Background Three-dimensional, ECG-gated, time-resolved, three-directional, velocity-encoded phase-contrast MRI (4D flow MRI) has been applied extensively to measure blood velocity in great vessels but has been much less used in diseased carotid arteries. Carotid artery webs (CaW) are non-inflammatory intraluminal shelf-like projections into the internal carotid artery (ICA) bulb that are associated with complex flow and cryptogenic stroke. Purpose: Optimize 4D flow MRI for measuring the velocity field of complex flow in the carotid artery bifurcation model that contains a CaW. Methods: A 3D printed phantom model created from computed tomography angiography (CTA) of a subject with CaW was placed in a pulsatile flow loop within the MRI scanner. 4D Flow MRI images of the phantom were acquired with five different spatial resolutions (0.50–2.00 mm3) and four different temporal resolutions (23–96 ms) and compared to a computational fluid dynamics (CFD) solution of the flow field as a reference. We examined four planes perpendicular to the vessel centerline, one in the common carotid artery (CCA) and three in the internal carotid artery (ICA) where complex flow was expected. At these four planes pixel-by-pixel velocity values, flow, and time average wall shear stress (TAWSS) were compared between 4D flow MRI and CFD. Hypothesis: An optimized 4D flow MRI protocol will provide a good correlation with CFD velocity and TAWSS values in areas of complex flow within a clinically feasible scan time (~ 10 min). Results: Spatial resolution affected the velocity values, time average flow, and TAWSS measurements. Qualitatively, a spatial resolution of 0.50 mm3 resulted in higher noise, while a lower spatial resolution of 1.50–2.00 mm3 did not adequately resolve the velocity profile. Isotropic spatial resolutions of 0.50–1.00 mm3 showed no significant difference in total flow compared to CFD. Pixel-by-pixel velocity correlation coefficients between 4D flow MRI and CFD were > 0.75 for 0.50–1.00 mm3 but were < 0.5 for 1.50 and 2.00 mm3. Regional TAWSS values determined from 4D flow MRI were generally lower than CFD and decreased at lower spatial resolutions (larger pixel sizes). TAWSS differences between 4D flow and CFD were not statistically significant at spatial resolutions of 0.50–1.00 mm3 but were different at 1.50 and 2.00 mm3. Differences in temporal resolution only affected the flow values when temporal resolution was > 48.4 ms; temporal resolution did not affect TAWSS values. Conclusion: A spatial resolution of 0.74–1.00 mm3 and a temporal resolution of 23–48 ms (1–2 k-space segments) provides a 4D flow MRI protocol capable of imaging velocity and TAWSS in regions of complex flow within the carotid bifurcation at a clinically acceptable scan time.

Background Rapid expansion of mechanical thrombectomy and swift manufacturing development has translated into significant evolution of large‐bore catheter technology. The objective of this study was to evaluate the association among diverse structural components of large‐bore aspiration catheters on procedural performance. Methods Retrospective analysis of a prospectively maintained mechanical thrombectomy consortium (SVIN [Society of Vascular Interventional Neurology] Registry) treated with stand‐alone contact aspiration for the first pass in the middle cerebral artery M1 or intracranial internal carotid artery occlusions from 2012 to 2021. Catheters were stratified on the basis of construction materials, tip technology, catheter sizing, and catheter lining. Factors associated with first‐pass effect (first‐pass eTICI 2c–3 reperfusion) as well as speed of clot engagement were analyzed. Results We identified 983 patients with proximal occlusion and aspiration as the first‐pass technique. First‐pass effect was observed in 34% and associated with age (odds ratio [OR], 1.02 [95% CI, 1.01–1.03]), cardioembolic stroke pathogenesis (OR, 1.69 [95% CI, 1.77–2.41]), middle cerebral artery M1 (OR, 2.74 [95% CI, 1.09–1.87]), nongeneral anesthesia (OR, 0.55 [95% CI, 0.39–0.767]), as well as with 0.070‐inch (OR, 2.04 95% CI, 1.01–3.78]), and 0.088‐inch (OR, 3.90 [95% CI, 1.58–9.61]) distal catheter inner diameter in the adjusted analysis. Mean time from arterial access to clot contact was 17 minutes, with faster times observed in younger patients (OR, 0.99 [95% CI, 0.98–0.996]) as well as with the use of aspiration catheters with shorter length of distal outer hydrophilic coating (18–30 cm) on multivariable regression (OR, 0.30 [95% CI, 0.11–0.82]). Conclusion Larger aspiration catheter distal inner diameter was associated with higher rates of first‐pass effect. Aspiration catheter construction components were found to influence times from arterial access to clot contact.

In December 2019, coronavirus disease 2019 (COVID-19), an infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) caused an international outbreak. The World Health Organization designated this as a global pandemic on March 11, 2020, with over 200 countries affected worldwide. As of April 24, 2020, there were 2 790 986 patients with confirmed COVID-19 and 195 775 deaths worldwide, with the United States, Spain, Italy, France, Germany, United Kingdom, Turkey, and Iran surpassing China in the number of confirmed cases.1 In a consecutive series of 221 patients with confirmed COVID-19 admitted to a hospital in Wuhan, China, acute ischemic stroke occurred in 11(5%) of patients with a broad range of stroke subtypes.2 These patients with stroke were older, more likely to have cardiovascular risk factors, presenting with severe COVID-19 with multiple organ involvement. Of note, presence of COVID-19 in these patients does not imply that COVID-19 was the mechanism leading to the patient s stroke. Shortages of Personal Protective Equipment (PPE) such as N95 masks, facial shields, hand sanitizer, and cleansing wipes have presented a major challenge in the allocation of resources, as healthcare workers are frontline in the treatment of these patients.3 Redeployment of clinical staff, nursing, stroke and neurocritical care specialists to care for patients with COVID-19 may create staffing shortages for dedicated stroke care. In an effort to mitigate the spread of COVID-19 to neuroscience healthcare workers, their patients, and their families, and to optimize allocation of healthcare resources, we present a modified algorithm to acute ischemic large vessel occlusion stroke workflow in the era of the COVID-19 pandemic. This guidance statement is based on shared best practices,4 6 consensus among academic and nonacademic practicing vascular and interventional neurologists, literature review, and would be adapted to the available resources of a local institution. The patients with acute stroke are a vulnerable group to address because these patients often come emergently from the community with little information. Radical changes are felt to be necessary to optimize the safety of the providing team and our patients, limit unnecessary tests, conserve PPE resources and mechanical ventilator usage. This document divides into the following: prehospital phase to the Emergency Department (ED), prethrombectomy procedure, thrombectomy intraprocedure, and postreperfusion therapy phases (Table).

Background: To evaluate overall ischemic stroke volumes and rates, specific subtypes, and clinical presentation during the COVID-19 pandemic in a multicenter observational study from eight states across US. Methods: We compared all ischemic strokes admitted between January 2019 and May 2020, grouped as; March-May 2020 (COVID-19 period) and March-May 2019 (seasonal pre-COVID-19 period). Primary outcome was stroke severity at admission measured by NIHSS stratified as mild (0−7), moderate [8–14], and severe (>14). Secondary outcomes were volume of large vessel occlusions (LVOs), stroke etiology, IV-tPA rates, and discharge disposition. Results: Of the 7969 patients diagnosed with acute ischemic stroke during the study period, 933 (12 %) presented in the COVID-19 period while 1319 (17 %) presented in the seasonal pre-COVID-19 period. Significant decline was observed in the mean weekly volumes of newly diagnosed ischemic strokes (98 ± 3 vs 50 ± 20,p = 0.003), LVOs (16.5 ± 3.8 vs 8.3 ± 5.9,p = 0.008), and IV-tPA (10.9 ± 3.4 vs 5.3 ± 2.9,p = 0.0047), whereas the mean weekly proportion of LVOs (18 % ±5 vs 16 % ±7,p = 0.24) and IV-tPA (10.4 % ±4.5 vs. 9.9 % ±2.4,p = 0.66) remained the same, when compared to the seasonal pre-COVID-19 period. Additionally, an increased proportion of patients presented with a severe disease (NIHSS > 14) during the COVID-19 period (29.7 % vs 24.5 %,p < 0.025). The odds of being discharged to home were 26 % greater in the COVID-19 period when compared to seasonal pre-COVID-19 period (OR:1.26, 95 % CI:1.07–1.49,p = 0.016). Conclusions: During COVID-19 period there was a decrease in volume of newly diagnosed ischemic stroke cases and IV-tPA administration. Patients admitted to the hospital had severe neurological clinical presentation and were more likely to discharge home.

BACKGROUND AND PURPOSE: Coronavirus disease 2019 (COVID-19) is associated with a small but clinically significant risk of stroke, the cause of which is frequently cryptogenic. In a large multinational cohort of consecutive COVID-19 patients with stroke, we evaluated clinical predictors of cryptogenic stroke, short-term functional outcomes and in-hospital mortality among patients according to stroke etiology. METHODS: We explored clinical characteristics and short-term outcomes of consecutively evaluated patients 18 years of age or older with acute ischemic stroke (AIS) and laboratory-confirmed COVID-19 from 31 hospitals in 4 countries (3/1/20-6/16/20). RESULTS: Of the 14.483 laboratory-confirmed patients with COVID-19, 156 (1.1%) were diagnosed with AIS. Sixty-one (39.4%) were female, 84 (67.2%) white, and 88 (61.5%) were between 60 and 79 years of age. The most frequently reported etiology of AIS was cryptogenic (55/129, 42.6%), which was associated with significantly higher white blood cell count, c-reactive protein, and D-dimer levels than non-cryptogenic AIS patients (p</=0.05 for all comparisons). In a multivariable backward stepwise regression model estimating the odds of in-hospital mortality, cryptogenic stroke mechanism was associated with a fivefold greater odds in-hospital mortality than strokes due to any other mechanism (adjusted OR 5.16, 95%CI 1.41-18.87, p = 0.01). In that model, older age (aOR 2.05 per decade, 95%CI 1.35-3.11, p < 0.01) and higher baseline NIHSS (aOR 1.12, 95%CI 1.02-1.21, p = 0.01) were also independently predictive of mortality. CONCLUSIONS: Our findings suggest that cryptogenic stroke among COVID-19 patients carries a significant risk of early mortality.

Cerebrovascular ischaemia is potentiated by hyperthermia, and even mild temperature elevation has proved detrimental to ischaemic brain. Infarction progression following endovascular reperfusion relates to multiple patient-specific and procedural variables; however, the potential influence of mild systemic temperature fluctuations is not fully understood. This study aims to assess the relationship between systemic temperatures in the early aftermath of acute ischaemic stroke and the loss of at-risk penumbral tissues, hypothesizing consumption of the ischaemic penumbra as a function of systemic temperatures, irrespective of reperfusion status. A cross-sectional, retrospective evaluation of a single-institution, prospectively collected endovascular therapy registry was conducted. Patients with anterior circulation, large vessel occlusion acute ischaemic stroke who underwent initial CT perfusion, and in whom at least four-hourly systemic temperatures were recorded beginning from presentation and until the time of final imaging outcome were included. Initial CT perfusion core and penumbra volumes and final MRI infarction volumes were computed. Systemic temperature indices including temperature maxima were recorded, and pre-defined temperature thresholds varying between 37°C and 38°C were examined in unadjusted and adjusted regression models which included glucose, collateral status, reperfusion status, CT perfusion-to-reperfusion delay, general anaesthesia and antipyretic exposure. The primary outcome was the relative consumption of the penumbra, reflecting normalized growth of the at-risk tissue volume ≥10%. The final study population comprised 126 acute ischaemic stroke subjects (mean 63 ± 14.5 years, 63% women). The primary outcome of penumbra consumption ≥10% occurred in 51 (40.1%) subjects. No significant differences in baseline characteristics were present between groups, with the exception of presentation glucose (118 ± 26.6 without versus 143.1 ± 61.6 with penumbra consumption, P = 0.009). Significant differences in the likelihood of penumbra consumption relating to systemic temperature maxima were observed [37°C (interquartile range 36.5 - 37.5°C) without versus 37.5°C (interquartile range 36.8 - 38.2°C) with penumbra consumption, P = 0.001]. An increased likelihood of penumbra consumption was observed for temperature maxima in unadjusted (odds ratio 3.57, 95% confidence interval 1.65 - 7.75; P = 0.001) and adjusted (odds ratio 3.06, 95% confidence interval 1.33 - 7.06; P = 0.009) regression models. Significant differences in median penumbra consumption were present at a pre-defined temperature maxima threshold of 37.5°C [4.8 ml (interquartile range 0 - 11.5 ml) versus 21.1 ml (0 - 44.7 ml) for subjects not reaching or reaching the threshold, respectively, P = 0.007]. Mild fever may promote loss of the ischaemic penumbra irrespective of reperfusion, potentially influencing successful salvage of at-risk tissue volumes following acute ischaemic stroke.

Background Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has been associated with a significant risk of thrombotic events in critically ill patients. Aim To summarize the findings of a multinational observational cohort of patients with SARS-CoV-2 and cerebrovascular disease. Methods Retrospective observational cohort of consecutive adults evaluated in the emergency department and/or admitted with coronavirus disease 2019 (COVID-19) across 31 hospitals in four countries (1 February 2020–16 June 2020). The primary outcome was the incidence rate of cerebrovascular events, inclusive of acute ischemic stroke, intracranial hemorrhages (ICH), and cortical vein and/or sinus thrombosis (CVST). Results Of the 14,483 patients with laboratory-confirmed SARS-CoV-2, 172 were diagnosed with an acute cerebrovascular event (1.13% of cohort; 1130/100,000 patients, 95%CI 970–1320/100,000), 68/171 (40.5%) were female and 96/172 (55.8%) were between the ages 60 and 79 years. Of these, 156 had acute ischemic stroke (1.08%; 1080/100,000 95%CI 920–1260/100,000), 28 ICH (0.19%; 190/100,000 95%CI 130–280/100,000), and 3 with CVST (0.02%; 20/100,000, 95%CI 4–60/100,000). The in-hospital mortality rate for SARS-CoV-2-associated stroke was 38.1% and for ICH 58.3%. After adjusting for clustering by site and age, baseline stroke severity, and all predictors of in-hospital mortality found in univariate regression (p < 0.1: male sex, tobacco use, arrival by emergency medical services, lower platelet and lymphocyte counts, and intracranial occlusion), cryptogenic stroke mechanism (aOR 5.01, 95%CI 1.63–15.44, p < 0.01), older age (aOR 1.78, 95%CI 1.07–2.94, p = 0.03), and lower lymphocyte count on admission (aOR 0.58, 95%CI 0.34–0.98, p = 0.04) were the only independent predictors of mortality among patients with stroke and COVID-19. Conclusions COVID-19 is associated with a small but significant risk of clinically relevant cerebrovascular events, particularly ischemic stroke. The mortality rate is high for COVID-19-associated cerebrovascular complications; therefore, aggressive monitoring and early intervention should be pursued to mitigate poor outcomes.

Objective: To assess the utility of computed tomographic (CT) perfusion for selection of patients for endovascular therapy up to 18 hours after symptom onset. Methods: We conducted a multicenter cohort study of consecutive acute stroke patients scheduled to undergo endovascular therapy within 90 minutes after a baseline CT perfusion. Patients were classified as “target mismatch” if they had a small ischemic core and a large penumbra on their baseline CT perfusion. Reperfusion was defined as >50% reduction in critical hypoperfusion between the baseline CT perfusion and the 36-hour follow-up magnetic resonance imaging. Results: Of the 201 patients enrolled, 190 patients with an adequate baseline CT perfusion study who underwent angiography were included (mean age = 66 years, median NIH Stroke Scale [NIHSS] = 16, median time from symptom onset to endovascular therapy = 5.2 hours). Rate of reperfusion was 89%. In patients with target mismatch (n = 131), reperfusion was associated with higher odds of favorable clinical response, defined as an improvement of ≥8 points on the NIHSS (83% vs 44%; p = 0.002, adjusted odds ratio [OR] = 6.6, 95% confidence interval [CI] = 2.1–20.9). This association did not differ between patients treated within 6 hours (OR = 6.4, 95% CI = 1.5–27.8) and those treated > 6 hours after symptom onset (OR = 13.7, 95% CI = 1.4–140). Interpretation: The robust association between endovascular reperfusion and good outcome among patients with the CT perfusion target mismatch profile treated up to 18 hours after symptom onset supports a randomized trial of endovascular therapy in this patient population. Ann Neurol 2017;81:849–856.

An uncommon complication of iodinated contrast administration is the development of bilateral sialadenitis. We report a unique case of hyperacute unilateral parotiditis during diagnostic cerebral angiography of the external carotid artery, which mimicked possible iatrogenic vascular event associated with cerebral endovascular procedures. Discussion includes the differential diagnosis, diagnostic studies, and treatments for this unusual condition.

Purpose: Carotid web (CaW) is an underrecognized cause of cryptogenic stroke in young patients. The optimal imaging for CaW is unknown. We aim to evaluate the diagnostic accuracy of diverse imaging modalities for the diagnosis of CaW. Methods: Retrospective analysis of institutional neurovascular database was performed to identify patients with multimodal (CT angiogram-CTA, digital subtraction angiogram-DSA, and/or ultrasound-US) imaging diagnosis of CaW or atherosclerosis. Baseline clinical demographics were recorded. Blinded image analysis was performed for each imaging modality by separate readers. Discrepancies were settled by consensus. Two-sided Cohen's Kappa (κ) coefficient was used to evaluate the inter-rater agreement for the etiological diagnosis between imaging modalities. Results: Thirty patients/60 carotids were evaluated by CTA and 55 carotids were included. Patients with symptomatic CaW (n = 20), compared to individuals with atherosclerosis (n = 10), were younger (49 ± 9 vs. 60 ± 8 years; p < 0.01), more commonly female (75% vs. 30%; p = 0.01), and less frequently presented vascular risk factors: Hypertension (40% vs. 100%; p < 0.01), hyperlipidemia (0% vs. 50%; p < 0.01), diabetes (10% vs. 40%; p = 0.05), and smoking (5% vs. 70%; p < 0.01). High inter-rater correlation strength existed for CTA (n = 55; κ = 0.88; p < 0.0001) and DSA (n = 28; κ = 0.86, p < 0.0001) readers for lesion diagnosis while US inter-rater agreement was lower (κ = 0.553; p = 0.001). Across modalities CTA and DSA shared very high strength of agreement (κ = 0.92; p < 0.0001), compared to a less pronounced agreement between US and CTA (κ = 0.553; p = 0.001). The strength of correlation between DSA-CTA was significantly more robust as compared to US-CTA (Z = 3.58; p = 0.0003). Conclusion: CTA and DSA demonstrated comparable and superior performance as compared to US in the diagnosis of CaW.