The Effect of Carotid Endarterectomy on Cerebral Blood Flow and Cognitive Function

Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion

PURPOSE

Compare extracranial internal carotid artery flow rates and intracranial collateral use between conventional ≥ 50% carotid stenosis and carotid near-occlusion, and between symptomatic and asymptomatic carotid near-occlusion.

METHODS

We included patients with ≥ 50% carotid stenosis. Degree of stenosis was diagnosed on CTA. Mean blood flow rates were assessed with four-dimensional phase-contrast MRI.

RESULTS

We included 110 patients of which 83% were symptomatic, and 38% had near-occlusion. Near-occlusions had lower mean internal carotid artery flow (70 ml/min) than conventional ≥ 50% stenoses (203 ml/min, P < .001). Definite use of ≥ 1 collateral was found in 83% (35/42) of near-occlusions and 10% (7/68) of conventional stenoses (P < .001). However, there were no differences in total cerebral blood flow (514 ml/min vs. 519 ml/min, P = .78) or ipsilateral hemispheric blood flow (234 vs. 227 ml/min, P = .52), between near-occlusions and conventional ≥ 50% stenoses, based on phase-contrast MRI flow rates. There were no differences in total cerebral or hemispheric blood flow, or collateral use, between symptomatic and asymptomatic near-occlusions.

CONCLUSION

Near-occlusions have lower internal carotid artery flow rates and more collateral use, but similar total cerebral blood flow and hemispheric blood flow, compared to conventional ≥ 50% carotid stenosis.

Evaluating the influence of altered cerebral hemodynamics on cognitive performance in asymptomatic carotid artery stenosis: A systematic review

OBJECTIVE

Substantial controversy exists regarding asymptomatic carotid stenosis (ACS) and its potential role in the pathophysiology of cognitive impairment. If proven, this hypothesis may suggest an additional definition for symptomatic carotid disease that would alter current management. This study aimed to synthesize the literature evaluating the relationship between impaired cerebral hemodynamics and cognition in patients with ACS.

METHODS

A literature search was performed using MEDLINE, Embase, and EBM Reviews through May 2022. We included prospective case-control studies that used validated, objective measure(s) of either global cognition or one or more domains of cognitive function and assessed cerebrovascular reserve (CVR).

RESULTS

Five studies were included, comprising a total of 782 patients with moderate (50%-69%) to severe (70%-99%) ACS. Patients with ACS and impaired ipsilateral CVR demonstrated significant cognitive impairment compared with controls. Patients with unilateral or bilateral ACS and normal CVR had cognitive scores similar to controls. Those with bilateral CVR impairment demonstrated the lowest cognitive scores.

CONCLUSIONS

This review lends support to the claim that cognitive impairment, likely the result of impaired cerebral hemodynamics, is an under-recognized morbidity in patients with ACS. CVR may serve as an additional tool to determine whether patients are in fact symptomatic from their carotid stenosis and warrant consideration for intervention.

This is Your Brain, and This is Your Brain on Atrial Fibrillation: The Roles of Cardiac Malperfusion Events and Vascular Dysfunction in Cognitive Impairment

AF is an independent and strong predictor of long-term cognitive decline. However, the mechanism for this cognitive decline is difficult to define and likely multifactorial, leading to many different hypotheses. Examples include macro- or microvascular stroke events, biochemical changes to the blood-brain barrier related to anticoagulation, or hypo-hyperperfusion events. This review explores and discusses the hypothesis that AF contributes to cognitive decline and dementia through hypo-hyperperfusion events occurring during cardiac arrhythmias. We briefly explain several brain perfusion imaging techniques and further examine the novel findings associated with changes in brain perfusion in patients with AF. Finally, we discuss the implications and areas requiring more research to further understand and treat patients with cognitive decline related to AF.

Carotid Intervention Improves Cognitive Function in Patients With Severe Atherosclerotic Carotid Disease

INTRODUCTION

Carotid revascularization procedures are effective in stroke prevention in appropriately selected patients. We sought to understand the effects of the carotid intervention on cognitive function in a well-defined cohort of prospectively recruited patients.

METHODS

A total of 170 consecutive patients undergoing carotid intervention for severe carotid stenosis were recruited. Patients received neuropsychometric testing preintervention, and at 1, 6, and 12 months postoperative. Patients were screened with the Mini-Mental State Examination. Rey Auditory Verbal Learning test (RAVLT) test was the primary outcome measure and multiple cognitive tests were used to evaluate executive function. Paired t test and McNemar test were performed to compare age-adjusted and education-adjusted postoperative scores at the individual time point with the preoperative scores.

RESULTS

Our patients had a high prevalence of cardiovascular risks and 51.2% of whom were symptomatic. The usages of statin and antiplatelet were high (88.8% and 69.4%, respectively). A total of 140 patients had 1 or more postoperative neuropsychometric tests in addition to their preoperative tests were included. The average RAVLT preoperative score was lower ( z =-0.79, SD=1.3, confidence interval: -1 to -0.53) than the age-adjusted norm. We observed a significant improvement in RAVLT memory scores at 1 and 6 months postoperative compared with preoperative. We also observed significant improvement in multiple executive functions measures up to 12 months postoperative. The improvement on patients with preoperative stroke symptoms was less consistent.

CONCLUSIONS

This prospective study showed that carotid intervention improved memory and executive function in patients with the severe carotid occlusive disease. It highlights the cognitive benefit of the carotid intervention in appropriately selected patients.

Associations between carotid atherosclerotic plaque characteristics determined by magnetic resonance imaging and improvement of cognition in patients undergoing carotid endarterectomy

BACKGROUND

To determine the predictive value of carotid plaque characteristics for the improvement of cognition in patients with moderate-to-severe carotid stenosis after carotid endarterectomy (CEA), using vessel wall magnetic resonance imaging (MRI).

METHODS

This was a prospective cohort study. Patients with unilateral, moderate-to-severe carotid stenosis referred to the Peking University Third Hospital for CEA were prospectively recruited and underwent carotid vessel wall MRI within 1 week before CEA. We performed Montreal Cognitive Assessment (MoCA) within 1 week before and 3-4 days after CEA. The morphological and compositional characteristics of carotid plaques on MRI were evaluated. Improvement of cognition was defined as >10% increase of the total MoCA score after CEA compared with baseline. Carotid plaque characteristics were compared between patients with and without cognitive improvement.

RESULTS

In total, 105 patients (91 males; mean age, 65.5±8.4 years) were included. The volume {48.0 [interquartile range (IQR), 21.0 to 91.6] vs. 16.3 (IQR, 8.1 to 53.1) mm3; P=0.005} and cumulative slice [4.0 (IQR, 3.0 to 7.0) vs. 3.0 (IQR, 2.0 to 5.0); P=0.019] of carotid calcification, and maximum percentage of calcification area [13.1% (IQR, 6.0% to 19.8%) vs. 6.2% (IQR, 3.7% to 10.8%); P=0.004] were significantly smaller in participants with cognitive improvement compared to those without. Univariate logistic regression analysis showed that volume [odds ratio (OR) =0.994; 95% confidence interval (CI): 0.989 to 1.000; P=0.043] and cumulative slice (OR =0.823; 95% CI: 0.698 to 0.970; P=0.020) of carotid calcification, and maximum percentage of calcification area (OR =0.949; 95% CI: 0.909 to 0.991; P=0.018) were significantly correlated with cognitive improvement. After adjusting for confounding factors, these associations remained statistically or marginally significant (volume: OR =0.994; 95% CI: 0.988 to 1.000; P=0.057; maximum percentage of calcification area: OR =0.937; 95% CI: 0.890 to 0.987; P=0.014; and cumulative slice: OR =0.791; 95% CI: 0.646 to 0.967; P=0.022). No significant associations were found between other plaque characteristics and cognitive improvement (all P>0.05).

CONCLUSIONS

More than half of the participants with unilateral, moderate-to-severe carotid atherosclerotic stenosis had cognitive improvement. The size of calcification might be an effective indicator of cognitive improvement after CEA.

Differential Cognitive Functioning and Benefit From Surgery in Patients Undergoing Coronary Artery Bypass Grafting and Carotid Endarterectomy

Background

Stenosing atherosclerosis in both coronary and carotid arteries can adversely affect cognition. Also their surgical treatments, coronary artery bypass grafting (CABG) and carotid endarterectomy (CEA), are associated with cognitive changes, but the mechanisms of cognitive decline or improvement may not be the same. This study was designed to compare the cognitive profile and outcome in patients undergoing surgical treatment for coronary or carotid disease.

Methods

A total of 100 CABG patients and 44 CEA patients were recruited in two previously reported studies. They were subjected to a comprehensive neuropsychological examination prior to surgery and in the acute (3-8 days) and stable (3 months) phase after operation. A group of 17 matched healthy controls were assessed with similar intervals. We used linear mixed models to compare cognitive trajectories within six functional domains between the CABG, CEA and control groups. Postoperative cognitive dysfunction (POCD) and improvement (POCI) were determined with the reliable change index method in comparison with healthy controls.

Results

Before surgery, the CEA patients performed worse than CABG patients or healthy controls in the domains of executive functioning and processing speed. The CABG patients exhibited postoperative cognitive dysfunction more often than the CEA patients in most cognitive domains in the acute phase but had regained their performance in the stable phase. The CEA patients showed more marked postoperative improvement in executive functioning than the CABG group in the acute phase, but the difference did not reach significance in the stable phase.

Conclusion

Our findings suggest that anterior cerebral dysfunction in CEA patients impairs preoperative cognition more severely than global brain dysfunction in CABG patients. However, CEA may have more beneficial effects on cognition than CABG, specifically in executive functions mainly operated by the prefrontal lobes. In addition, the results underline that POCD is a heterogeneous condition and dependent on type of revascularization surgery.

A systematic review of cognitive function after carotid endarterectomy in asymptomatic patients

OBJECTIVE

Asymptomatic carotid stenosis has been associated with a progressive decline in neurocognitive function. However, the effect of carotid endarterectomy on this process is poorly understood. We aimed to evaluate pre and post-operative cognitive function changes in asymptomatic patients after carotid endarterectomy METHODS: A systematic review of the existing reports in PubMed/MEDLINE, Embase, and Cochran databases was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement recommendations. All original retrospective or prospective studies (including cohort, cross-sectional, case-control, pilot studies, etc.) and clinical trials that compared pre and post-operative neurocognitive function in asymptomatic patients with carotid stenosis after CEA, which were published from January 2000 to April 2021 were identified and considered eligible for inclusion in the study.

RESULTS

Thirteen studies (502 CEAs) comparing cognitive function changes before and after CEA were identified. In seven studies with a total number of 272 patients, a mean age range of 67.3 ± 4.8 to 76.35 years old and after follow-up ranging between 1 and 12 months, overall cognitive function improved after CEA. However, in six studies with a total sample of 230, a mean age range of 68.6 ± 6.9 to 74.4±6.1 years, and follow-up ranged from 24 hours to 3 years, showed no change or decline in overall cognitive function after procedures.

CONCLUSIONS

The lack of standardization of specific cognitive tests and cognitive function assessment timing after CEA does not allow for definite conclusions to be made. However, improving the brain perfusion with combination of CEA and statin therapy may be a protective strategy against cognitive function decline.

Effect of Carotid Interventions on Cognitive Function in Patients With Asymptomatic Carotid Stenosis: A Systematic Review

OBJECTIVE

To determine the effect of carotid endarterectomy (CEA) and carotid artery stenting (CAS) on early (baseline vs. maximum three months) and late (baseline vs. at least five months) cognitive function in patients with exclusively asymptomatic carotid stenoses (ACS).

METHOD

Searches were conducted in PubMed/Medline, Embase, Scopus, and the Cochrane library. This systematic review includes 31 non-randomised studies.

RESULTS

Early post-operative period: In 24 CEA/CAS/CEA+CAS cohorts (n = 2 059), two cohorts (representing 91/2 059, 4.4% of the overall study population) reported significant improvement in cognitive function, while one (28/2 059, 1%) reported significant decline. Three cohorts (250/2 059, 12.5% reported "mixed findings" where some cognitive scores significantly improved, and a similar proportion declined. The majority (nine cohorts; 1 086/2 059, 53%) reported no change. Seven cohorts (250/2 059, 12.1%) were mostly unchanged but one to two individual test scores improved, while two cohorts (347/2 059, 16.8%) were mostly unchanged with one to two individual test scores worse. Late post-operative period: In 21 cohorts (n = 1 554), one (28/1 554, 1.8%) reported significantly worse cognitive function, one reported significant improvement (24/1 554, 1.5%), while a third (19/1 554, 1.2%) reported "mixed findings". The majority were unchanged (six cohorts; 1 073/1 554, 69%) or mostly unchanged, but with one to two cognitive tests showing significant improvement (11 cohorts; 386/1 554, 24.8%). Overall, there was a similar distribution of findings in small, medium, and large studies, in studies with controls vs. no controls, in studies comparing CEA vs. CAS, and in studies with shorter/longer late follow up.

CONCLUSION

Notwithstanding accepted limitations regarding heterogeneity within non-randomised studies, CEA/CAS rarely improved overall late cognitive function in ACS patients (< 2%) and the risk of significant cognitive decline was equally low (< 2%). In the long term, the majority were either unchanged (69%) or mostly unchanged with one to two test scores improved (24.8%). Until new research identifies vulnerable ACS subgroups (e.g., impaired cerebral vascular reserve) or provides evidence that silent embolisation from ACS causes cognitive impairment, evidence supporting intervention in ACS patients to prevent/reverse cognitive decline is lacking.

Impact of carotid stenosis on cerebral hemodynamic failure and cognitive impairment progression: a narrative review

Carotid atherosclerosis has a relevant impact on cerebral blood flow regulation. There is accruing evidence that hemodynamic impairment related to the presence of a significant carotid lumen narrowing may predispose to the development of cerebral dysfunctions, including a reduction in cognitive abilities. In the last years an increasing number of findings showed that carotid stenosis did contribute to cognitive impairment not only in relation to the occurrence of cerebral ischemic lesions, but also as an independent risk factor. The principal mechanisms involved are chronic hypoperfusion, microembolization and cerebrovascular reactivity impairment. Moreover, more recent studies showed alterations of regional functional connectivity. In this narrative review, we analyzed the relationships between carotid stenosis, cerebral hemodynamic derangement and cognitive impairment onset and progression, and underlined that cognitive impairment is the final result of the complex interaction between different elements, including also collateral circulation, cerebral hemodynamic status, brain connectivity and pro-inflammatory state. Further, therapeutic approaches, with a specific focus on vascular risk factors correction and on the effectiveness of surgical or endovascular interventions were discussed. We particularly focused our attention on the concept of “asymptomatic carotid stenosis”, and how could a cognitive impairment improve after an intervention, and how this could change the indications to surgical approach. Larger studies and randomized controlled trials are urgently required to better define time, characteristics and effectiveness of both medical and surgical/endovascular approaches.

The association between carotid blood flow and resting-state brain activity in patients with cerebrovascular diseases

Cerebral hypoperfusion impairs brain activity and leads to cognitive impairment. Left and right common carotid arteries (CCA) are the major source of cerebral blood supply. It remains unclear whether blood flow in both CCA contributes equally to brain activity. Here, CCA blood flow was evaluated using ultrasonography in 23 patients with cerebrovascular diseases. Resting-state brain activity and cognitive status were also assessed using magnetoencephalography and a cognitive subscale of the Functional Independence Measure, respectively, to explore the relationships between blood flow, functional brain activity, and cognitive status. Our findings indicated that there was an association between blood flow and resting-state brain activity, and between resting-state brain activity and cognitive status. However, blood flow was not significantly associated with cognitive status directly. Furthermore, blood velocity in the right CCA correlated with resting-state brain activity, but not with the resistance index. In contrast, the resistance index in the left CCA correlated with resting-state brain activity, but not with blood velocity. Our findings suggest that hypoperfusion is important in the right CCA, whereas cerebral microcirculation is important in the left CCA for brain activity. Hence, this asymmetry should be considered when designing appropriate therapeutic strategies.

Revascularization for asymptomatic carotid artery stenosis improves balance and mobility

OBJECTIVE

Balance and mobility function worsen with age, more so for those with underlying chronic diseases. We recently found that asymptomatic carotid artery stenosis (ACAS) restricts blood flow to the brain and might also contribute to balance and mobility impairment. In the present study, we tested the hypothesis that ACAS is a modifiable risk factor for balance and mobility impairment. Our goal was to assess the effect of restoring blood flow to the brain by carotid revascularization on the balance and mobility of patients with high-grade ACAS (≥70% diameter-reducing stenosis).

METHODS

Twenty adults (age, 67.0 ± 9.4 years) undergoing carotid endarterectomy for high-grade stenosis were enrolled. Balance and mobility assessments were performed before and 6 weeks after revascularization. These included the Short Physical Performance Battery, the Berg Balance Scale, the Four Square Step Test, the Dynamic Gait Index (DGI), the Timed Up and Go test, gait speed, the Mini-Balance Evaluation Systems Test (Mini-BESTest), and the Walking While Talking complex test.

RESULTS

Consistent with our previous findings, patients demonstrated reduced scores on the Short Physical Performance Battery, Berg Balance Scale, DGI, and Timed Up and Go test and in gait speed. Depending on the outcome measure, 25% to 90% of the patients had scored in the impaired range at baseline. After surgery, significant improvements were observed in the outcome measures that combined walking with dynamic movements, including the DGI (P = .02) and Mini-BESTest (P = .002). The proportion of patients with Mini-BESTest scores indicating a high fall risk had decreased significantly from 90% (n = 18) at baseline to 40% (n = 8) after surgery (P = .02). We used Pearson's correlations to examine the relationship between balance and mobility before surgery and the change after surgery. Patients with lower baseline DGI and Mini-BESTest scores demonstrated the most improvement after surgery (r = -0.59, P = .006; and r = -0.70, P = .001, respectively).

CONCLUSIONS

Carotid revascularization improved patients' balance and mobility, especially for measures that combine walking and dynamic movements. The greatest improvements were observed for the patients who had been most impaired at baseline.

Changes in Cognition and Hemodynamics 1 Year after Carotid Endarterectomy for Asymptomatic Stenosis

OBJECTIVES

 The impact of a change in hemodynamics on cognitive skills in patients with asymptomatic carotid stenosis (ACS) after carotid endarterectomy (CEA) remains unclear. The aim of this study was to evaluate the results of CEA for ACS at 1 year by assessing the changes in anterior, middle, and posterior cerebral artery blood flow in tandem with changes in cognitive efficiency.

METHODS

 Flow volume in cerebral arteries using quantitative magnetic resonance angiography was measured in a group of 14 males and 5 females before and at 1 year after CEA for ACS. Cognitive efficiency was assessed by Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The values of flow volume were processed using simple ratio (SR) and were used for covariance analyses with changes in cognitive skills after CEA.

RESULTS

 A significant improvement in cognitive efficiency indexes of immediate memory and visuospatial perception at 1 year after CEA for ACS was observed. Simultaneously, a significant deterioration of speech index was noted. During the analysis of association between flow and cognition, the highest correlation could be seen between the middle cerebral artery (MCA) flow and the visuospatial perception. A change in posterior cerebral artery (PCA) flow was associated with an increase in immediate memory index and anterior cerebral artery (ACA) flow change with the speech index.

CONCLUSION

 Convergence of data supporting the association between revascularization and cognitive improvement were added in a small, single-center cohort of ACS patients undergoing CEA. No significant differences in cognition were seen between preoperative findings and at 1 year after CEA. Visuospatial perception improvement was linked to flow change in MCA, immediate memory improvement to flow change in PCA, and speech index change to flow change in ACA. Methodical limitations of this small study preclude formulating larger generalizations. Hemodynamic factors in CEA should be assessed in a larger-scale study.

Carotid Revascularization Improves Cognition in Patients With Asymptomatic Carotid Artery Stenosis and Cognitive Decline. Greater Improvement in Younger Patients With More Disordered Neuropsychological Performance

OBJECTIVES

There has been a growing interest in whether carotid revascularization may reverse cognitive decline. In this study the aim was to assess cognitive changes after carotid artery endarterectomy and stenting, using neuropsychological assessment with MoCA and CANTAB test.

MATERIALS AND METHODS

Seventy patients with asymptomatic carotid artery stenosis, qualified for CEA (study group A) and CAS (study group B) have been prospectively assessed. 20 patients with lower extremity artery disease (control group C) and 15 patients qualified for inguinal hernia surgery (control group D) have served as a control group. Patients have been evaluated 1 day before surgery and 6 months after, using MoCA and CANTAB test. Logistic regression models were built to determine variables affecting cognitive performance.

RESULTS

After the procedure in the study group A the cognitive evaluation showed improvement in 5 cognitive domains tested in MoCA: visuospatial/executive (p=.0496), naming (p=.0831), language (p=.0009), abstraction (p=.0126) and delayed recall (p=.0016). In CANTAB there were improvement in PAL (p=.0290) and SWM (p=.0105). In study group B positive cognitive changes were seen in visuospatial/executive (p=.0827) and delayed recall (p=.0041) tested with MoCA and in PAL (PALFAMS28 p=.0315, PALNPR28 p=.0090, PALTEA28 p=.0058) and SWM (p=.0882) tested with CANTAB. Using a regression model, the only strong predictors of cognitive improvement on the follow-up visit were younger age and lower MoCA score on the first visit.

CONCLUSIONS

Carotid revascularization, both open and endovascular, lead to cognitive improvement in patients with severe carotid stenosis and cognitive decline. This effect seems to be stronger in younger patients with worst cognitive performance before surgery.

Chronic total occlusion and spontaneous recanalization of the internal carotid artery: Natural history and management strategy

OBJECTIVES

Spontaneous recanalization of a chronic total occlusion of the extra-cranial internal carotid artery is an under-reported clinical entity. This paper reviews the different etiologies of internal carotid artery occlusion, its natural course, as well as the significance and our recommendations for the management of spontaneous internal carotid artery recanalization.

METHODS

A review of literature on etiology, diagnosis, and treatment of internal carotid artery occlusion and recanalization was conducted. PubMed database was searched using the terms "internal carotid occlusion" and "recanalization". Articles were reviewed and studies involving the management of internal carotid artery occlusion and spontaneous recanalization were included. We subsequently developed a management algorithm for chronic total occlusion of the internal carotid artery and spontaneous recanalization of such lesions based on the available evidence.

RESULTS

Common etiologies of chronic total occlusion of the internal carotid artery include carotid atherosclerotic disease, cardioembolic, and carotid dissection. Progression of an asymptomatic to symptomatic occlusion is estimated at 2-8% annually. Well-compensated patients can be asymptomatic. In others, clinical symptoms range from ipsilateral or global hypoperfusion to embolic stroke in some cases of spontaneous recanalization. Spontaneous recanalization occurs in 2.3-10.3% of patients but rarely results in a cerebrovascular event.

CONCLUSIONS

Progression of an asymptomatic chronic total occlusion of the internal carotid artery to symptomatic is infrequent. The management algorithm of chronic total occlusion of the internal carotid artery and spontaneous recanalization of the internal carotid artery must be tailored to the patient based on symptoms, etiology of the lesion, imaging findings, surgical risk, and reliability for follow-up.

Associations Between Carotid Plaque Characteristics and Improvement of Cerebral Blood Perfusion in Patients With Moderate to Severe Carotid Stenosis Undergoing Carotid Endarterectomy

BACKGROUND

The relationship between plaque characteristics and their predictive value for perioperative cerebral blood flow (CBF) are unknown.

PURPOSE

To investigate the relationship between carotid plaque characteristics and perioperative CBF utilizing MRI.

STUDY TYPE

Prospective.

POPULATION

In all, 131 patients with carotid moderate-to-severe stenosis referred for carotid endarterectomy (CEA).

FIELD STRENGTH/SEQUENCE

3T, black-blood T₁ - and T₂ -weighted, 3D time-of-flight, and simultaneous noncontrast angiography intraplaque hemorrhage.

ASSESSMENT

The relative CBF (rCBF = CBF_{index-hemisphere} /CBF_{contralateral-hemisphere} ) and the CBF difference ratio (DR_CBF = [CBF_post-CEA - CBF_pre-CEA ]/CBF_pre-CEA ) in the middle cerebral artery territory were measured. The pre- and post-CEA CTP data were used as the assessment standard for CBF change. Carotid lipid-rich necrotic core (LRNC), intraplaque hemorrhage, calcification, fibrous cap rupture, maximum wall thickness, normalized wall index (NWI), and stenosis were determined.

STATISTICAL TESTS

Pearson or Spearman correlation, Mann-Whitney U-test, and linear regression.

RESULTS

Patients with LRNC had higher rCBF_pre-CEA than those without (1.0 ± 0.1 vs. 0.9 ± 0.1, P < 0.05). NWI was weakly correlated with rCBF_pre-CEA (r = -0.213, P < 0.05) and DR_CBF (r = 0.185, P < 0.05) and marginally correlated with rCBF_post-CEA (r = 0.166, P = 0.057). LRNC was weakly correlated with rCBF_pre-CEA (r = 0.179, P < 0.05). NWI was associated with rCBF_pre-CEA (β = -0.035; 95% confidence interval [CI] [-0.064, -0.006]; P < 0.05), rCBF_post-CEA (β = 0.042; 95% CI [0.002, 0.081]; P < 0.05) and DR_CBF (β = 0.105; 95% CI [0.026, 0.185]; P < 0.05). After adjusting for confounding factors, associations of NWI with rCBF_post-CEA (β = 0.059; 95% CI [0.016, 0.103]; P < 0.05) and DR_CBF (β = 0.110; 95% CI [0.021, 0.199]; P < 0.05) remained statistically significant, while the association between NWI and rCBF_pre-CEA was no longer significant (β = -0.026; 95% CI [-0.058, 0.006]; P = 0.112).The associations of LRNC with rCBF_pre-CEA (β = 0.057; 95% CI [-0.0006, 0.114]; P = 0.052) and DR_CBF (β = -0.157; 95% CI [-0.314, 0.001]; P = 0.051) were close to statistical significance. After adjusting for confounding factors, these associations were statistically significant (of LRNC vs. rCBF_pre-CEA : β = 0.060; 95% CI [0.003, 0.118]; P < 0.05; LRNC vs. DR_CBF : β = -0.205; 95% CI [-0.375, -0.036]; P < 0.05).

DATA CONCLUSION

Carotid plaque burden and components, particularly LRNC, might be effective indicators for CBF change following CEA. Level of Evidence 1 Technical Efficacy Stage 5.

Changes in Cognition, Depression and Quality of Life after Carotid Stenosis Treatment

BACKGROUND

Although several studies have evaluated the change of cognitive performance after severe carotid artery stenosis, the results still remain elusive. The objective of this study was to assess changes in cognitive function, depressive symptoms and Health Related Quality of Life (HRQoL) after carotid stenosis revascularisation and Best Medical Treatment (BMT).

METHODS

Study involved 213 patients with ≥70% carotid stenosis who underwent assessment of cognitive function using Montreal Cognitive Assessment scale (MoCA), depressive symptoms - using Patient Health Questionnaire-9 (PHQ-9) and HRQoL - using Medical Outcome Survey Short Form version 2 (SF-36v2). The assessment was performed before and at 6 and 12 months followup periods in patients who had Carotid Endarterectomy (CEA), Carotid Artery Stenting (CAS) or received BMT only.

RESULTS

Improvement in the total MoCA scores was observed after 6 and 12 months (p<0.001, Kendall's W=0.28) in the CEA group. In the CAS group - after 12 months (p=0.01, Kendall's W=0.261) whereas in the BMT group - no significant changes (p=0.295, Kendall's W=0.081) were observed. Reduction of depressive symptoms was not found in any of the study groups. Comparing mean SF-36v2 scores in the CEA group, there was no significant difference in any of 10 subscales. Likewise in the CAS group - no significant difference in 9 of 10 subscales (p=0.028, η2=0.343) was observed. Three subscales worsened in the BMT group during the 1-year follow-up period.

CONCLUSION

Patients with severe carotid stenosis who underwent revascularisation enhanced their cognitive performance without exerting significant change of depressive symptoms. Preoperative HRQoL may be maintained for at least one year in the CEA group.

Carotid Revascularization and Its Effect on Cognitive Function: A Prospective Nonrandomized Multicenter Clinical Study

BACKGROUND

There is conflicting data on the effect of carotid revascularization on cognitive function.

OBJECTIVE

To examine cerebral blood flow and cognitive function after carotid revascularization.

METHODS

Patients with unilateral, asymptomatic hemodynamically significant carotid artery stenosis (80% by computed tomography angiography or magnetic resonance angiography) were eligible. Cerebral blood flow was measured preoperatively and 1 month postoperatively using quantitative phase contrast magnetic resonance angiography. Preoperative flow impairment was defined as ipsilateral flow at least 20% less than contralateral flow (ie, an ipsilateral and/or contralateral flow ratio ≤0.8). Significant improvement in blood flow was defined as at least a 0.15 increase in flow ratio from pre- to postoperative. A control group was managed medically. Four cognitive domains were assessed at baseline, 1 month, and 6-12 months postoperatively.

RESULTS

Seventy-five patients were enrolled at 6 sites; 53 carotid endarterectomy, 11 carotid artery stenting, and 11 medical management only controls. Preoperative Trails B scores were similar between groups. Revascularization was associated with significant improvement in executive function (Trials B) while no improvement was observed in controls (P = .007). Of patients with improvement in middle cerebral artery (MCA) flow, 90% had improved Trails B scores compared to 46.5% of patients without MCA flow improvement (P = .01). Greater absolute improvement in mean Trails B scores was observed in patients with MCA flow improvement compared to those without (48 seconds versus 24.7 seconds, P = .001).

CONCLUSIONS

In a cohort of patient with asymptomatic carotid stenosis, improvement in MCA flow following carotid revascularization is associated with improvement in executive functioning.

Neurocognitive Changes After Carotid Revascularization According to Perfusion Parameters: A Meta-analysis of Current Literature

BACKGROUND

Although the clinical outcomes continue to be scrutinized, there are a few data summarizing the changes in perfusion parameters in postoperative patients. The objective was to undertake a systematic literature review and perform a meta-analysis to assess the effects of cerebral perfusion changes in cognitive and functional status.

METHODS

A systematic search was conducted in July 2018 identifying articles comparing perfusion parameter changes before and after carotid revascularization in patients with carotid artery stenosis. Combined overall effect sizes were calculated using random-effects models.

RESULTS

The literature search identified 1031 unique articles eligible for analysis. Sixteen studies including 755 patients were identified. The studies were different for many methodological factors, for example, sample size, type of patients, statistical measure, type of test, timing of assessment, and so on. There were no differences in cerebral blood volume (CBV), cerebral metabolic rate of oxygen (CMRO₂), and relative cerebral blood volume (rCBV) between preintervention and postintervention, but there was a significant increase of cerebral blood flow (CBF) (95% confidence interval [CI] standardized mean difference [Std. MD] : -0.83 [-1.27, -0.40]; P = 0.0002; I² = 68%) and relative cerebral blood flow (rCBF) (95% CI Std. MD: -0.72 [-1.61, -0.27]; P < 0.0001; I² = 48%) after operation. In addition, the perfusion of mean transit time (MTT) (95% CI Std. MD: 1.26 [0.62, 1.90]; P = 0.0001; I² = 84%), oxygen extraction fraction (OEF) (95% CI Std. MD: 0.78 [0.24, 1.33]; P = 0.005; I² = 0%), time to peak (TTP) (95% CI Std. MD: 0.46 [0.16, 0.77]; P = 0.003; I² = 47%), and relative mean transit time (rMTT) (95% CI Std. MD: 0.41 [0.33, 0.50]; P < 0.00001; I² = 67%) was higher before than after operation.

CONCLUSIONS

The increase in changes in CBF and rCBF and the decrease in MTT, OEF, TTP, and rMTT after operation may indicate the improvement of cognition in the short term. Intraoperative perfusion parameters could be an important adjuvant monitoring method in neurocognitive changes after carotid revascularization.

Carotid Flow Velocities and Blood Pressures Are Independently Associated With Cognitive Function

BACKGROUND

Few studies simultaneously addressed associations between carotid flow velocities, blood pressure (BP), and cognitive function.

MATERIALS AND METHODS

Subject without dementia (N = 1,684) underwent measurements of BP and biochemical markers. Mini-Mental State Examination (MMSE) and comprehensive neuropsychological tests were used to evaluate cognitive function. Peak systolic velocity (PSV) and end-diastolic velocity (EDV) were measured in common and internal carotid artery. Subjects with MMSE score of ≤24 (25th percentile) was defined as low MMSE. Multivariable linear and logistic regression were used to evaluate the relationship of cognitive function with carotid flow velocities and BP.

RESULTS

Carotid flow velocities (PSV: standardized β = 0.067, P = 0.0009; and EDV: standardized β = 0.067, P = 0.0021) and systolic blood pressure (standardized β = -0.061, P = 0.005) were positively and negatively associated with MMSE, respectively, in the model with adjustments for age, sex, educational attainment, nutritional status, and smoking. Similar trends were noted for the associations between flow velocities and different neuropsychological tests. By multivariable logistic regression, the group with the lowest quartile (<25th percentile) of flow velocities had increased probability of low MMSE (odds ratio: 1.538; 95% confidence intervals: 1.142 to 2.071, P = 0.0046 for PSV; and odds ratio: 1.699; 95% confidence intervals: 1.233 to 2.341; P = 0.0012 for EDV), compared to those with the highest quartile (≥75th) flow velocities.

CONCLUSION

Both low carotid flow velocity and high BP were independently and comparably associated with cognitive dysfunction.

Convergence Analysis of Micro-Lesions (CAML): An approach to mapping of diffuse lesions from carotid revascularization

Carotid revascularization (endarterectomy, stenting) prevents stroke; however, procedure-related embolization is common and results in small brain lesions easily identified by diffusion weighted magnetic resonance imaging (DWI). A crucial barrier to understanding the clinical significance of these lesions has been the lack of a statistical approach to identify vulnerable brain areas. The problem is that the lesions are small, numerous, and non-overlapping. Here we address this problem with a new method, the Convergence Analysis of Micro-Lesions (CAML) technique, an extension of the Anatomic Likelihood Analysis (ALE). The method combines manual lesion tracing, constraints based on known lesion patterns, and convergence analysis to represent regions vulnerable to lesions as probabilistic brain atlases. Two studies were conducted over the course of 12 years in an active, vascular surgery clinic. An analysis in an initial group of 126 patients at 1.5 T MRI was cross-validated in a second group of 80 patients at 3T MRI. In CAML, lesions were manually defined and center points identified. Brains were aligned according to side of surgery since this factor powerfully determines lesion distribution. A convergence based analysis, was performed on each of these groups. Results indicated the most consistent region of vulnerability was in motor and premotor cortex regions. Smaller regions common to both groups included the dorsolateral prefrontal cortex and medial parietal regions. Vulnerability of motor cortex is consistent with previous work showing changes in hand dexterity associated with these procedures. The consistency of CAML also demonstrates the feasibility of this new approach to characterize small, diffuse, non-overlapping lesions in patients with multifocal pathologies.

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Convergence Analysis of Micro-Lesions technique finds patterns in diffuse lesions.

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Lesions from carotid revascularization affect consistent brain targets.

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Motor cortex is the most vulnerable brain region to these lesions.

Quantitative magnetic resonance angiography as a potential predictor for cerebral hyperperfusion syndrome: a preliminary study

OBJECTIVE

Cerebral hyperperfusion syndrome (CHS) is a rare but devastating complication of carotid endarterectomy (CEA). This study sought to determine whether quantitative hemodynamic assessment using MR angiography can stratify CHS risk.

METHODS

In this prospective trial, patients with internal carotid artery (ICA) stenosis were randomly selected for pre- and postoperative quantitative phase-contrast MR angiography (QMRA). Assessment was standardized according to a protocol and included Doppler/duplex sonography, MRI, and/or CT angiography and QMRA of the intra- and extracranial supplying arteries of the brain. Clinical and radiological data were analyzed to identify CHS risk factors.

RESULTS

Twenty-five of 153 patients who underwent CEA for ICA stenosis were randomly selected for pre- and postoperative QMRA. QMRA data showed a 2.2-fold postoperative increase in blood flow in the operated ICA (p < 0.001) and a 1.3-fold increase in the ipsilateral middle cerebral artery (MCA) (p = 0.01). Four patients had clinically manifested CHS. The mean flow increases in the patients with CHS were significantly higher than in the patients without CHS, both in the ICA and MCA (p < 0.001). Female sex and a low preoperative diastolic blood pressure were the clearest clinical risk factors for CHS, whereas the flow differences and absolute postoperative flow values in the ipsilateral ICA and MCA were identified as potential radiological predictors for CHS.

CONCLUSIONS

Cerebral blood flow in the ipsilateral ICA and MCA as assessed by QMRA significantly increased after CEA. Higher mean flow differences in ICA and MCA were associated with the development of CHS. QMRA might have the potential to become a noninvasive, operator-independent screening tool for identifying patients at risk for CHS.

Perceived Cognition after Percutaneous Coronary Intervention: Association with Quality of Life, Mood and Fatigue in the THORESCI Study

Purpose

Percutaneous coronary intervention (PCI) is a common invasive procedure for the treatment of coronary artery diseases. Long-term cognitive functioning after PCI and its association with health-related quality of life (HRQL) and psychological factors is relatively unknown. The aim of this study is to examine whether perceived cognitive functioning during the year after PCI is associated with HRQL over this time period, and whether mood, fatigue, and age are associated with changes in perceived cognition and HRQL.

Methods

Patients undergoing PCI (n = 384, 79% male, mean age = 63, SD = 10) were recruited in the observational Tilburg Health Outcome Registry of Emotional Stress after Coronary Intervention (THORESCI) cohort study. Perceived concentration and attention problems, HRQL, mood, and fatigue were assessed at baseline, at 1-month and 12-month follow-up.

Results

General linear mixed modeling analysis showed that across time, between- and within-subject differences in perceived concentration problems were associated with a reduced HRQL in all domains independent of clinical and demographic covariates. Only a part of this association could be explained by negative mood, fatigue, and older age. Similar findings were found for between-subject differences in perceived attention problems.

Conclusions

Between-subject differences and within-subject changes in perceived cognition in PCI patients were strongly associated with HRQL across time, such that poorer perceived cognition was associated with poorer HRQL, independent of demographic and clinical variables. Most of the associations were also independent of mood and fatigue. The results should increase the awareness of clinicians for the role of cognition in the cardiac rehabilitation and recovery post-PCI.

Carotid Stenosis and Impaired Cognition: The Effect of Intervention

There is a clear association between carotid artery stenosis and cognitive impairment. However, there is no consensus as to how to interpret this association, and what, if any, impact this connection should have on the management of carotid stenosis. A review of the relevant literature suggests that although an intervention to relieve carotid stenosis in patients without clinically significant cognitive impairment does not improve cognition, there may be a cognitive benefit with intervention for carotid stenosis in those patients with clinically significant cognitive disorders.

Atherosclerotic carotid stenosis and cognitive function

Atherosclerosis carotid stenosis is associated with stroke and cognitive impairment. Progressive cognitive decline may be an even greater problem than stroke, but it has not been widely recognized and therefore must be adequately addressed. Although both Carotid Endarterectomy (CEA) and Carotid Artery Stenting (CAS) have been proven can prevent future stroke in patients with atherosclerotic carotid stenosis, the influence of CEA and CAS on cognitive function is not clear. In the first part of this review, we evaluated the literature concerning carotid stenosis and the risk of cognitive impairment. Studies have suggested that both symptomatic and asymptomatic carotid stenosis are associated with cognitive impairment. In the second part, we reviewed the impact of CEA and CAS on cognitive function, some studies have shown benefits, but others have not.

Patients with carotid atherosclerosis who underwent or did not undergo carotid endarterectomy: outcome on mood, cognition and quality of life

BACKGROUND

To compare the six-month outcome on mood, cognition and quality of life (QoL) in patients with severe carotid atherosclerosis (CA) who underwent carotid endarterectomy (CEA) with subjects who refused treatment.

METHODS

Cohort study on consecutive inpatients with CA (stenosis ≥ 50 %) (N = 46; age 72.56 ± 7.26; male 65.2 %). Intervention cohort: subjects who decided to undergo CEA (N = 35); Control cohort patients who refused CEA (N = 11). DSM-IV-Psychiatric diagnosis made by clinicians using interviews, QoL measured by Short Form Health Survey (SF-12); cognitive performance by WAIS Intelligent Coefficient (IC).

RESULTS

The study showed a better improvement during six months in Overall IC, Performance IC and Verbal IC in the group that underwent CEA. QoL in the two cohorts did not reach statistical significance. Percentages of patients who improved in the CEA group were significantly higher with regard to Overall and Verbal IC scores, and at the limits of statistical significance in Performance IC. The differences of subject with improvement in SF-12 score in the two groups did not reach statistical significance. Ages below 68 were found to be determinant of a good outcome in Overall IC score. Limit: study conducted with a small sample size.

CONCLUSIONS

Patients with severe carotid atherosclerosis who underwent CEA enhanced their cognitive performance.

Improvement in venous outflow following superior sagittal sinus decompression after a gunshot wound to the head: case report

The most commonly described indications for surgical management of closed depressed skull fractures are hematoma evacuation and repair of extensive cosmetic deformity. Venous sinus injury, which occurs in a subset of depressed skull fractures, is not typically listed as an indication for surgical treatment due to the potential for major venous hemorrhage associated with surgery near these structures. However, if patients exhibit signs and symptoms of intracranial hypertension and radiographic findings demonstrate sinus compromise, surgical elevation of the depressed skull fragments is indicated. The authors present the case of a 25-year-old woman with a depressed skull fracture secondary to a gunshot wound with symptomatic compromise in venous outflow of the posterior one-third of the superior sagittal sinus. The patient was treated with surgical decompression via bilateral craniectomy along with intracranial pressure-lowering medical therapy and had almost full resolution of her presenting symptoms with documented improvement in flow through the superior sagittal sinus. While the use of surgical treatment for these types of injuries is highly debated, the authors demonstrate here that safe, effective surgical management of these patients is possible and that surgical decompression should always be considered in the case of symptomatic venous sinus flow obstruction.

Carotid endarterectomy versus stenting: Does the flow really change? An Echo-Color-Doppler analysis

To assess potential hemodynamic differences after carotid endarterectomy (CEA) and carotid artery stenting (CAS) and their eventual impact on clinical management. Between July 2012 and October 2013 two groups of 30 patients each referred for CEA or CAS were prospectively enrolled in two tertiary hospital care centers. Pre-procedural imaging assessment of carotid artery disease was performed with Echo-Color-Doppler (ECD) and computed tomography angiography (CTA). ECD was repeated within 24 h and 1, 6 and 12 months after surgical/endovascular procedures. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were assessed at two standard sites: common carotid artery (CCA) and distal internal carotid artery (ICA). Twenty-four hours ECD findings highly differ between the two populations. CCA PSV in the CEA and CAS groups was respectively 44.88 ± 9.16 and 69.20 ± 20.04 cm/s (p = 0.002); CCA EDV was 16.11 ± 2.29 and 19.13 ± 6.42 cm/s (p = 0.065); ICA PSV was 46.11 ± 7.9 and 94.02 ± 57.7 cm/s (p = 0.0012); ICA EDV was 20.22 ± 4.33 and 30.47 ± 18.33 cm/s (p = 0.025). One month, 6 months and 1 year findings confirmed the different trend in the two cohorts; in particular, at 1 year: CCA PSV was 50.94 ± 12.44 and 60.59 ± 26.84 cm/s (p = 0.181); CCA EDV was 17.11 ± 3.46 and 19 ± 16.35 cm/s (p = 0.634); ICA PSV was 51.66 ± 10.1 and 70.86 ± 20.64 cm/s (p = 0.014); ICA EDV was 25.05 ± 8.65 and 32.66 ± 13 cm/s (p = 0.0609). ECD follow-up of patients undergone CEA or CAS may play a critical role in the clinical management. Strict surveillance of blood flow velocities allows reducing false positive re-stenosis diagnosis and choosing the best anti-aggregation therapies. Within the first month CEA patients benefit from a lower risk condition in comparison with CAS patients, due to a significantly faster PSV drop; moreover, long-term CCA PSV after CEA could be used as a surrogate marker of neointima formation.

Influence of stent-assisted angioplasty on cognitive function and affective disorder in elderly patients with symptomatic vertebrobasilar artery stenosis

BACKGROUND

We aimed to investigate cognitive function and affective disorder in elderly patients with symptomatic vertebrobasilar artery stenosis (SVAS) after stent-assisted angioplasty (SAA) and to explore the potential mechanism.

MATERIAL AND METHODS

The study subjects were 26 elderly SVAS patients who were non-responsive to pharmacotherapy and received SAA (study group) and 30 patients receiving intracoronary stent implantation (control group). Montreal cognitive assessment (MoCA), Hamilton depression rating scale (HAMD), and Hamilton anxiety rating scale (HAMA) were used.

RESULTS

The total MoCA score, scores of line connection, copying cube, drawing clock, and delayed recall increased significantly in the study group after surgery (P<0.05, P<0.01). In addition, the MoCA score increased over time and the total MoCA score at 12 months was markedly higher than that at 1 month (P<0.05). The scores of HAMD and HAMA decreased dramatically after surgery compared with before surgery in these patients (P<0.01). A comparison at the corresponding period was performed between study group and control group, and it was found that the differences in total MoCA scores and scores of line connection, copying cube, drawing clock, and delayed recall before surgery and at 1 month after surgery were significant (P<0.05, P<0.01).

CONCLUSIONS

SAA may improve the visuospatial/executive abilities and delayed recall, as well as the depression and anxiety in patients with SVAS. Larger and controlled trails are needed to investigate the effect of SAA on cognition and affection in these patients.

Neurocognitive functioning after carotid revascularization: a systematic review

BACKGROUND

The objective of this study was to review the recent literature regarding the neurocognitive consequences of carotid endarterectomy (CEA) and carotid stenting (CAS).

METHODS AND RESULTS

A PubMed and Web of Science search was conducted using the key words 'carotid' in combination with 'cognitive', 'cognition', 'neurocognition', 'neurocognitive', 'neuropsychology', and 'neuropsychological'. Bibliographies of relevant articles were cross-referenced. We included 37 studies published since 2007 of which 18 examined CEA, 12 CAS, and 7 compared CEA to CAS. There is a wide variability in the reported neurocognitive outcome following CEA and CAS. Nonetheless, none of the included studies unveiled significant differences between CEA and CAS on postoperative neurocognitive functioning. Postoperative changes observed for CEA and CAS separately seem limited to a small percentage (around 10-15%) of patients and can either present as an improvement or impairment.

KEY MESSAGES

The available data seem to suggest that no obvious cognitive differences between CAS and CEA can be observed after intervention. Both improvement and deterioration in cognitive functioning can be observed following CAS or CEA. Methodological differences such as patient heterogeneity, implementation and type of control groups, type of psychometric tests used, statistical analyses, or timing of the assessments play an important role in explaining the sometimes divergent results of the included studies. Large-scale and methodologically solid studies comparing CEA and CAS on neurocognitive outcome remain warranted. Future studies should implement adequate control groups to correct for practice effects in the target groups.

Middle cerebral artery pulsatility index and cognitive improvement after carotid endarterectomy for symptomatic stenosis

OBJECT

Transcranial Doppler (TCD) is frequently used to evaluate peripheral cerebral resistance and cerebral blood flow (CBF) in the middle cerebral artery prior to and during carotid endarterectomy (CEA). Patients with symptomatic carotid artery stenosis may have reduced peripheral cerebral resistance to compensate for inadequate CBF. The authors aim to determine whether symptomatic patients with reduced peripheral cerebral resistance prior to CEA demonstrate increased CBF and cognitive improvement as early as 1 day after CEA.

METHODS

Fifty-three patients with symptomatic CEA were included in this observational study. All patients underwent neuropsychometric evaluation 24 hours or less preoperatively and 1 day postoperatively. The MCA was evaluated using TCD for CBF mean velocity (MV) and pulsatility index (PI). Pulsatility index ≤ 0.80 was used as a cutoff for reduced peripheral cerebral resistance.

RESULTS

Significantly more patients with baseline PI ≤ 0.80 exhibited cognitive improvement 1 day after CEA than those with PI > 0.80 (35.0% vs 6.1%, p = 0.007). Patients with cognitive improvement had a significantly greater increase in CBF MV than patients without cognitive improvement (13.4 ± 17.1 cm/sec vs 4.3 ± 9.9 cm/sec, p = 0.03). In multivariate regression model, a baseline PI ≤ 0.80 was significantly associated with increased odds of cognitive improvement (OR 7.32 [1.40-59.49], p = 0.02).

CONCLUSIONS

Symptomatic CEA patients with reduced peripheral cerebral resistance, measured as PI ≤ 0.80, are likely to have increased CBF and improved cognitive performance as early as 1 day after CEA for symptomatic carotid artery stenosis. Revascularization in this cohort may afford benefits beyond prevention of future stroke. Clinical trial registration no: NCT00597883 ( ClinicalTrials.gov ).

Cholinergic control of the cerebral vasculature in humans

Despite growing evidence of autonomic nervous system involvement in the regulation of cerebral blood flow, the specific contribution of cholinergic vasodilatation to cerebral autoregulation remains unknown. We examined cerebral and forearm blood flow responses to augmented arterial pressure oscillations with and without cholinergic blockade. Oscillatory lower body negative pressure was applied at six frequencies from 0.03 to 0.08 Hz in nine healthy subjects with and without cholinergic blockade via glycopyrrolate. Cholinergic blockade increased cross-spectral coherence between arterial pressure and cerebral flow at all frequencies except 0.03 Hz and increased the transfer function gain at frequencies above 0.05 Hz. In contrast, gain between pressure and forearm flow increased only at frequencies below 0.06 Hz. These data demonstrate that the cholinergic system plays an active and unique role in cerebral autoregulation. The frequency region and magnitude of effect is very similar to what has been seen with sympathetic blockade, indicating a possible balance between the two reflexes to most effectively respond to rising and falling pressure. These findings might have implications for the role of dysfunction in autonomic control of the vasculature in cerebrovascular disease states.

Cognitive function and carotid stenosis: Review of the literature

Stroke is a known cause of cognitive impairment but the relationship between asymptomatic carotid artery stenosis and cognitive function is not clear. The main risk factors for vascular disease are also related to carotid stenosis and cognitive impairment. The association of high-grade stenosis of the internal carotid artery with cognitive impairment is related to silent embolization and hypoperfusion, but it may also be present without evidence of infarction on magnetic resonance imaging. Carotid stenosis treatment may lead to a decline in cognitive function due to complications related to the procedures (endarterectomy or stenting). On the other hand, reperfusion may improve cognitive impairment. The best treatment choice is unclear, considering possible deterioration of cognitive function related to carotid artery stenosis. There is insufficient evidence to consider cognitive impairment an important factor in determining the therapy for carotid stenosis.