Atheromatous embolism in the brain: a clinicopathologic analysis of 15 autopsy cases

Mechanisms and Neuroimaging Patterns of Hypereosinophilia-Related Ischemic Stroke: A Narrative Review through Three Cases

Background: Hypereosinophilic syndromes (HES) are a group of relatively rare disorders in which neurological manifestations, including ischemic stroke, are common. The hypothesized pathophysiological mechanisms are hypercoagulability, cardioembolism (mainly mediated by myocardial involvement) and damage to the endothelium. A variable ischemic pattern has been described, including an association of territorial and border zone ischemic stroke. Methods: Three patients who presented to our department with acute stroke were selected aiming to show these three different mechanisms inferred from the stroke pattern on brain Magnetic Resonance Imaging (MRI) and to simultaneously illustrate the three main causes of HES. Results and Discussion: The first patient is a 55-year-old man with an abrupt onset of aphasia due to an acute ischemic stroke involving the left parietal lobule and the angular gyrus; recent lab test had shown hypereosinophilia. An extensive workup excluded primary and secondary causes of hypereosinophilia so a diagnosis of idiopathic hypereosinophilia was done and he was treated with high doses of steroids. The second patient had severe hypereosinophilia and developed multiple small, scattered ischemic lesions, mainly in border zone zones. The history of severe asthma and recurrent sinusitis supported the diagnosis of EGPA (Eosinophilic Granulomatosis with Polyangiitis); considering the severe clinical conditions and the presumptive role of hypereosinophilia in determining her symptoms, steroid treatment was promptly started, with good clinical response. The third patient also presented with multiple metachronous ischemic lesions, both in cortical and border zone distribution and marked eosinophilia; the diagnostic work-up found an ovarian cancer. She was treated with steroids and then underwent surgery and adjuvant chemotherapy. Conclusions: HES should be considered in stroke etiological evaluation, although it is a rare disorder, and border zones pattern without large artery steno-occlusion on neuroimaging may help to raise the suspicion in the neurovascular diagnostic pathway. A thorough research of the sources of hypereosinophilia should be performed to select the appropriate therapy.

Imaging patterns of cerebral ischemia in hypereosinophilic syndrome: case report and systematic review

INTRODUCTION

Ischemic stroke is a potential complication of hypereosinophilic syndromes (HES), and little is known about underlying pathophysiological mechanisms. We aimed to describe the imaging patterns of cerebral ischemia in patients with HES.

METHODS

An individual case is reported. A systematic PubMed review of all records reporting adult patients with HES who suffered ischemic stroke and for whom neuroimaging details of ischemic lesions were available was performed.

RESULTS

A 60-year-old man presented with progressive subacute gait difficulty and psychomotor slowing as well as an absolute eosinophilia (2.2 × 109/L) at admission. Brain magnetic resonance tomography revealed multiple acute and subacute internal and external border zone infarcts. Cardiac diagnostic suggested the presence of endomyocarditis. After extensive diagnostic workup, idiopathic HES was diagnosed. The systematic review yielded 183 studies, of which 40 fulfilled the inclusion criteria: a total of 64 patients (31.3% female), with mean age 51.1 years and a median absolute eosinophile count at diagnosis of 10.2 × 109/L were included in the analyses. A border zone pattern of cerebral ischemic lesions was reported in 41 patients (64.1%). Isolated peripheral infarcts were reported in 7 patients (10.9%). Sixteen patients had multiple acute infarcts with no border zone distribution (25.0%). An intracardiac thrombus was reported in 15/60 patients (25%), and findings suggestive of endomyocarditis or endomyocardial fibrosis were found in 31/60 patients (51.7%).

CONCLUSIONS

Border zone distribution of cerebral ischemia without hemodynamic compromise is the most frequent imaging pattern in patients with HES, occurring in 2/3 of patients who develop ischemic stroke.

Cholesterol crystal embolism-related cerebral infarction: Magnetic resonance imaging and clinical characteristics

Background and aims

Cholesterol crystal embolism-related cerebral infarction (CCE-CI) is frequently misdiagnosed due to the lack of specific symptoms. To aid in differential diagnosis, this study comprehensively characterized the magnetic resonance imaging (MRI) and clinical manifestations of CCE-CI and compared these features to those of atherothrombotic cerebral infarction (ACI).

Methods

This single-center, retrospective, observational study was conducted at Kitasato University Hospital, Kanagawa, Japan. We identified 37 clinically or histopathologically confirmed CCE-CI cases and 110 ACI cases treated from January 2006 to May 2020. Groups were compared for mean age, sex ratio, clinical presentations, imaging manifestations, precipitating factors, comorbid conditions, medications, and smoking history.

Results

Of 37 eligible patients with CCE-CI, 10 (27.0%) received brain MRI, of which 8 (21.6%) exhibited high-intensity signals indicative of brain lesions on diffusion-weighted imaging (DWI). However, two patients with DWI lesions exhibited no detectable neurological abnormalities. Patients with CCE-CI frequently demonstrated bilateral DWI lesions involving the bilateral anterior and posterior circulation, a pattern absent in ACI (50% vs. 0%, p < 0.001). Compared to patients with ACI, CCE-CI patients also demonstrated significantly lower estimated glomerular filtration rate (p < 0.001) as well as more frequent eosinophilia (p = 0.006), atherosclerotic plaques ≥4-mm thick in the ascending aorta or proximal arch (p = 0.001), and aortic aneurysm (p < 0.001).

Conclusions

Patients with CCE-CI develop multiple DWI lesions across several vascular territories, even in the absence of neurological symptoms. Comorbid aortic aneurysm may increase CCE-CI risk. These findings could help in the differential diagnosis of CCE-CI.

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Diagnosis of CCE-CI is challenging due to nonspecific neurological symptoms.

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Brain DWI revealed multiple small ischemic lesions among patients with CCE-CI.

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CCE-CI was associated with atherosclerotic plaques in the ascending aorta and arch.

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CCE-CI was also associated with lower eGFR and higher blood eosinophil count.

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CCE-CI is associated with aortic aneurysm morbidity.

Novel Methods for Detecting Human Cholesterol Crystals from Sampled Blood

OBJECTIVE

Nonobstructive general angiography (NOGA) is a novel modality to detect and sample spontaneous ruptured aortic plaques (SRAPs). We aimed to establish novel methods to detect cholesterol crystals (CCs) in sampled SRAPs.

METHODS

Blood specimens containing SRAPs were obtained from patients using NOGA. Blood was instantly frozen on a glass slide and subsequently thawed for quantitative analysis and spread onto a filter paper that was rinsed using distilled water. Qualitative analysis was performed for the rinsed water using polarized light microscopy, and the filter paper was embedded in paraffin for histologic analysis.

RESULTS

The CCs were clearly observed after hemolysis using the instant freeze-thaw method. The filter paper rinse method indicated free CCs of varying shapes under polarized light microscopy without erythrocytes. On the filter paper, sampled SRAPs showed Lamé-like small particles. Histopathology revealed various atheromatous components.

CONCLUSION

A set of novel methods for detecting CCs from sampled blood was established.

A narrative review of the pathophysiology of ischemic stroke in carotid plaques: a distinction versus a compromise between hemodynamic and embolic mechanism

Atherosclerotic carotid artery stenosis causes about 10–20% of all ischemic strokes through two main mechanisms: hemodynamic impairment in case of significant stenosis and thromboembolism from an atherosclerotic plaque regardless of the degree of stenosis. The latter is the most frequent mechanism and appear to result from embolization from a vulnerable atherosclerotic plaque or acute occlusion of the carotid artery and propagation of thrombus distally. Downstream infarcts may occur in a territory of major cerebral artery or at the most distal areas between two territories of major cerebral arteries, the so-called watershed (WS), or border zone area. Although WS infarcts, especially deep WS infarct, were historically thought to be due to hemodynamic compromise, the role of microembolism has also been documented, both mechanisms may act synergistically to promote WS infarcts. Routine and more advanced imaging techniques may provide information on the underlying mechanism involved in ipsilateral ischemic stroke. A better understanding of ischemic stroke pathogenesis in carotid stenosis may limit the use of routine non-selective shunt, whose benefit-risk balance is debated, to patients with hemodynamic impairment.

After reviewing existing evidence underpinning the contribution of the two mechanisms in downstream ischemic stroke and the various imaging techniques available to investigate them, we will focus on the pathogenesis of WS infarcts that remains debated.

White matter integrity of watershed areas is potentially influenced by hypoperfusion in the presence permanent atrial fibrillation

Aim. To test a hypothesis of hypoperfusion-induced white matter changes in patients with atrial fibrillation (AFib) and to present statistics to compute sample size for the upcoming studies.

Material and methods. We included 30 inpatients with AFib and investigated them with magnetic resonance imaging (MRI) with standard sequencies and diffusion tensor imaging (DTI). DTI data were analyzed with conventional ROI analysis in the Olea Sphere software and with watershed areas (WSA) mask in the FSL toolbox after nonlinear transformation of images to the Montreal Neurological Institute (MNI) space. Wilcoxon test was used to compare diffusion characteristics across subgroups.

Results. Median age of participants was 73 years (69-78), 18 (60%) patients had moderate signs of small vessel disease with Fazekas score of one. Twenty-one patients had paroxysmal AFib. Analysis of WSA revealed decreased white matter integrity in the parieto-occipital cortical WSA with a pattern of significantly increased mean diffusivity (p=0,039), and marginally significant decrease in fractional anisotropy (p=0,056). Rank-based effect size across areas under comparison was either small (0,2) or negligible, and with statistical power in the range of 0,05-1.

Conclusion. Atrial fibrillation could have pathophysiologically feasible mechanism to affect white matter integrity in the watershed areas.

 

Is Hybrid Repair for an Entire Shaggy Aorta Feasible?

OBJECTIVE

This paper reviewed clinical experiences to evaluate the feasibility of a surgical strategy for an entire shaggy aorta.

METHODS

Fifty-two (52) surgeries (47 men, average age 72±7 years) were performed for an entire shaggy aorta at the current institution from 2002-2017. Open surgery was performed in 30 cases, including total arch replacement in 12, extended aortic arch replacement via L-shaped thoracotomy in 10 and median sternotomy combined with left thoracotomy in two, and thoracoabdominal aortic replacement in six. Hybrid procedures were performed in 22 cases: type I hybrid arch repair in six, type II hybrid arch repair in seven and type III hybrid arch repair in nine.

RESULTS

Hospital mortality was significantly higher with a hybrid repair: surgical, one case (3%); hybrid, six cases (27%), (p=0.0125). Stroke occurred at relatively high rates in both groups: surgical, seven cases (23%); hybrid, six cases (27%) (p=0.75). Spinal cord injury was significantly higher in hybrid repair: surgical, one case (3%); hybrid, seven cases (32%), (p=0.004). Open surgery revealed a better long-term survival rate than the hybrid procedure at 5 and 10 years: surgical, 82%, 65.7%; hybrid, 53%, 35.1%, respectively (p=0.0452). The rate of freedom from aortic events was significantly better with open surgery than a hybrid procedure at 5 and 10 years: surgical, 96%, 85%; hybrid, 83%, 41.3%, respectively (p=0.0082).

CONCLUSIONS

Surgery for an entire shaggy aorta was frequently associated with embolic complications such as stroke, paraplegia, renal failure, and bowel necrosis. However, open surgical repair may produce better early and late outcomes and freedom from aortic events compared with hybrid repair.

Massive Cerebral Microemboli after Protected Carotid Artery Angioplasty and Stenting Using a Distal Filter Embolic Protection Device for a Vulnerable Plaque with a Lipid Rich Necrotic Core and Intraplaque Hemorrhage: A Case Report

A major concern associated with carotid artery angioplasty and stenting (CAS) is a periprocedural distal cerebral embolization. To prevent distal embolization, embolic protection devices (EPDs) have been developed. However, the risk of cerebral embolism after protected CAS in patents with a vulnerable plaque is controversial and either a silent or a symptomatic stroke can occur despite the use of EPDs. Here, we report a case of a massive cerebral microemboli after a protected CAS using a distal filter EPD for a vulnerable plaque with a lipid rich necrotic core and intraplaque hemorrhage.

Spontaneous ruptured aortic plaque and injuries: insights for aging and acute aortic syndrome from non-obstructive general angioscopy

Recent advances in non-obstructive general angioscopy (NOGA) have enabled the detection of aortic atherosclerosis. The incidence of spontaneous ruptured aortic plaques (SRAPs) and aortic injuries was found to be high in patients diagnosed with or suspected of having coronary artery disease. These facts may result in a paradigm shift for diseases such as aging and acute aortic syndrome because the incidence of systemic embolic diseases and aortic disease are assumed be high. Aortic thromboembolism has been thought to be mainly iatrogenic and is referred to as "cholesterol embolization syndrome" or "cholesterol crystal embolization", although the cholesterol crystals (CCs) were not demonstrated routinely as real images. Atheromatous materials, fibrins, calcifications, macrophages, and a mixture of such substances are released through a puff or puff-chandelier rupture. Among atheromatous materials, CCs can be easily detected clinically in sampled blood via polarized light microscopy. Atheromatous materials include rich CCs and free monolayers, and multilayer CCs are released when the atheromatous materials from vulnerable plaques break into pieces, such as in puff or puff-chandelier rupture. Released SRAPs seem to be asymptomatic; however, accumulation of SRAPs referred to as accumulated spontaneous asymptomatic plaques may cause aging through systemic "embolic" processes, such as mechanical obstruction and an inflammasome pathway. Unique findings in "atherosclerotic" acute aortic syndrome, such as a clear boundary between the dissected lesion and the normal lesion, fissure/fissure bleeding suggesting an entry or a reentry, and subintimal blood flow detected through NOGA are reported. Fissure/fissure bleeding and subintimal blood flow may be the first or last triggers of "atherosclerotic" acute aortic syndrome. Pre-emptive diagnosis and risk stratification of acute "atherosclerotic" aortic dissection and feedback for endovascular therapy may be enabled through the use of NOGA in the future.

Simultaneous R2* and quantitative susceptibility mapping measurement enables differentiation of thrombus hematocrit and age: an in vitro study at 3 T

BACKGROUND

The efficacy of acute ischemic stroke treatment is affected by thrombus composition and age, yet no diagnostic method capable of quantitative thrombus characterization currently exists. This in vitro study evaluates the use of R_2^* , quantitative susceptibility mapping (QSM), and proton density fat fraction (FF) maps derived from a single gradient echo (GRE) MRI acquisition for characterizing clot of various hematocrit, as well as added calcified and lipidic components, throughout aging.

METHODS

Two thrombus phantoms containing porcine clots (10-60% hematocrit, one with added calcium or lard) were scanned serially throughout 6 days of aging. Three-dimensional multi-echo GRE imaging was used to generate R_2^* , QSM, and FF maps, from which mean values for all clots at every time point were obtained. Receiver operating characteristic analysis was used to derive thresholds differentiating acute from chronic clot, and measured R_2^* and QSM were tested for their ability to estimate clot hematocrit.

RESULTS

R_2^* and QSM varied minimally over the first 6 hours of aging (acute), and QSM was found to linearly relate to clot hematocrit. Beyond 6 hours (chronic), R_2^* and QSM increased considerably over time and hematocrit could be estimated from the R_2^* /QSM ratio. R_2^* and QSM thresholds of 22 s^-1 and 0.165 ppm differentiated acute from chronic clots with a sensitivity/specificity of 100%/100% and 85%/92%, respectively. QSM and FF maps definitively distinguished calcium and lipid, respectively, from clots of any hematocrit and age.

CONCLUSIONS

R_2^* , QSM, and FF from a single multi-echo GRE scan discriminated hematocrit and age, and distinguished calcification and lipid withinin vitro clot.

Microemboli versus hypoperfusion as an etiology of acute ischemic stroke in Egyptian patients with watershed zone infarction

Background

Brain perfusion is most likely to be impaired in border zone regions, and clearance of emboli will be most impaired in these regions of least blood flow. Severe occlusive disease of the internal carotid artery causes both embolization and decreased perfusion as well as some cardiac diseases that cause microembolization.

Objectives

To differentiate between hypoperfusion and microemboli as etiology of acute ischemic stroke in watershed zone.

Subject and methods

Fifty patients of acute ischemic stroke in watershed zones were recruited within 7 days from stroke onset. Methods used were transcranial Doppler (TCD) monitoring for the intracranial vessels to detect microembolic signals and magnetic resonance imaging (MRI) perfusion image to detect hypoperfusion signs.

Results

We detect embolic causes of watershed infarction (WSI) by using TCD with 61.1% sensitivity and 84.4% specificity and hypoperfusion causes of WSI by using MRI perfusion studies with 94.9% sensitivity and 54.5% specificity.

Conclusion

We detected the etiology of WSI, either embolic by using TCD or hypoperfusion by using MRI perfusion. The embolic causes of WSI usually cause external or mixed WSI, and hypoperfusion causes of WSI cause internal WSI.

Visible-free cholesterol crystal emboli adjacent to microinfarcts in myocardial capillaries and arterioles on H&E-stained frozen sections of an autopsied patient

The number of released free cholesterol crystal emboli (fCCE) and their role during percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) have not been documented yet. Furthermore, fCCE manifesting in the coronary lumen following plaque rupture has been historically overlooked owing to the standard tissue preparation for light microscopy which uses ethanol as a dehydrating agent that can dissolve fCCE, leaving behind empty tissue. In this case report, we evaluated fCCE released during PCI for ACS and their relationship with myocardial injury and coronary artery obstruction on the H&E-stained sections by using polarised light microscopy. To our knowledge, there has been no mention of the visibility of fCCE on H&E-stained frozen polarised sections before.

Diameter of fluorescent microspheres determines their distribution throughout the cortical watershed area in mice

A hemodynamic mechanism has long been assumed to play an important role in watershed infarction. In recent years, however, clinical evidence has indicated that an embolic mechanism is involved. The mechanism by which emboli are trapped preferentially in watershed areas remains unclear. In the present study, we developed a mouse embolus model using fluorescent microspheres with different diameters and evaluated the role of the microspheres' diameters in the generation of a watershed-patterned distribution. We injected fluorescent microspheres of four different diameters (i.e., 13, 24, 40, and 69 μm) into the internal carotid artery of C57BL/6 mice either (1) without ligation of the common carotid artery (normal perfusion pressure model: NPPM) or (2) with ligation of the common carotid artery (low perfusion pressure model: LPPM). Left common carotid artery ligation induced reductions in local cerebral blood flow in both the periphery and the core area of the left middle cerebral artery. A greater reduction in the border-zone area between the left anterior cerebral artery and the middle cerebral artery was also noted. After 24 h, the brains were removed and the distribution of the microspheres in the brain was evaluated using a fluorescence microscope. The 24-μm microspheres were distributed in the watershed area more frequently than the other microsphere sizes (P < .05, ANOVA followed by Tukey's test). Meanwhile, the distribution rates were similar between the NPPM and LPPM models for all microsphere sizes. This study suggested that the distribution pattern of the microspheres was only affected by the microspheres' diameters.

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.

The Pathophysiology of Watershed Infarction: A Three-Dimensional Time-of-Flight Magnetic Resonance Angiography Study

BACKGROUND

Most of the time, watershed infarcts (WIs) involve steno-occlusive carotid disease. The pathophysiological mechanism could be predicted by their pattern: internal WIs (IWIs) are thought to be due to hemodynamic impairment in contrast to cortical WIs (CWIs), which are more likely to be caused by microembolic phenomena. We used a 3D time-of-flight (TOF) magnetic resonance angiography (MRA) study to assess this hypothesis.

METHODS

In 45 consecutive patients with a recent WI and ipsilateral cervical carotid stenosis, clinical and radiological data were obtained retrospectively. 3D TOF MRA were analyzed both qualitatively and quantitatively (internal carotid and anterior, middle and posterior cerebral arteries). Then, 2 groups were determined depending on their radiological patterns: WIs with (IWI+) or without (IWI-) an internal watershed.

RESULTS

Thirty-two of the 45 patients (71%) had IWIs that were or were not associated with CWIs (IWI+), while 13 patients (29%) had only CWIs (IWI-). There was no significant relationship between the radiological pattern and the demographic data, the cardiovascular risk factors, or the degree of stenosis. However, IWI+ patients more frequently had motor weakness (P = .03) than CWI patients. An ipsilateral reduced middle cerebral artery intensity on 3D TOF MRA in both qualitative and quantitative analyses was significantly associated with IWI+. Instead within IWI-, no significantly reduced signal intensity was found.

CONCLUSION

These findings originally support the view that IWIs are mainly caused by a hemodynamic impairment related to carotid stenosis, whereas CWIs are mostly due to a microembolic mechanism. 3D TOF MRA, which gives pertinent information on pathophysiology on IWIs, can help in decision making.

Cerebrovascular risk factors for patients with cerebral watershed infarction: A case-control study based on computed tomography angiography in a population from Southwest China

To determine cerebrovascular risk factors for patients with cerebral watershed infarction (CWI) from Southwest China.Patients suffering from acute ischemic stroke were categorized into internal CWI (I-CWI), external CWI (E-CWI), or non-CWI (patients without CWI) groups. Clinical data were collected and degrees of steno-occlusion of all cerebral arteries were scored. Arteries associated with the circle of Willis were also assessed. Data were compared using Pearson chi-squared tests for categorical data and 1-way analysis of variance with Bonferroni post hoc tests for continuous data, as appropriate. Multivariate binary logistic regression analysis was performed to determine independent cerebrovascular risk factors for CWI.Compared with non-CWI, I-CWI had higher degrees of steno-occlusion of the ipsilateral middle cerebral artery, ipsilateral carotid artery, and contralateral middle cerebral artery. E-CWI showed no significant differences. All the 3 arteries were independent cerebrovascular risk factors for I-CWI confirmed by multivariate binary logistic regression analysis. I-CWI had higher degrees of steno-occlusion of the ipsilateral middle cerebral artery compared with E-CWI. No significant differences were found among arteries associated with the circle of Willis.The ipsilateral middle cerebral artery, carotid artery, and contralateral middle cerebral artery were independent cerebrovascular risk factors for I-CWI. No cerebrovascular risk factor was identified for E-CWI.

Routine Shunting During Carotid Endarterectomy in Patients With Acute Watershed Stroke

Aim:

To evaluate the protective role of routine shunting in patients with acute watershed stroke (WS) undergoing carotid endarterectomy (CEA).

Methods:

A total of 138 patients with symptomatic carotid stenosis (SCS) who underwent CEA after acute ischemic stroke from March 2008 to March 2015 were included in this study. Transient ischemic attacks were excluded. These patients were divided into 2 groups according to the topographic pattern of the stroke on magnetic resonance imaging: group 1, territorial strokes (TS) caused by emboli of carotid origin, and group 2, WS caused by a hemodynamic mechanism related to an SCS. Primary end points were 30-day mortality and postoperative neurological morbidity. The insertion of a Pruitt carotid shunt was performed systematically.

Results:

Ninety (65.2%) patients presented a TS of carotid origin and were included in group 1, and 48 (34.8%) of the 138 patients had a WS related to an SCS and were included in group 2. The median time between clinical onset of the cerebral ischemic event and surgery was 9 days (range: 0-89 days). Postoperative mortality was 0%. Seven (5.1%) patients had an aggravation of the neurological status during the postoperative period, of whom 2 presented a complete regression of the symptoms in less than 1 hour (definitive postoperative neurologic morbidity: 3.6%). Postoperative neurologic morbidity rate was significantly higher in the TS group (7 of 90; 7.8%) compared to the WS group (0 of 48; P = .04). No other independent predictive factor of neurologic morbidity after CEA for an SCS was found.

Conclusions:

Our results suggest that routine shunting should be considered in case of acute WS since it may play a protective role. Further studies are eagerly awaited to better define the timing and the best treatment option for both acute WS and TS related to an SCS in order to reduce postoperative neurologic morbidity.

Incidence and risk factors of embolized particles in carotid artery stenting and association with clinical outcome

BACKGROUND

One of the mechanisms for periprocedural neurologic events in carotid artery stenting (CAS) is catheter manipulation within the aorta and supraaortic arteries causing plaque embolization. Therefore, the present analysis sought to determine risk factors for embolic particle dimensions and their relationship with adverse clinical events after CAS.

METHODS

Between 1999 and 2015 embolic protection devices (EPD) of a total of 944 CAS procedures were evaluated regarding the occurrence and size of captured particles.

RESULTS

Particles were found in 819 of 944 (87%) EPDs. Larger particles were detected in procedures using open cell stents (150±282μm vs. 107±177μm; p=0.005) and longer stents (≥40mm) (165±315μm vs. 122±215μm; p=0.026). With increasing learning curve, particle size was continually reduced (168±282μm in the first third of the cohort vs. 127±309μm in the second third vs. 108±114μm in the last third; p=0.009). Longer stents and use of Acculink stent were found to be independent predictors for particle diameter. In patients who died or sustained a stroke during long-term follow-up (median 5.5years [IQR 2.6-7.9]) significantly larger particles were captured during CAS compared to those patients with an uneventful follow-up (160±330μm vs. 121±195μm; p=0.047).

CONCLUSIONS

In the vast majority of CAS procedures particles could be retrieved from the EPDs used. Procedural characteristics such as stent type and stent length were associated with larger particles.

Atheromatous embolization

Atheromatous embolization is a multisystem disease complicating advanced atherosclerosis. It occurs most often as a complication of angiography, an endovascular procedure or cardiovascular surgery. Atheromatous embolization can present in a subtle manner where it is often under-recognized, or with catastrophic results including myocardial infarction, strake or acute renal failure. It may mimic other disease processes and often goes underdiagnosed and undertreated. A high clinical suspicion is the key to diagnosis. Atheromatous embolization results in significant morbidity and mortality; therefore, early recognition followed by aggressive management may help to prevent end-organ damage and improve overall clinical outcomes. Management strategies should include risk factor modification, prevention of further insults by discontinuing or avoiding predisposing factors, supportive treatment and interventional or surgical approaches to remove the atheroembolic source. Atheromatous embolization is expected to increase as our population ages and the epidemics of diabetes mellitus and obesity increase.

An Approach to Working Up Cases of Embolic Stroke of Undetermined Source

Background

From a therapeutic viewpoint, it is important to differentiate the underlying causes of embolism in patients with cryptogenic stroke, such as aortic arch atheroma, patent foramen ovale, and paroxysmal atrial fibrillation. We investigated the clinical and radiological characteristics of these 3 common causes of cryptogenic embolism to develop models for decision making in etiologic workups.

Methods and Results

A total of 321 consecutive patients with acute infarcts from cryptogenic embolism were included. Patients were divided into 3 groups—aortic arch atheroma (n=40), patent foramen ovale (n=153), and paroxysmal atrial fibrillation (n=128)—based on extensive cardiologic workups. We used a multinomial logistic regression analysis to detect the clinical and diffusion‐weighted imaging factors associated with the probability of aortic arch atheroma, patent foramen ovale, and paroxysmal atrial fibrillation. Clinical and radiological features differed among the groups. The patent foramen ovale group had a healthy vascular risk factor profile and showed posterior circulation involvement compared with other groups (P<0.01). In contrast, paroxysmal atrial fibrillation–related strokes had higher initial National Institutes of Health Stroke Scale (NIHSS) scores and larger lesions than the other groups (P<0.001). The aortic arch atheroma group had clinical features similar to those of the paroxysmal atrial fibrillation group but showed small lesions scattered in multiple vascular territories (P<0.001). Multivariate regression analysis revealed that age, initial NIHSS score, lesion size (≥20 mm), multiple (≥3) lesions, and involvement of posterior circulation or multiple vascular territories differentiated the 3 groups (pseudo, R²=0.656). The prediction ability of this model was validated in the external validation cohort (n=117, area under the curve 0.78).

Conclusions

Our data indicate that patients with cryptogenic embolic stroke show distinct clinical and radiological features depending on the underlying causes.

Etiologic Subtypes of Watershed Infarcts

BACKGROUND

Two types of watershed infarcts (WI) are recognized. Internal WI are usually attributed to either severe stenosis in large arteries or acute hypotensive events, whereas external WI are thought to be caused by embolism. The aim of this study was to determine the etiologic background and prognosis of external and internal WI in our patients.

METHODS

We reviewed the medical records and diffusion-weighted images of the patients who were admitted to our stroke unit with acute ischemic stroke between January 2012 and November 2014. The demographics, clinical features, radiologic investigations, and other etiologic tests of the patients with internal or external WI were recorded. We determined etiologic stroke subtypes according to the automated Causative Classification System.

RESULTS

Fifty-three patients with WI were detected in our registry. Twenty-two (41.5%) of them were women. The mean age was 69 ± 12.8 (33-98) years. Twenty-one (39.6%) patients had external WI: 7 (33.3%) of them had large-artery atherosclerosis (LAA), 8 (38.1%) patients had cardioembolism, 3 (14.3%) patients had stroke due to other causes (vasculitis; n = 3), and etiologic subtype was undetermined in 3 patients (14.3%). Thirty-two (60.4%) patients had internal WI: 21 (65.6.%) of them had LAA, 5 (15.6%) patients had cardioembolism, 3 (9.4%) patients had stroke due to other causes (aneurysm; n = 1, hypercoagulability due to chronic myeloid leukemia; n = 1, vasculitis; n = 1), and etiologic subtype of 3 (9.4%) patients remained cryptogenic. LAA was significantly associated with internal WI (P = .024). Hypertension was more common in patients with internal WI (P = .035).

CONCLUSIONS

In this series, cardioembolism was the most common etiologic subtype in the patients with external WI, whereas internal WI were significantly associated with LAA. Uncommon causes should also be investigated in cryptogenic patients.

Cortical Ischemic Lesion Burden Measured by DIR Is Related to Carotid Artery Disease Severity

Background: Over time, exposure to cerebrovascular risk factors and carotid artery disease may cause multiple asymptomatic brain cortical and subcortical microinfarcts, which are commonly found at brain autopsy. So far, lack of convenient neuroimaging tools limited the investigation of grey matter ischemic damage in vivo. We applied the Double Inversion Recovery (DIR) sequence to explore the impact of carotid artery disease on intracortical ischemic lesion load in vivo, taking into account the impact of demographic characteristics and vascular risk factors. Methods: DIR was acquired in 62 patients with common cerebrovascular risk factors stratified in three groups according to carotid artery disease severity. Intracortical lesions scored on DIR (DIRlns) were classified by vascular territory, lobe and hemisphere. White matter hyperintensities (WMHs) volume was also quantified on Fluid Attenuated Inversion Recovery sequence (FLAIR). Results: Among demographic characteristics and cerebrovascular risk variables explored, General Linear Model indicated that age and carotid artery disease were significantly associated to DIRlns. After correcting for age, DIRlns load was found to be significantly dependent on carotid artery stenosis severity (F(2, 58) = 5.56, p = 0.006). A linear positive correlation between DIRlns and WMHs was found after correcting for age (p = 0.003). Conclusions: Carotid disease severity is associated with DIRlns accrual. Microembolism and impaired cerebral hemodynamics may act as physiopathological mechanisms underlying cortical ischemic damage. The role of other factors, such as small vessel disease and the possible interaction with carotid disease, remains to be further explored.

Embolic and Hemodynamic Transcranial Doppler Characteristics in Patients with Acute Ischemic Stroke due to Carotid Occlusive Disease: Contribution to the Different Infarct Patterns on MRI

BACKGROUND AND PURPOSE

Whether hemodynamic and/or embolic transcranial Doppler (TCD) features of internal carotid artery (ICA) stenosis contribute to the classification of stroke patterns on MRI.

PATIENTS AND METHODS

Consecutive patients presenting symptomatic ≥50% ICA stenosis were included. Microembolic signals (MES) detection and measurement of cerebral vasoreactivity (VR) were performed by TCD. Only acute MRI lesions, territorial (TT) and/or borderzone (BZ) were considered.

RESULTS

A total of 72 ICA stenoses, 27 (38%) moderate (50-69%), and 45 (62%) high grade (70-99%) were included. MRI lesions showed 32 (44%) pure TT, 20 (28%) pure BZ, and 20 (28%) mixed TT and BZ. Impaired VR was found more frequently among patients with higher degrees of stenoses (P < .001) whereas MES were similarly encountered in both groups (P = NS). Impaired VR was more common in the BZ (10/20, 50%) than in the TT group (9/32, 28%, P < .1) while MES were present in 47% (15/32) of patients with TT and in 30% (6/20, P < .1) of those with BZ lesions, in particular in cortical BZ infarcts (P < .02).

CONCLUSION

Our findings suggest that TCD characteristics of the ICA stenosis contribute to better define stroke patterns on MRI in about one-third of the patients presenting with pure TT or BZ lesions.

Relationship between watershed infarcts and recent intra plaque haemorrhage in carotid atherosclerotic plaque

Objective

Watershed infarcts (WSI) are thought to result from hemodynamic mechanism, but studies have suggested that microemboli from unstable carotid plaques may distribute preferentially in watershed areas, i.e., between two cerebral arterial territories. Intraplaque haemorrhage (IPH) is an emerging marker of plaque instability and microembolic activity. We assessed the association between WSI and IPH in patients with recently symptomatic moderate carotid stenosis.

Methods and Results

We selected 65 patients with symptomatic moderate (median NASCET degree of stenosis = 31%) carotid stenosis and brain infarct on Diffusion-Weighted Imaging (DWI) on Magnetic Resonance Imaging (MRI) from a multicentre prospective study. Fourteen (22%) had WSI (cortical, n = 8; internal, n = 4; cortical and internal, n = 2). Patients with WSI were more likely to have IPH than those without WSI although the difference was not significant (50% vs. 31%, OR = 2.19; 95% CI, 0.66–7.29; P = 0.20). After adjustment for degree of stenosis, age and gender, the results remained unchanged.

Conclusion

About one in fifth of brain infarcts occurring in patients with moderate carotid stenosis were distributed in watershed areas. Albeit not significant, an association between IPH - more generally plaque component - and WSI, still remains possible.

Watershed infarcts in a patient after carotid endarterectomy

We report a case that developed watershed infarcts after undergoing carotid endarterectomy. Our patient had been having episodes of transient ischaemic attacks before admission. Carotid Doppler scan before admission showed severe unilateral carotid stenosis on left side. She underwent a carotid endarterectomy procedure. Her continuous blood pressure monitoring stayed normal during and after the procedure. One and half hour after the procedure, she developed right arm weakness. CT scan later revealed watershed infarcts in left cerebral hemisphere. The pathogenesis of watershed infarcts remain debated despite haemodynamic and embolic mechanisms being postulated.

Ischemic stroke in Takayasu's arteritis: lesion patterns and possible mechanisms

Background and Purpose

The purpose of the present study was to use brain magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) to identify the mechanism of stroke in patients with Takayasu's arteritis (TA).

Methods

Among a retrospective cohort of 190 TA patients, 21 (3 males and 18 females) with a mean age of 39.9 years (range 15-68 years) who had acute cerebral infarctions were included in lesion pattern analyses. The patients' characteristics were reviewed, and infarction patterns and the degree of cerebral artery stenosis were evaluated. Ischemic lesions were categorized into five subgroups: cortical border-zone, internal border-zone, large lobar, large deep, and small subcortical infarctions.

Results

In total, 21 ischemic stroke events with relevant ischemic lesions on MRI were observed. The frequencies of the lesion types were as follows: large lobar (n=7, 33.3%), cortical border zone (n=6, 28.6%), internal border zone (n=1, 4.8%), small cortical (n=0, 0%), and large deep (n=7, 33.3%). MRA revealed that 11 patients had intracranial artery stenosis.

Conclusions

Hemodynamic compromise in large-artery stenosis and thromboembolic mechanisms play significant roles in ischemic stroke associated with TA.

Border zone infarcts: pathophysiologic and imaging characteristics

Border zone or watershed infarcts are ischemic lesions that occur in characteristic locations at the junction between two main arterial territories. These lesions constitute approximately 10% of all brain infarcts and are well described in the literature. Their pathophysiology has not yet been fully elucidated, but a commonly accepted hypothesis holds that decreased perfusion in the distal regions of the vascular territories leaves them vulnerable to infarction. Two types of border zone infarcts are recognized: external (cortical) and internal (subcortical). To select the most appropriate methods for managing these infarcts, it is important to understand the underlying causal mechanisms. Internal border zone infarcts are caused mainly by hemodynamic compromise, whereas external border zone infarcts are believed to result from embolism but not always with associated hypoperfusion. Various imaging modalities have been used to determine the presence and extent of hemodynamic compromise or misery perfusion in association with border zone infarcts, and some findings (eg, multiple small internal infarcts) have proved to be independent predictors of subsequent ischemic stroke. A combination of several advanced techniques (eg, diffusion and perfusion magnetic resonance imaging and computed tomography, positron emission tomography, transcranial Doppler ultrasonography) can be useful for identifying the pathophysiologic process, making an early clinical diagnosis, guiding management, and predicting the outcome.

A typical example of cerebral watershed infarct

Watershed infarcts (WI) evolve in hemodynamic risk zones. Clinical picture of WI can be associated to partial epileptic seizures. Diffusion weighted brain magnetic resonance imaging (MRI) allows a clear diagnosis. WI pathogenesis involves either embolic or hemodynamic mechanism. A 69-year old patient presented with sub-acute occurrence of right hemiparesis and partial epileptic seizures of the right arm. Carotid ultrasounds demonstrated occlusion of the right extra-cranial internal carotid artery (ICA) and tight stenosis of the contralateral ICA. Brain Diffusion-Weighted magnetic resonance revealed acute ischemic lesions within the watershed area of the left hemisphere. Our case supports the hypothesis of impaired washout of emboli in low-perfusion brain areas as the mechanism underlying cortical WI.

The determinants of stroke phenotypes were different from the predictors (CHADS2 and CHA2DS2-VASc) of stroke in patients with atrial fibrillation: a comprehensive approach

Background

Atrial fibrillation (AF) is a leading cause of fatal ischemic stroke. It was recently reported that international normalized ratio (INR) levels were associated with infarct volumes. However, factors other than INR levels that affect stroke phenotypes are largely unknown. Therefore, we evaluated the determinants of stroke phenotypes (pattern and volume) among patients with AF who were not adequately anticoagulated.

Methods

We analyzed data pertaining to consecutive AF patients admitted over a 6-year period with acute MCA territory infarcts. We divided the patients according to DWI (diffusion-weighted imaging) lesion volumes and patterns, and the relationship between stroke predictors (the CHADS₂ and CHA₂DS₂-VASc score), systemic, and local factors and each stroke phenotype were then evaluated.

Results

The stroke phenotypes varied among 231 patients (admission INR median 1.06, interquartile range (IQR) 1.00-1.14). Specifically, (1) the DWI lesion volumes ranged from 0.04-338.62 ml (median 11.86 ml; IQR, 3.07-44.20 ml) and (2) 46 patients had a territorial infarct pattern, 118 had a lobar/deep pattern and 67 had a small scattered pattern. Multivariate testing revealed that the CHADS₂ and CHA₂DS₂-VASc score were not related to either stroke phenotype. Additionally, the prior use of antiplatelet agents was not related to the stroke phenotypes. Congestive heart failure and diastolic dysfunction were not associated with stroke phenotypes.

Conclusions

The results of this study indicated that the determinants of stroke phenotypes were different from the predictors (i.e., CHADS2 and CHA₂DS₂-VASc score) of stroke in patients with AF.

Watershed infarcts in a multiple microembolic model of monkey

It has long been debated whether watershed infarcts are caused by hemodynamic or embolic mechanisms. In the present study, we investigated microembolic roles in the pathogenesis of watershed infarcts by examining MRI in a macaque monkey model of multiple microinfarcts. 50 μm microbeads were injected into each internal carotid artery twice with a month interval. Monkeys (n=4) injected with 2250-2800 microbeads per unilateral side showed both cortical and internal watershed infarcts in the acute phase and atrophic changes with microbleeds in the chronic phase. These results suggest embolic pathogenesis can contribute to the genesis of both cortical and internal watershed infarcts in primates.

Classification for carotid artery stenting complications: manifestation, management, and prevention

Carotid artery stenting is a rapidly evolving method for treating carotid artery disease. Various intraprocedural and postprocedural complications have been reported in the literature. However, the absence of a unified classification scheme for these complications makes it difficult, if not impossible, to study their precise incidence, predictors, and management. The aim of this article is to propose the first joint classification of periprocedural complications, to analyze their incidence and etiology, and suggest possible ways to manage and prevent them. This classification is intended to be used as a common platform for prompt recognition, evaluation, treatment, and universal study of the complications during carotid stenting procedures. For this purpose, the opinions of the major experts on carotid interventions worldwide were merged with all the available information reported in the English-language literature to present as accurately as possible the management and prevention of carotid stenting complications according to this proposed classification.

Haemodynamic stroke: clinical features, prognosis, and management

Haemodynamic stroke is a type of ischaemic stroke that is caused by hypoperfusion rather than by embolism or local vasculopathy. It can be caused by systemic diseases such as heart failure or hypotension, but also by severe obstruction of the carotid or vertebral arteries. Patients with haemodynamic stroke or transient ischaemic attack might show specific clinical features that distinguish them from patients with embolism or local small-vessel disease. Ancillary investigations of cerebral perfusion can show whether blood flow to the brain is compromised and provide important prognostic information. Management of patients who have hypoperfusion as the major cause of ischaemic stroke or as a contributing factor is hampered by the lack of clinical trials. Treatment aimed at increasing cerebral blood flow might be considered in selected patients on the basis of information from case series. Further research is needed to define criteria for the diagnosis of haemodynamic stroke and to investigate treatment options in controlled studies.

Atheroembolic renal disease

Atheroembolic renal disease develops when atheromatous aortic plaques rupture, releasing cholesterol crystals into the small renal arteries. Embolisation often affects other organs, such as the skin, gastrointestinal system, and brain. Although the disease can develop spontaneously, it usually develops after vascular surgery, catheterisation, or anticoagulation. The systemic nature of atheroembolism makes diagnosis difficult. The classic triad of a precipitating event, acute or subacute renal failure, and skin lesions, are strongly suggestive of the disorder. Eosinophilia further supports the diagnosis, usually confirmed by biopsy of an affected organ or by the fundoscopic finding of cholesterol crystals in the retinal circulation. Renal and patient prognosis are poor. Treatment is mostly preventive, based on avoidance of further precipitating factors, and symptomatic, aimed to the optimum treatment of hypertension and cardiac and renal failure. Statins, which stabilise atherosclerotic plaques, should be offered to all patients. Steroids might have a role in acute or subacute progressive forms with systemic inflammation.