Internal Carotid Artery Disease Research Articles

Abstract TP142: Perfusion Profiles to Identify Acute Extracranial Internal Carotid Artery Atherosclerosis-Related Stroke Prior to Endovascular Therapy

Introduction: Perfusion imaging has been used to assess collateral status in patients with acute ischemic stroke secondary to anterior large-vessel occlusion. We aimed to evaluate the hypoperfusion intensity ratio (HIR), a surrogate of collateral status, in acute stroke secondary to extracranial atherosclerosis disease (AD) compared with extracranial non-AD etiologies prior to EVT. Methods: We retrospectively reviewed the data of consecutive EVT stroke patients in our prospectively collected registry from January 2019 to December 2022. Inclusion criteria: patients with anterior circulation stroke with concomitant extracranial internal carotid artery (ICA) disease with 70-100% stenosis per NASCET criteria and patients who underwent computed tomography perfusion (CTP) before EVT. Patients were divided into those with extracranial AD and non-AD based on clinical and radiological characteristics. HIR was calculated as the volume of ischemic brain tissue with a Tmax>10s divided by a Tmax>6s. A relative CBF<30% was also obtained. Multivariable regression was used to identify the HIR independently associated with extracranial ICA AD-related stroke; adjusted odds ratio with 95%CIs were calculated using the non-AD group as a reference. Results: Among all 624 EVT patients, 79 met inclusion criteria. Of these patients (21 women [36.2%]; median age 67 [60-75] years), 58 (72.5%) had extracranial ICA AD. Patients in the AD group had significantly lower CBF<30% (median 8ml [0-17] vs 19ml [9-36]), lower Tmax>10s (median 29ml [11-69] vs 68ml [38-117]), and lower HIR (median 0.27 [0.13-0.45] vs 0.49 [0.42-0.59]). There was no significant difference in time from last know well to CTP between groups. Lower HIR was independently associated with AD after adjusting for variables related to AD (Figure1). Conclusions: Low HIR values was a predictor of stroke secondary to extracranial ICA AD and could be helpful to differentiate from other non-AD etiologies prior to EVT.

Relation between severity of cerebral small vessel disease and pulsatility index of internal carotid artery in small vessel occlusion

Background and purposeThe total small vessel disease (SVD) score, calculated using magnetic resonance imaging (MRI), is used to assess the risk of cerebral infarction. Stroke patients with total SVD scores of three or higher are reported to have a significantly increased risk of recurrent stroke. Similar to the total SVD score, carotid ultrasonography findings have been reported to be indicators of atherosclerosis. Although the total SVD score effectively reflects SVD progression, its correlation with carotid ultrasonography findings remains unknown. We aimed to investigate whether there is a relationship between these two factors. MethodsPatients with small-vessel occlusion within 24 h of onset were retrospectively selected. Atherosclerotic factors were evaluated using the left-right average Gosling pulsatility index (PI) in the internal carotid artery (ICA-PI) and cardio-ankle vascular index (CAVI). Differences in clinical backgrounds, including atherosclerotic factors, were evaluated by dividing patients into two groups: those with a total SVD score of two or less (low-score group) and those with scores of three or more (high-score group). ResultsA total of 122 patients were included in this study. ICA-PI was significantly higher in the high-score group than in the low-score group. A high score was independently correlated with ICA-PI after adjusting for age, CAVI, smoking, and history of secondary atherosclerosis. ConclusionsIncreased ICA-PI was associated with a high total SVD score in acute small-vessel occlusion and may be an alternative method for predicting the total SVD score, enabling the administration of interventions to prevent stroke relapse without the need for MRI.

Assessment of Collateral Flow in Patients with Carotid Stenosis Using Random Vessel-Encoded Arterial Spin-Labeling: Comparison with Digital Subtraction Angiography.

Collateral circulation plays an important role in steno-occlusive internal carotid artery disease (ICAD) to reduce the risk of stroke. We aimed to investigate the utility of planning-free random vessel-encoded arterial spin-labeling (rVE-ASL) in assessing collateral flows in patients with ICAD. Forty patients with ICAD were prospectively recruited. The presence and extent of collateral flow were assessed and compared between rVE-ASL and DSA by using Contingency (C) and Cramer V (V) coefficients. The differences in flow territory alterations stratified by stenosis ratio and symptoms, respectively, were compared between symptomatic (n = 19) and asymptomatic (n = 21) patients by using the Fisher exact test. Good agreement was observed between rVE-ASL and DSA in assessing collateral flow (C = 0.762, V = 0.833, both P < .001). Patients with ICA stenosis of ≥90% were more likely to have flow alterations (P < .001). Symptomatic patients showed a higher prevalence of flow alterations in the territory of the MCA on the same side of ICAD (63.2%), compared with asymptomatic patients (23.8%, P = .012), while the flow alterations in the territory of anterior cerebral artery did not differ (P = .442). The collateral flow to MCA territory was developed primarily from the contralateral internal carotid artery (70.6%) and vertebrobasilar artery to a lesser extent (47.1%). rVE-ASL provides comparable information with DSA on the assessment of collateral flow. The flow alterations in the MCA territory may be attributed to symptomatic ICAD.

A case of surgical treatment of an aneurysm of the internal carotid artery with severe angulation

The leading role among causes of CVA (cerebrovascular accident) is occupied by pathology of the internal carotid artery. The most common etiological factor is a pronounced atherosclerotic process in the area of carotid artery bifurcation. Significantly less common factors are non-atherosclerotic causes of internal carotid artery disease, which include aneurysm and pathological tortuosity. Their combination significantly increases the risk of cerebral events, which requires timely surgical treatment. Surgical treatment is associated with certain intraoperative difficulties. The following is a clinical case of surgical treatment of an aneurysm of the internal carotid artery extracranial segment in combination with its deformation correlated with hemodynamic stenosis of more than 70%. A resection of the tortuosity-aneurysm complex with the formation of an end-to-end anastomosis of the internal carotid artery was performed.

Quantification of new intracerebral lesions on diffusion-weighted magnetic resonance imaging after transcarotid artery revascularization for treatment of carotid artery stenosis

Transcarotid artery revascularization (TCAR) has been used with increasing prevalence for treatment of carotid artery stenosis. TCAR holds potential benefits over traditional carotid endarterectomy (CEA) or transfemoral carotid artery stenting by its nature of being less invasive than CEA but more neuroprotective than transfemoral carotid artery stenting. The purpose of this pilot study is to evaluate the effectiveness of the neuroprotection system of TCAR with flow reversal by quantifying the incidence and degree of new intracerebral lesions using diffusion-weighted magnetic resonance imaging (DW-MRI). This study is the first to evaluate these findings in a real-world, high-risk cohort, who would have been excluded from the ROADSTER and ENROUTE transcarotid neuroprotection system DW-MRI studies. Patients undergoing unilateral TCAR for symptomatic or asymptomatic severe internal carotid artery disease were eligible and prospectively enrolled in the study. All patients had high risk features, including comorbidities or medications, which excluded them from industry-sponsored DW-MRI trials. Patients underwent a preoperative DW-MRI to obtain a baseline intracerebral evaluation within 1 week of the scheduled surgery. The follow-up DW-MRI occurred within 48hours postoperatively. The primary outcome was new, acute postoperative lesion(s) identified on DW-MRI. Secondary outcomes include any major stroke, myocardial infarction, or death during hospitalization. Five consecutive patients underwent TCAR with preoperative and postoperative imaging. All five patients were on dual antiplatelet therapy before their procedure and verified to be therapeutic on these agents. All patients underwent a right-sided TCAR and three were symptomatic as the indication for their procedure. All five patients demonstrated chronic lesions on the preoperative DW-MRI. Technical success was achieved in all five patients, with one operative complication involving a dissection of the common carotid at the access site, which was stented using the TCAR system. Postoperative DW-MRI did not identify any new intracerebral lesions in any patient following the procedure. No patient had a stroke, myocardial infarction, or death during hospitalization. In this real-world, high-risk cohort, TCAR was completed with no evidence of new, postoperative DW-MRI lesions. These data further demonstrate that TCAR with flow reversal is an effective neuroprotective strategy for carotid revascularization. Further study is warranted to evaluate DW-MRI differences between TCAR and CEA.

Abstract Number ‐ 243: The Non‐stenosing Carotid Artery Plaque in Embolic Stroke of Undetermined Source: A Retrospective Study

Introduction Atherosclerotic cervical internal carotid artery disease is one of the major causes of ischemic stroke and transient ischemic attacks. The risk of stroke from mild to moderate stenoses (i.e., &lt; 50% stenosis) might be underestimated, and further investigation is mandated to describe the association between high‐risk plaque features and ESUS. Methods This was a retrospective observational study. Using the stroke registry of our hospital’s system between June 20th 2016 and June 20th 2021. We reviewed data for patients diagnosed with ESUS according to previously published definition criteria. Using computed tomography angiography (CTA), we analyzed laterality of high‐risk plaque features in relation to the stroke side, and then we identified the incidence of recurrent stroke events. Results Out of 1779 patients with cryptogenic ischemic stroke, only 152 met the inclusion criteria for ESUS. We Compared high‐risk plaque features ipsilateral to stroke side as to contralaterally. There were significantly more ulcerations defined as &gt;1 mm depression (19.08% vs 5.26%, p&lt; .0001), plaque thickness &gt;3 mm (19.08% vs 7.24%, p = 0.001), and plaque length &gt;1cm (13.16% vs 5.92%, p = 0.0218).Also, there was a significant difference in stenosis of ipsilateral to stroke when compared contralaterally, especially for stenoses of 10–30% and 31–49% (17.76% vs 10.53% and 5.26% vs 2.63%, respectively. p = 0.0327). There was also a significant difference in plaque component; both components (soft and calcified) and only soft plaque (42.76% vs 23.68% and 17.76% vs 9.21%, respectively. p&lt; .0001) were more prevalent ipsilaterally. In total, 17patients were found to have a recurrent stroke event, 8 patients had an ipsilateral stroke to the index event, 7 had a bilateral and 2 had a contralateral event. Conclusions ESUS is more commonly found ipsilateral to high‐risk plaque features. Qualitative assessment of plaque features using CTA could be easily implemented in clinical practice. The small number of our sample is definitely a limitation. Further large and multicenter studies aiming to form precise prediction models and scoring systems are needed to help guide treatment with carotid artery stenting or carotid endarterectomy versus maximizing medical therapy.

Assessment of extracranial carotid artery disease using digital twins – A pilot study

To improve risk stratification in extracranial internal carotid artery disease (CAD), patients who would benefit maximally from revascularization must be identified. In cardiology, the fractional flow reserve (FFR) has become a reference standard for evaluating the functional severity of coronary artery stenosis, and noninvasive surrogates thereof relying on computational fluid dynamics (CFD) have been developed. Here, we present a CFD-based workflow using digital twins of patients’ carotid bifurcations derived from computed tomography angiography for the noninvasive functional assessment of CAD. We reconstructed patient-specific digital twins of 37 carotid bifurcations. We implemented a CFD model using common carotid artery peak systolic velocity (PSV) acquired with Doppler ultrasound (DUS) as inlet boundary condition and a two-element Windkessel model as oulet boundary condition. The agreement between CFD and DUS on the PSV in the internal carotid artery (ICA) was then compared. The relative error for the agreement between DUS and CFD was 9% ± 20% and the intraclass correlation coefficient was 0.88. Furthermore, hyperemic simulations in a physiological range were feasible and unmasked markedly different pressure drops along two ICA stenoses with similar degree of narrowing under comparable ICA blood flow. Hereby, we lay the foundation for prospective studies on noninvasive CFD-based derivation of metrics similar to the FFR for the assessment of CAD.

The role of non-stenosing carotid artery plaques in embolic stroke of undetermined source, is it a silent offender? A review of literature.

Atherosclerotic cervical internal carotid artery disease is one of the major causes of ischemic stroke and transient ischemic attacks. The risk of stroke from mild to moderate stenoses (i.e. <50% stenosis) might be underestimated. There is increasing evidence that plaque morphological features reflect plaque instability that may harbor high risk for embolization. In this narrative review, we will review the literature on plaque features that predict vulnerability beyond the degree of stenosis, discuss the clinical association with stroke, and evaluate the evidence that these lesions serve as a source for embolic stroke of unknown source (ESUS). We performed a literature search using PubMed, EMBASE, and Web of Science. The terms "embolic stroke of undetermined source" and "plaque morphology" were used either alone or in combination with "non-flow limiting stenosis," "non-stenosing plaques," "high-risk plaque features" or "internal carotid artery plaque." Data on plaque morphology and ESUS were mainly taken from review articles, observational studies including retrospective cohort and cross-sectional studies, meta-analyses, and systematic reviews. Nonstenosing carotid artery plaques with high-risk features carry a remarkable risk for stroke occurrence and randomized clinical trials are warranted for further evaluation of using carotid artery stenting or carotid endarterectomy to mitigate the risk of stroke.

Misery Perfusion and Tau Deposition in Atherosclerotic Major Cerebral Artery Disease: A 18F-Florzolotau Positron Emission Tomography Study.

Studies using animal models have shown that cerebral hypoperfusion causes hyperphosphorylation of tau protein, leading to neuronal damage. However, the relationship between hypoperfusion and tau deposition in humans is unclear. Hence, we aimed to determine whether cerebral hypoperfusion leading to decreased blood flow relative to metabolic demand [increased oxygen extraction fraction (OEF), misery perfusion] is associated with increased tau deposition in patients with atherosclerotic internal carotid artery or middle cerebral artery disease. We prospectively evaluated the distribution of tau aggregate deposition using positron emission tomography and 18F-florzolotau (PMPBB3 [1-fluoro-3-((2-((1E,3E)-4-(6-(methylamino)pyridine-3-yl)buta-1,3-dien-1-yl)benzo[d]thiazol-6-yl)oxy)propan-2-ol)]) in 8 patients with atherosclerotic disease of the internal carotid artery or middle cerebral artery. The standardized uptake value ratio of 18F-florzolotau at 100 to 110 minutes after injection was calculated using the cerebellar cortex as a reference region and was correlated with OEF obtained from 15O-gas positron emission tomography in the middle cerebral artery distributions. Significant decreases in cerebral blood flow and cerebral metabolic rate of oxygen and increases in OEF were found in the hemisphere ipsilateral to the arterial lesion. 18F-florzolotau standardized uptake value ratio in this region was also greater than that in the contralateral hemisphere. In the ipsilateral hemisphere, 18F-florzolotau standardized uptake value ratio positively correlated with OEF values. This pilot study with a small sample size suggests that increases in OEF-misery perfusion-may be associated with increased tau aggregates deposition in atherosclerotic internal carotid artery or middle cerebral artery disease.

Is External Carotid Artery Hemodynamics Helpful in Detecting Internal Carotid Artery Stenosis?

Introduction: There is a paucity of validated external carotid artery (ECA) velocity criteria and data on the association between ECA velocities and internal carotid artery (ICA) stenosis by carotid duplex ultrasound (CDU) scanning. Our objectives were to determine the relationships between ECA peak systolic velocity (PSV) and percent stenosis seen on confirmatory imaging, as well as to correlate ECA hemodynamics with known ICA disease by CDU. Methods: A retrospective chart review was performed for patients who had CDU, as well as confirmatory testing such as angiography, at a single academic medical center. ICA stenosis was grouped into 4 categories (0 = &lt;50%, 1 = 50%-69%, 2 = 70%-99%, 3 = 100%) based on validated CDU criteria. ECA PSVs were analyzed, in addition to degree of both ECA and ICA stenosis from the same CDU study. Results: Of 247 carotid arteries reviewed, 136 vessels were included in the final analysis. The mean PSV of the normal ECA cohort (&lt;50% ECA stenosis per the NASCET measurement method) was 135.3 ± 82.1 cm/s, and the mean PSV of the diseased ECA cohort was 279.7 ± 112.2 cm/s. Mean ECA PSV for each category of ICA stenosis was: ICA category 0 = 119.9 cm/s; category 1 = 200.4 cm/s; category 2 = 167.7 cm/s; and category 3 = 155.5 cm/s. There was a statistically significant but non-linear difference in ECA velocities between ICA stenosis categories 0 vs 1 (mean rank diff. −49.91 cm/s; P = .0007); and 0 vs 2 (mean rank diff. −32.61 cm/s; P = .0047). Conclusion: We have demonstrated a possible separation of &lt;50% vs ≥50% stenosis of the ICA using ECA PSV. Although the data suggest a weak but statistically significant correlation between ECA PSV and degree of ICA stenosis, further data with a larger sample size and confirmatory studies are needed to utilize ECA hemodynamics to indicate ICA disease.

Quantification of New Intracerebral Lesions on Diffusion-weighted Magnetic Resonance Imaging After Transcarotid Artery Revascularization for Treatment of Carotid Stenosis

Quantification of New Intracerebral Lesions on Diffusion-weighted Magnetic Resonance Imaging After Transcarotid Artery Revascularization for Treatment of Carotid Stenosis

Neuronal Alterations in Secondary Thalamic Degeneration Due to Cerebral Infarction: A 11C-Flumazenil Positron Emission Tomography Study.

Background:Studies using animal experiments have shown secondary neuronal degeneration in the thalamus after cerebral infarction. Neuroimaging studies in humans have revealed changes in imaging parameters in the thalamus, remote to the infarction. However, few studies have directly demonstrated neuronal changes in the thalamus in vivo. The purpose of this study was to determine whether secondary thalamic neuronal damage may manifest as a decrease in central benzodiazepine receptors in patients with cerebral infarction and internal carotid artery or middle cerebral artery disease.Methods:We retrospectively analyzed the data of 140 patients with unilateral cerebral infarction ipsilateral to internal carotid artery or middle cerebral artery disease. All patients had quantitative measurements of 11C-flumazenil binding potential (FMZ-BP), cerebral blood flow, and cerebral metabolic rate of oxygen using positron emission tomography in the chronic stage. Region of interest analysis was performed using NeuroFlexer—an automated region of interest analysis software using NEUROSTAT.Results:In the thalamus ipsilateral to the infarcts, the values of FMZ-BP, cerebral blood flow, and cerebral metabolic rate of oxygen were significantly lower than those in the contralateral thalamus. Significant correlations were found between the ipsilateral-to-contralateral ratio of FMZ-BP and the ipsilateral-to-contralateral ratio of cerebral blood flow or cerebral metabolic rate of oxygen in the thalamus. Patients with corona radiata infarcts and striatocapsular infarcts had significantly decreased ipsilateral-to-contralateral FMZ-BP ratio in the thalamus compared with those without. The ipsilateral-to-contralateral ratio of FMZ-BP in the thalamus was significantly correlated with the ipsilateral-to-contralateral cerebral metabolic rate of oxygen ratio in the frontal cortex and showed a significant negative correlation with the number of perseverative errors on the Wisconsin Card Sorting Test.Conclusions:Secondary thalamic neuronal damage may manifest as a decrease in central benzodiazepine receptors in patients with cerebral infarction and internal carotid artery or middle cerebral artery disease, which may be associated with frontal lobe dysfunction.

Extracranial-to-Intracranial Bypass for Distal Internal Carotid Artery and/or Proximal Middle Cerebral Artery Steno-Occlusive Disease: A Case Series of Clinical Outcomes at a Single, High-Volume Cerebrovascular Center.

Extracranial-to-intracranial (EC-IC) bypass was first described by Yasargil in the 1960s for treatment of symptomatic distal internal carotid artery (ICA) and/or proximal middle cerebral artery (MCA) steno-occlusive disease through direct anastomosis. Subsequent bypass trials failed to demonstrate benefit for overall outcomes and stroke rates compared with best medical therapy. However, the procedure remained in the neurosurgeon's armament, with studies showing benefits in select patient populations. With advancements in technology, patient selection has become more comprehensive. To provide a contemporary evaluation of EC-IC bypass from our high-volume cerebrovascular center, focusing on associated clinical outcomes. Consecutive patients who underwent direct EC-IC bypass surgeries for symptomatic distal ICA and/or proximal MCA steno-occlusive disease between April 2015 and September 2019 were identified retrospectively. Medical records were reviewed to collect demographics, clinical presentation, computed tomography perfusion imaging findings, transcranial Doppler results, procedure indication, donor vessel types, anastomosis site, bypass patency, periprocedural complications, postprocedural complications, symptom recrudescence, repeat or new interventions, subjective improvements, and modified Rankin Scale scores. We identified 27 patients who underwent 32 EC-IC bypass procedures. The rate of ipsilateral stroke was 9.4%, with a median follow-up of 8 months (IQR, 4-13 months). Patients experienced a 22.3% improvement in modified Rankin Scale scores, and 70.3% of patients reported subjective improvement and satisfaction at follow-up. Direct EC-IC bypass remains a viable option for revascularization in symptomatic patients with distal ICA and/or proximal MCA steno-occlusive disease.

MicroRNA-134-5p and the Extent of Arterial Occlusive Disease Are Associated with Risk of Future Adverse Cardiac and Cerebral Events in Diabetic Patients Undergoing Carotid Artery Stenting for Symptomatic Carotid Artery Disease.

There is little known about the prognostic value of serum microRNAs (miRs) in diabetic patients with symptomatic internal carotid artery disease (ICAS) who underwent stent supported angioplasty (PTA) for ICAS. The present study aimed to investigate expression levels of selected miRs for future major adverse cardiac and cerebral events (MACCE) as a marker in diabetic patients following ICAS-PTA. The expression levels of 11 chosen circulating serum miRs were compared in 37 diabetic patients with symptomatic ICAS and 64 control group patients with symptomatic ICAS, but free of diabetes. The prospective median follow-up of 84 months was performed for cardiovascular outcomes. Diabetic patients, as compared to control subjects, did not differ with respect to age (p = 0.159), distribution of gender (p = 0.375), hypertension (p = 0.872), hyperlipidemia (p = 0.203), smoking (p = 0.115), coronary heart disease (p = 0.182), lower extremities arterial disease (LEAD, p = 0.731), and miRs expressions except from lower miR-16-5p (p < 0.001). During the follow-up period, MACCE occurred in 16 (43.2%) diabetic and 26 (40.6%) non-diabetic patients (p = 0.624). On multivariate Cox analysis, hazard ratio (HR) and 95% Confidence Intervals (95%CI) for diabetic patients associated with MACCE were miR-134-5p (1.12; 1.05–1.21, p < 0.001), miR-499-5p (0.16; 0.02–1.32, p = 0.089), hs-CRP (1.14; 1.02–1.28; p = 0.022), prior myocardial infarction (8.56, 1.91–38.3, p = 0.004), LEAD (11.9; 2.99–47.9, p = 0.005), and RAS (20.2; 2.4–167.5, p = 0.005), while in non-diabetic subjects, only miR-16-5p (1.0006; 1.0001–1.0012, p = 0.016), miR-208b-3p (2.82; 0.91–8.71, p = 0.071), and hypertension (0.27, 0.08–0.95, p = 0.042) were associated with MACCE. Our study demonstrated that different circulating miRs may be prognostic for MACCE in diabetic versus non-diabetic patients with symptomatic ICAS. Higher expression levels of miR-134 were prognostic for MACCE in diabetic patients, while higher expression levels of miR-16 were prognostic in non-diabetic patients.

Evolution of Extracranial Internal Carotid Artery Disease in Children With Sickle Cell Anemia.

Cerebral arteriopathy in patients with sickle cell anemia mainly affects the intracranial anterior circulation. However, the extracranial internal carotid artery (eICA) can also be stenosed and responsible for ischemic lesions. In children with sickle cell anemia, we perform routine annual Doppler ultrasound assessment of the eICA and magnetic resonance imaging with 3-dimensional time-of-flight magnetic resonance angiography of the Willis circle and neck arteries in those with abnormal velocity. Our aim was to report the evolution of eICA stenoses from 2011 to the present as a function of therapy in a retrospective case-series study. We hypothesized that chronic transfusion (CTT) would be more effective than hydroxyurea and simple observation on the evolution of eICA stenosis. Eligibility criteria were a history of eICA velocity ≥160 cm/s with a minimum Doppler and magnetic resonance imaging follow-up of 1 year. eICAs were graded for stenosis according to NASCET (The North American Symptomatic Carotid Endarterectomy Trial). Magnetic resonance imaging was investigated for ischemic lesions. Treatment with hydroxyurea and CTT were obtained from the chart review. Fifty-four patients were included. Eight patients had a stroke history. The median (range) follow-up was 4.7 years (1.1-9.2 years). On the first neck magnetic resonance angiography, stenosis was present in 48/54 (89%) patients. Kinking was found in 39/54 (72%) patients. On the last neck magnetic resonance angiography, the proportion of patients with eICA stenosis decreased to 39/54 (72%). ICA occlusion occurred in 5 patients despite CTT. Three patients had carotid webs without intracranial stenosis. The proportion of patients with improvement in stenosis score was 8% with no treatment intensification, 20% with hydroxyurea, and 48% with CTT (P=0.016). The mean (SD) change per year in stenosis score was 0.40 (0.60) without intensification, 0.20 (0.53) with hydroxyurea, and -0.18 (0.55) with CTT (P=0.006). Ischemic lesions were present initially in 46% of patients, and the incidence of progressive ischemic lesions was 2.5 events/100 patient-years. Cox regression analysis showed that the initial score for eICA stenosis was a significant predictive factor for the risk of new silent cerebral infarct events. Our study reinforces the need to assess cervical arteries for better prevention of cerebral ischemia and encourage initiation of CTT in sickle cell anemia children with eICA stenosis.

Ischemic Stroke Revascularization.

Extracranial-intracranial (EC-IC) bypass is one of the most fundamental techniques for ischemic cerebrovascular disease (CVD). We describe the standard surgical strategies, advanced techniques, and controversies concerning revascularization of ischemic stroke. The standard surgical strategies and techniques emphasize how to determine surgical indication, which should be decided for symptomatic internal carotid artery or middle cerebral artery (MCA) occlusive disease with misery perfusion detected by quantitative single photon emission computed tomography. Advanced techniques are available for complex situations such as posterior circulation revascularization, Bonnet bypass for common carotid artery obstruction, and various EC-IC bypasses for ischemia in the MCA and/or anterior cerebral artery territories using inter-grafts such as femoral veins and radial arteries, illustrated by our surgical results and experiences. Controversies include endovascular treatment complementary to EC-IC bypass. Finally, we advocate emergent EC-IC bypass for progressive ischemic CVD, particularly for contraindication or unsuccessful treatment after intravenous tissue plasminogen activator administration and/or endovascular thrombolysis. EC-IC bypass surgery can be reliable for ischemic CVD under strict optimal surgical indications using safe and reliable surgical techniques.

Transradial approach in neuroendovascular procedures

To evaluate safety and feasibility of transradial approach for neuroendovascular procedures and to familiarize neurosurgeons and neuroradiologists with the capabilities and limitations of this approach, as well as technical features influencing its effectiveness. A retrospective analysis was performed in 270 patients who underwent transradial neuroendovascular procedures between January 2015 and December 2019. Diagnostic and surgical interventions were performed in 203 (75.2%) and 67 (24.8%) patients, respectively. The authors comprehensively describe catheterization technique and choosing the instrument for effective and safe transradial access. The right vertebral and both common carotid arteries were the most accessible for selective catheterization (100% of cases). The left common carotid artery was catheterized in all cases, the left internal carotid artery - only in 92% of cases. If catheterization of the left vertebral artery was necessary, we used the left-sided radial approach. Conversion to femoral approach was required in 2.6% of cases for the left internal carotid artery disease (n=7). Radial artery occlusion occurred in 3.7% of cases (n=10) and was asymptomatic in all cases. We present a video clip (https://youtu.be/3wZ6O8u-lpk) devoted to various surgical interventions through radial approach. Radial approach is safe and feasible and may be used for neuroendovascular procedures.

Visit-to-Visit Blood PressureVariations and Hemodynamic Deterioration in Atherosclerotic Major Cerebral ArteryDisease

ObjectiveVisit-to-visit variations in blood pressure (BP) in patients with atherosclerotic major cerebral artery disease could impair the function of cerebral collaterals, leading to hemodynamic deterioration at follow-up. However, few studies have investigated the relationship between visit-to-visit BP variability and changes in hemodynamic parameters at follow-up. Materials and methodsWe evaluated 35 medically treated patients with atherosclerotic internal carotid artery or middle cerebral artery disease with no ischemic episodes during follow-up (mean: 35 ± 20 months); these patients had a three-time visit for positron emission tomography examinations with 15O-gas. Differences in the mean hemispheric values of hemodynamic parameters in the cortical territory of the diseased artery between the first and third examinations (changes at follow-up) were correlated with the coefficient of variation (CoV) in three systolic BP (SBP) values at the three examinations (BP variability during follow-up). ResultsCoV values were negatively correlated with changes in oxygen metabolism or cerebral blood flow/cerebral blood volume (CBF/CBV) ratio. In 17 patients with higher CoV values (> group median, 0.072), decreases in CBF, cerebral metabolic rate of oxygen, and CBF/CBV ratio were observed at follow-up; CBV decreased in 18 patients without elevated CoV. A higher CoV was associated with a lack of statin use. ConclusionIn patients with atherosclerotic major cerebral artery disease, high visit-to-visit SBP variations during follow-up may be associated with deterioration in cerebral hemodynamics and metabolism.

Abstract 1122‐000078: C‐Guard Stent for the Treatment of Cervical Internal Carotid Artery Aneurysms: Report of 2 Cases

Introduction : C‐Guard carotid stent is a self‐expandable open cell stent covered with a double‐layer mesh which was developed for the treatment of internal carotid artery disease. Lower procedural and complications rates, as well as lower post‐operative infarctions are some advantages of this device. Nevertheless, the use of C‐Guard in the treatment of cervical internal carotid artery (ICA) aneurysms is scarce. Therefore, we present two cases in which the C‐Guard stent achieved complete angiographic occlusion at follow‐up. Methods : We identified two cases in which the C‐Guard carotid stent was used to treat symptomatic cervical ICA aneurysms. Angiographic follow‐up was performed. Results : Case 1: 47‐yo female presented left‐sided motor deficit. CT showed ischemic areas in the right hemisphere and CTA demonstrated an unruptured aneurysm in the C1 segment of the right ICA. The patient started dual antiplatelet therapy (DAPT) with aspirin and clopidogrel. A 6mm x 40 mm C‐Guard carotid stent was deployed without complications. One‐year follow‐up CTA showed complete obliteration of the aneurysm with reconstruction of the ICA. Case 2: 38‐yo male presented decreased left visual acuity. CTA and DSA showed an unruptured aneurysm in the C1 segment of the ICA. The patient started DAPT with aspirin and clopidogrel. A 7mm x 30 mm C‐Guard carotid stent was deployed without complications. Three‐month follow‐up DSA showed complete obliteration of the aneurysm with adequate filling of distal vessels. Conclusions : C‐Guard stent is a potential alternative to conventional carotid stents in the treatment of cervical ICA aneurysms with high obliteration rates at follow‐up.

Cerebral collateral circulation in acute stroke with occlusive internal carotid artery disease

Acute brain infarction due to carotid artery occlusion has been associated with poor outcome in the absence of cerebral collaterals. The incipient development of collaterals does not guarantee their persistence while available data are strongly indicative that good collateral flow is key in cerebral perfusion, and in reducing infarct size, this knowledge has resulted in only limited therapeutic applications.