic changes and therefore may not represent embolic phenomena. Larger-scale investigations are warranted to discern whether large or multifocal subcortical infarcts ought to be excluded from the ESUS designation.

Deep profiling of multiple ischemic lesions in a large, multi-center cohort: Frequency, spatial distribution, and associations to clinical characteristics

Background purpose

A substantial number of patients with acute ischemic stroke (AIS) experience multiple acute lesions (MAL). We here aimed to scrutinize MAL in a large radiologically deep-phenotyped cohort.

Materials and methods

Analyses relied upon imaging and clinical data from the international MRI-GENIE study. Imaging data comprised both Fluid-attenuated inversion recovery (FLAIR) for white matter hyperintensity (WMH) burden estimation and diffusion-weighted imaging (DWI) sequences for the assessment of acute stroke lesions. The initial step featured the systematic evaluation of occurrences of MAL within one and several vascular supply territories. Associations between MAL and important imaging and clinical characteristics were subsequently determined. The interaction effect between single and multiple lesion status and lesion volume was estimated by means of Bayesian hierarchical regression modeling for both stroke severity and functional outcome.

Results

We analyzed 2,466 patients (age = 63.4 ± 14.8, 39% women), 49.7% of which presented with a single lesion. Another 37.4% experienced MAL in a single vascular territory, while 12.9% featured lesions in multiple vascular territories. Within most territories, MAL occurred as frequently as single lesions (ratio ∼1:1). Only the brainstem region comprised fewer patients with MAL (ratio 1:4). Patients with MAL presented with a significantly higher lesion volume and acute NIHSS (7.7 vs. 1.7 ml and 4 vs. 3, p FDR < 0.001). In contrast, patients with a single lesion were characterized by a significantly higher WMH burden (6.1 vs. 5.3 ml, p FDR = 0.048). Functional outcome did not differ significantly between patients with single versus multiple lesions. Bayesian analyses suggested that the association between lesion volume and stroke severity between single and multiple lesions was the same in case of anterior circulation stroke. In case of posterior circulation stroke, lesion volume was linked to a higher NIHSS only among those with MAL.

Conclusion

Multiple lesions, especially those within one vascular territory, occurred more frequently than previously reported. Overall, multiple lesions were distinctly linked to a higher acute stroke severity, a higher total DWI lesion volume and a lower WMH lesion volume. In posterior circulation stroke, lesion volume was linked to a higher stroke severity in multiple lesions only.

Diffusion-weighted imaging as predictor of acute ischemic stroke etiology

BACKGROUND

Topographic patterns may correlate with causes of ischemic stroke.

OBJECTIVE

To investigate the association between diffusion-weighted imaging (DWI) and Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification.

METHODS

We included 1019 ischemic stroke patients. DWI were classified as: i) negative; ii) DWI single lesion (cortico-subcortical, cortical, subcortical ≥20 mm, or subcortical <20 mm); iii) scattered lesions in one territory (small scattered lesions or confluent with additional lesions); and iv) multiple lesions (multiple unilateral anterior circulation [MAC], multiple posterior circulation [MPC], multiple bilateral anterior circulation [MBAC], and multiple anterior and posterior circulations [MAP]).

RESULTS

There was a relationship between DWI patterns and TOAST classification (p<0.001). Large artery atherosclerosis was associated with small, scattered lesions in one vascular territory (Odds Ratio [OR] 4.22, 95% confidence interval [95%CI] 2.61-6.8), MPC (OR 3.52; 95%CI 1.54-8.03), and subcortical lesions <20 mm (OR 3.47; 95%CI 1.76-6.85). Cardioembolic strokes correlated with MAP (OR 4.3; 95%CI 1.64-11.2), cortico-subcortical lesions (OR 3.24; 95%CI 1.9-5.5) and negative DWI (OR 2.46; 95%CI 1.1-5.49). Cryptogenic strokes correlated with negative DWI (OR 4.1; 95%CI 1,84-8.69), cortical strokes (OR 3.3; 95%CI 1.25-8.8), MAP (OR 3.33; 95%CI 1.25-8.81) and subcortical lesion ≥20 mm (OR 2.44; 95%CI 1,04-5.73). Lacunar strokes correlated with subcortical lesions diameter <20 mm (OR 42.9; 95%CI 22.7-81.1) and negative DWI (OR 8.87; 95%CI 4.03-19.5). Finally, MBAC (OR 9.25; 95%CI 1.12-76.2), MAP (OR 5.54; 95%CI 1.94-15.1), and MPC (OR 3.61; 95%CI 1.5-8.7) correlated with stroke of other etiologies.

CONCLUSIONS

A relationship exists between DWI and stroke subtype.

Bihemispheric ischemic strokes in patients with COVID-19

BACKGROUND:

There is emerging evidence that COVID-19 can trigger thrombosis because of a hypercoagulable state, including large-vessel occlusion ischemic strokes. Bihemispheric ischemic stroke is uncommon and is thought to indicate an embolic source. Here, we examine the findings and outcomes of patients with bihemispheric stroke in the setting of COVID-19.

METHODS:

We performed a retrospective cohort study at a quaternary academic medical center between March 1, 2020, and April 30, 2020. We identified all patients with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection who presented with simultaneous bihemispheric ischemic strokes.

RESULTS:

Of 637 COVID-19 admissions during the 2-month period, 13 had a diagnosis of acute ischemic stroke, including 5 who developed bihemispheric cerebral infarction. Three of those 5 (60%) were female, median age was 54 (range 41–67), and all five were being managed for severe COVID-19-related pneumonia complicated by acute kidney injury and liver failure before the diagnosis of cerebral infarction was established. Five presented with elevated ferritin, lactate dehydrogenase, and interleukin-6 (IL-6) levels, and four had lymphopenia and elevated D-dimer levels. All patients underwent neuroimaging with computed tomography for persistent depressed mentation, with or without a focal neurologic deficit, demonstrating multifocal ischemic strokes with bihemispheric involvement. Outcome was poor in all patients: two were discharged to a rehabilitation facility with moderate-to-severe disability and three (60%) patients died.

CONCLUSIONS:

Stroke is implicated in SARS-CoV-2 infection. Although causality cannot be established, we present the imaging and clinical findings of patients with COVID-19 and simultaneous bihemispheric ischemic strokes. Multifocal ischemic strokes with bihemispheric involvement should be considered in COVID-19 patients with severe infection and poor neurologic status and may be associated with poor outcomes.

Associations Between Neuroanatomic Patterns of Cerebral Infarctions and Vascular Dementia

OBJECTIVE

A history of multiple cerebral infarctions is generally regarded as an important risk factor for vascular dementia. The authors examined the risk of vascular dementia in patients with multiple acute ischemic lesions.

METHODS

The authors conducted a hospital-based prospective study of 11,200 patients with first-time stroke who underwent 1.5 or 3-T MRI and a global cognitive assessment. Univariate and multivariate logistic regression analyses estimated the risk of dementia associated with multiple lesions versus a single lesion.

RESULTS

Having multiple lesions, compared with having a single lesion, was significantly associated with dementia in patients with stroke (odds ratio=5.83, 95% CI=5.08, 6.70; p<0.001). The apoliproprotein ε4 allele was more frequent in patients with multiple lesions than in those with a single lesion (odds ratio=1.70, 95% CI=1.39, 2.07; p<0.001). Severe leukoaraiosis (odds ratio=15.77, 95% CI=8.38, 29.68; p<0.001) and microbleedings (odds ratio=1.31, 95% CI=1.06, 1.63; p<0.01) were strong confounders for dementia in the multivariate analysis. Multiple logistic regression analysis showed that multiple lesions in one hemisphere versus a single lesion (odds ratio=2.14, 95% CI=1.83, 2.51; p<0.001), involvement of strategic regions (odds ratio=4.73, 95% CI=4.07, 5.49; p<0.001), and stroke lesion volume (odds ratio=1.31, 95% CI=1.03, 1.66; p=0.03) were significantly associated with dementia. There was a preponderance of lesions on the left side in patients with dementia (odds ratio=2.56, 95% CI=2.11, 3.11; p<0.001).

CONCLUSIONS

Multiple spontaneous anterior or posterior circulation lesions after stroke increase a patient's risk of developing dementia. Recognition of multiple ischemic lesions after stroke may allow targeted rapid therapeutic interventions to prevent subsequent cognitive deterioration.

Successful treatment of ischemic stroke associated with brachiocephalic artery stenosis using alteplase

Introduction: Brachiocephalic artery stenosis rarely causes right hemispheric infarction with associated left hemiparesis. To date, there have been no reported cases of stroke associated with brachiocephalic artery stenosis that were successfully treated with recombinant tissue-type plasminogen activator (rt-PA), alteplase.

Case Report: An 80-year-old woman presented with left hemiparesis. Brain computed tomography showed no hemorrhage, and computed tomography angiography demonstrated brachiocephalic artery stenosis. Alteplase was administered based on a diagnosis of ischemic stroke. Brain magnetic resonance imaging showed multiple acute infarctions. Thereafter, the blood pressure of the right arm was found to be lower than that of the left arm. The patient’s neurological deficits gradually improved; she was eventually able to walk again and was thus discharged home.

Conclusion: While the combination of left hemiparesis and a decrease in blood pressure in the right arm are well known in patients with stroke associated with Stanford type A aortic dissections, it may also occur in patients with stroke due to brachiocephalic artery stenosis. Unlike stroke associated with Stanford type A aortic dissections, stroke due to brachiocephalic artery stenosis may be treated with alteplase.

Arterial culprit plaque characteristics revealed by magnetic resonance Vessel Wall imaging in patients with single or multiple infarcts

PURPOSE

To investigate characteristics of intra- and extracranial arterial culprit plaques between patients with single infarct and multiple-infarcts by a head-neck combined high resolution magnetic resonance vessel wall imaging (HR-MRVWI).

MATERIALS AND METHODS

Forty-three patients with recent ischemic stroke due to large artery atherosclerosis were enrolled. The head-neck combined HR-MRVWI was performed in all patients both pre- and post-contrast administration. Based on diffusion weighted imaging findings, patients were divided into single-infarction and multiple-infarction groups. For patients with anterior circulation ischemic stroke, they were also divided into perforating artery infarction (PAI) and non-PAI groups. Patient demographics, number and location of culprit plaques, artery stenosis percentage, intraplaque hemorrhage, and plaque enhancement were evaluated and compared between single-infarction and multiple-infarction groups, as well as between PAI and non-PAI groups.

RESULTS

A total of 83 culprit plaques were identified. The artery stenosis degree was more severe and plaque enhancement more prominent in multiple-infarction group than in single-infarction group. Patients with multiple infarcts also had more culprit plaques per patient than those with single infarct, which contributed to the occurrence of multiple infarcts. For comparison of PAI and non-PAI groups, a higher artery stenosis percentage was observed in non-PAI group, and patients with non-PAI had more culprit plaques per patient, which contributed to a variety of infarct manifestations.

CONCLUSION

A higher stenosis grade and higher number of culprit plaques seem to be associated with a higher number of cerebral infarcts in patients with large artery atherosclerosis.

Clinical manifestation of non-ketotic hyperglycemia chorea: A case report and literature review

INTRODUCTION

Chorea is considered a special complication of diabetes mellitus. Here we report a case of chorea associated with non-ketotic hyperglycemia (NKH).

PATIENT CONCERNS

The patient was a 79-year-old Asian woman. She had a history of type 2 diabetes mellitus more than 30 years, but with a poor control of blood sugar. She complained of acute onset of right limb involuntary activities, and being admitted to neurology department.

DIAGNOSIS

The patient was then diagnosed with NKH chorea.

INTERVENTIONS

Intravenous infusion of insulin was given to reduce blood glucose. Haloperidol was used to control motor symptoms.

OUTCOMES

Her symptoms improved quickly after treatment. In the past year, the patient's blood sugar was well controlled and her chorea did not recur.

LESSONS

If there are sudden abnormal movements in patients, in addition to thinking of chorea, hepatolenticular degeneration and other diseases, we should also pay attention to blood sugar, especially in diabetic patients with poor blood sugar control and negative ketone, we should consider the possibility of NKK chorea.

CONCLUSIONS

NKH chorea is a special complication of diabetes.

The usefulness of Time-of-Flight MR angiography in detection of intraplaque hemorrhage in patients with acute ischemic stroke with symptomatic carotid stenosis

Objective

Carotid intraplaque hemorrhage (IPH) is a well-known risk indicator of thromboembolism, but it is not easy to rapidly detect IPH in acute symptomatic carotid disease. The aim of this study was to assess the utility of time-of-flight (TOF) magnetic resonance angiography (MRA) in the detection of IPH and evaluate the degree of stenosis and stroke patterns in patients with acute symptomatic carotid disease.

Methods

We retrospectively identified consecutive patients with acute symptomatic carotid disease who were admitted within 12 h after stroke onset. Fifty-nine patients underwent TOF MRA at admission and were categorized according to the presence or absence of intraplaque high signal intensity (HSI). The severity of carotid stenosis and diffusion-weighted magnetic resonance imaging lesion patterns were evaluated.

Results

Intraplaque HSI was detected in 28.8% of the enrolled patients (17/59). Mild-to-moderate symptomatic carotid stenosis was more frequent in the intraplaque HSI-positive group (70.6%) than in the intraplaque HSI-negative group (42.8%) (p = 0.015). The patients with intraplaque HSI more frequently exhibited a disseminated small infarction pattern (76.5% in the intraplaque HSI-positive group, 47.6% in the -negative group), and did not exhibit a border-zone infarction pattern (0% in the positive group, 16.7% in the negative group).

Conclusions

TOF MRA may be a useful noninvasive and rapid tool to detect IPH in patients with acute symptomatic carotid disease. IPH was common in those with a lower degree of carotid stenosis and manifested as a disseminated small infarction pattern. Intraplaque HSI on TOF MRA in acute symptomatic carotid disease may help to determine the mechanism of stroke and establish early treatment plans.

[Lacunar stroke]

Lacunar stroke occupies a special place among the various subtypes of ischemic stroke, accounting for about 25% in its structure and pathogenetically most often associated with cerebral microangiopathy caused by arterial hypertension (AH) and stenotic tandem atherosclerosis (AS) of cerebral arteries. Small deep (lacunar) infarction (SDI) of the brain is its structural basis. In recent years, understanding of its heterogeneous pathogenesis, clinical and practical significance was significantly expanded in connection with the widespread introduction into practice of highly informative neuroimaging methods (first of all, the newest MRI methods), which make it possible to identify SDI of the brain at various stages of their development, including in the acute period of lacunar stroke. This review covers in the historical aspect the issues of morphology, pathogenesis, clinical and neuroimaging dynamics of hypertensive and atherosclerotic SDI, including the criteria for their differential diagnosis. Particular attention is paid to the problems of asymptomatic ('silent') SDI, which, according to recent research, along with the diffuse pathology of the cerebral white matter, make a large contribution to the development of cognitive impairment up to the development of vascular dementia, and also are predictors of severe hemorrhagic and ischemic stroke in patients with AH and AS.

Preprocedure Intravenous Recombinant Tissue Plasminogen Activator and Risk of Distal Embolization with Thrombectomy in Acute Ischemic Stroke

BACKGROUND

Intravenous recombinant tissue plasminogen activator (IV rt-PA) prior to thrombectomy may reduce the risk of intraprocedural distal embolization in acute ischemic stroke patients.

METHODS

We analyzed the diffusion-weighted imaging acquired with 1.5- or 3-T magnetic resonance imaging (MRI) scans obtained within 24 hours of thrombectomy in consecutive acute ischemic stroke patients. An independent physician identified distal embolization, defined as discrete foci of restricted diffusion independent of the primary area of infarction on MRI scan. Patients were stratified based on whether they had or did not receive IV rt-PA prior to thrombectomy.

RESULTS

Distal embolization was seen in 59 (ipsilateral in 56) of 63 patients (mean age ± SD; 64.6 ± 15.3 years) who underwent thrombectomy (mean number 8.6; range 0-32). There was no difference in mean number of ipsilateral hemispheric distal embolization between the 2 groups (7.9 ± 6.1 versus 7.5 ± 7.6, P = .82). After adjusting for age, admission National Institutes of Health Stroke Scale score, the time interval between symptom onset and thrombectomy, there was no association between receiving IV rt-PA prior to thrombectomy and number of ipsilateral distal emboli (P = .90). There was no relationship between the number of ipsilateral emboli and rates of favorable outcome after adjusting for other confounders (adjusted odds ratio 1.0; 95% confidence interval .89 - 1.0; P = .40).

CONCLUSIONS

Although distal embolization is very common after thrombectomy, IV rt-PA prior to procedure does not reduce the risk of intraprocedural distal embolization.

Systematic review with network meta-analysis: Diagnostic values of ultrasonography, computed tomography, and magnetic resonance imaging in patients with ischemic stroke

BACKGROUND AND OBJECTIVE

Ischemic stroke is a foremost cause for disability and death worldwide. This study is conducted in order to compare the diagnostic values between transcranial Doppler ultrasound (ultrasonography), computed tomography (CT), and magnetic resonance imaging (MRI) in patients suffering from ischemic stroke by performing a network meta-analysis.

METHODS

We made use of Cochrane Library, PubMed, and Embase in order to obtain literature and papers. The combination analysis of both direct and indirect evidence in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy was conducted so as to assess the odds ratios (ORs) and surface under the cumulative ranking curve (SUCRA) values of the seven different imaging methods. These imaging techniques include ultrasonography, computed tomography (traditional CT, computed tomography angiography [CTA], computed tomography perfusion [CTP]), and MRI (traditional MRI, diffusion-weighted imaging [DWI], magnetic resonance angiography), in order to properly diagnose ischemic stroke patients.

RESULTS

Thirteen eligible diagnostic trials were enrolled into this network meta-analysis. The results of the traditional meta-analysis showed that among CT methods, CTP showed higher sensitivity, NPV, and accuracy; among MRI methods, DWI had relatively higher sensitivity, NPV, and accuracy. The results of network meta-analysis showed that DWI had relatively higher sensitivity, NPV, and accuracy when compared with traditional CT, CTA, magnetic resonance angiography and traditional MRI. CTP showed higher SUCRA among CT methods while DWI showed higher SUCRA among MRI methods. A cluster analysis revealed that DWI had the highest diagnostic value in terms of sensitivity, PPV, NPV, and accuracy amongst the aforementioned seven imaging techniques.

CONCLUSION

This network meta-analysis provides supporting evidence to the idea that DWI has a higher diagnostic value regarding ischemic stroke among MRI methods, and CTP has a poor diagnostic value among CT methods, which provide therapeutic considerations for Ischemic stroke intervention.

D-dimer >2.785 μg/ml and multiple infarcts ≥3 vascular territories are two characteristics of identifying cancer-associated ischemic stroke patients

BACKGROUND

The patterns and mechanisms underlying stroke in cancer patients differ from those of the conventional etiology. In this study, we further investigated the characteristics distinguishing cancer-associated ischemic stroke (CAIS) and the relationship of D-dimer value with CAIS.

METHODS

Sixty-one acute ischemic stroke patients with cancer (cancer group) and 76 stroke patients without cancer (control group) were recruited. Cerebrovascular distribution was divided into 3 circulations and 23 vascular territories, and acute multiple brain infarcts (AMBIs) were defined as discrete MRI diffusion-weighted imaging (DWI) lesions in >1 vascular territory.

RESULTS

Cancer patients had higher average D-dimer and fibrinogen degradation product values, and fewer stroke risk factors. The numbers of infarct-affected vascular territories, AMBIs, and AMBIs in multiple circulations were significantly higher in the cancer group. Receiver operating characteristic analysis showed that the cutoff value of D-dimer was 2.785 μg/ml; and above features were particularly evident in cancer patients whose D-dimer values were >2.785 μg/ml, while those with D-dimer values ≤2.785 μg/ml were similar to controls.

CONCLUSIONS

D-dimer >2.785 μg/ml may be an effective cutoff value and a sensitive index for identifying CAIS patients. AMBIs in ≥3 vascular territories and AMBIs in both the anterior and posterior circulations are two imaging characteristics of CAIS.

Changes in Serial D-Dimer Levels Predict the Prognoses of Trousseau's Syndrome Patients

Background: The development of acute multiple embolic infarctions (AMEI) resulting from cancer is known as Trousseau's syndrome (TS). At present, however, there is no good marker for predicting the prognosis of TS patients. In the present study, we evaluated the use of serial D-dimer levels as a prognostic marker for TS.

Methods: This retrospective cohort study included 1,409 consecutive acute ischemic stroke patients. We selected a group of patients with TS showing AMEI (n = 38; TS group) and a group of patients with atrial fibrillation (Af) and AMEI (n = 35; Af group) as controls. Serial D-dimer levels were measured between days 7 and 28 after stroke (sub-acute phase) in 21 patients of the TS group and 24 patients of the Af group.

Results: D-dimer levels at onset (acute phase) were significantly higher in the TS group (8.45 ± 1.79 μg/mL, n = 38) compared with the Af group (1.14 ± 0.14 μg/mL, n = 35) (p < 0.0001). In patients for whom serial D-dimer measurements were made, D-dimer levels measured at the sub-acute phase decreased to 0.48 ± 0.12 μg/mL (n = 24) in the Af group, but remained elevated in the TS group during the sub-acute phase (11.20 ± 2.77 μg/mL, n = 21) (p < 0.0001). In all TS patients in whom serial D-dimer measurements were made, D-dimer levels in 17 patients who died within 500 days (13.31 ± 3.23 μg/mL) were significantly higher than those of the four surviving patients (2.23 ± 0.38 μg/mL) (cut-off D-dimer level = 3.0 μg/mL) during this period. Moreover, serial D-dimer levels of 10 patients who died within 90 days (17.78 ± 4.60 μg/mL) were significantly higher than those of the 11 patients who survived up to 90 days (5.21 ± 2.12 μg/mL) (p < 0.05).

Conclusions: Serial D-dimer levels may be a good biomarker for TS as well as a useful predictor of the prognosis of TS patients.

Incidence and Etiology of Microinfarcts in Patients with Ischemic Stroke

BACKGROUND AND PURPOSE

Cerebral microinfarcts (CMI) are associated with intracerebral hemorrhage due to small vessel disease (SVD) in studies not including an ischemic etiologic workup. We aimed to determine their incidence and potential causes in a large ischemic stroke (IS) cohort.

METHODS

Consecutive patients with MRI-confirmed IS within 72 hours of onset were enrolled. Subjects had either single high-risk embolic source (cardioembolic or large vessel disease) or no embolic source. CMIs were classified by their relationship to the primary infarct as within or outside the same vascular territory. White matter hyperintensities (WMH) and microbleeds were markers SVD severity. Multivariable regression tested the association between CMIs and potential etiologies.

RESULTS

We analyzed 946 IS patients, mean age 69 ± 15 years, 46% female. We detected CMI (≤5 mm) on diffusion-weighted imaging in 269 (28%) subjects, 190 (71%) within the vascular territory of the primary infarct. Large-vessel atherosclerosis (P <.001), cardioembolic source (P <.001), higher WMH (P = .032) and lower systolic blood pressure (SBP, P = .024) were independently associated with the presence of CMI. While SBP was associated with CMI in any location (P <.05), WMH was only associated with CMI outside the territory of the primary infarct (P = .033), and large vessel atherosclerosis with CMI within the primary infarct territory (P = .004).

CONCLUSIONS

CMIs occurring within the vascular territory of a larger infarct are more likely embolic, but those occurring outside are probably related to SVD. Our findings suggest a role for SVD in pathogenesis of CMIs and emphasize the importance of etiologic workup to identify alternate etiologies.

[Cerebral infarctions in vertebrobasilar artery atherosclerosis]

AIM

to obtain more specific information on the morphology and pathogenesis of cerebral infarctions occurring in vertebrobasilar artery (VBA) atherosclerosis.

MATERIAL AND METHODS

Macro- and microscopic investigations of the brain, its arterial system, and heart were conducted in 69 autopsy cases with infarctions located in the vertebrobasilar system (VBS) in atherosclerosis.

RESULTS

69 cases were found to have 206 VBA infarctions of various extent and locations. The detected infarctions were single and multiple in 27 and 42 cases, respectively. The detected infarctions included extensive (n=7), large (n=9), medium (n=63), small deep (lacunar) (n=97), and small superficial (n=30). The brain stem showed lacunar infarctions most frequently (76% of the infarctions at this site). Medium and small infarctions were identified at the same frequency in the cerebral hemispheres and cerebellum. The occurrence of 94% of the extensive and large infarctions was ascertained to be pathogenetically associated with atherothrombotic occlusion of the intracranial arteries in the VBS. 76% of the small infarctions occurred through the mechanism of cerebral vascular insufficiency in tandem atherostenosis of VBAs in conjunction with an additional decrease in cerebral blood flow under the influence of an extracerebral factor (coronary heart disease). Medium infarctions were approximately equifrequently due to the two aforementioned causes and, in some cases, to cardiogenic thromboembolism of VBAs. Infarctions were multiple in most cases; while recent large atherothrombotic infarctions were frequently concurrent with small organized infarctions resulting from tandem atherostenosis of VBAs.

CONCLUSION

This investigation could establish the relationship between the site, extent, and pathogenetic factors of infarctions in the VBA bed in atherosclerosis, as well as the prognostic value of small infarctions as predictors for severe ischemic stroke.

Significance of Multiple Acute Ischemic Lesions on Initial Diffusion-weighted Imaging in Stroke Patients and Relation of Toast Classification

Background

It is important to know whether or not the stroke risk factors and etiologies of patients with multiple acute infarcts are different to those of patients with a single acute infarct.

Aim

The frequency of multiple acute infarct was investigated in ischemic stroke patients and a comparison was made of the characteristics of stroke patients with and without multiple acute infarct.

Patients and Methods

We reviewed the clinical records of 988 ischemic stroke patients who were admitted within 1 week of the onset of stroke and diffusion-weighted imaging (DWI) was performed on first presentation. The clinical characteristics, laboratory, and imaging results were noted from the patient records. According to the DWI findings, the patients were separated into three groups as those with a single acute infarct in a single vascular territory (SI group), those with multiple acute infarcts in a single vascular territory (SMI group) and those with multiple acute infarcts in multiple vascular (MMI group) territories. The frequency of multiple acute infarcts was investigated, and a comparison was made of the characteristics of stroke patients with and without multiple acute infarcts.

Results

The SMI group included 119 (12%) patients and the MMI group 126 (12.8%). The most common mechanisms of multiple acute infarcts are large artery atherosclerosis and cardiac origin emboli. Moreover, the risk factors most determined were hypertension, diabetes mellitus, and hyperlipidemia in the MMI group.

Conclusion

No difference was determined between the groups in respect of stroke etiology and risk factors.

Different infarction patterns in patients with aortic atheroma compared to those with cardioembolism or large artery atherosclerosis

Aortic atheroma is a known cause of ischemic stroke. However, it is unclear whether ischemic stroke is caused by emboli from aortic atheroma or by accompanying atherosclerosis. In this study, we evaluated lesion patterns of patients with complex aortic plaque (CAP) to assume the underlying pathophysiology. Acute ischemic stroke patients who underwent transesophageal echocardiography were included. CAP was defined as a plaque in the proximal aorta ≥ 4 mm thick or with a mobile component. The diffusion-weighted imaging lesion patterns of patients with CAP were compared to those with large arterial atherosclerosis (LAA) or cardioembolism (CE). A total of 64 CAP patients, 127 LAA patients, and 80 CE patients were included. Small cortical pattern was more common in the CAP group (45.3%) than in the LAA (7.9%, p < 0.001) or the CE group (23.8%, p = 0.018). A large cortical pattern was more common in the CE group than in the CAP group (p < 0.001), whereas subcortical only pattern tended to be more common in the CAP group than in the CE group (p = 0.057). In multinominal analysis, the CAP group was more likely to have a small cortical lesion than the LAA group [odds ratio (OR) 14.63; 95% confidence interval (CI) 4.67-45.85] or the CE (OR 3.69, 95% CI 1.19-11.39) group. In conclusion, patients with CAP frequently had small cortical lesions or subcortical single lesion. These findings imply that ischemic stroke in aortic atheroma patients is associated with either small emboli or small artery disease.

Acute cerebral infarcts in multiple arterial territories associated with cardioembolism

OBJECTIVES

It is generally believed that cardioembolism is the main cause of multiple acute cerebral infarcts (MACI). However, there are surprisingly few DWI studies and results are conflicting. Based on a large prospective study we hypothesized that MACI are associated with cardioembolism.

MATERIALS AND METHODS

We studied 2697 patients with acute cerebral infarcts between February 2006 and October 2013 who were prospectively registered in The Bergen NORSTROKE Registry. Among them, 2220 (82.3%) patients underwent magnetic resonance imaging (MRI) and 2125 (96%) of these 2220 patients had DWI lesions. Only patients with DWI lesions were included. MACI were defined as at least two DWI lesions in at least two different arterial territories.

RESULTS

MACI were detected in 187/2125 (8.8%) patients with DWI lesions. MACI patients were older and more often females. MACI were associated with cardioembolism (P = 0.042), especially atrial fibrillation (P = 0.002). Other associations were symptomatic internal carotid artery (ICA) stenosis (P = 0.014), asymptomatic ICA stenosis (P = 0.036), and higher NIHSS score on admission (P < 0.001). Among patients with no cardioembolism, 34 (35%) with MACI had symptomatic ICA stenosis versus 268 (25.0%) with non-MACI (P = 0.037); 20 (20%) with MACI had asymptomatic ICA stenosis versus 134 (13%) with non-MACI (P = 0.031). In the logistic regression analysis, cardiac embolism and symptomatic ICA stenosis were independently associated with MACI.

CONCLUSIONS

Acute cerebral infarcts in more than one arterial territory occur among almost 10% of the patients and are associated with cardioembolism.

Other cerebrovascular occlusive disease

In this chapter we review the optimal imaging modalities for subacute and chronic stroke. We discuss the utility of computed tomography (CT) and multimodal CT imaging. Further, we analyze the importance of specific magnetic resonance imaging sequences, such as diffusion-weighted imaging for acute ischemic stroke, T2/fluid-attenuated inversion recovery for subacute and chronic stroke, and susceptibility imaging for detection of intracranial hemorrhages. Different ischemic stroke mechanisms are reviewed, and how these imaging modalities may aid in the determination of such. Further, we analyze how topographic patterns in ischemic stroke may provide important clues to the diagnosis, in addition to the temporal evolution of the stroke. Lastly, specific cerebrovascular occlusive diseases are reviewed, with emphasis on the optimal imaging modalities and their findings in each condition.

Silent ischemic lesion laterality in asymptomatic internal carotid artery stenosis relates to reduced cerebral vasoreactivity

BACKGROUND

We investigated the relationship between silent ischemic lesions, defined as hyperintense lesions on T2-weighted magnetic resonance imaging scans of brain white matter and cerebral hemodynamics (baseline cerebral blood flow and cerebral vasoreactivity).

METHODS

Between January 2007 and December 2012, 61 patients with asymptomatic internal carotid artery stenosis were evaluated for asymptomatic silent ischemic lesions, acute infarction, and cerebral hemodynamics. Patients were divided into 2 groups based on silent ischemic lesion distribution; the Symmetry group (n = 34) included patients who showed symmetrical distribution of lesions (or had no lesions), and the Asymmetry group (n = 27) included patients with a greater number of lesions in the ipsilateral than that in the contralateral hemisphere. The Asymmetry group was further divided into Internal (n = 15) and External (n = 12) types.

RESULTS

Two External-type patients (17%) showed spotty asymptomatic acute infarction in the ipsilateral hemisphere. There were no significant differences in patient characteristics, histopathological findings, vascular risk factors, or cerebral blood flow values between the groups. The mean cerebral vasoreactivity value in the ipsilateral hemisphere for the Internal type was 13.0 ± 15.2% (range: -11.4% to 41.6%), which was significantly lower than values of the contralateral hemisphere (36.7 ± 20.8%; range: 3.9% to 75.7%; P <.01) and ipsilateral hemispheres of the other groups (P <.01).

CONCLUSIONS

The finding that increased ipsilateral asymmetrical silent ischemic lesions correlated with cerebral vasoreactivity reduction may help predict the risk of cerebral infarction in patients with asymptomatic internal carotid artery stenosis.

Time patterns in multiple acute cerebral infarcts

Background

Multiple acute cerebral infarcts in different arterial territories may be caused by several emboli concurrently or successively.

Aim and/or hypothesis

We hypothesized that the time from stroke onset to magnetic resonance imaging may shed light on underlying mechanisms of multiple acute cerebral infarcts.

Methods

This is a prospective observational cohort study involving 2697 ischemic stroke patients conducted at Haukeland University Hospital between February 2006 and October 2013. Only patients with diffusion-weighted imaging lesions in more than one arterial territory (left or right anterior circulation or posterior circulation) were included. The time from stroke onset to magnetic resonance imaging was registered and correlated with the etiology of multiple acute cerebral infarcts in each patient.

Results

We reviewed 2697 consecutive patients and 2220 (82%) underwent magnetic resonance imaging. Among these 2125 (96%) had diffusion-weighted imaging lesions. We found 187 multiple acute cerebral infarct patients who were then included in the study. There was positive correlation (0.20; p < .001) between time to magnetic resonance imaging and frequency of multiple acute cerebral infarcts caused by internal carotid stenosis. There was no correlation (−.02) between time to magnetic resonance imaging and frequency of multiple acute cerebral infarcts caused by cardiogenic embolism.

Conclusions

Multiple acute cerebral infarcts associated with cardiogenic embolism seem to happen concurrently as a shower of emboli whereas multiple acute cerebral infarcts associated with internal carotid artery stenosis seem to occur successively separated by hours or days.

Early consciousness disorder in acute ischemic stroke: incidence, risk factors and outcome

Background

Little is known about the incidence and risk factors of early consciousness disorder (ECD) in patients with acute ischemic stroke, or about how ECD may affect complications and outcomes.

Methods

Patients admitted to our hospital within 24 h of onset of acute ischemic stroke were consecutively enrolled. ECD was evaluated clinically and using the Glasgow coma scale. Multivariate analysis was used to identify risk factors of ECD, as well as associations between ECD and clinical outcomes.

Results

Of the 569 patients enrolled, 199 (35 %) had ECD. Independent risk factors of ECD were advanced age (OR 1.027, 95 % CI 1.007 to 1.048), National Institutes of Health Stroke Score on admission (OR 1.331, 95 % CI 1.257 to 1.410), and massive cerebral infarct (OR 3.211, 95 % CI 1.642 to 6.279). ECD was associated with higher frequency of stroke-related complications (83.4 % vs. 31.1 %, P < 0.001) and higher in-hospital mortality (17.1 % vs. 0.5 %, P < 0.001). ECD independently predicted 3-month death/disability (OR 3.272, 95 % CI 1.670 to 6.413).

Conclusions

ECD is prevalent in Chinese patients with acute ischemic stroke. Risk factors include advanced age, stroke severity, and massive cerebral infarct. ECD is associated with higher frequency of stroke-related complications and 3-month death/disability.

Recent Advances in Imaging in Management of Symptomatic Internal Carotid Artery Disease

The management of patients with internal carotid artery stenosis needs to focus on the occurrence and identification of neurological symptoms, the degree and morphology of the stenosis and the determination of the mechanism of cerebral ischemia. Thus neuroimaging studies are an integral part of the neurologist's assessment of these patient and individual therapeutic decisions. Since a differentiated approach is not always taken and patients by far too often undergo surgical or interventional treatment without a proper neurological evaluation, the material presented in this review demonstrates the possibilities of such a critical assessment concerning brain and vascular imaging findings and new techniques as well as modern concepts of plaque vulnerability improving the understanding of the pathophysiology and mechanisms of ischemic symptoms in internal carotid artery disease. Furthermore, the results of recent clinical trails that need to be integrated in the optimal treatment plan of these patients are discussed.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Distribution of ischemic infarction and stenosis of intra- and extracranial arteries in young Chinese patients with ischemic stroke

Background

The distribution of cerebral ischemic infarction and stenosis in ischemic stroke may vary with age-group, race and gender. This study was conducted to understand the risk factors and characteristics of cerebral infarction and stenosis of vessels in young Chinese patients with ischemic stroke.

Methods

This was a retrospective study, from January 2007 to July 2012, of 123 patients ≤50 years diagnosed with acute ischemic stroke. Patient characteristics were compared according to sex (98 males and 25 females) and age group (51 patients were ≤45 years and 72 patients were 46–50 years). Characteristics of acute ischemic infarction were studied by diffusion weighted imaging. Stenosis of intra- and extracranial arteries was diagnosed by duplex sonography, head magnetic resonance angiography (MRA) or cervical MRA.

Results

Common risk factors were hypertension (72.4 %), dyslipidemia (55.3 %), smoking (54.4 %) and diabetes (33.3 %). Lacunar Infarction was most common in our patients (41.5 %). Partial anterior circulation infarction was predominant in females (52.0 vs 32.7 %; P = 0.073) and posterior circulation infarction in males (19.8 vs 4 %; P = 0.073). Multiple brain infarctions were found in 38 patients (30.9 %). Small artery atherosclerosis was found in 54 patients (43.9 %), with higher prevalence in patients of the 46–50 years age-group. Intracranial stenosis was more common than extracranial stenosis, and middle cerebral artery stenosis was most prevalent (27.3 %). Stenosis in the anterior circulation was more frequent than in the posterior circulation (P < 0.001).

Conclusions

In these young patients, hypertension, smoking, dyslipidemia and diabetes were common risk factors. Intracranial stenosis was most common. The middle cerebral artery was highly vulnerable.

Unusual Cerebral Emboli

The heart and the carotid arteries are the most common sites of origin of embolic disease to the brain. Clots arising from these locations are the most common types of brain emboli. Less common cerebral emboli include air, fat, calcium, infected vegetations, and tumor cells as well as emboli originating in the venous system. Although infarcts can be the final result of any type of embolism, described herein are the ancillary and sometimes unique imaging features of less common types of cerebral emboli that may allow for a specific diagnosis to be made or at least suspected in many patients.

Silent New Brain Lesions: Innocent Bystander or Guilty Party?

With the advances in magnetic resonance imaging, previously unrecognized small brain lesions, which are mostly asymptomatic, have been increasingly detected. Diffusion-weighted imaging can identify small ischemic strokes, while gradient echo T2* imaging and susceptibility-weighted imaging can reveal tiny hemorrhagic strokes (microbleeds). In this article, we review silent brain lesions appearing soon after acute stroke events, including silent new ischemic lesions and microbleeds appearing 1) after acute ischemic stroke and 2) after acute intracerebral hemorrhage. Moreover, we briefly discuss the clinical implications of these silent new brain lesions.

Acute Bilateral Opercular Strokes Causing Loss of Emotional Facial Movements

The classic anterior opercular syndrome of Foix-Chavany-Marie presents with loss of voluntary facial, pharyngeal, lingual, and mastication movements, with preservation of emotional and automatic movements. Most commonly, sequential strokes affecting bilateral opercula cause this syndrome. The inverse clinical presentation, with selective loss of emotional facial movements, has only rarely been reported, and is less well-localized.

Case report:

We report a case of selective loss of emotional facial movements which resulted from bilateral acute infarcts. No etiology was discovered, and the syndrome was reversible.

Discussion:

The available literature, and findings in this case, suggest that voluntary and automatic facial movements have distinct pathways, and damage to the insula bilaterally may lead to the selective loss of emotional facial movements. The clinical presentation of this inverse automatic/voluntary dissocation needs to be recognized as a rare syndrome with bilateral localization, so that patients at higher risk of further stroke can quickly be identified.

Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification and vascular territory of ischemic stroke lesions diagnosed by diffusion-weighted imaging

Background

The association between the location and the mechanism of a stroke lesion remains unclear. A diffusion‐weighted imaging study may help resolve this lack of clarity.

Methods and Results

We studied a consecutive series of 2702 acute ischemic stroke patients whose stroke lesions were confirmed by diffusion‐weighted imaging and who underwent a thorough etiological investigation. The vascular territory in which an ischemic lesion was situated was identified using standard anatomic maps of the dominant arterial territories. Stroke subtype was based on the Trial of ORG 10172 in Acute Stroke Treatment, or TOAST, classification. Large‐artery atherosclerosis (37.3%) was the most common stroke subtype, and middle cerebral artery (49.6%) was the most frequently involved territory. Large‐artery atherosclerosis was the most common subtype for anterior cerebral, middle cerebral, vertebral, and anterior and posterior inferior cerebellar artery territory infarctions. Small vessel occlusion was the leading subtype in basilar and posterior cerebral artery territories. Cardioembolism was the leading cause in superior cerebellar artery territory. Compared with carotid territory stroke, vertebrobasilar territory stroke was more likely to be caused by small vessel occlusion (21.4% versus 30.1%, P<0.001) and less likely to be caused by cardioembolism (23.2% versus 13.8%, P<0.001). Multiple‐vascular‐territory infarction was frequently caused by cardioembolism (44.2%) in carotid territory and by large‐artery atherosclerosis (52.1%) in vertebrobasilar territory.

Conclusions

Information on vascular territory of a stroke lesion may be helpful in timely investigation and accurate diagnosis of stroke etiology.

Infarct patterns, collaterals and likely causative mechanisms of stroke in symptomatic intracranial atherosclerosis

BACKGROUND

There are limited data on the specific mechanisms of stroke in patients with intracranial atherosclerotic stenosis (ICAS). We undertook this study to describe infarct patterns and likely mechanisms of stroke in a large cohort of patients with ICAS, and to evaluate the relationship of these infarct patterns to angiographic features (collaterals, stenosis location and stenosis severity).

METHODS

We evaluated infarct patterns in the territory of a stenotic intracranial artery on neuroimaging performed at baseline and during follow-up if a recurrent stroke occurred in patients enrolled in the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial. We defined the likely mechanism of stroke (artery-to-artery embolism, perforator occlusion, hypoperfusion or mixed) according to the site of ICAS and based on the infarct patterns on neuroimaging. Collaterals were assessed using American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) grades, and stenosis severity using the WASID trial's measurement technique. We evaluated the association of infarct patterns with angiographic features using χ(2) tests.

RESULTS

The likely mechanisms of stroke based on the infarct patterns at baseline in the 136 patients included in the study were artery-to-artery embolism (n = 69; 50.7%), perforator occlusion (n = 34; 25%), hypoperfusion (n = 12; 8.8%) and mixed (n = 21; 15.5%). Perforator-occlusive infarcts were more frequent in the posterior circulation, and mixed patterns were more prevalent in the anterior circulation (both p < 0.01). Most of the mixed patterns in the anterior circulation combined small pial or scattered multiple cortical infarcts with infarcts in border-zone regions, especially the cortical ones. Isolated border-zone infarcts were not significantly associated with a poor grading for collaterals or the severity of stenosis. Among 47 patients with a recurrent infarct during follow-up, the infarct patterns suggested an artery-to-artery embolic mechanism in 29 (61.7%).

CONCLUSIONS

Artery-to-artery embolism is probably the most common mechanism of stroke in both the anterior and the posterior circulations in patients with ICAS. An extension of intracranial atherosclerosis at the site of stenosis into adjacent perforators also appears to be a common mechanism of stroke, particularly in the posterior circulation, whereas hypoperfusion as the sole mechanism is relatively uncommon. Further research is important to accurately establish the specific mechanisms of stroke in patients with ICAS, since preliminary data suggest that the underlying mechanism of stroke is an important determinant of prognosis.

Brain magnetic resonance imaging findings in cryptogenic stroke patients under 60 years with patent foramen ovale

PURPOSE

To compare magnetic resonance imaging (MRI) brain feature in cryptogenic stroke patients with patent foramen ovale (PFO), cryptogenic stroke patients without PFO and patients with cardioembolic stroke.

MATERIALS AND METHODS

The ethics committee required neither institutional review board approval nor informed patient consent for retrospective analyses of the patients' medical records and imaging data. The patients' medical files were retrospectively reviewed in accordance with human subject research protocols. Ninety-two patients under 60 years of age were included: 15 with cardioembolic stroke, 32 with cryptogenic stroke with PFO and 45 with cryptogenic stroke without PFO. Diffusion-weighted imaging of brain MRI was performed by a radiologist blinded to clinical data. Univariate, Fischer's exact test for qualitative data and non-parametric Wilcoxon test for quantitative data were used.

RESULTS

There was no statistically significant difference found between MRI features of patients with PFO and those with cardioembolic stroke (p<.05). Patients without PFO present more corticosubcortical single lesions (p<.05) than patients with PFO. Patients with PFO have more often subcortical single lesions larger than 15mm, involvement of posterior cerebral arterial territory and intracranial occlusion (p<.05) than patients with cryptogenic stroke without PFO.

CONCLUSION

Our study suggests a cardioembolic mechanism in ischemic stroke with PFO.

Symptomatic steno-occlusion in patients with acute cerebral infarction: prevalence, distribution, and functional outcome

Background and Purpose

Symptomatic steno-occlusion (SYSO) in acute ischemic stroke has a significant impact on treatment options and prognosis. However, the prevalence, distribution, clinical characteristics, and outcome of SYSO are not well known.

Methods

We retrospectively identified 3,451 patients hospitalized because of ischemic stroke within 24 hours of symptom onset at 9 stroke centers in South Korea. Patients who did not undergo magnetic resonance imaging were excluded. SYSO was defined as stenosis or occlusion of cerebral arteries with relevant ischemic lesions in the corresponding arterial territory. The number, location, and severity of SYSOs and their effects on functional outcome were analyzed.

Results

In total, 1,929 of 3,057 subjects (63.1%) had SYSO. The most frequently affected vessels were the middle cerebral artery (34.6%), extracranial internal carotid artery (14%), vertebral artery (12.4%), and basilar artery (8.7%). SYSO predicted poor outcome on the modified Rankin Scale 3-6 (odds ratio, 1.77; 95% confidence interval, 1.46-2.15) with adjustments. Involvement of 2 or more vessels was observed in 30.6% of patients with SYSO and independently increased the risk of poor outcome (odds ratio, 2.76; 95% confidence interval, 2.12-3.59). The severity of SYSO was associated with outcome and showed a significant dose-response trend (P<0.001). The effect of SYSO on outcome did not significantly differ by individual arterial location (P for contrast=0.21).

Conclusions

Approximately 60% of patients with acute ischemic stroke had SYSO, and the severity and number were inversely correlated with outcome. The results suggest that SYSO could predict stroke outcome.