Cerebral Collateral Circulation in the Era of Reperfusion Therapies for Acute Ischemic Stroke

The potential mechanism and clinical application value of remote ischemic conditioning in stroke

Some studies have confirmed the neuroprotective effect of remote ischemic conditioning against stroke. Although numerous animal researches have shown that the neuroprotective effect of remote ischemic conditioning may be related to neuroinflammation, cellular immunity, apoptosis, and autophagy, the exact underlying molecular mechanisms are unclear. This review summarizes the current status of different types of remote ischemic conditioning methods in animal and clinical studies and analyzes their commonalities and differences in neuroprotective mechanisms and signaling pathways. Remote ischemic conditioning has emerged as a potential therapeutic approach for improving stroke-induced brain injury owing to its simplicity, non-invasiveness, safety, and patient tolerability. Different forms of remote ischemic conditioning exhibit distinct intervention patterns, timing, and application range. Mechanistically, remote ischemic conditioning can exert neuroprotective effects by activating the Notch1/phosphatidylinositol 3-kinase/Akt signaling pathway, improving cerebral perfusion, suppressing neuroinflammation, inhibiting cell apoptosis, activating autophagy, and promoting neural regeneration. While remote ischemic conditioning has shown potential in improving stroke outcomes, its full clinical translation has not yet been achieved.

A novel NIR-II albumin-escaping probe for cerebral arteries and perfusion imaging in stroke mice model

In order to guide the formulation of post-stroke treatment strategy in time, it is necessary to have real-time feedback on collateral circulation and revascularization. Currently used near-infrared II (NIR-II) probes have inherent binding with endogenous albumin, resulting in significant background signals and uncontrollable pharmacokinetics. Therefore, the albumin-escaping properties of the new probe, IR-808AC, was designed, which achieved timely excretion and low background signal, enabling the short-term repeatable injection for visualization of cerebral vessels and perfusion. We further achieved continuous observation of changes in collateral vessels and perfusion during the 7-d period in middle cerebral artery occlusion mice using IR-808AC in vivo. Furthermore, using IR-808AC, we confirmed that remote ischemic conditioning could promote collateral vessels and perfusion. Finally, we evaluated the revascularization after thrombolysis on time in embolic stroke mice using IR-808AC. Overall, our study introduces a novel methodology for safe, non-invasive, and repeatable assessment of collateral circulation and revascularization in real-time that is crucial for the optimization of treatment strategies.

Thrombectomy improves functional independence in severe basilar artery occlusion with favorable collateral circulation

BACKGROUND AND PURPOSE

This study aimed to investigate the effect of collateral circulation on the outcomes of thrombectomy versus medical management alone in basilar artery occlusion (BAO) patients with varying stroke severities.

METHODS

Data from the ATTENTION cohort were used to perform a post-hoc analysis comparing the outcomes of thrombectomy with medical management in BAO patients with varying degrees of collateral circulation and stroke severity. Basilar Artery on Computed Tomography Angiography (BATMAN) scores were used to quantify the collateral circulation, and the effect was estimated through a primary outcome of 90-day functional independence (modified Rankin Scale score, mRS ≤2). Favorable versus unfavorable BATMAN scores were analyzed as both continuous and categorical variables, and an adjusted multivariate regression model was applied.

RESULTS

Among 221 BAO patients, thrombectomy significantly improved functional independence compared to medical management in patients with favorable BATMAN scores (aOR 7.75, 95% CI 2.78-26.1), but not in those with unfavorable BATMAN scores (aOR 1.33, 95% CI 0.28-6.92; pinteraction = 0.028). When treated as a continuous variable, increased BATMAN score was found to be associated with a higher likelihood of functional independence in the thrombectomy group (aOR 1.97, 95% CI 1.44-2.81; pinteraction = 0.053). In severe stroke patients with higher BATMAN scores (National Institutes of Health Stroke Scale (NIHSS) ≥21), we identified a significant interaction for treatment effect with thrombectomy compared to medical management (pinteraction = 0.042).

CONCLUSION

An increased BATMAN score was significantly associated with a higher probability of functional independence after thrombectomy than after medical management, particularly in patients with severe BAO.

Hypoperfusion Intensity Ratio and Hemorrhagic Transformation in Patients with Successful Recanalization after Thrombectomy

BACKGROUND AND PURPOSE

Hemorrhagic transformation remains a potentially devastating complication of acute ischemic stroke. We aimed to evaluate whether the hypoperfusion intensity ratio, a parameter derived from CT perfusion imaging, is associated with the development of hemorrhagic transformation in patients with anterior large-artery occlusion who had undergone thrombectomy.

MATERIALS AND METHODS

We retrospectively reviewed data from patients with consecutive acute ischemic strokes who had achieved successful recanalization (Thrombolysis in Cerebral Infarction score ≥2b) between January 2020 and December 2023. HIR was defined as the ratio of the volume of lesions with a time-to-maximum (Tmax) >6 seconds to those with a Tmax >10 second delay. The primary outcome, based on the European Cooperative Acute Stroke Study, was hemorrhagic transformation, diagnosed by follow-up imaging assessment in 24-hour windows, and radiologically classified as hemorrhagic infarction and parenchymal hematoma. The secondary outcome was a 3-month mRS score of ≥3.

RESULTS

Among 168 patients, 35 of 168 developed hemorrhagic transformation; 14 of 168 developed hemorrhagic infarction, and 21 of 168 developed parenchymal hematoma PH. After adjusting the latent covariates, increased hypoperfusion intensity ratio (per 0.1, adjusted OR [aOR] 1.68, 95% CI 1.26-2.25), ASPECTS (aOR 0.44, 95% CI 0.27-0.72), onset-to-puncture (aOR 1.01, 95% CI 1.00-1.02), and cardioembolism (aOR 5.6, 95% CI 1.59-19.7) were associated with hemorrhagic transformation in multivariable regression. The receiver operating characteristic curve indicated that hypoperfusion intensity ratio can predict hemorrhagic transformation accurately (area under the curve = 0.81; 95% CI, 0.738-0.882; P < .001) and predict parenchymal hematoma (area under the curve = 0.801; 95% CI, 0.727-0.875; P < .001).

CONCLUSIONS

Upon admission, hypoperfusion intensity ratio, an imaging parameter, predicted hemorrhagic transformation after reperfusion therapy in this patient population.

β-Caryophyllene mitigates ischemic stroke-induced white matter lesions by inhibiting pyroptosis

β-Caryophyllene (BCP), a selective agonist for cannabinoid receptor 2 (CB2R), has demonstrated promising protective effects in various pathological conditions. However, the neuroprotective effects of BCP on white matter damage induced by ischemic stroke have not been elucidated previously. In this study, we find that BCP not only improves sensorimotor and cognitive function via CB2R but also mitigates white matter lesions in mice following ischemic stroke. Furthermore, BCP enhances the viability of MO3.13 oligodendrocytes after oxygen-glucose deprivation and reoxygenation (OGD/R), attenuating OGD/R-induced cellular damage and pyroptosis. Notably, these protective effects of BCP are partially enhanced by the NLRP3 inhibitor MCC950 and counteracted by the NLRP3 activator nigericin. In addition, nigericin significantly exacerbates neurological outcomes and increases white matter lesions following BCP treatment in middle cerebral artery occlusion (MCAO) mice. These results suggest that BCP may ameliorate neurological deficits and white matter damage induced by cerebral ischemia through inhibiting NLRP3-mediated pyroptosis.

Multi-phase CT-Angiography outperforms angiographic careggi collateral score and predicts functional outcome in acute ischemic stroke

BACKGROUND

Collaterals are a strong determinant of clinical outcome in acute ischemic stroke (AIS) patients undergoing Endovascular Treatment (EVT). Careggi Collateral Score (CCS) is an angiographic score that demonstrated to be superior to the widely suggested ASITN/SIR score. Multi-phase CT-Angiography (mCTA) could be alternatively adopted for collateral assessment. We investigated whether mCTA had an equivalent predictive performance for functional outcome compared to CCS.

METHODS

Consecutive AIS patients undergoing EVT for large vessel occlusion within 24 h from onset were analyzed. Receiver operating characteristic curves and multivariable logistic regression were investigated to evaluate the predictive performance of mCTA collateral score (range 0-5) and CCS (range 0-4) for good functional outcome (three-months modified Rankin Scale 0-2).

RESULTS

We included 201 subjects (59.7% females, mean age 75), of whom 96 (47.7%) had good outcome at three-months. Both CCS (OR = 14.4, 95% CI = 6.3-33.8) and mCTA (OR = 23.8, 95% CI = 10.1-56.4) collateral scores were independent predictors of outcome. The AUC of CCS was 0.80 (95% CI 0.73-0.86) and the best cut-off was ≥ 3 (87% sensitivity, 71% specificity), while the AUC of mCTA collateral score was 0.84 (95% CI 0.78-0.90) with an optimal cut-off of ≥ 4 (85% sensitivity, 87% specificity). Patients with good mCTA collaterals experienced smaller (16.6 vs. 63.7 mL, p < 0.001) infarct lesion as compared to those with mCTA poor collaterals.

CONCLUSION

mCTA discriminative ability for three-months 0-2 mRS was found to be comparable to CCS. mCTA appears a valid, non-invasive imaging modality for evaluating collaterals of AIS patients potentially eligible for EVT.

Circle of Willis integrity in acute middle cerebral artery occlusion: does the posterior communicating artery matter?

BACKGROUND

Collateral circulation is an important determinant of outcome in people with acute ischemic stroke due to large vessel occlusion (LVO).

OBJECTIVE

To explore the impact of the circle of Willis (CW) anatomical characteristics ipsilateral to the occlusion site, particularly the posterior communicating artery (PComA) and the A1-portion of the anterior cerebral artery (A1-ACA), on stroke outcomes in a cohort of patients with LVO and middle cerebral artery (MCA) occlusion, undergoing endovascular thrombectomy (EVT).

METHODS

This is a retrospective cohort study performed in a comprehensive tertiary stroke center. The study population consisted of consecutive patients with LVO with proximal MCA occlusion (M1) between June 2016 and April 2021, undergoing EVT. Demographic, clinical, and imaging information was extracted from patient files. Patency and diameters of ipsilateral A1-ACA and PComA were manually measured on admission CT angiography images in the core laboratory.

RESULTS

One hundred and five patients with LVO comprised the study cohort, mean age 72.3 years, 43.8% were male, mean National Institutes of Health Stroke Scale score at admission 15.2. The cohort was grouped according to CW vessel characteristics. On univariate analysis, a well-developed PComA was associated with lower rates of hemorrhagic transformation (1.8% vs 14.3%, P=0.01) and a trend towards lower mortality rates (8.9% vs 20.4%, P=0.08).On multivariable regression analysis a well-developed PComA emerged as an independent predictor for survival (aOR=0.09, 95% CI 0.01 to 0.4 for survival at discharge, P=0.009, aOR=0.22, 95% CI 0.05 to 0.8 for survival at 90 days, P=0.02).

CONCLUSIONS

In a cohort of patients with LVO due to M1 occlusion undergoing EVT, a well-developed PComA was associated with significantly lower hemorrhagic transformation rates, a trend towards better functional outcomes, and independently predicted survival. Larger studies are needed to understand the differential effect of CW collateral conduits on stroke outcome and evaluate the practicality of incorporating such factors in the clinical decision-making process prior to EVT.

Collaterals at angiography guide clinical outcomes after endovascular stroke therapy in HERMES

BACKGROUND

Robust collateral circulation has been linked with better reperfusion and clinical outcomes. It remains unclear how individual assessments of collateral circulation may be translated into clinical practice.

METHODS

The pooled Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials (HERMES) angiography dataset was analyzed by a centralized, independent imaging core blinded to other clinical data. Conventional angiography was acquired immediately prior to endovascular therapy. Collaterals were graded with the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN) system and associated with baseline patient characteristics, reperfusion, and day 90 modified Rankin Score (mRS). Both 90-day all-cause mortality and day 90 mRS were modeled via multivariable logistic regression.

RESULTS

Angiography was available in 376/605 (62%) patients. Baseline ASPECTS (Alberta Stroke Program Early CT Score) (p=0.043), history of diabetes mellitus (p=0.048), site of occlusion (p<0.001), and degree of subsequent Thrombolysis in Cerebral Infarction (TICI) reperfusion (p<0.001) were associated with collateral grades. ASITN collateral grade was strongly associated with ordinal mRS from baseline to 90 days in an unadjusted analysis (p<0.001). Multivariable regression demonstrated that collateral status is a strong determinant of mRS outcome in the presence of other predictors (OR=1.37 per grade, 95% CI [1.05 to 1.74], p=0.018). By comparing ORs, 1 unit of ASITN was determined to be approximately equivalent to 4.5 points of NIHSS, 11 years of age, 1.5 points of ASPECTS, or 100 min less delay from onset to puncture, in terms of impact on mRS.

CONCLUSIONS

Individual collateral physiology may contribute significantly to reperfusion success and clinical outcomes after acute ischemic stroke. Building a consensus for the role of angiographic collateral assessment in the allocation of adjuvant reperfusion therapies may help galvanize a precision medicine approach in stroke.

Difference between arterial and venous peak optical density after thrombectomy is associated with functional outcomes

Background

The density of contrast medium in digital subtraction angiography (DSA) have been used to evaluate the cerebral circulation function. Our aim was to study the effect of difference in arteriovenous peak optical density (POD) after thrombectomy on functional outcomes.

Methods

Consecutive patients with acute ischemic stroke due to large vessel occlusion who underwent thrombectomy were reviewed. We processed DSA images with ImageJ software to measure the POD of internal carotid artery (ICA) and cortical veins. The average POD of cortical veins (PODVA) and the POD difference between ICA and cortical veins (PODICA-CV) were calculated. Primary outcome was good functional outcome (modified Rankin scale score of 0-2 at 90 days).

Results

One hundred sixty-six patients were finally included in the study. Patients with good functional outcome had lower ipsilateral PODVA (median [interquartile range (IQR)], 257.198 [216.623-296.631] vs. 290.944 [248.647-338.819], p < 0.001) and lower ipsilateral PODICA-CV (median [IQR], 128.463 [110.233-153.624] vs. 182.01 [146.621-211.331], p < 0.001). Multivariable logistic regression analyses showed that ipsilateral PODVA (odds ratio [OR] 0.991, 95% confidence interval [CI] 0.984-0.999, p = 0.019) and ipsilateral PODICA-CV (OR 0.975, 95% CI 0.963-0.986, p < 0.001) were associated with good functional outcome. The predictive ability was significantly enhanced in the model including ipsilateral PODICA-CV (0.893 vs. 0.842, p = 0.027). No correlation was found between ipsilateral PODICA-CV and expanded Thrombolysis in Cerebral Infarction grades (r = -0.133, p = 0.099).

Conclusion

Ipsilateral PODICA-CV is an additional indicator of cerebral reperfusion status and predicts functional outcomes after thrombectomy.

A Minimalist Iron Oxide Nanoprobe for the High-Resolution Depiction of Stroke by Susceptibility-Weighted Imaging

The precise mapping of collateral circulation and ischemic penumbra is crucial for diagnosing and treating acute ischemic stroke (AIS). Unfortunately, there exists a significant shortage of high-sensitivity and high-resolution in vivo imaging techniques to fulfill this requirement. Herein, a contrast enhanced susceptibility-weighted imaging (CE-SWI) using the minimalist dextran-modified Fe3O4 nanoparticles (Fe3O4@Dextran NPs) are introduced for the highly sensitive and high-resolution AIS depiction under 9.4 T for the first time. The Fe3O4@Dextran NPs are synthesized via a simple one-pot coprecipitation method using commercial reagents under room temperature. It shows merits of small size (hydrodynamic size 25.8 nm), good solubility, high transverse relaxivity (r2) of 51.3 mM-1s-1 at 9.4 T, and superior biocompatibility. The Fe3O4@Dextran NPs-enhanced SWI can highlight the cerebral vessels readily with significantly improved contrast and ultrahigh resolution of 0.1 mm under 9.4 T MR scanner, enabling the clear spatial identification of collateral circulation in the middle cerebral artery occlusion (MCAO) rat model. Furthermore, Fe3O4@Dextran NPs-enhanced SWI facilitates the precise depiction of ischemia core, collaterals, and ischemic penumbra post AIS through matching analysis with other multimodal MR sequences. The proposed Fe3O4@Dextran NPs-enhanced SWI offers a high-sensitivity and high-resolution imaging tool for individualized characterization and personally precise theranostics of stroke patients.

Hypoperfusion intensity ratio correlates with collaterals and predicts outcome and infarct volume in acute ischemic stroke patients

BACKGROUND

Hypoperfusion Intensity Ratio (HIR) is associated with collaterals and outcome in acute ischemic stroke (AIS). We investigated whether a combined assessment of HIR and collaterals could provide an added value.

METHODS

Retrospective single-center study, including AIS patients with large vessel occlusion and endovascular treatment 0-24 h from onset. Predictors of FIV and outcome (90 days modified Rankin Scale 0-1) were investigated with linear and logistic regression respectively. Subjects were stratified in three groups: poor collaterals (grade 0-3) with poor HIR (≥.4), good collaterals (grade 4-5) with poor HIR/poor collaterals with good HIR (<.4) and good collaterals with good HIR.

RESULTS

We included 337 patients (median age 77, 53.1% males), of whom 100 (29.7%) had excellent outcome. One hundred and forty five patients with favourable collateral and HIR profiles had smaller infarct (median poor collaterals with poor HIR 41 mL, good collaterals with poor HIR/poor collaterals with good HIR 21 mL and good collaterals with good HIR 11 mL, p <.001) and higher rates of excellent outcome (poor collaterals with poor HIR 15.7%, good collaterals with poor HIR/poor collaterals with good HIR 26.2% and good collaterals with good HIR 39.3% p =.001). Logistic regression showed that patients with favourable collateral and HIR profiles had the highest odds of good outcome (OR: 3.83, 95% CI 1.62-9.08, p =.002).

CONCLUSION

Collaterals and HIR are independent predictors of final infarct lesion and outcome in stroke patients and their integration provides an added value. These findings might inform clinical practice and future trials.

Chronic hypertension alters the relationship between collateral blood flow, cortical cerebral blood flow, and brain tissue oxygenation

This study measured the relationship between pial collateral (leptomeningeal anastomoses, LMA) flow, intraparenchymal cortical cerebral blood flow (cCBF) and brain tissue oxygenation (btO2) during acute ischemic stroke to investigate how pial flow translates to downstream cCBF and btO2 and examined how this relationship is altered in hypertension. Proximal transient middle cerebral artery occlusion (tMCAO) was performed in male Wistar (n = 8/group) and Spontaneously Hypertensive Rats (SHR, n = 8/group). A combination laser Doppler-oxygen probe was placed within the expected cortical peri-infarct in addition to a surface laser doppler probe which measured LMA flow. Phenylephrine (PE) was infused 30 minutes into tMCAO to increase blood pressure (BP) by 30% for 10 minutes and assessed CBF autoregulation. During the initial 30-minute period of tMCAO, btO2 and cCBF were lower in SHR compared to Wistar rats (btO2: 11.5 ± 10.5 vs 17.5 ± 10.8 mmHg and cCBF: -29.7 ± 23.3% vs -17.8 ± 41.9%); however, LMA flow was similar between groups. The relationship between LMA flow, cCBF and btO2 were interdependent in Wistar rats. However, this relationship was disrupted in SHR rats and partially restored by induced hypertension. This study provides evidence that cCBF and btO2 were diminished during tMCAO in chronic hypertension, and that induced hypertension was beneficial regardless of hypertensive status.

Importance of computed tomography perfusion on assessing collateral circulation and prognosis of patients with acute anterior circulation large vessel occlusion after endovascular therapy

This study probed the importance of computed tomography perfusion (CTP) on assessing collateral circulation and prognosis in patients with acute anterior circulation large vessel occlusion (AAC-LVO) after endovascular therapy (EVT). Retrospective analysis was performed on the case data of 124 AAC-LVO patients who achieved EVT in the First People's Hospital of Lianyungang. All patients received computed tomography (CT) examination. Based on the multi-phase computed tomography angiography (mCTA) score, patients were separated into poor collateral circulation group and good collateral circulation group. Based on modified Rankin scale (mRS) score, patients were separated into good prognosis group and poor prognosis group. The receiver operating characteristic (ROC) curve was used to measure the efficacy of CTP parameters in predicting good collateral circulation or good prognosis. Correlation between CTP parameters with mCTA collateral and 90-day mRS circulation score was analyzed using the Spearman correlation analysis. The age and admission national Institutes of Health stroke scale (NIHSS) scores of the good collateral circulation group were lower than the poor collateral circulation group, and low perfusion area volume with Tmax > 6 s (VTmax>6 s), infarct core area volume (VCBF<30 %)and hypoperfusion intensity ratio (HIR) were also lower. The mCTA collateral cycle score was negatively related to VTmax>6s, VCBF<30 % and HIR. The area under the curve (AUC) values of VTmax>6s and VCBF<30 % and HIR for predicting good collateral circulation were 0.763, 0.884 and 0.842, respectively, which suggested that perfusion parameters VTmax>6s, VCBF<30 % and HIR could effectively indicate the status of patients' collateral circulation. Relative to the poor prognosis group, patients in the good prognosis group possessed lower admission NIHSS score, younger age, smaller final infarct volume, lower HIR, VCBF<30 %, VTmax>6 s, Alberta Stroke Program Early CT(ASPECT) score, and higher mCTA score. Spearman correlation analysis unveiled that ASPECT score, mCTA score and 90-day mRS were negatively correlated. The final infarct volume, perfusion parameters HIR and VCBF<30 % were positively correlated with 90-day mRS. ROC analysis showed that all variates had good prognostic value for acute anterior circulation great vessel occlusion patients, while VCBF<30 % and HIR had high diagnostic value for prognosis. To sum up, CTP can provide a comprehensive imaging assessment of the collateral circulation of patients with AAC-LVO and has a higher predictive value for the prognosis assessment of patients with EVT in terms of VCBF<30 %, HIR score and mCTA collateral circulation score.

Sex Alters the Effect of Perfusion Deficits on Functional Outcome in Patients with Acute Ischemic Stroke Undergoing Mechanical Thrombectomy

INTRODUCTION

The discourse surrounding differences in cerebral hemodynamics and clinical outcomes among male and female patients treated with mechanical thrombectomy (MT) for acute ischemic stroke (AIS) remains unresolved. We aimed to elucidate these differences by employing computed tomography perfusion (CTP) imaging before MT and examining the influence of perfusion deficits on the 90-day functional outcome.

METHODS

This single-center retrospective analysis involved patients with anterior circulation AIS treated with MT at the Comprehensive Stroke Center, University Hospital, Krakow, from January 2019 to July 2023. We compared male and female patients in terms of baseline characteristics, CTP deficits, hypoperfusion intensity ratio (HIR, defined as T10max/T6max), and complications. The endpoints included the 90-day excellent functional outcome, defined as modified Rankin Score <2, and the 90-day mortality rate.

RESULTS

We included 794 patients, of whom 408 were female (51.4%). Female patients had a smaller early infarct volume (median [interquartile range]: 7 mL [0-24.8] vs. 10 mL [0-33], p = 0.004), smaller penumbra volume (77.5 mL [46-117] vs. 99.5 mL [59.8-140], p < 0.001), lower HIR (0.34 [0.16-0.5] vs. 0.37 [0.2-9.53], p = 0.043) and were less likely to achieve an excellent functional outcome (55.6% vs. 66.1%, p = 0.003). For every 10 mL increase in early infarct volume, the odds for achieving an excellent outcome were lower in females (odds ratio [OR]: 0.82 [95% confidence interval: 0.73-0.92]) compared to males (OR: 0.96 [0.88-1.04]), whereas the risk of death was higher for females (OR: 1.25 [1.13-1.39] than for males (OR: 1.05 [0.98-1.14]).

DISCUSSION

Despite more favorable cerebral hemodynamic profile, female AIS patients have worse outcomes than their male counterparts. This effect seems to be independently mediated by the more pronounced impact of early infarct volume on the prognosis in female patients. These findings underscore the possible explanatory power arising from sex-specific interpretation of early infarct volume in clinical practice.

Synchronous Superficial Middle Cerebral Vein Outflow Correlates Favorable Tissue Fate After Mechanical Thrombectomy for Acute Ischemic Stroke

RATIONALE AND OBJECTIVES

The purpose of this study was to determine the association between hemispheric synchrony in venous outflow at baseline and tissue fate after mechanical thrombectomy (MT) for acute ischemic stroke (AIS).

MATERIALS AND METHODS

A two-center retrospective analysis involving AIS patients who underwent MT was performed. The four cortical veins of interest include the superficial middle cerebral vein (SMCV), sphenoparietal sinus (SS), vein of Labbé (VOL), and vein of Trolard (VOT). Baseline computed tomography perfusion data were used to compare the following outflow parameters between the hemispheres: first filling time (△FFT), time to peak (△TTP) and total filling time (△TFT). Synchronous venous outflow was defined as △FFT = 0. Multivariable regression analyses were performed to evaluate the association of venous outflow synchrony with penumbral salvage, infarct growth, and intracranial hemorrhage (ICH) after MT.

RESULTS

A total of 151 patients (71.4 ± 13.2 years, 65.6% women) were evaluated. Patients with synchronous SMCV outflow demonstrated significantly greater penumbral salvage (41.3 mL vs. 33.1 mL, P = 0.005) and lower infarct growth (9.0 mL vs. 14.4 mL, P = 0.015) compared to those with delayed SMCV outflow. Higher △FFTSMCV (β = -1.44, P = 0.013) and △TTPSMCV (β = -0.996, P = 0.003) significantly associated with lower penumbral salvage, while higher △FFTSMCV significantly associated with larger infarct growth (β = 1.09, P = 0.005) and increased risk of ICH (odds ratio [OR] = 1.519, P = 0.047).

CONCLUSION

Synchronous SMCV outflow is an independent predictor of favorable tissue outcome and low ICH risk, and thereby carries the potential as an auxiliary radiological marker aiding the treatment planning of AIS patients.

Posterior circulation collaterals as predictors of outcome in basilar artery occlusion: a sub-analysis of the BASICS randomized trial

Introduction and purpose

Basilar artery occlusion (BAO) is still one of the most devastating neurological conditions associated with high morbidity and mortality. In the present study, we aimed to assess the role of posterior circulation collaterals as predictors of outcome in the BASICS trial and to compare two grading systems (BATMAN score and PC-CS) in terms of prognostic value.

Methods

We performed a sub-analysis of the BASICS trial. Baseline clinical and imaging variables were analyzed. For the imaging analysis, baseline CT and CTA were analyzed by a central core lab. Only those patients with good or moderate quality of baseline CTA and with confirmed BAO were included. Multivariable binary logistic regression analysis was used to test the independent association of clinical and imaging characteristics with a favorable outcome at 3 months (defined as a modified Rankin Score of ≤3). ROC curve analysis was used to assess and compare accuracy between the two collateral grading systems.

Results

The mean age was 67.0 (±12.5) years, 196 (65.3%) patients were males and the median NIHSS was 21.5 (IQR 11-35). Median NCCT pc-ASPECTS was 10 (IQR10-10) and median collateral scores for BATMAN and PC-CS were 8 (IQR 7-9) and 7 (IQR 6-8) respectively. Collateral scores were associated with favorable outcome at 3 months for both BATMAN and PC-CS but only with a modest accuracy on ROC curve analysis (AUC 0.62, 95% CI [0.55-0.69] and 0.67, 95% CI [0.60-0.74] respectively). Age (OR 0.97, 95% CI [0.95-1.00]), NIHSS (OR 0.91, 95% CI [0.89-0.94]) and collateral score (PC-CS - OR 1.2495% CI [1.02-1.51]) were independently associated with clinical outcome.

Conclusion

The two collateral grading systems presented modest prognostic accuracy. Only the PC-CS was independently associated with a favorable outcome at 3 months.

The effectiveness and safety of human urinary kallidinogenase in acute ischemic stroke patients undergoing endovascular therapy

The effectiveness and safety of human urinary kallidinogenase (HUK) in acute ischemic stroke (AIS) patients undergoing endovascular therapy (EVT) due to large vessel occlusion (LVO) was unclear. A pooled analysis was performed using individual data from the DEVT and RESCUE BT trials. Patients were divided into two groups based on HUK treatment. The primary outcome was the 90-day modified Rankin Scale (mRS) score. Safety outcomes included 90-day mortality and symptomatic intracranial hemorrhage (sICH) within 48 hours. A total of 1174 patients were included in the study. Of these, 150 (12.8%) patients received HUK. The adjusted common odds ratio (OR) of the mRS score was 1.458 (95% confidence interval [CI] = 1.072-1.983; p = 0.016) favoring HUK. The incidence of sICH (2.0% vs. 8.6%; adjusted OR: 0.198; 95% CI: 0.061-0.638; p = 0.007) and mortality (11.3% vs.18.5%; adjusted OR: 0.496; 95% CI: 0.286-0.862; p = 0.013) was lower in HUK group than non-HUK group. This association was consistent with propensity score-matching and the inverse probability of treatment weighting analysis. In conclusion, HUK was safe and associated with a preferable prognosis in AIS patients due to LVO in the anterior circulation.

Initial and follow-up high-resolution vessel wall MRI study of spontaneous cervicocranial artery dissection

OBJECTIVES

To explore the factors associated with ischemic stroke secondary to spontaneous cervicocranial artery dissection (sCCAD) and evaluate the initial imaging markers related to outcomes.

METHODS

Initial and follow-up high-resolution vessel wall MRI (VW-MRI) in consecutive patients with sCCAD were retrospectively analyzed. The associations of clinical and imaging factors and variants of the circle of Willis (COW) with ischemic stroke were evaluated using binary logistic regression analyses. The anatomical outcomes were categorized as complete, partial, and no remodeling based on changes of the vessel wall and lumen. Ordinal logistic regression analysis was used to assess associations between initial features and outcomes.

RESULTS

A total of 115 dissected arteries (79 strokes, 36 non-strokes) were detected in 103 patients. Follow-up VW-MRI was available in 46 patients (44.7%, with 51 vessels), with a median interval of 8.5 months. Pseudoaneurysm (odd ratio [OR], 0.178; 95% confidence interval [CI], 0.039-0.810; p = 0.026) tended to rarely cause ischemic stroke, while intraluminal thrombus (OR, 5.558; 95% CI, 1.739-17.765; p = 0.004), incomplete COW (OR, 9.309; 95% CI, 2.122-40.840; p = 0.003), and partial complete COW (OR, 4.463; 95% CI, 1.211-16.453; p = 0.025) were independently associated with stroke occurrence. Furthermore, the presence of double lumen (OR, 5.749; 95% CI, 1.358-24.361; p = 0.018) and occlusion (OR, 12.975; 95% CI, 3.022-55.645; p = 0.001) were associated with no remodeling of sCCAD.

CONCLUSIONS

Multiple initial factors were found to be related to stroke occurrence and anatomical outcomes of sCCAD. High-resolution VW-MRI may provide valuable insights into the pathophysiology and evolution of sCCAD.

CLINICAL RELEVANCE STATEMENT

Initial and follow-up high-resolution vessel wall MRI may help elucidate the pathophysiology of spontaneous cervicocranial artery dissection and provide important insights into the evolution and further facilitate the optimal management of patients with spontaneous cervicocranial artery dissection.

KEY POINTS

• Clinical and imaging factors, as well as the status of primary collateral circulation, are associated with ischemic stroke secondary to spontaneous cervicocranial artery dissection. • The follow-up high-resolution vessel wall MRI provides valuable insights into the long-term evolution and anatomical outcomes of spontaneous cervicocranial artery dissection. • The high-resolution vessel wall MRI features related to ischemic stroke and anatomical outcomes may further facilitate the optimal management of patients with spontaneous cervicocranial artery dissection.

Benefit of endovascular treatment for primary versus secondary medium vessel occlusion: A multi-center experience

AIMS

This study aimed to compare the clinical outcomes and safety of endovascular treatment (EVT) in patients with primary versus secondary medium vessel occlusion (MeVO).

METHODS

From the endovascular treatment for acute ischemic stroke in the China registry, we collected consecutive patients with MeVO who received EVT. The primary endpoint was a good outcome, defined as a modified Rankin Scale (mRS) 0 to 2 at 90 days.

RESULTS

154 patients were enrolled in the final analysis, including 74 primary MeVO and 80 secondary MeVO. A good outcome at 90 days was achieved in 42 (56.8%) patients with primary MeVO and 33 (41.3%) patients with secondary MeVO. There was a higher probability of good outcomes in patients with the primary vs secondary MeVO (adjusted odds ratio, 2.16; 95% confidence interval, 1.04 to 4.46; p = 0.04). There were no significant differences in secondary and safety outcomes between MeVO groups. In the multivariable analysis, baseline ASPECTS (p = 0.001), final modified thrombolysis in cerebral infarction score (p = 0.01), and any ICH (p = 0.03) were significantly associated with good outcomes in primary MeVO patients, while baseline National Institutes of Health Stroke Scale (p = 0.002), groin puncture to recanalization time (p = 0.02), and early neurological improvement (p < 0.001) were factors associated with good outcome in secondary MeVO patients.

CONCLUSION

In MeVO patients who received EVT, there was a higher likelihood of poor outcomes in patients with secondary versus primary MeVO.

Diagnostic Value of Perfusion Parameters for Differentiation of Underlying Etiology in Internal Carotid Artery Occlusions

PURPOSE

Occlusions of the internal carotid artery (ICA) may be caused by dissection, embolic or macroangiopathic pathogenesis, which partially influences the treatment; however, inferring the underlying etiology in computed tomography angiography can be challenging. In this study, we investigated whether computed tomography perfusion (CT-P) parameters could be used to distinguish between etiologies.

METHODS

Patients who received CT‑P in acute ischemic stroke due to ICA occlusion between 2012 and 2019 were retrospectively analyzed. Group comparisons between etiologies regarding the ratios of CT‑P parameters between both hemispheres for relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), time to maximum (Tmax), and mean transit time (MTT) were calculated by one-factorial analysis of variance (ANOVA) and compared by pairwise Bonferroni post hoc tests. An receiver operating characteristics (ROC) analysis was performed if differences in group comparisons were found. Multinomial logistic regression (MLR) including pretherapeutic parameters was calculated for etiologies.

RESULTS

In this study 69 patients (age = 70 ± 14 years, dissection = 10, 14.5%, embolic = 19, 27.5% and macroangiopathic = 40, 58.0%) were included. Group differences in ANOVA were only found for MTT ratio (p = 0.003, η2 = 0.164). In the post hoc test, MTT ratio showed a differentiability between embolic and macroangiopathic occlusions (p = 0.002). ROC analysis for differentiating embolic and macroangiopathic ICA occlusions based on MTT ratio showed an AUC of 0.77 (p < 0.001, CI = 0.65-0.89) and a cut-off was yielded at a value of 1.15 for the MTT ratio (sensitivity 73%, specificity 68%). The MLR showed an overall good model performance.

CONCLUSION

It was possible to differentiate between patients with embolic and macroangiopathic ICA occlusions based on MTT ratios and to define a corresponding cut-off. Differentiation from patients with dissection versus the other etiologies was not possible by CT‑P parameters in our sample.

Bridging therapy improves functional outcomes and reduces 90-day mortality compared with direct endovascular thrombectomy in patients with acute posterior ischemic stroke: a systematic review and meta-analysis

BACKGROUND

It remains unclear whether bridging therapy can achieve better neurologic outcomes than direct endovascular thrombectomy (EVT) in patients with posterior ischemic stroke.

METHODS

We systematically searched PubMed, EMBASE, and Cochrane databases with posterior artery occlusion treated with bridging therapy vs. EVT. Efficacy was assessed based on functional independence at 90 days and successful recanalization, whereas safety was assessed by mortality, rate of symptomatic intracranial hemorrhage (sICH), and occurrence of any hemorrhage. All data were analyzed with Review Manager software v5.3 and the risk of bias was determined using the Methodological Index for Non-randomized Studies.

RESULTS

We included 17 studies with a total of 3278 patients (1211 in the bridging therapy group and 2067 in the EVT group). Patients in the bridging group had a better functional outcome at 90 days, as evidenced by a higher proportion with a Modified Rankin Scale (mRS) score of 0-2 compared with the EVT group (odds ratio (OR) = 1.83, 95% confidence interval (CI): 1.54-2.19, P < 0.01), while no difference in mRS score of 0-3 (OR = 1.18, 95% CI: 0.96-1.45, P = 0.11). Patients in the bridging therapy group also had lower 90-day mortality rate (OR = 0.75, 95% CI: 0.59-0.95, P = 0.02). There were no significant differences between groups in rates of successful recanalization (OR = 0.96, 95% CI: 0.74-1.25, P = 0.77), sICH (OR = 1.27, 95% CI: 0.86-1.89, P = 0.24), and hemorrhage (OR = 1.22, 95% CI: 0.60-2.50, P = 0.58).

CONCLUSIONS

Among patients with posterior ischemic stroke, bridging therapy may be superior to EVT in achieving a good functional outcome and lowering the mortality without increasing the risks of hemorrhage.

Pretreatment CT perfusion collateral parameters correlate with penumbra salvage in middle cerebral artery occlusion

BACKGROUND AND PURPOSE

Acute ischemic stroke due to large vessel occlusion (AIS-LVO) is a major cause of functional dependence. Collateral status (CS) is an important determinant of functional outcomes. Pretreatment CT perfusion (CTP) parameters serve as reliable surrogates of CS. Penumbra Salvage Index (PSI) is another parameter predictive of functional outcomes in AIS-LVO. The aim of this study is to assess the relationship of pretreatment CTP parameters with PSI.

METHODS

In this prospectively collected, retrospectively reviewed multicenter analysis, inclusion criteria were as follows: (1) CT angiography confirmed middle cerebral artery (MCA) M1-segment and proximal M2-segment occlusion from 9/1/2017 to 9/22/2022; (2) diagnostic CTP; and (3) available diagnostic Magnetic resonance Imaging (MRI) diffusion-weighted images. Pearson correlation analysis was performed to assess the association between cerebral blood volume (CBV) index and hypoperfusion intensity ratio (HIR) with PSI. p value ≤.05 was considered statistically significant.

RESULTS

In total, 131 patients (n = 86, M1 and n = 45, proximal M2 occlusion) met our inclusion criteria. CBV index showed a modest positive correlation with PSI (r = 0.34, p<.001) in patients with proximal MCA occlusion. Similar trends were noted in subgroup analysis of patients with M1 occlusion, and proximal M2 occlusion. Whereas, HIR did not have a strong trend or correlation with PSI.

CONCLUSION

CBV index correlates with PSI, whereas HIR does not. Future studies are needed to expand our understanding of the adjunct role of CBV index with other similar pretreatment CTP-based markers in clinical evaluation and decision-making in patients with MCA occlusion.

Emerging diagnostic markers and therapeutic targets in post-stroke hemorrhagic transformation and brain edema

Stroke is a devastating condition that can lead to significant morbidity and mortality. The aftermath of a stroke, particularly hemorrhagic transformation (HT) and brain edema, can significantly impact the prognosis of patients. Early detection and effective management of these complications are crucial for improving outcomes in stroke patients. This review highlights the emerging diagnostic markers and therapeutic targets including claudin, occludin, zonula occluden, s100β, albumin, MMP-9, MMP-2, MMP-12, IL-1β, TNF-α, IL-6, IFN-γ, TGF-β, IL-10, IL-4, IL-13, MCP-1/CCL2, CXCL2, CXCL8, CXCL12, CCL5, CX3CL1, ICAM-1, VCAM-1, P-selectin, E-selectin, PECAM-1/CD31, JAMs, HMGB1, vWF, VEGF, ROS, NAC, and AQP4. The clinical significance and implications of these biomarkers were also discussed.

MiR-199a-5p enhances neuronal differentiation of neural stem cells and promotes neurogenesis by targeting Cav-1 after cerebral ischemia

AIMS

MicroRNAs (miRs) are involved in endogenous neurogenesis, enhancing of which has been regarded as a potential therapeutic strategy for ischemic stroke treatment; however, whether miR-199a-5p mediates postischemic neurogenesis remains unclear. This study aims to investigate the proneurogenesis effects of miR-199a-5p and its possible mechanism after ischemic stroke.

METHODS

Neural stem cells (NSCs) were transfected using Lipofectamine 3000 reagent, and the differentiation of NSCs was evaluated by immunofluorescence and Western blotting. Dual-luciferase reporter assay was performed to verify the target gene of miR-199a-5p. MiR-199a-5p agomir/antagomir were injected intracerebroventricularly. The sensorimotor functions were evaluated by neurobehavioral tests, infarct volume was measured by toluidine blue staining, neurogenesis was detected by immunofluorescence assay, and the protein levels of neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP), caveolin-1 (Cav-1), vascular endothelial growth factor (VEGF), and brain-derived neurotrophic factor (BDNF) were measured by Western blotting.

RESULTS

MiR-199a-5p mimic enhanced neuronal differentiation and inhibited astrocyte differentiation of NSCs, while a miR-199a-5p inhibitor induced the opposite effects, which can be reversed by Cav-1 siRNA. Cav-1 was through the dual-luciferase reporter assay confirmed as a target gene of miR-199a-5p. miR-199a-5p agomir in rat stroke models manifested multiple benefits, such as improving neurological deficits, reducing infarct volume, promoting neurogenesis, inhibiting Cav-1, and increasing VEGF and BDNF, which was reversed by the miR-199a-5p antagomir.

CONCLUSION

MiR-199a-5p may target and inhibit Cav-1 to enhance neurogenesis and thus promote functional recovery after cerebral ischemia. These findings indicate that miR-199a-5p is a promising target for the treatment of ischemic stroke.

Association of culprit plaque enhancement ratio, hypoperfusion and HbA1c with recurrent ischemic stroke in patients with atherosclerotic stenosis of the middle cerebral artery

PURPOSE

To investigate the differences in intracranial culprit plaque characteristics of the middle cerebral artery (MCA), collateral circulation and hypoperfusion in patients with and without recurrent ischemic stroke and to identify the association with the recurrent ischemic cerebrovascular events.

METHOD

Eighty-six patients with acute/subacute ischemic stroke caused by atherosclerotic plaques of the MCA were retrospectively enrolled and grouped into patients with recurrence (n = 36) and without recurrence (n = 50). All patients underwent high-resolution vessel wall imaging and dynamic susceptibility contrast-enhanced perfusion weighted imaging. The differences in culprit plaque characteristics, collateral circulation and hypoperfusion in the territory of the stenotic MCA were assessed between the two groups. The relationship between plaque characteristics and hypoperfusion was evaluated. The independent factors of recurrent ischemic stroke were identified by logistic regression analyses.

RESULTS

Higher HbA1c, culprit plaque enhancement grade, culprit plaque enhancement ratio, and lower time to peak map based on the Alberta Stroke Program Early CT score (TTP-ASPECTS) were observed in the recurrence group(all p < 0.050). Both plaque enhancement grade and enhancement ratio were significantly associated with TTP-ASPECTS (p = 0.030 and 0.039, respectively). HbA1c, culprit plaque enhancement ratio and TTP-ASPECTS were independent factors of the recurrence of ischemic stroke (all p < 0.050). The area under the curve of the combination including the above factors (AUC = 0.819) was significantly higher than that of any variable alone after adjustment (all p < 0.050).

CONCLUSIONS

Culprit plaque enhancement ratio, TTP-ASPECTS and HbA1c were independent factors of recurrent ischemic stroke. Their combination improved the accuracy in identifying the risk of recurrent ischemic stroke.

Efficacy and safety of bridging therapy versus direct thrombectomy for tandem lesions in acute stroke: A systematic review and meta-analysis

BACKGROUND

Current studies have concluded that MT (Mechanical Thrombectomy) is safe and effective for tandem lesions (TL). However, The benefit of bridging therapy for TL is controversial.

OBJECTIVE

To compare efficacy and safety between bridging therapy and direct thrombectomy of tandem lesions.

METHOD

We conducted a systematic review and meta-analysis of studies comparing bridging therapy versus direct thrombectomy among TL patients with regards to symptomatic intracerebral hemorrhage(sICH), Parenchymal hemorrhage (PH), 3-month mortality, modified Rankin Scale (mRS) score within 3 months, successful reperfusion, and excellent reperfusion. The meta-analysis of proportions was conducted with a common effects model.

RESULT

Five studies (n = 1198 patients) were identified for the systematic review. For safety outcomes, the bridging group had no significant difference in the rate of symptomatic intracranial hemorrhage (OR = 0.78, 95% CI = 0.49-1.25, P = 0.31) and the rate of PH (OR = 0.67, 95% CI = 0.39-1.13, P = 0.13) but significantly lower rate of 3-month mortality (OR = 0.53, 95% CI = 0.37-0.75, P = 0.0004) compared to the direct thrombectomy group. In terms of efficacy outcomes, the bridging therapy group had a significantly higher rate of 3- month good functional outcome (mRS 0-2) (OR = 1.76, 95% CI = 1.38-2.24, P < 0.00001) and successful recanalization (OR = 1.69, 95% CI = 1.27-2.25, P = 0.0003) but no significant difference in the rate of excellent recanalization(OR = 1.21, 95% CI = 0.91-1.59, P = 0.19) in patients with TL compared to direct thrombectomy group.

CONCLUSION

Bridging therapy is effective in improving the 3-month functional prognosis and increasing the rate of arterial recanalization without increasing the risk of intracranial hemorrhage in patients with TL compared to direct thrombectomy. A large multicentre clinical RCT is expected, as are advanced intravenous thrombolysis and endovascular thrombectomy techniques.

Large differences in collateral blood vessel abundance among individuals arise from multiple genetic variants

Collateral blood flow varies greatly among humans for reasons that remain unclear, resulting in significant differences in ischemic tissue damage. A similarly large variation has also been found in mice that is caused by genetic background-dependent differences in the extent of collateral formation, termed collaterogenesis-a unique angiogenic process that occurs during development and determines collateral number and diameter in the adult. Previous studies have identified several quantitative trait loci (QTL) linked to this variation. However, understanding has been hampered by the use of closely related inbred strains that do not model the wide genetic variation present in the "outbred" human population. The Collaborative Cross (CC) multiparent mouse genetic reference panel was developed to address this limitation. Herein we measured the number and average diameter of cerebral collaterals in 60 CC strains, their 8 founder strains, 8 F1 crosses of CC strains selected for abundant versus sparse collaterals, and 2 intercross populations created from the latter. Collateral number evidenced 47-fold variation among the 60 CC strains, with 14% having poor, 25% poor-to-intermediate, 47% intermediate-to-good, and 13% good collateral abundance, that was associated with large differences in post-stroke infarct volume. Collateral number in skeletal muscle and intestine of selected high- and low-collateral strains evidenced the same relative abundance as in brain. Genome-wide mapping demonstrated that collateral abundance is a highly polymorphic trait. Subsequent analysis identified: 6 novel QTL circumscribing 28 high-priority candidate genes harboring putative loss-of-function polymorphisms (SNPs) associated with low collateral number; 335 predicted-deleterious SNPs present in their human orthologs; and 32 genes associated with vascular development but lacking protein coding variants. Six additional suggestive QTL (LOD > 4.5) were also identified in CC-wide QTL mapping. This study provides a comprehensive set of candidate genes for future investigations aimed at identifying signaling proteins within the collaterogenesis pathway whose variants potentially underlie genetic-dependent collateral insufficiency in brain and other tissues.

Impact of volemia at admission on the effect of collateral status on functional outcomes in patients undergoing endovascular thrombectomy

BACKGROUND AND PURPOSE

Having good collaterals is associated with better clinical outcomes in patients undergoing endovascular thrombectomy. This study aims to evaluate whether the effect of collateral status on functional outcomes is modified by volemia at admission.

METHODS

This is a single-center, retrospective analysis of patients who had acute proximal anterior circulation occlusion and underwent endovascular thrombectomy between January 2019 and June 2022. Volemia at admission, evaluated by blood urea nitrogen-to-creatinine ratio, was used to dichotomize patients into dehydrated and hydrated groups. The primary outcome was functional independence (90-day modified Rankin Scale score = 0-2). Secondary outcomes were the rates of successful reperfusion, 24-h symptomatic intracranial hemorrhage, and 90-day all-cause mortality. Multivariable logistic regression analysis was used to assess the interaction between collateral status and volemia at admission on outcomes.

RESULTS

A total of 290 patients were enrolled, among whom having good collaterals was associated with functional independence (adjusted odds ratio [OR] = 2.71, 95% confidence interval [CI] = 1.41-5.22, p = 0.003). Having good collaterals benefited dehydrated patients (adjusted OR = 3.33, 95% CI = 1.45-7.63, p = 0.004) but not hydrated patients (adjusted OR = 2.21, 95% CI = 0.73-6.68, p = 0.161). However, an interaction between collaterals and volemia at admission on functional independence was not observed (p = 0.319). The rates of successful reperfusion, symptomatic intracerebral hemorrhage, and all-cause mortality were similar between those with good and poor collaterals in both dehydrated and hydrated patients.

CONCLUSIONS

The effect of collateral status on the functional independence of patients undergoing thrombectomy is not modified by volemia at admission.

Predicting Penumbra Salvage and Infarct Growth in Acute Ischemic Stroke: A Multifactor Survival Game

BACKGROUND

Effective treatment of acute ischemic stroke requires reperfusion of salvageable tissue. We investigated the predictors of penumbra salvage (PS) and infarct growth (IG) in a large cohort of stroke patients.

METHODS

In the ASTRAL registry from 2003 to 2016, we selected middle cerebral artery strokes <24 h with a high-quality CT angiography and CT perfusion. PS and IG were correlated in multivariate analyses with clinical, biochemical and radiological variables, and with clinical outcomes.

RESULTS

Among 4090 patients, 551 were included in the study, 50.8% male, mean age (±SD) 66.3 ± 14.7 years, mean admission NIHSS (±SD 13.3 ± 7.1) and median onset-to-imaging-time (IQR) 170 (102 to 385) minutes. Increased PS was associated with the following: higher BMI and lower WBC; neglect; larger penumbra; absence of early ischemic changes, leukoaraiosis and other territory involvement; and higher clot burden score. Reduced IG was associated with the following: non-smokers; lower glycemia; larger infarct core; absence of early ischemic changes, chronic vascular brain lesions, other territory involvement, extracranial arterial pathology and hyperdense middle cerebral artery sign; and higher clot burden score. When adding subacute variables, recanalization was associated with increased PS and reduced IG, and the absence of haemorrhage with reduced IG. Collateral status was not significantly associated with IG nor with PS. Increased PS and reduced IG correlated with better 3- and 12-month outcomes.

CONCLUSION

In our comprehensive analysis, multiple factors were found to be responsible for PS or IG, the strongest being radiological features. These findings may help to better select patients, particularly for more aggressive or late acute stroke treatment.

Influence of the integrity of circle of Willis on asymptomatic or mild patients with first diagnosed chronic internal carotid artery occlusion

BACKGROUND

In order to identify individuals with chronic internal carotid artery occlusion (CICAO), it is essential to understand the integrity of the circle of Willis (CoW). This understanding is important as it may determine the potential benefits of active medical and endovascular treatments.

PURPOSE

The objective of this study is to assess whether diminished integrity of the CoW can serve as a useful marker for identifying individuals with more severe impairment in cerebral blood perfusion and a higher incidence of cerebral infarction among asymptomatic or mildly affected patients with CICAO.

MATERIALS AND METHODS

We conducted a retrospective review of asymptomatic or mildly affected patients with newly diagnosed CICAO who did not receive reperfusion therapies. The categorization of patients into good or poor integrity groups was based on the assessment of CoW integrity using CTA. We evaluated the volume and value of prolonged time to peak (TTP) in both groups, as well as the occurrence of new cerebral infarctions. Our analysis involved multivariate regression and receiver operating characteristic (ROC) analysis.

RESULTS

Hemodynamic abnormalities characterized by prolonged TTP were observed in the affected side's blood supply region in all 38 patients. There was a notable difference in the volume and value of prolonged TTP between the two groups (P < 0.001). Correlation analyses based on CTP and CTA parameters revealed a negative relationship between CoW scores and both the abnormal volume (r = -0.624, P = 0.000) and value (r = -0.589, P = 0.000) of prolonged TTP. Upon multivariable adjustment, the independent predictors for new cerebral infarction and higher volume of prolonged TTP were solely the CoW status, with respective estimates of (b = 6.05; 95% confidence interval [CI]: 1.619, 22.619; P = 0.007) and (b = 35.486; 95% CI: 4.697, 268.088; P = 0.001).

CONCLUSION

Assessing the integrity of the CoW is crucial in evaluating abnormal perfusion in asymptomatic or mildly affected individuals who are newly diagnosed with CICAO and have not undergone reperfusion therapy.

Prediction of delayed reperfusion in patients with incomplete reperfusion following thrombectomy

BACKGROUND

The clinical course of patients with incomplete reperfusion after thrombectomy, defined as an expanded Thrombolysis in Cerebral Infarction (eTICI) score of 2a-2c, is heterogeneous. Patients showing delayed reperfusion (DR) have good clinical outcomes, almost comparable to patients with ad-hoc TICI3 reperfusion. We aimed to develop and internally validate a model that predicts DR occurrence in order to inform physicians about the likelihood of a benign natural disease progression.

PATIENTS AND METHODS

Single-center registry analysis including all consecutive, study-eligible patients admitted between 02/2015 and 12/2021. Preliminary variable selection for the prediction of DR was performed using bootstrapped stepwise backward logistic regression. Interval validation was performed with bootstrapping and the final model was developed using a random forests classification algorithm. Model performance metrics are reported with discrimination, calibration, and clinical decision curves. Primary outcome was concordance statistics as a measure of goodness of fit for the occurrence of DR.

RESULTS

A total of 477 patients (48.8% female, mean age 74 years) were included, of whom 279 (58.5%) showed DR on 24 follow-up. The model's discriminative ability for predicting DR was adequate (C-statistics 0.79 [95% CI: 0.72-0.85]). Variables with strongest association with DR were: atrial fibrillation (aOR 2.06 [95% CI: 1.23-3.49]), Intervention-To-Follow-Up time (aOR 1.06 [95% CI: 1.03-1.10]), eTICI score (aOR 3.49 [95% CI: 2.64-4.73]), and collateral status (aOR 1.33 [95% CI: 1.06-1.68]). At a risk threshold of R = 30%, use of the prediction model could potentially reduce the number of additional attempts in one out of four patients who will have spontaneous DR, without missing any patients who do not show spontaneous DR on follow-up.

CONCLUSIONS

The model presented here shows fair predictive accuracy for estimating chances of DR after incomplete thrombectomy. This may inform treating physicians on the chances of a favorable natural disease progression if no further reperfusion attempts are made.

Large differences in collateral blood vessel abundance among individuals arise from multiple genetic variants

Collateral blood flow varies greatly among humans for reasons that remain unclear, resulting in significant differences in ischemic tissue damage. A similarly large variation has also been found in mice that is caused by genetic background-dependent differences in the extent of collateral formation, termed collaterogenesis-a unique angiogenic process that occurs during development and determines collateral number and diameter in the adult. Previous studies have identified several quantitative trait loci (QTL) linked to this variation. However, understanding has been hampered by the use of closely related inbred strains that do not model the wide genetic variation present in the "outbred" human population. The Collaborative Cross (CC) multiparent mouse genetic reference panel was developed to address this limitation. Herein we measured the number and average diameter of cerebral collaterals in 60 CC strains, their 8 founder strains, 8 F1 crosses of CC strains selected for abundant versus sparse collaterals, and 2 intercross populations created from the latter. Collateral number evidenced 47-fold variation among the 60 CC strains, with 14% having poor, 25% poor-to-intermediate, 47% intermediate-to-good, and 13% good collateral abundance, that was associated with large differences in post-stroke infarct volume. Genome-wide mapping demonstrated that collateral abundance is a highly polymorphic trait. Subsequent analysis identified: 6 novel QTL circumscribing 28 high-priority candidate genes harboring putative loss-of-function polymorphisms (SNPs) associated with low collateral number; 335 predicted-deleterious SNPs present in their human orthologs; and 32 genes associated with vascular development but lacking protein coding variants. This study provides a comprehensive set of candidate genes for future investigations aimed at identifying signaling proteins within the collaterogenesis pathway whose variants potentially underlie genetic-dependent collateral insufficiency in brain and other tissues.

Engineered Extracellular Vesicles as a Targeted Delivery Platform for Precision Therapy

Extracellular vesicles (EVs)-based cell-free strategy has shown therapeutic potential in tissue regeneration. Due to their important roles in intercellular communications and their natural ability to shield cargos from degradation, EVs are also emerged as novel delivery vehicles for various bioactive molecules and drugs. Accumulating studies have revealed that EVs can be modified to enhance their efficacy and specificity for the treatment of many diseases. Engineered EVs are poised as the next generation of targeted delivery platform in the field of precision therapy. In this review, the unique properties of EVs are overviewed in terms of their biogenesis, contents, surface features and biological functions, and the recent advances in the strategies of engineered EVs construction are summarized. Additionally, we also discuss the potential applications of engineered EVs in targeted therapy of cancer and damaged tissues, and evaluate the opportunities and challenges for translating them into clinical practice.

Rescue intracranial stenting for acute ischemic stroke after the failure of mechanical thrombectomy: A systematic review, meta-analysis, and trial sequential analysis

Background

Intracranial rescue stenting (RS) might be an option for acute ischemic stroke after the failure of mechanical thrombectomy (MT). However, the findings were not consistent in previous systematic reviews, and whether the conclusion was supported by sufficient statistical power is unknown.

Aim

To examine the effect of RS on acute ischemic stroke after the failure of MT with a systematic review, meta-analysis, and trial sequential analysis (TSA).

Methods

We searched Ovid Medline, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to 15 June 2022, without any language restriction. Studies assessing the effect of RS for acute ischemia stroke after MT failure were included. Two reviewers independently screened the retrieved articles, extracted data, and evaluated the quality of the included studies through the New Ottawa Scale (NOS). The primary outcome was the recanalization rate after RS. Secondary outcomes included modified Rankin Scale (mRS) at 3 months after stroke, symptomatic intracranial hemorrhage (sICH), and mortality rate. We synthesized the data through a random-effects model and performed a TSA analysis.

Results

We included 15 studies (containing 1,595 participants) after screening 3,934 records. The pooled recanalization rate for rescue stenting was 82% (95% CI 77-87%). Compared with non-stenting, rescue stenting was associated with a higher proportion of patients with 0-2 mRS score (OR 3.96, 95% CI 2.69-5.84, p < 0.001) and a lower 90-day mortality rate (OR 0.46, 95% CI 0.32-0.65, p < 0.001), and stenting did not increase sICH rate (OR 0.63, 95% CI 0.39-1.04, p = 0.075). The TSA analysis showed that the meta-analysis of the mRS score had a sufficient sample size and statistical power.

Conclusions

Our study showed that rescue stenting was effective and safe for patients with acute ischemia stroke who also had a failed MT, and this result was confirmed in a TSA analysis.

The role of neurophysiological tools in the evaluation of ischemic stroke evolution: a narrative review

Ischemic stroke is characterized by a complex cascade of events starting from vessel occlusion. The term "penumbra" denotes the area of severely hypo-perfused brain tissue surrounding the ischemic core that can be potentially recovered if blood flow is reestablished. From the neurophysiological perspective, there are local alterations-reflecting the loss of function of the core and the penumbra-and widespread changes in neural networks functioning, since structural and functional connectivity is disrupted. These dynamic changes are closely related to blood flow in the affected area. However, the pathological process of stroke does not end after the acute phase, but it determines a long-term cascade of events, including changes of cortical excitability, that are quite precocious and might precede clinical evolution. Neurophysiological tools-such as Transcranial Magnetic Stimulation (TMS) or Electroencephalography (EEG)-have enough time resolution to efficiently reflect the pathological changes occurring after stroke. Even if they do not have a role in acute stroke management, EEG and TMS might be helpful for monitoring ischemia evolution-also in the sub-acute and chronic stages. The present review aims to describe the changes occurring in the infarcted area after stroke from the neurophysiological perspective, starting from the acute to the chronic phase.