Demographic and clinical predictors of leptomeningeal collaterals in stroke patients

Endovascular treatment for young patients with acute large vessel occlusion stroke in China: analysis of the ANGEL-ACT registry

Background

The incidence of acute ischemic stroke caused by large vessel occlusion is relatively infrequent in the young adult population. We sought to evaluate their clinical outcomes after endovascular treatment (EVT) and stroke etiology compared with older patients.

Methods

We examined data from the ANGEL-ACT registry, a nationwide study in China focusing on EVT for acute ischemic stroke. We compared two age groups: <50 years old and ≥50 years old. Our analysis focused on outcome measures such as the 90-day modified Rankin Scale (mRS) score, mortality, and symptomatic intracranial hemorrhage (sICH). We adjusted for confounding variables.

Results

We included 1,691 patients, and 216 patients (13%) were <50 years old. Young patients had lower median National Institutes of Health Stroke Scale (NIHSS) scores (14 vs. 17, P < 0.001) and fewer cardiovascular comorbidities than older patients. Underlying intracranial atherosclerosis disease (ICAD) was higher in young patients (39.4 vs. 28.7%, P = 0.001). Clinical outcome was less favorable in older compared to younger patients (mRS shift: 0.76 [95% confidence interval (CI), 0.58-0.99]); functional independence [mRS score 0-2] 61% vs. 39% (adjusted odds ratio (OR), 0.7 [95% CI, 0.51-0.97]). Mortality and sICH did not differ between groups. Onset to puncture time (OTP) was longer in young patients (357 min vs. 294 min, P = 0.001).

Conclusion

An estimated 13% of patients who underwent endovascular thrombectomy for acute ischemic stroke were <50 years old. Symptomatic underlying ICAD was more prevalent in the younger patient population. Despite a prehospital delay, younger patients exhibited more favorable outcomes than their older counterparts.

The negative effect of aging on cerebral venous outflow in acute ischemic stroke

Cortical venous outflow (VO) represents an imaging biomarker of increasing interest in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). We conducted a retrospective multicenter cohort study to investigate the effect of aging on VO. A total of 784 patients met the inclusion criteria. Cortical Vein Opacification Score (COVES) was used to assess VO profiles on admission CT angiography. Cerebral microperfusion was determined using the hypoperfusion intensity ratio (HIR) derived from perfusion imaging. Arterial collaterals were assessed using the Tan scale. Multivariable regression analysis was performed to identify independent determinants of VO, HIR and arterial collaterals. In multivariable regression, higher age correlated with worse VO (adjusted odds ratio [95% CI]; 0.83 [0.73-0.95]; P = 0.006) and poorer HIR (β coefficient [95% CI], 0.014 [0.005-0.024]; P = 0.002). The negative effect of higher age on VO was mediated by the extent of HIR (17.3%). We conclude that higher age was associated with worse VO in AIS-LVO, partially explained by the extent of HIR reflecting cerebral microperfusion. Our study underlines the need to assess collateral blood flow beyond the arterial system and provides valuable insights into deteriorated cerebral blood supply in elderly AIS-LVO patients.

Exploring sex differences for acute ischemic stroke clinical, imaging and thrombus characteristics in the INTERRSeCT study

Women, especially following menopause, are known to have worse outcomes following acute ischemic stroke. One primary postulated biological mechanism for worse outcomes in older women is a reduction in the vasculoprotective effects of estrogen. Using the INTERRseCT cohort, a multicentre international observational cohort studying recanalization in acute ischemic stroke, we explored the effects of sex, and modifying effects of age, on neuroradiological predictors of recanalization including robustness of leptomeningeal collaterals, thrombus burden and thrombus permeability. Ordinal regression analyses were used to examine the relationship between sex and each of the neuroradiological markers. Further, we explored both multiplicative and additive interactions between age and sex. All patients (n = 575) from INTERRseCT were included. Mean age was 70.2 years (SD: 13.1) and 48.5% were women. In the unadjusted model, female sex was associated with better collaterals (OR 1.37, 95% CIs: 1.01-1.85), however this relationship was not significant after adjusting for age and relevant comorbidities. There were no significant interactions between age and sex. In a large prospective international cohort, we found no association between sex and radiological predictors of recanalization including leptomeningeal collaterals, thrombus permeability and thrombus burden.

Comparing the predictive value of quantitative magnetic resonance imaging parametric response mapping and conventional perfusion magnetic resonance imaging for clinical outcomes in patients with chronic ischemic stroke

Predicting clinical outcomes after stroke, using magnetic resonance imaging (MRI) measures, remains a challenge. The purpose of this study was to investigate the prediction of long-term clinical outcomes after ischemic stroke using parametric response mapping (PRM) based on perfusion MRI data. Multiparametric perfusion MRI datasets from 30 patients with chronic ischemic stroke were acquired at four-time points ranging from V2 (6  weeks) to V5 (7  months) after stroke onset. All perfusion MR parameters were analyzed using the classic whole-lesion approach and voxel-based PRM at each time point. The imaging biomarkers from each acquired MRI metric that was predictive of both neurological and functional outcomes were prospectively investigated. For predicting clinical outcomes at V5, it was identified that PRM_Tmax-, PRM_rCBV-, and PRM_rCBV+ at V3 were superior to the mean values of the corresponding maps at V3. We identified correlations between the clinical prognosis after stroke and MRI parameters, emphasizing the superiority of the PRM over the whole-lesion approach for predicting long-term clinical outcomes. This indicates that complementary information for the predictive assessment of clinical outcomes can be obtained using PRM analysis. Moreover, new insights into the heterogeneity of stroke lesions revealed by PRM can help optimize the accurate stratification of patients with stroke and guide rehabilitation.

Case Report: Successful Anterior Circulation Thrombectomy After 24 Hours in An Adolescent

BACKGROUND

Arterial ischemic stroke in children comes with the potential for morbidity and mortality and can result in high cost of care and decreased quality of life among survivors. Children with arterial ischemic stroke are increasingly being treated with mechanical thrombectomy, but little is known about the risks and benefits 24 hours after a patient's last known well (LKW) time.

METHODS

A 16-year-old female presented with acute onset of dysarthria and right hemiparesis with LKW time 22 hours prior. Pediatric National Institutes of Health Stroke Scale score was 12. Magnetic resonance imaging showed diffusion restriction and T2 hyperintensity primarily in the left basal ganglia. Magnetic resonance angiography revealed left M1 occlusion. Arterial spin labeling showed a large apparent perfusion deficit. She underwent thrombectomy with TICI3 recanalization 29.5 hours after LKW time.

RESULTS

At 2-month follow-up, her examination showed moderate right-hand weakness and mild diminished sensation of the right arm.

CONCLUSIONS

Adult thrombectomy trials include patients up to 24 hours from their LKW time and suggest that some patients maintain a favorable perfusion profile for over 24 hours. Without intervention many go on to experience infarct expansion. The persistence of a favorable perfusion profile likely reflects robust collateral circulation. We hypothesized our patient was relying on collateral circulation to maintain the noninfarcted areas of her left middle cerebral artery territory. Owing to concern for eventual collateral failure, thrombectomy outside of the 24-hour window was performed. This case serves as a call to action to better understand the impact of collateral circulation on cerebral perfusion in children with large vessel occlusions and delineate which children may benefit from thrombectomy in a delayed time window.

The determinants of collateral circulation status in patients with chronic cerebral arterial circle occlusion: A STROBE Study

The condition of collateral pathways is an important predictor of stroke prognoses; however the major determinants of collaterals are still unknown. The purpose of this study is to identify potentially determinants for collateral circulation status in patients with chronic occlusion of cerebral arterial circle. All patients with chronic occlusion of either unilateral internal carotid artery or middle cerebral artery M1 or M2 segment, diagnosed by digital subtraction angiography at the neurology department of the First Medical Centre of Chinese PLA General Hospital from January 2015 to December 2017, were retrospectively collected in our sample. After screening according to inclusion and exclusion criteria, the patients' relevant clinical data were collected and analyzed. Collateral circulations were assessed by 2 independent raters using the American society of interventional and therapeutic neuroradiology/society of interventional radiology flow-grading system. Baseline characteristics (n = 163): our sample consists of 116 (71.2%) male and 47 (28.8%) female patients with an average age of 57.5 ± 11.9 years. Cerebral collateral flow was poor in 59 (36.2%) patients. Our univariate analyses showed that poor collateral circulation was associated with lower high-density lipoproteins cholesterol (HDL), elevated homocysteine levels, aging and hyperlipidemia. A multivariate analysis identified HDL, homocysteine levels and ageing as major predictors for collateral circulation status. In the subgroup analysis, the HDL contributed to collateral angiogenesis internal carotid artery occlusion group. In the middle cerebral artery occlusion group, the homocysteine and ageing were related to the poor collateral status. Low HDL, high levels of homocysteine and ageing are identified as possible risk factors for a poor collateral vessel blood flow in patients with chronic anterior circulation occlusion.

Pre-stroke Physical Activity and Cerebral Collateral Circulation in Ischemic Stroke: A Potential Therapeutic Relationship?

Favorable cerebral collateral circulation contributes to hindering penumbral tissue from progressing to infarction and is associated with positive clinical outcomes after stroke. Given its clinical importance, improving cerebral collateral circulation is considered a therapeutic target to reduce burden after stroke. We provide a hypothesis-generating discussion on the potential association between pre-stroke physical activity and cerebral collateral circulation in ischemic stroke. The recruitment of cerebral collaterals in acute ischemic stroke may depend on anatomical variations, capacity of collateral vessels to vasodilate, and individual risk factors. Physical activity is associated with improved cerebral endothelial and vascular function related to vasodilation and angiogenic adaptations, and risk reduction in individual risk factors. More research is needed to understand association between cerebral collateral circulation and physical activity. A presentation of different methodological considerations for measuring cerebral collateral circulation and pre-stroke physical activity in the context of acute ischemic stroke is included. Opportunities for future research into cerebral collateral circulation, physical activity, and stroke recovery is presented.

The Hyperdense middle cerebral artery sign is associated with poor leptomeningeal collaterals in acute ischemic stroke: a retrospective study

Background

The hyperdense middle cerebral artery sign (HMCAS) is an early radiological marker to provide an early diagnosis and to identify ischemia. As reported, HMCAS is associated with heavy clot burden. Moreover, a heavy clot burden may cause obstruction of the orifices of arteries for leptomeningeal collateral flows and can lead to severe clinical conditions. However, the direct relationship between HMCAS and collateral flows remains unclear. Therefore, we explored the association between HMCAS and leptomeningeal collaterals in patients with acute ischemic stroke.

Methods

Consecutive ischemic stroke patients were enrolled from January 2015 to April 2021. HMCAS appearance and collateral status were detected by multimodal computed tomography at admission. Logistic regression analyses helped to identify the association between HMCAS, collateral flows and stroke severity.

Results

In 494 included patients, 180 (36.4%) presented with HMCAS. Ipsilateral collaterals were not seen or less prominent in patients with HMCAS (P < 0.001). The HMCAS appearance was significantly associated with less collaterals (odds ratio 5.17, 95% confidence interval 3.27-8.18, P < 0.001), internal carotid artery + M1/M1 occlusion, the initial stroke severity and follow-up outcomes. Subgroup analyses further confirmed HMCAS as an indicator of poor collaterals in ischemic stroke (all P values < 0.05).

Conclusions

HMCAS is associated with poor leptomeningeal collaterals, the stroke severity and a poor neurological outcome. Therefore, the HMCAS appearance can act as an early warning sign for healthcare professionals to be alert for poor collateral flows and poor neurological outcomes in ischemic stroke patients with middle cerebral artery occlusion.

Combination of High-Density Lipoprotein Cholesterol and Lipoprotein(a) as a Predictor of Collateral Circulation in Patients With Severe Unilateral Internal Carotid Artery Stenosis or Occlusion

BACKGROUND AND PURPOSE

Collateral circulation is considered an important factor affecting the risk of stroke, but the factors that affect collateral circulation remain unclear. This study was performed to identify the factors associated with collateral circulation, especially blood lipids.

METHODS

The study involved patients who had undergone digital subtraction angiography and were confirmed as having severe unilateral stenosis or occlusion of the internal carotid artery (ICA). We classified the collateral circulation status of each patient as good (Grade 3 or 4) or poor (Grade 0, 1, or 2) according to the grading system of the American Society of Interventional and Therapeutic Neuroradiology/American Society of Interventional Radiology. We collected data on patients' characteristics and identified the factors that affect collateral circulation.

RESULTS

This study included 212 patients. The multivariate logistic regression analysis showed that the high-density lipoprotein cholesterol (HDL-C) concentration and a complete anterior half of the circle of Willis were independent protective factors for good collateral circulation, whereas elevated lipoprotein(a) [Lp(a)] and serum creatinine concentrations were independent risk factors for good collateral circulation. The area under the receiver operating characteristics curve (AUC) was 0.68 (95% confidence interval [CI], 0.61-0.76) for HDL-C and 0.69 (95% CI, 0.62-0.76) for Lp(a). A binary logistic regression model analysis of the joint factor of HDL-C and Lp(a) yielded an AUC of 0.77 (95% CI, 0.71-0.84).

CONCLUSIONS

In patients with severe unilateral ICA stenosis or occlusion, the combination of HDL-C and Lp(a) is a useful predictor of collateral circulation.

Predictive value of time-variant color-coded multiphase CT angiography (mCTA) regarding clinical outcome of acute ischemic stroke: in comparison with conventional mCTA and CT perfusion

BACKGROUND

Color-coded multiphase computed tomography angiography (mCTA) can provide time-variant blood flow information of collateral circulation for acute ischemic stroke (AIS).

PURPOSE

To compare the predictive values of color-coded mCTA, conventional mCTA, and CT perfusion (CTP) for the clinical outcomes of patients with AIS.

MATERIAL AND METHODS

Consecutive patients with anterior circulation AIS were retrospectively reviewed at our center. Baseline collateral scores of color-coded mCTA and conventional mCTA were assessed by a 6-point scale. The reliabilities between junior and senior observers were assessed by weighted Kappa coefficients. Receiver operating characteristic (ROC) curves and multivariate logistic regression model were applied to evaluate the predictive capabilities of color-coded mCTA and conventional mCTA scores, and CTP parameters (hypoperfusion and infarct core volume) for a favorable outcome of AIS.

RESULTS

A total of 138 patients (including 70 cases of good outcomes) were included in our study. Patients with favorable prognoses were correlated with better collateral circulations on both color-coded and conventional mCTA, and smaller hypoperfusion and infarct core volume (all P < 0.05) on CTP. ROC curves revealed no significant difference between the predictive capability of color-coded and conventional mCTA (P = 0.427). The predictive value of CTP parameters tended to be inferior to that of color-coded mCTA score (all P < 0.001). Both junior and senior observers had consistently excellent performances (κ = 0.89) when analyzing color-coded mCTA maps.

CONCLUSION

Color-coded mCTA provides prognostic information of patients with AIS equivalent to or better than that of conventional mCTA and CTP. Junior radiologists can reach high diagnostic accuracy when interpreting color-coded mCTA images.

Endovascular Thrombectomy in Young Patients With Stroke: A MR CLEAN Registry Study

BACKGROUND AND PURPOSE

Acute ischemic stroke due to large vessel occlusion is uncommon in young adults. We assessed stroke cause in young patients and compared their outcomes after endovascular thrombectomy with older patients.

METHODS

We used data (March 2014 until November 2017) of patients with an anterior circulation large vessel occlusion stroke from the MR CLEAN (Multicenter Randomized Controlled Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) Registry, a nationwide, prospective study on endovascular thrombectomy in the Netherlands. We compared young patients (18-49 years) with older patients (≥50 years). Outcomes included modified Rankin Scale score after 90 days (both shift and dichotomized analyses), expanded Thrombolysis in Cerebral Infarction score, and symptomatic intracranial hemorrhage. Analyses were adjusted for confounding.

RESULTS

We included 3256 patients, 310 (10%) were 18 to 49 years old. Young patients had lower median National Institutes of Health Stroke Scale scores (14 versus 16, P<0.001) and less cardiovascular comorbidities than older patients. Stroke etiologies in young patients included carotid dissection (16%), cardio-embolism (15%), large artery atherosclerosis (10%), and embolic stroke of undetermined source (31%). Clinical outcome was better in young than older patients (acOR for modified Rankin Scale shift: 1.8 [95% CI, 1.5-2.2]; functional independence [modified Rankin Scale score 0-2] 61 versus 39% [adjusted odds ratio, 2.1 [95% CI, 1.6-2.8]); mortality 7% versus 32%, adjusted odds ratio, 0.2 [95% CI, 0.1-0.3]). Symptomatic intracranial hemorrhage occurred less frequently in young patients (3% versus 6%, adjusted odds ratio, 0.5 [95% CI, 0.2-1.00]). Successful reperfusion (expanded Thrombolysis in Cerebral Infarction Score 2b-3) did not differ between groups. Onset to reperfusion time was shorter in young patients (253 versus 255 minutes, adjusted B in minutes 12.4 [95% CI, 2.4-22.5]).

CONCLUSIONS

Ten percent of patients with acute ischemic stroke undergoing endovascular thrombectomy were younger than 50. Cardioembolism and carotid dissection were common underlying causes in young patients. In one-third of cases, no cause was identified, indicating the need for more research on stroke cause in young patients. Young patients had better prognosis and lower risk of symptomatic intracranial hemorrhage than older patients.

Determinants of Leptomeningeal Collateral Status Variability in Ischemic Stroke Patients

BACKGROUND

Collateral status is an indicator of a favorable outcome in stroke. Leptomeningeal collaterals provide alternative routes for brain perfusion following an arterial occlusion or flow-limiting stenosis. Using a large cohort of ischemic stroke patients, we examined the relative contribution of various demographic, laboratory, and clinical variables in explaining variability in collateral status.

METHODS

Patients with acute ischemic stroke in the anterior circulation were enrolled in a multi-center hospital-based observational study. Intracranial occlusions and collateral status were identified and graded using multiphase computed tomography angiography. Based on the percentage of affected territory filled by collateral supply, collaterals were graded as either poor (0-49%), good (50-99%), or optimal (100%). Between-group differences in demographic, laboratory, and clinical factors were explored using ordinal regression models. Further, we explored the contribution of measured variables in explaining variance in collateral status.

RESULTS

386 patients with collateral status classified as poor (n = 64), good (n = 125), and optimal (n = 197) were included. Median time from symptom onset to CT was 120 (IQR: 78-246) minutes. In final multivariable model, male sex (OR 1.9, 95% CIs [1.2, 2.9], p = 0.005) and leukocytosis (OR 1.1, 95% CIs [1.1, 1.2], p = 0.001) were associated with poor collaterals. Measured variables only explained 44.8-53.0% of the observed between-patient variance in collaterals.

CONCLUSION

Male sex and leukocytosis are associated with poorer collaterals. Nearly half of the variance in collateral flow remains unexplained and could be in part due to genetic differences.

Workforce Attachment after Ischemic Stroke - The Importance of Time to Thrombolytic Therapy

OBJECTIVES

The ability to remain in employment addresses an important consequence of stroke beyond the usual clinical parameters. However, data on the association between time to intravenous thrombolysis and workforce attachment in patients with acute ischemic stroke are sparse.

MATERIALS AND METHODS

In this nationwide cohort study, stroke patients of working age (18-60 years) treated with thrombolysis (2011-2016) who were part of the workforce prior to admission and alive at discharge were identified using the Danish Stroke Registry. The association between time to thrombolysis and workforce attachment one year later was examined with multivariable logistic regression.

RESULTS

The study population comprised 1,329 patients (median age 51 years [25^th-75^th percentile 45-56], 67.3% men). The median National Institutes of Health Stroke Scale score at presentation was 4 (25^th-75^th percentile 2-8), and the median time from symptom-onset to initiation of thrombolysis was 140min (25^th-75^th percentile 104-196min). The proportion of patients who were part of the workforce at one-year follow-up was 64.6%, 64.3%, 64.9%, and 60.0% in patients receiving thrombolysis within 90min, between 91-180min, between 181-270min, and after 270min, respectively. In adjusted analysis, time to thrombolysis between 91-180min, 181-270min, and >270min was not significantly associated with workforce attachment compared with thrombolysis received ≤90min of symptom-onset (ORs 0.89 [95%CI 0.60-1.31], 0.93 [0.66-1.31], and 0.80 [0.43-1.52], respectively).

CONCLUSIONS

In patients of working age admitted with stroke and treated with thrombolysis, two out of three were part of the workforce one year after discharge. There was no graded relationship between time to thrombolysis and the likelihood of workforce attachment.

Prestroke statin use enhances collateralization in acute ischemic stroke patients

BACKGROUND

Statin therapy has been shown to be effective in the prevention of ischemic stroke. In addition, recent studies have suggested that prior statin therapy could lower the initial stroke severity and improve stroke functional outcomes in the event of stroke. It was speculated that prestroke statin use may enhance collateral circulation and result in favorable functional outcomes.

OBJECTIVE

The aim of the study was to investigate the association of prestroke statin use with leptomeningeal collaterals and to determine the association of prestroke statin use with stroke severity and functional outcome in acute ischemic stroke patients.

METHODS

We prospectively and consecutively enrolled 239 acute ischemic stroke patients with acute infarction due to occlusion of the middle cerebral artery within 24 h in the neurology department of West China Hospital from May 2011 to April 2017. Computed tomographic angiography (CTA) imaging was performed for all patients to detect middle cerebral artery thrombus; regional leptomeningeal collateral score (rLMCS) was used to assess the degree of collateral circulation; the National Institutes of Health Stroke Scale (NIHSS) was used to measure stroke severity at admission; the modified Rankin scale (mRS) was used to measure outcome at 90 days; and premorbid medications were recorded. Univariate and multivariate analyses were performed.

RESULTS

Overall, 239 patients met the inclusion criteria. Fifty-four patients used statins, and 185 did not use statins before stroke onset. Prestroke statin use was independently associated with good collateral circulation (rLMCS > 10) (odds ratio [OR], 4.786; 95% confidence interval [CI], 1.195-19.171; P = 0.027). Prestroke statin use was not independently associated with lower stroke severity (NIHSS score≤14) (OR, 1.955; 95% CI, 0.657-5.816; p = 0.228), but prestroke statin use was independently associated with favorable outcome (mRS score≤2) (OR, 3.868; 95% CI, 1.325-11.289; P = 0.013).

CONCLUSIONS

Our findings suggest that prestroke statin use was associated with good leptomeningeal collaterals and clinical outcomes in acute ischemic stroke (AIS) patients presenting with occlusion of the middle cerebral artery. However, clinical studies should be conducted to verify this claim.

Clinical and Imaging Determinants of Collateral Status in Patients With Acute Ischemic Stroke in MR CLEAN Trial and Registry

Background and Purpose- Collateral circulation status at baseline is associated with functional outcome after ischemic stroke and effect of endovascular treatment. We aimed to identify clinical and imaging determinants that are associated with collateral grade on baseline computed tomography angiography in patients with acute ischemic stroke due to an anterior circulation large vessel occlusion. Methods- Patients included in the MR CLEAN trial (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands; n=500) and MR CLEAN Registry (n=1488) were studied. Collateral status on baseline computed tomography angiography was scored from 0 (absent) to 3 (good). Multivariable ordinal logistic regression analyses were used to test the association of selected determinants with collateral status. Results- In total, 1988 patients were analyzed. Distribution of the collateral status was as follows: absent (7%, n=123), poor (32%, n=596), moderate (39%, n=735), and good (23%, n=422). Associations for a poor collateral status in a multivariable model existed for age (adjusted common odds ratio, 0.92 per 10 years [95% CI, 0.886-0.98]), male (adjusted common odds ratio, 0.64 [95% CI, 0.53-0.76]), blood glucose level (adjusted common odds ratio, 0.97 [95% CI, 0.95-1.00]), and occlusion of the intracranial segment of the internal carotid artery with occlusion of the terminus (adjusted common odds ratio 0.50 [95% CI, 0.41-0.61]). In contrast to previous studies, we did not find an association between cardiovascular risk factors and collateral status. Conclusions- Older age, male sex, high glucose levels, and intracranial internal carotid artery with occlusion of the terminus occlusions are associated with poor computed tomography angiography collateral grades in patients with acute ischemic stroke eligible for endovascular treatment.

Association of atherosclerotic plaque features with collateral circulation status in elderly patients with chronic carotid stenosis

OBJECTIVE

To determine the association of carotid plaque features with collateral circulation status in elderly patients with moderate to severe carotid stenosis.

METHODS

Elderly patients (> 60 years) with moderate to severe carotid stenosis were recruited and categorized into good and poor collateral circulation groups, and underwent magnetic resonance imaging and computed tomography imaging. The carotid plaque features including lipid-rich necrotic core, intraplaque hemorrhage, calcification, and fibrous cap rupture (FCR) were evaluated, and maximum wall thickness, normalized wall index (NWI), and luminal stenosis were measured. The association between these variables and collateral circulation status was analyzed.

RESULTS

Of the 97 patients (78 males, mean age: 69.0 ± 6.1 years), 19 (19.6%) had poor collaterals. The poor collateral group had a significantly higher NWI (93.7% ± 5.0% vs. 89.0% ± 7.9%, P = 0.011), a greater extent of stenosis (80.0% ± 11.4% vs. 75.3% ± 9.4%, P = 0.036) and FCR (84.2% vs. 55.1%, P = 0.020) compared with good collateral group. Carotid NWI (OR = 3.83, 95% CI: 1.36-10.82, P = 0.011) and more FCR (OR = 6.77, 95% CI: 1.35-33.85, P = 0.020) were associated with poor collateral circulation after adjustment for the confounding factors. The combination of NWI, FCR, systolic blood pressure, and triglycerides had the highest area-under-the-curve (AUC = 0.85) for detection of poor collaterals.

CONCLUSIONS

Carotid plaque features, specifically NWI and FCR, are independently associated with poor collateral circulation, and the combination of carotid plaque features and traditional risk factors has a stronger predictive value for poor collateral circulation than plaque features alone.

Clinical characteristics and leptomeningeal collateral status in pediatric and adult patients with ischemic moyamoya disease

AIM

Previous studies have found significant differences in clinical characteristics between pediatric and adult moyamoya disease (MMD) patients, but few studies have focused on the factors underlying these differences. We aimed to investigate the differences in leptomeningeal collateral (LMC) status between pediatric and adult MMD patients and to analyze the effects of LMCs on clinical characteristics and therapeutic prognosis.

METHODS

We retrospectively analyzed 214 MMD patients from January 2014 to January 2016. Clinical characteristics and LMC status were compared between the pediatric and adult patients. LMC status was graded as good or poor depending on the retrograde flow from the posterior cerebral artery (PCA) on digital subtraction angiography (DSA).

RESULTS

A total of 83 pediatric and 131 adult (1:1.6) MMD patients were analyzed. Pediatric patients were more likely to experience a transient ischemic attack (81%), whereas adult patients were more likely to experience infarction (51%). Regarding the different MMD stages (the early, medium, and advanced stages corresponded to Suzuki stages 1-2, 3-4, and 5-6, respectively), the prevalence of good LMC status was higher for pediatric patients than for adult patients in the early stage (P = 0.047) and the medium stage (P = 0.001), but there were no differences between these patient groups in the advanced stage (P = 0.547). Worse postoperative angiographic outcomes (P = 0.017) were found in adult patients than in pediatric patients in the medium stage. Poor LMC status had strong correlations with infarction (P < 0.001 and P = 0.017) and poor postoperative outcomes (P = 0.003 and P = 0.043) in both pediatric and adult patients.

CONCLUSIONS

Pediatric MMD patients have greater patency and a greater ability to establish good LMC status than adult patients, and poor LMC status has a strong correlation with severe clinical symptoms and poor postoperative outcomes. LMC status may be an important factor in the differences in clinical characteristics and prognosis between pediatric and adult MMD patients.

Results From DEFUSE 3: Good Collaterals Are Associated With Reduced Ischemic Core Growth but Not Neurologic Outcome

Background and Purpose- The effect of leptomeningeal collaterals for acute ischemic stroke patients with large vessel occlusion in the late window (>6 hours from last known normal) remains unknown. We sought to determine if collateral status on baseline computed tomography angiography impacted neurological outcome, ischemic core growth, and moderated the effect of endovascular thrombectomy in the late window. Methods- This is a prespecified analysis of DEFUSE 3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke). We included patients with computed tomography angiography as their baseline imaging and rated collateral status using the validated scales described by Tan and Maas. The primary outcome is functional independence (modified Rankin Scale score of ≤2). Additional outcomes include the full range of the modified Rankin Scale, baseline ischemic core volume, change from baseline in the ischemic core volume at 24 hours, and death at 90 days. Results- Of the 130 patients in our cohort, 33 (25%) had poor collaterals and 97 (75%) had good collaterals. There was no difference in the rate of functional independence with good versus poor collaterals in unadjusted analysis (30% versus 39%; P=0.3) or after adjustment for treatment arm (odds ratio [95% CI], 0.61 [0.26-1.45]). Good collaterals were associated with significantly smaller ischemic core volume and less ischemic core growth. The difference in the treatment effect of endovascular thrombectomy was not significant ( P=0.8). Collateral status also did not affect the rate of stroke-related death (n [%], good versus poor collaterals, 18/97 [19%] versus 8/33 [24%], P=0.5]. Conclusions- In DEFUSE 3 patients, good leptomeningeal collaterals on single phase computed tomography angiography were not predictive of functional independence or death and did not impact the treatment effect of endovascular thrombectomy. These unexpected findings require further study to confirm their validity and to better understand the role of collaterals for stroke patients with anterior circulation large vessel occlusion in the late therapeutic window. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: NCT02586415.

Collateral Circulation in Moyamoya Disease: A New Grading System

Background and Purpose- Predicting the risk of stroke and determining intervention indications are highly important for patients with Moyamoya disease (MMD). Here, we evaluated a novel MMD grading system based on collateral circulation and Suzuki stage to evaluate symptoms and predict prognosis. Methods- In total, 301 idiopathic MMD patients were retrospectively analyzed between 2014 and 2016. A collateral circulation grading system with scores ranging from 1 to 12 was established: the anatomic extent of pial collateral blood flow from posterior cerebral artery to middle cerebral artery and anterior cerebral artery was scored from 1 to 6; perforator collateral and internal cerebral artery flow were scored as 6 to 1, which corresponded to Suzuki stages 1 to 6. Dynamic susceptibility contrast-magnetic resonance imaging was used to evaluate hemodynamic status. We assessed the association between the grading system and clinical characteristics. Results- We analyzed 364 symptomatic hemispheres of 301 patients (146 males, 28±16 years). Ischemic patients who presented with infarction were more likely to score <8 points (P<0.001), whereas those with ischemia symptoms (transient ischemic attack and headache) were more likely to score >8 points. Hemorrhagic patients who presented with intraparenchymal hemorrhage were more likely to score <8 points, whereas those who presented with intraventricular hemorrhage were more likely to score >8 points (P<0.001). According to dynamic susceptibility contrast-magnetic resonance imaging, lower scores were correlated with more severe time to peak delay (P<0.001) and worse relative cerebral blood volume ratio (P=0.016) and cerebral flow ratio (P=0.002). Encephaloduroarteriosynangiosis was performed in 348 symptomatic hemispheres. Patients who had collateral scores <4 points were more likely to have a postoperative stroke and a worse prognosis during the follow-up. Conclusions- This new MMD collateral grading system correlated well with clinical symptoms, hemodynamic status, and therapeutic prognosis and may facilitate risk stratification and prognosis predictions in patients with MMD.

Collateral Vessels Have Unique Endothelial and Smooth Muscle Cell Phenotypes

Collaterals are unique blood vessels present in the microcirculation of most tissues that, by cross-connecting a small fraction of the outer branches of adjacent arterial trees, provide alternate routes of perfusion. However, collaterals are especially susceptible to rarefaction caused by aging, other vascular risk factors, and mouse models of Alzheimer’s disease—a vulnerability attributed to the disturbed hemodynamic environment in the watershed regions where they reside. We examined the hypothesis that endothelial and smooth muscle cells (ECs and SMCs, respectively) of collaterals have specializations, distinct from those of similarly-sized nearby distal-most arterioles (DMAs) that maintain collateral integrity despite their continuous exposure to low and oscillatory/disturbed shear stress, high wall stress, and low blood oxygen. Examination of mouse brain revealed the following: Unlike the pro-inflammatory cobble-stoned morphology of ECs exposed to low/oscillatory shear stress elsewhere in the vasculature, collateral ECs are aligned with the vessel axis. Primary cilia, which sense shear stress, are present, unexpectedly, on ECs of collaterals and DMAs but are less abundant on collaterals. Unlike DMAs, collaterals are continuously invested with SMCs, have increased expression of Pycard, Ki67, Pdgfb, Angpt2, Dll4, Ephrinb2, and eNOS, and maintain expression of Klf2/4. Collaterals lack tortuosity when first formed during development, but tortuosity becomes evident within days after birth, progresses through middle age, and then declines—results consistent with the concept that collateral wall cells have a higher turnover rate than DMAs that favors proliferative senescence and collateral rarefaction. In conclusion, endothelial and SMCs of collaterals have morphologic and functional differences from those of nearby similarly sized arterioles. Future studies are required to determine if they represent specializations that counterbalance the disturbed hemodynamic, pro-inflammatory, and pro-proliferative environment in which collaterals reside and thus mitigate their risk factor-induced rarefaction.

Determining factors of better leptomeningeal collaterals: a study of 857 consecutive acute ischemic stroke patients

BACKGROUND

In acute ischemic stroke (AIS) collaterals correlate with infarct size, recanalization rate and clinical outcome. We aimed to identify factors associated with better collateral status in a large series of AIS patients with middle cerebral artery (MCA) occlusion.

METHODS

In the Acute STroke Registry and Analysis of Lausanne (ASTRAL) from 2003 to 2016, we identified all consecutive AIS with proximal MCA occlusion on CT-angiography performed < 24 h. Collaterals were scored from 0 (absent) to 3 (≥ 100%) and related to multiple demographic, clinical, metabolic and radiological variables in a multivariate regression analysis (MVA).

RESULTS

The 857 included patients had a median age of 72.3 years, 48.4% were female and median admission NIHSS was 16. Better collaterals were associated with younger age (OR 0.99; 95% CI 0.98-1.00), hemineglect (OR 1.35; 95% CI 1.03-1.76), absence of visual field defects (OR 0.64; 95% CI 0.46-0.90), eye deviation (OR 0.58; 95% CI 0.43-0.79) and decreased vigilance (OR 0.62; 95% CI 0.44-0.88). Better collaterals were also associated with dyslipidemia (OR 1.57; 95% CI 1.16-2.13), no previous statin use (OR 0.69; 95% CI 0.50-0.95), and lower creatinine levels (OR 0.99; 95% CI 0.99-1.00). On neuroimaging, better collaterals related to higher ASPECTS score (OR 1.27; 95% CI 1.20-1.35) and higher clot burden score (OR 1.09; 95% CI 1.03-1.14).

CONCLUSIONS

Younger age, dyslipidemia and lower creatinine levels were predictors of better collaterals in AIS patients from proximal MCA occlusions. Greater degree of collaterals related to lower stroke severity on admission. On neuroimaging, better collaterals were independently associated with minor early ischemic changes and lower clot burden. These data may add knowledge on pathophysiology of collaterals development and may help to identify patients with better collaterals for late or aggressive recanalization treatments.

Mouse models of Alzheimer's disease cause rarefaction of pial collaterals and increased severity of ischemic stroke

Vascular dysfunction contributes to the progression and severity of Alzheimer's disease (AD). Patients with AD also sustain larger infarctions after ischemic stroke; however, the responsible mechanisms are unknown. Pial collaterals are the primary source of protection in stroke. Unfortunately, natural aging and other vascular risk factors cause a decline in collateral number and diameter (rarefaction) and an increase in stroke severity. Herein, we tested the hypothesis that AD accelerates age-induced collateral rarefaction and examined potential underlying mechanisms. Triple and double transgenic mouse models of AD both sustained collateral rarefaction by 8 months of age, well before the onset of rarefaction caused by aging alone (16 months of age). Rarefaction, which did not progress further at 18 months of age, was accompanied by a twofold increase in infarct volume after MCA occlusion. AD did not induce rarefaction of similarly sized pial arterioles or penetrating arterioles. Rarefaction was minimal and occurred only at 18 months of age in a parenchymal vascular amyloid-beta model of AD. Rarefaction was not associated with amyloid-beta deposition on collaterals or pial arteries, nor was plaque burden or CD11b⁺ cell density greater in brain underlying the collateral zones versus elsewhere. However, rarefaction was accompanied by increased markers of oxidative stress, inflammation, and aging of collateral endothelial and mural cells. Moreover, rarefaction was lessened by deletion of CX₃CR1 and prevented by overexpression of eNOS. These findings demonstrate that mouse models of AD promote rarefaction of pial collaterals and implicate inflammation-induced accelerated aging of collateral wall cells. Strategies that reduce vascular inflammation and/or increase nitric oxide may preserve collateral function.

Translesional pressure gradient and leptomeningeal collateral status in symptomatic middle cerebral artery stenosis

BACKGROUND AND PURPOSE

Leptomeningeal collateral (LMC) status governs the prognosis of large artery occlusive stroke, although factors determining LMC status are not fully elucidated. The aim was to investigate metrics affecting LMC status in such patients by using computational fluid dynamics (CFD) models based on computed tomography angiography (CTA).

METHODS

In this cross-sectional study, patients with recent ischaemic stroke or transient ischaemic attack attributed to atherosclerotic M1 middle cerebral artery (MCA) stenosis (50%-99%) were recruited. Demographic, clinical and imaging data of these patients were collected. Ipsilesional LMC status was graded as good or poor by assessing the laterality of anterior and posterior cerebral arteries in CTA. A CFD model based on CTA was constructed to reflect focal hemodynamics in the distal internal carotid artery, M1 MCA and A1 anterior cerebral artery. Pressure gradients were calculated across culprit MCA stenotic lesions in CFD models. Predictors for good LMC status were sought in univariate and multivariate analyses.

RESULTS

Amongst the 85 patients enrolled (mean age 61.5 ± 10.9 years), 38 (44.7%) had good ipsilesional LMC status. The mean pressure gradient across MCA lesions was 14.8 ± 18.1 mmHg. Advanced age (P = 0.030) and a larger translesional pressure gradient (P = 0.029) independently predicted good LMCs. A lower fasting blood glucose level also showed a trend for good LMCs (P = 0.058).

CONCLUSIONS

Our study suggested a correlation between translesional pressure gradient and maturation of LMCs in intracranial atherosclerotic disease. Further studies with more exquisite and dynamic monitoring of cerebral hemodynamics and LMC evolution are needed to verify the current findings.

Acute Ischemic Pediatric Stroke Management: An Extended Window for Mechanical Thrombectomy?

Ischemic stroke is a rare condition to afflict the pediatric population. Congenital cardiomyopathy represents one of several possible etiologies in children. We report a 9-year-old boy who developed right middle cerebral artery stroke secondary to primary restrictive cardiomyopathy. In the absence of pediatric guidelines, the child met adult criteria for mechanical thrombectomy given the small core infarct and large penumbra. The literature suggests children may benefit from mechanical thrombectomy in carefully selected cases. Our patient exemplifies specific circumstances in which acute stroke therapy with thrombolysis and thrombectomy may be safe.

Internal Carotid Artery Stenosis and Collateral Recruitment in Stroke Patients

Purpose

Leptomeningeal collaterals improve outcome in stroke patients. There is great individual variability in their extent. Internal carotid artery (ICA) stenosis may lead to more extensive recruitment of leptomeningeal collaterals. The purpose of this study was to evaluate the association of pre-existing ICA stenosis with leptomeningeal collateral filling visualized with computed tomography perfusion (CTP).

Methods

From a prospective acute ischemic stroke cohort, patients were included with an M1 middle cerebral artery (MCA) occlusion and absent ipsilateral, extracranial ICA occlusion. ICA stenosis was determined on admission CT angiography (CTA). Leptomeningeal collaterals were graded as good (>50%) or poor (≤50%) collateral filling in the affected MCA territory on CTP-derived vessel images of the admission scan. The association between ipsilateral ICA stenosis ≥70% and extent of collateral filling was analyzed using logistic regression. In a multivariable analysis the odds ratio (OR) of ICA stenosis ≥70% was adjusted for complete circle of Willis, gender and age.

Results

We included 188 patients in our analyses, 50 (26.6%) patients were classified as having poor collateral filling and 138 (73.4%) as good. Of the patients 4 with poor collateral filling had an ICA stenosis ≥70% and 14 with good collateral filling. Unadjusted and adjusted ORs of ICA stenosis ≥70% for good collateral filling were 1.30 (0.41–4.15) and 2.67 (0.81–8.77), respectively. Patients with poor collateral filling had a significantly worse outcome (90-day modified Rankin scale 3–6; 80% versus 52%, p = 0.001).

Conclusion

No association was found between pre-existing ICA stenosis and extent of CTP derived collateral filling in patients with an M1 occlusion.

Determinants of leptomeningeal collateral flow in stroke patients with a middle cerebral artery occlusion

Introduction

Poor leptomeningeal collateral flow is related to worse clinical outcome in acute ischemic stroke, but the factors that determine leptomeningeal collateral patency are largely unknown. We explored the determinants of leptomeningeal collateral flow and assessed their effect on the relation between leptomeningeal collateral flow and clinical outcome.

Methods

We included 484 patients from the Dutch acute stroke study (DUST) with a middle cerebral artery (MCA) occlusion. The determinants of poor leptomeningeal collateral flow (≤50 % collateral filling) were identified with logistic regression. We calculated the relative risk (RR) of poor leptomeningeal collateral flow in relation to poor clinical outcome (90-day modified Rankin Scale 3–6) using Poisson regression and assessed whether the determinants of leptomeningeal collateral flow affected this relation.

Results

Leptomeningeal collateral flow was poor in 142 patients (29 %). In multivariable analyses, higher admission glucose level (odds ratio (OR) 1.1 per mmol/L increase (95 % CI 1.0–1.2)), a proximal MCA occlusion (OR 1.9 (95 % CI 1.3–3.0)), and an incomplete posterior circle of Willis (OR 1.7 (95 % CI 1.1–2.6)) were independently related to poor leptomeningeal collateral flow. Poor leptomeningeal collateral flow was related to poor clinical outcome (unadjusted RR 1.7 (95 % CI 1.4–2.0)), and this relation was not affected by the determinants of leptomeningeal collateral flow.

Conclusion

Our study shows that admission glucose level, a proximal MCA occlusion, and an incomplete ipsilateral posterior circle of Willis are determinants of leptomeningeal collateral flow that represent a combination of congenital, acquired, and acute factors. After adjustment for these determinants, leptomeningeal collateral flow remains related to clinical outcome.

Collateral blood vessels in acute ischemic stroke: a physiological window to predict future outcomes

Collateral circulation is a physiologic pathway that protects the brain against ischemic injury and can potentially bypass the effect of a blocked artery, thereby influencing ischemic lesion size and growth. Several recent stroke trials have provided information about the role of collaterals in stroke pathophysiology, and collateral perfusion has been recognized to influence arterial recanalization, reperfusion, hemorrhagic transformation, and neurological outcomes after stroke. Our current aim is to summarize the anatomy and physiology of the collateral circulation and to present and discuss a comprehensible review of the related knowledge, particularly the effects of collateral circulation on the time course of ischemic injury and stroke severity, as well as imaging findings and therapeutic implications.

Statins in Acute Ischemic Stroke: A Systematic Review

BACKGROUND AND PURPOSE

Statins have pleiotropic effects of potential neuroprotection. However, because of lack of large randomized clinical trials, current guidelines do not provide specific recommendations on statin initiation in acute ischemic stroke (AIS). The current study aims to systematically review the statin effect in AIS.

METHODS

From literature review, we identified articles exploring prestroke and immediate post-stroke statin effect on imaging surrogate markers, initial stroke severity, functional outcome, and short-term mortality in human AIS. We summarized descriptive overview. In addition, for subjects with available data from publications, we conducted meta-analysis to provide pooled estimates.

RESULTS

In total, we identified 70 relevant articles including 6 meta-analyses. Surrogate imaging marker studies suggested that statin might enhance collaterals and reperfusion. Our updated meta-analysis indicated that prestroke statin use was associated with milder initial stroke severity (odds ratio [OR] [95% confidence interval], 1.24 [1.05-1.48]; P=0.013), good functional outcome (1.50 [1.29-1.75]; P<0.001), and lower mortality (0.42 [0.21-0.82]; P=0.0108). In-hospital statin use was associated with good functional outcome (1.31 [1.12-1.53]; P=0.001), and lower mortality (0.41 [0.29-0.58]; P<0.001). In contrast, statin withdrawal was associated with poor functional outcome (1.83 [1.01-3.30]; P=0.045). In patients treated with thrombolysis, statin was associated with good functional outcome (1.44 [1.10-1.89]; P=0.001), despite an increased risk of symptomatic hemorrhagic transformation (1.63 [1.04-2.56]; P=0.035).

CONCLUSIONS

The current study findings support the use of statin in AIS. However, the findings were mostly driven by observational studies at risk of bias, and thereby large randomized clinical trials would provide confirmatory evidence.

Infarction Distribution Pattern in Acute Stroke May Predict the Extent of Leptomeningeal Collaterals

Objective

The aim of this study was to evaluate whether the distribution pattern of early ischemic changes in the initial MRI allows a practical method for estimating leptomeningeal collateralization in acute ischemic stroke (AIS).

Methods

Seventy-four patients with AIS underwent MRI followed by conventional angiogram and mechanical thrombectomy. Diffusion restriction in Diffusion weighted imaging (DWI) and correlated T2-hyperintensity of the infarct were retrospectively analyzed and subdivided in accordance with Alberta Stroke Program Early CT score (ASPECTS). Patients were angiographically graded in collateralization groups according to the method of Higashida, and dichotomized in 2 groups: 29 subjects with collateralization grade 3 or 4 (well-collateralized group) and 45 subjects with grade 1 or 2 (poorly-collateralized group). Individual ASPECTS areas were compared among the groups.

Results

Means for overall DWI-ASPECTS were 6.34 vs. 4.51 (well vs. poorly collateralized groups respectively), and for T2-ASPECTS 9.34 vs 8.96. A significant difference between groups was found for DWI-ASPECTS (p<0.001), but not for T2-ASPECTS (p = 0.088). Regarding the individual areas, only insula, M1-M4 and M6 showed significantly fewer infarctions in the well-collateralized group (p-values <0.001 to 0.015). 89% of patients in the well-collateralized group showed 0–2 infarctions in these six areas (44.8% with 0 infarctions), while 59.9% patients of the poor-collateralized group showed 3–6 infarctions.

Conclusion

Patients with poor leptomeningeal collateralization show more infarcts on the initial MRI, particularly in the ASPECTS areas M1 to M4, M6 and insula. Therefore DWI abnormalities in these areas may be a surrogate marker for poor leptomeningeal collaterals and may be useful for estimation of the collateral status in routine clinical evaluation.

Intralesional Patterns of MRI ADC Maps Predict Outcome in Experimental Stroke

BACKGROUND

After acute ischemia, the tissue that is at risk of infarction can be detected by perfusion-weighted imaging/diffusion-weighted imaging (PWI/DWI) mismatch but the time that is needed to process PWI limits its use. As DWI is highly sensitive to acute ischemic tissue damage, we hypothesized that different ADC patterns represent areas with a different potential for recovery.

METHODS

In a model of permanent middle cerebral artery occlusion (pMCAO), Sprague-Dawley rats were randomly distributed to sham surgery and pMCAO. We further separated the pMCAO group according to intralesional ADC pattern (homogeneous or heterogeneous). At 24 h after ischemia induction, we analyzed lesion size, functional outcome, cell death expression, and brain protection markers including ROS enzyme NOX-4. MRI included DWI (ADC maps), DTI (tractography), and PWI (CBF, CBV and MTT).

RESULTS

The lesion size was similar in pMCAO rats. Animals with a heterogeneous pattern in ADC maps showed better functional outcome in Rotarod test (p = 0.032), less expression of cell death (p = 0.014) and NOX-4 (p = 0.0063), higher intralesional CBF (p = 0.0026) and larger PWI/DWI mismatch (p = 0.007).

CONCLUSIONS

In a rodent model for ischemic stroke, intralesional heterogeneity in ADC maps was related to better functional outcome in lesions of similar size and interval after pMCAO. DWI ADC maps may assist in the early identification of ischemic tissue with an increased potential for recovery as higher expression of acute protection markers, lower expression of cell death, increased PWI/DWI mismatch, and higher intralesional CBF were present in animals with a heterogeneous ADC pattern.