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Background: Previous studies on unilateral internal carotid artery occlusive disease have focused on the mechanisms of ipsilateral hemispheric stroke, and contralateral stroke is considered to be an accidental phenomenon. Little is known about the relationship between severe stenosis (including occlusion) of the unilateral extracranial segment of the internal carotid artery and contralateral cerebral stroke, and the infarct patterns and pathogenesis require further study. The purpose of this study was to investigate the clinical characteristics and pathogenesis of contralateral acute stroke with unilateral extracranial internal carotid artery stenosis (including occlusion). Methods: Thirty‐four patients were enrolled in this study, and all patients underwent routine clinical evaluation, including medical history, physical examination, laboratory tests, and various imaging evaluations. The morphological characteristics of diffusion‐weighted magnetic resonance imaging were applied to determine infarct patterns. The etiological classification was confirmed according to the TOAST classification. Results: There were six distinctive lesion patterns: small subcortical infarcts (six patients), large subcortical infarcts (one patient), diffuse infarcts (eight patients), multiple anterior circulation infarcts (eight patients), multiple posterior circulation infarcts (two patients), and multiple anterior and posterior circulation infarcts (nine patients). Conclusion: Diffuse and multiple infarcts were the most common topographic patterns in ischemic stroke contralateral to internal carotid artery stenosis or occlusion. Hemodynamic impairment of the contralateral hemisphere due to hypoperfusion and blood theft is regarded as the basis of stroke occurrence. Low ischemic tolerance and embolism are the main causes of acute ischemic stroke. [ABSTRACT FROM AUTHOR]

Introduction: Around 9–25% of ischemic strokes are embolic stroke of undetermined source (ESUS) with an annual recurrence risk of 4.5–5%. Regarding ESUS, studies from India are limited. Here, we studied the prevalence of cryptogenic ESUS among stroke subtypes, recurrence risk and outcome at 1 year, and their predictors. Materials and Methods: We performed a single-center study of ambispective nature. Patients above 18 years of age with a diagnosis of cryptogenic (ESUS) strokes from January 1, 2017, to December 31, 2020 (4 years), with a 1-year follow-up were recruited in our study. All the patients underwent neuroimaging computerised tomography/magnetic resonance tomography (CT/MRI) with angiography, electrocardiogram (ECG), transthoracic echo (TTE), and rhythm monitoring. Functional outcome was measured using the modified Rankin scale with scores 0–2 taken as good outcome. Results: We had 234 (11.21% of total ischemic strokes) subjects satisfying the criteria for ESUS over the study period with a mean age of 58.2 ± 12.8 years. 46 patients had a history of stroke/transient ischemic attack (TIA) at admission. 9.4% had a recurrent event at 1 year. The most important neuroimaging predictor of recurrent strokes was multiple embolic followed by superficial watershed pattern. Around 10% had more than one marker of atrial cardiopathy positive. While the risk factors, coronary artery disease (CAD), and neuroimaging pattern showed an association with recurrent events at 1 year on bivariate analysis, only the latter two remained significant on multivariate analysis. Conclusions: Our cohort of ESUS had a higher annual recurrence risk than reported before. Though vascular risk factors and ipsilateral vessel abnormalities were more in the recurrent ESUS group, it did not significantly affect the recurrence risk at 1 year. CAD and multiple embolic patterns on imaging showed an association with recurrent strokes, suggesting a possible cardiac substrate in our ESUS population as well.

BackgroundThere 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).MethodsWe 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.ResultsThe 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%).ConclusionsArtery-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.

• Multiple acute infarctions (MAIs) may have different predictive effect on prognosis between the anterior and posterior circulation. • The patterns of MAIs in posterior circulation stroke (PCS) could be further classified into multiple infarcts or single infarct, multilevel infarcts or single level infarct, and multiterritorial infarcts or single territorial infarct according to the number, level, and vascular territory of the infarcts. • Different patterns of MAIs provide different predictive performances for PCS prognosis. It is imperative to perform more detailed image interpretation of MAIs in patients with PCS. Different classification of multiple acute infarctions (MAIs) existed in minor posterior circulation stroke (PCS). We aimed to explore the association between different patterns of MAIs and long-term prognosis in minor PCS. We derived data from Chinese Intracranial Atherosclerosis (CICAS) study. We analyzed the clinical features and outcomes in MAIs among anterior circulation stroke (ACS) and PCS. The patterns of MAIs in PCS were further classified into multiple infarcts, multilevel infarcts, or multiterritorial infarcts. The long-term prognosis included ischemic events recurrence and poor functional outcome (modified Rankin Scale, mRS=2–6) in 1 year. Multivariable Cox and logistic regression were adopted respectively to evaluate the correlation of different patterns of MAIs with recurrence and poor functional outcome. We totally enrolled 802 patients with minor stroke in CICAS study, including 484 ACS and 318 PCS. In univariate analysis, MAIs were significantly associated with recurrence in ACS (P<0.01), but were significantly correlated with poor functional outcome in PCS (P=0.044). Among the PCS patients, there were 90 patients with multiple infarcts, 32 patients with multilevel infarcts and 36 patients with multiterritorial infarcts. Multivariable Cox regression showed that multiterritorial infarcts were independently associated with ischemic events recurrence (HR, 3.083; 95 % CI, 1.078–8.813). In multivariable logistic regression, significant correlation with poor functional outcome in 1 year was revealed in multilevel infarcts (OR, 2.788; 95 % CI, 1.144–6.797). Different patterns of MAIs provide different predictive performances for PCS prognosis. It is imperative to perform more detailed image interpretation of MAIs in PCS. [ABSTRACT FROM AUTHOR]