Impaired Glymphatic Function and Pulsation Alterations in a Mouse Model of Vascular Cognitive Impairment

Large vessel disease and carotid stenosis are key mechanisms contributing to vascular cognitive impairment (VCI) and dementia. Our previous work, and that of others, using rodent models, demonstrated that bilateral common carotid stenosis (BCAS) leads to cognitive impairment via gradual deterioration of the neuro-glial-vascular unit and accumulation of amyloid-β (Aβ) protein. Since brain-wide drainage pathways (glymphatic) for waste clearance, including Aβ removal, have been implicated in the pathophysiology of VCI via glial mechanisms, we hypothesized that glymphatic function would be impaired in a BCAS model and exacerbated in the presence of Aβ. Male wild-type and Tg-SwDI (model of microvascular amyloid) mice were subjected to BCAS or sham surgery which led to a reduction in cerebral perfusion and impaired spatial learning acquisition and cognitive flexibility. After 3 months survival, glymphatic function was evaluated by cerebrospinal fluid (CSF) fluorescent tracer influx. We demonstrated that BCAS caused a marked regional reduction of CSF tracer influx in the dorsolateral cortex and CA1-DG molecular layer. In parallel to these changes increased reactive astrogliosis was observed post-BCAS. To further investigate the mechanisms that may lead to these changes, we measured the pulsation of cortical vessels. BCAS impaired vascular pulsation in pial arteries in WT and Tg-SwDI mice. Our findings show that BCAS influences VCI and that this is paralleled by impaired glymphatic drainage and reduced vascular pulsation. We propose that these additional targets need to be considered when treating VCI.

Cognitive Sequelae of Silent Ischemic Lesions Following Carotid Artery Stenting: Possible Role of Age-Related Moderation

Background: The occurrence of ischemic lesions is common in patients receiving carotid artery stenting (CAS), and most of them are clinically silent. However, few studies have directly addressed the cognitive sequelae of these procedure-related silent ischemic lesions (SILs).Objective: In this study, we attempted to investigate the effects of SILs on cognition using a comprehensive battery of neuropsychological tests.Method: Eighty-five patients with unilateral carotid stenosis and 25 age-matched healthy volunteers participated in this study. Brain MRI was performed within 1 week before and 1 week after CAS to monitor the occurrence of post-CAS SILs. A comprehensive battery tapping reading ability, verbal and non-verbal memory, visuospatial function, manual dexterity, executive function, and processing speed was administered 1 week before and 6 months after CAS. To control for practice effects on repeated cognitive testing, the reliable change index (RCI) derived from the healthy volunteers was used to determine the cognitive changes in patients with carotid stenosis.Results: Among the 85 patients with carotid stenosis, 21 patients received medical treatment (MED group), and procedure-related SILs were noted in 17 patients (SIL+ group) but not observed in 47 patients (SIL– group) after undergoing CAS. Two-way (group × phase) ANOVA revealed that the volunteer group showed improved scores in most cognitive tests while only limited improvement was noted in the SIL– group. The MED and control groups tended to show improvement in the follow-up cognitive testing than the SIL+ group. However, most of the cognitive changes for each patient group did not exceed the upper or lower limits (z = ±1.0) of the RCI.Conclusions: Although the occurrence of procedure-related SILs is common in patients undergoing CAS, their impacts on cognitive changes after CAS may be limited. The practice effect should be taken into consideration when interpreting cognitive changes following CAS.

Late Outcomes of Carotid Artery Stenting for Radiation Therapy-Induced Carotid Stenosis

Purpose: Carotid artery stenting (CAS) appears as a promising alternative treatment to carotid endarterectomy for radiation therapy (RT)-induced carotid stenosis. However, this is based on a poor level of evidence studies (small sample size, primarily single institution reports, few long-term data). The purpose of this study was to report the long-term outcomes of a multicentric series of CAS for RT-induced stenosis. Methods: All CAS for RT-induced stenosis performed in 11 French academic institutions from 2005 to 2017 were collected in this retrospective study. Patient demographics, clinical risk factors, elapsed time from RT, clinical presentation and imaging parameters of carotid stenosis were preoperatively gathered. Long-term outcomes were determined by clinical follow-up and duplex ultrasound. The primary endpoint was the occurrence of cerebrovascular events during follow-up. Secondary endpoints included perioperative morbidity and mortality rate, long-term mortality rate, primary patency, and target lesion revascularization. Results: One hundred and twenty-one CAS procedures were performed in 112 patients. The mean interval between irradiation and CAS was 15 ± 12 years. In 31.4% of cases, the lesion was symptomatic. Mean follow-up was 42.5 ± 32.6 months (range 1–141 months). The mortality rate at 5 years was 23%. The neurologic event-free survival and the in-stent restenosis rates at 5 years were 87.8% and 38.9%, respectively. Diabetes mellitus (p=0.02) and single postoperative antiplatelet therapy (p=0.001) were found to be significant predictors of in-stent restenosis. Freedom from target lesion revascularization was 91.9% at 5 years. Conclusion: This study showed that CAS is an effective option for RT-induced stenosis in patients not favorable to carotid endarterectomy. The CAS was associated with a low rate of neurological events and reinterventions at long-term follow-up.

Cerebral hemodynamic effects of early blood pressure lowering after TIA and stroke in patients with carotid stenosis

Background: Effects of early blood pressure (BP) lowering on cerebral perfusion in patients with moderate/severe occlusive carotid disease after transient ischemic attack (TIA) and non-disabling stroke are uncertain. Aims: We aimed to evaluate the changes in transcranial Doppler (TCD) indices in patients undergoing blood pressure lowering soon after TIA/non-disabling stroke. Methods: Consecutive eligible patients (1 November 2011 to 30 October 2018) attending a rapid-access clinic with TIA/non-disabling stroke underwent telemetric home blood pressure monitoring (HBPM) for 1 month and middle cerebral artery velocities measurements ipsilateral to carotid stenosis on TCD ultrasound in the acute setting and at 1 month. Hypertensive patients (HBPM ⩾ 135/85) underwent intensive BP-lowering guided by HBPM unless they had bilateral severe occlusive disease (⩾ 70%). Changes in BP and TCD parameters were compared in patients with extracranial moderate/severe carotid stenosis (between 50% and occlusion) versus those with no or mild (< 50%) stenosis. Results: Of 764 patients with repeated TCD measures, 42 had moderate/severe extracranial carotid stenosis without bilateral severe occlusive disease. HBPM was reduced from baseline to 1 month in hypertensive patients both with versus without moderate/severe carotid stenosis (−12.44/15.99 vs −13.2/12.2 mmHg, respectively, p-difference = 0.82), and changes in TCD velocities (4.69/14.94 vs 2.69/13.86 cm/s, respectively, p-difference = 0.52 for peak systolic velocity and 0.33/7.06 vs 1.75/6.84 cm/s, p-difference = 0.34 for end-diastolic velocity) were also similar, with no evidence of greater hemodynamic compromise in patients with stenosis/occlusion. Conclusion: There was no evidence of worsening of TCD hemodynamic indices in patients with moderate/severe occlusive carotid disease treated with BP-lowering soon after TIA/non-disabling stroke, suggesting that antihypertensive treatment in this group of patients is safe in the acute setting of TIA clinics.

Health Screening Program to Enhance Enrollment of Women and Minorities in CREST-2

Background and Purpose: The CREST-2 (Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trial) consists of 2 parallel randomized stroke prevention trials in patients with asymptomatic high-grade stenosis of the cervical carotid artery. The purpose of this report is to detail the outcomes of a health screening effort to increase trial enrollment of women and minorities. Methods: Life Line screening (LLS) conducts nationwide screening for vascular disease. Screenings within a 50-mile radius of each CREST-2 center were identified for participation in a joint CREST-LLS program over the course of one year (November 2018 to October 2019) whereby patients with an abnormal carotid ultrasound were referred to the local CREST-2 center for further workup, management, and potential consideration for trial enrollment. Results: LLS completed the screening of 588 198 individuals in 29 732 zip codes across the United States. Of those, 230 021 individuals were screened at events occurring near a CREST-2 clinical center and 646 (0.3%) were found to have abnormal carotid ultrasound findings. Each of the 646 individuals was contacted by CREST-LLS program staff for permission to be referred to their local CREST-2 center; 200 (31%) consented to be contacted by CREST-2. Of those, 39 (19.5%) agreed to be, and were, evaluated at their local CREST-2 center. High-grade stenosis was confirmed in 27 patients. A total of 3 patients were eligible for the trial and were enrolled, one woman but no racial/ethnic minorities. Conclusions: The LLS program appears to identify community-living individuals with high-grade carotid stenosis through ultrasonography. However, the prevalence of abnormal carotid findings was low. In addition, screening and offering participation into the CREST-2 trial had no substantial impact on the proportion of women and minorities enrolled in the trial. Additional innovative strategies are needed to promote enrollment of diverse patients with carotid stenosis into stroke prevention trials.

Sex Differences in Plaque Composition and Morphology Among Symptomatic Patients With Mild-to-Moderate Carotid Artery Stenosis

Background and Purpose: Incidence of ischemic stroke differs between men and women, with substantially higher rates in men. The underlying mechanism of this difference remains poorly understood but may be because of differences in carotid atherosclerosis. Using an in-depth imaging-based approach, we investigated differences between carotid plaque composition and morphology in male and female patients with stroke, taking into account differences in total plaque burden. Additionally, we investigated all possible within-artery combinations of plaque characteristics to explore differences between various plaque phenotypes. Methods: We included 156 men and 68 women from the PARISK (Plaque At Risk) study, a prospective cohort study of patients with recent ischemic cerebrovascular symptoms and <70% ipsilateral carotid stenosis. Plaque characteristics (intraplaque hemorrhage [IPH], lipid-rich necrotic core [LRNC], calcifications, thin-or-ruptured fibrous cap, ulcerations, total plaque volume) were assessed with magnetic resonance imaging and multidetector-row computed tomography angiography. We used multivariable logistic and linear regression analyses to assess sex differences in plaque characteristics. Results: We found significant difference in total plaque volume between men and women (β=22.9 mm 3 [95% CI, 15.4–30.5]; mean volume in men 1399±425 mm 3 , in women 1011±242 mm 3 ). Additionally, men were more likely to have IPH (odds ratio [OR]=2.8 [95% CI, 1.3–6.3]; IPH proportion in men 49%, in women 16%) and LRNC (OR=2.4 [95% CI, 1.2–4.7]; LRNC proportion in men 73%, in women 41%) even after adjustment for total plaque volume. We found no sex-specific differences in plaque volume-corrected volumes of IPH, LRNC, and calcifications. In terms of coexistence of plaque characteristics, we found that men had more often a plaque with coexistence of calcifications, LRNC, and IPH (OR=2.7 [95% CI, 1.2–7.0]), with coexistence of thin-or-ruptured fibrous cap/ulcerations, LRNC, and IPH (OR=2.4 [95% CI, 1.1–5.9]), and with coexistence of all plaque characteristics (OR=3.0 [95% CI, 1.2–8.6]). Conclusions: In symptomatic patients with mild-to-moderate carotid stenosis, men are more likely to have a high-risk carotid plaque with IPH and LRNC than women, regardless of total plaque burden. Men also have more often a plaque with multiple vulnerable plaque components, which could comprise an even higher stroke risk. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01208025.

Physician Approaches to Imaging and Revascularization for Acutely Symptomatic Carotid Stenosis: Insights from the Hot Carotid Qualitative Study

Background Evidence informing the choice between carotid endarterectomy and carotid artery stenting for acutely symptomatic carotid stenosis (“hot carotid”) is dated and does not factor in contemporary therapies or techniques. The optimal imaging modality is also uncertain. We explored the attitudes of stroke physicians regarding imaging and revascularization of patients with acute symptomatic carotid stenosis. Methods We used a qualitative descriptive methodology to examine decision‐making approaches and opinions of physicians regarding the choice of imaging and revascularization procedures for hot carotids. We conducted semistructured interviews with purposive sampling of 22 stroke physicians from 16 centers in 6 world regions and various specialties: 11 neurologists, 3 geriatricians, 5 interventional neuroradiologists, and 3 neurovascular surgeons. Results Qualitative analysis revealed several themes regarding clinical decision‐making for hot carotids. Whereas CT angiography was favored by most participants, timely imaging availability, breadth of information gained, and surgeon/interventionalist preferences were important themes influencing the choice of imaging modality. Carotid endarterectomy was generally favored over carotid artery stenting, but participants’ choice of intervention was influenced by healthcare system factors such as use of multidisciplinary vascular teams and operating room or angiography suite availability, and patient factors like age and infarct size. Areas of uncertainty included choice of imaging modality for borderline stenosis, utility of carotid plaque imaging, timing of revascularization, and the role of intervention with borderline stenosis or intraluminal thrombus. Conclusions This qualitative study highlights practice patterns common in different centers around the world, such as the general preference for CT angiography imaging and carotid endarterectomy over carotid artery stenting but also identified important differences in availability, selection, and timing of imaging and revascularization options. To gain widespread support, future carotid trials will need to accommodate identified variations in practice patterns and address areas of uncertainty, such as optimal timing of revascularization with modern best medical management and risk‐stratification with imaging features other than just degree of stenosis.