Radiographic absence of the posterior communicating arteries and the prediction of cognitive dysfunction after carotid endarterectomy

Association of Cerebral Hypoperfusion and Poor Collaterals with Cognitive Impairment in Patients with Severe Vertebrobasilar Artery Stenosis

Background

Effect of stenosis of vertebrobasilar artery (VBA) on cognitive function is elusive.

Objective

To investigate association of cerebral hypoperfusion and poor collaterals with vascular cognitive impairment (VCI) in severe VBA stenosis patients.

Methods

We consecutively enrolled patients with severe VBA stenosis confirmed by digital subtraction angiography who underwent computed tomographic perfusion (CTP) and cognitive assessments. Patients were divided into poor or good collaterals groups according to the collateral circulation status, and were grouped into different perfusion groups according to CTP. Cognitive function was measured by Montreal Cognitive Assessment (MoCA), Clock Drawing Test, Stroop Color Word Test, Trail Making Test, Digital Span Test, Auditory Verbal Learning Test, and Boston Naming Test scales. The association of cerebral perfusion and collaterals with VCI were explored.

Results

Among 88 eligible patients, VCI occurred in 51 (57.9%) patients experienced. Poor collateral was present in 73 (83.0%) patients, and hypoperfusion in 64 (72.7%). Compared with normal perfusion patients, the odds ratio with 95% confidence interval for VCI was 12.5 (3.7-42.4) for overall hypoperfusion, 31.0 (7.1-135.5) for multiple site hypoperfusion, 3.3 (1.0-10.5) for poor collaterals, and 0.1 (0-0.6) for presence of posterior communicating artery (PcoA) compensated for posterior cerebral artery (PCA) and basilar artery (BA). Additionally, decreased scores of cognitive function tests occurred in patients with decompensated perfusion or poor collaterals.

Conclusions

Hypoperfusion and poor collaterals were positively associated with cognitive impairment in patients with severe VBA. However, PcoA compensated for the PCA and BA had a protective role in cognitive impairment development.

The role of early cerebral edema and hematoma assessment in aneurysmal subarachnoid hemorrhage (a-SAH) in predicting early brain injury (EBI) and cognitive impairment: a case controlled study

BACKGROUND

Early assessment and management of cerebral edema and hematoma following aneurysmal subarachnoid hemorrhage (a-SAH) can significantly impact clinical cognitive outcomes. However, current clinical practices lack predictive models to identify early structural brain abnormalities affecting cognition. To address this gap, the authors propose the development of a predictive model termed the a-SAH Early Brain Edema/Hematoma Compression Neural (Structural Brain) Networks Score System (SEBE-HCNNSS).

METHODS

In this study, 202 consecutive patients with spontaneous a-SAH underwent initial computed tomography (CT) or MRI scans within 24 h of ictus with follow-up 2 months after discharge. Using logistic regression analysis (univariate and multivariate), the authors evaluated the association of clinically relevant factors and various traditional scale ratings with cognitive impairment (CI). Risk factors with the highest area under the curve (AUC) values were included in the multivariate analysis and least absolute shrinkage and selection operator (LASSO) analysis or Cox regression analysis.

RESULTS

A total of 177 patients were enrolled in the study, and 43 patients were classified with a high SEBE-HCNNSS grade (3-5). After a mean follow-up of 2 months, 121 individuals (68.36%) with a-SAH and three control subjects developed incident CI. The CT interobserver reliability of the SEBE-HCNNSS scale was high, with a Kappa value of 1. Furthermore, ROC analysis identified the SEBE-HCNNSS scale (OR 3.322, 95% CI: 2.312-7.237, P =0.00025) as an independent predictor of edema, CI, and unfavorable prognosis. These results were also replicated in a validation cohort.

CONCLUSION

Overall, the SEBE-HCNNSS scale represents a simple assessment tool with promising predictive value for CI and clinical outcomes post-a-SAH. Our findings indicate its practical utility as a prognostic instrument for risk evaluation after a-SAH, potentially facilitating early intervention and treatment.

Non-Invasive Tools in Perioperative Stroke Risk Assessment for Asymptomatic Carotid Artery Stenosis with a Focus on the Circle of Willis

This review aims to explore advancements in perioperative ischemic stroke risk estimation for asymptomatic patients with significant carotid artery stenosis, focusing on Circle of Willis (CoW) morphology based on the CTA or MR diagnostic imaging in the current preoperative diagnostic algorithm. Functional transcranial Doppler (fTCD), near-infrared spectroscopy (NIRS), and optical coherence tomography angiography (OCTA) are discussed in the context of evaluating cerebrovascular reserve capacity and collateral vascular systems, particularly the CoW. These non-invasive diagnostic tools provide additional valuable insights into the cerebral perfusion status. They support biomedical modeling as the gold standard for the prediction of the potential impact of carotid artery stenosis on the hemodynamic changes of cerebral perfusion. Intraoperative risk assessment strategies, including selective shunting, are explored with a focus on CoW variations and their implications for perioperative ischemic stroke and cognitive function decline. By synthesizing these insights, this review underscores the potential of non-invasive diagnostic methods to support clinical decision making and improve asymptomatic patient outcomes by reducing the risk of perioperative ischemic neurological events and preventing further cognitive decline.

The risk factors of postoperative cognitive dysfunction in patients undergoing carotid endarterectomy: an updated meta-analysis

OBJECTIVE

The purpose of the current meta-analysis was to determine the incidence and risk factors to provide a scientific basis for prevention and treatment of postoperative cognitive dysfunction (POCD) after carotid endarterectomy (CEA).

METHODS

Relevant articles published before October 2022 were searched from Pubmed/MEDLINE, Cochrane and Embase databases. The outcomes were the incidence and risk factors for POCD. A random-effects model was applied to estimate the overall odds ratios (ORs) and mean differences (MDs) for all risk factors through STATA 14.0 and RevMan 5.4. The quality of eligible studies was evaluated by Newcastle-Ottawa Scale (NOS) as previously described.

RESULTS

A total of 22 articles involving 3459 CEA patients were finally identified. The weighted mean incidence of POCD was 19% (95% confidence intervals (95% CI) 0.16-0.24, P < 0.001). Of the 16 identified risk factors, hyperperfusion (OR: 0.54, 95% CI 0.41-0.71) and degree of internal carotid artery (ICA) stenosis (OR: 5.06, 95% CI 0.86-9.27) were the potential risk factors of POCD, whereas patients taking statins preoperative had a lower risk of POCD (OR: 0.54, 95% CI 0.41-0.71). Subgroup analysis revealed that the risk of POCD at 1 month after CEA was higher in patients with diabetes (OR: 1.70, 95% CI 1.07-2.71).

CONCLUSION

The risk factors of POCD were hyperperfusion and degree of ICA stenosis, while diabetes could significantly increase the incidence of POCD at 1 month after surgery. Additionally, preoperative statin use could be a protective factor for POCD following CEA.

Morphologic variants of the Cerebral Arterial Circle on computed tomographic angiography (CTA): a large retrospective study

PURPOSE

To confirm and illustrate the great variability of morphology of the Cerebral Arterial Circle (CAC)-also commonly called "Circle of Willis"-in current clinical Computed Tomography Angiography (CTA) practice.

METHODS

Computed Tomographic Angiographic 3D Volume Rendering reconstructions of the CAC performed in a series of 511 patients were retrospectively reviewed and classified following their anatomic configuration.

RESULTS

An amount of 27 CAC configurations were listed. Complete and "nearly complete" (1 missing segment) CACs were found in 115 (22.58%) and 157 (28.6%) patients. The posterior arch was much more frequently incomplete (374 patients = 73.18%) than the anterior arch (96 patients = 18.4%). The main cause was a high prevalence of missing posterior communicating arteries (PCoAs). The left or right PCoA were unilaterally lacking in 156 patients (30.53%) and both PCoAs were lacking in 179 patients (35.02%). Cases with 2 and 3 missing segments were observed in 184 (36%) and 44 patients (8.6%). Precarious situations were also identified including 7 cases (1.4%) of complete isolation of the middle cerebral artery (MCA), 11 cases (2.15%) of absence of interhemispheric supply, 205 cases (40.1%) of full separation of the carotid and vertebra-basilar (VB) territories and 44 cases (8.6%) of full separation of the three main arterial axes (both ICAs and VB). The prevalence of Fetal Posterior Cerebral Arteries (FPCA) variants was also reported. A "Full" FPCA was found unilaterally in 48 (9.4%) and bilaterally in 13 (2.54%) of patients. Apart from agenesis and hypoplasia reported in our study, various other variations of the anterior complex of the CAC (ACoA and A2 segments of the ACA) were also noted.

CONCLUSION

CTA with 3D Volume Rendering may powerfully assess the numerous variations of the CAC. This assessment is of prime importance for the evaluation of patients presenting with risk factors or in whom neurosurgery, cardiac surgery, interventional radiology or carotid endarterectomy (CEA) are being considered.

Limitations of median nerve somatosensory evoked potential monitoring during carotid endarterectomy

OBJECTIVE

Hypoperfusion during carotid artery cross-clamping (CC) for carotid endarterectomy (CEA) may result in the major complication of perioperative stroke. Median nerve somatosensory evoked potential (MNSSEP) monitoring, which is an established method for the prediction of cerebral ischemia, has low sensitivity in detecting such hypoperfusion. In this study the authors sought to explore the limitations of MNSSEP monitoring compared to tibial nerve somatosensory evoked potential (TNSSEP) monitoring for the detection of CC-related hypoperfusion.

METHODS

The authors retrospectively analyzed data from patients who underwent unilateral CEA with routine shunt use. All patients underwent preoperative magnetic resonance angiography and were monitored for intraoperative cerebral ischemia by using MNSSEP, TNSSEP, and carotid stump pressure during CC. First, the frequency of MNSSEP and TNSSEP changes during CC were analyzed. Subsequently, variables related to stump pressure were determined by using linear analysis and those related to each of the somatosensory evoked potential (SSEP) changes were determined by using logistic regression analysis.

RESULTS

A total of 94 patients (mean age 74 years) were included in the study. TNSSEP identified a greater number of SSEP changes during CC than MNSSEP (20.2% vs 11.7%; p < 0.05). Linear regression analysis demonstrated that hypoplasia of the contralateral proximal segment of the anterior cerebral artery (A1 hypoplasia) (p < 0.01) and hypoplasia of the ipsilateral precommunicating segment of the posterior cerebral artery (P1 hypoplasia) (p = 0.02) independently and negatively correlated with stump pressure. Both contralateral A1 hypoplasia (OR 26.25, 95% CI 4.52-152.51) and ipsilateral P1 hypoplasia (OR 8.75, 95% CI 1.83-41.94) were independently related to the TNSSEP changes. However, only ipsilateral P1 hypoplasia (OR 8.76, 95% CI 1.61-47.67) was independently related to MNSSEP changes.

CONCLUSIONS

TNSSEP monitoring appears to be superior to MNSSEP in detecting CC-related hypoperfusion. Correlation with stump pressure and SSEP changes indicates that TNSSEP, and not MNSSEP monitoring, is a reliable indicator of cerebral ischemia in the territory of the anterior cerebral artery.

Stroke mechanisms and outcomes of isolated symptomatic basilar artery stenosis

Background

While diffuse atherosclerotic disease affecting the posterior circulation has been described extensively, the prevalence, natural history and angiographic characteristics of isolated symptomatic basilar artery stenosis (ISBAS) remain unknown.

Methods

We reviewed our prospective institutional database to identify patients with ≥50% symptomatic basilar artery (BA) stenosis without significant atherosclerotic burden in the vertebral or posterior cerebral arteries. Stroke mechanism, collateral circulation, and degree and length of stenosis were analysed. The primary outcome was time from index event to new transient ischaemic attack (TIA), acute ischaemic stroke (AIS) or death. Other outcome variables included modified Rankin Scale (mRS) score on discharge and last follow-up.

Results

Of 6369 patients with AIS/TIA, 91 (1.43%) had ISBAS. Seventy-three (80.2%) patients presented with AIS and 18 (19.8%) with TIA. Twenty-nine (31.9%) were women and the median age was 66.8±13.6 years. The mean follow-up time was 2.7 years. The most common stroke mechanism was artery-to-artery thromboembolism (45.2%), followed by perforator occlusion (28.7%) and flow-dependent/hypoperfusion (15.1%). The percentage of stenosis was lower in patients who had favourable outcome compared with those with mRS 3-6 on discharge (78.3±14.3 vs 86.9±14.5, p=0.007). Kaplan-Meier curves showed higher recurrence/death rates in patients with ≥80% stenosis, mid-basilar location and poor collateral circulation. Approximately 13% of patients with ISBAS presented with complete BA occlusion.

Conclusion

ISBAS is an uncommon (1.43%) cause of TIA and AIS. Men in their 60s are mostly affected, and artery-to-artery embolism is the most common stroke mechanism. Mid-basilar location, ≥80% stenosis and poor collateral circulation are important factors associated with worse prognosis.

Influence of collateral circulation on cerebral blood flow and frontal lobe cognitive function in patients with severe internal carotid artery stenosis

BACKGROUND

This study aimed to investigate the cerebral blood flow (CBF) and frontal lobe cognitive function in severe internal carotid artery (ICA) stenosis patients with different types of collateral circulation.

METHODS

One hundred twenty-six patients with severe unilateral ICA stenosis were enrolled. Digital subtraction angiography (DSA) was performed to recruit patients with one of three common types of collateral circulation: anterior communicating artery (AcoA), posterior communicating artery (PcoA) and ophthalmic artery (OA). The hemodynamic parameters of the middle cerebral artery (MCA) were measured using transcranial Doppler (TCD), and the individual frontal lobe cognitive attention functions were evaluated using Word Fluency Test, Trail-Making Test (TMT), Digit Span, and Stroop Color Word Test (SCWT). The correlation between hemodynamic changes and the scores of all tasks was analyzed.

RESULTS

On the side of arterial stenosis, the CBF velocities were highest in AcoA group and lowest in the OA group. All patients performed worse in TMT and Digit Span than the matched normal controls. The AcoA group exhibited a lower pulsatility index (PI) and a longer response time in the Stroop task, but had a higher accuracy rate in the Stroop task and higher scores in Word Fluency Test than the PcoA and OA groups. In all the three groups, PI was positively correlated with the accuracy rate for Stroop interference effects.

CONCLUSIONS

Our findings suggested that the frontal lobe cognitive function of patients with ICA was impaired, and AcoA collaterals may be beneficial for selective attention functions, whereas OA collaterals may be associated with impairment of selective attention functions. Additionally, a high PI may be an indicator for identifying impaired selective attention in patients with severe ICA stenosis.

Proportion of Variant Anatomy of the Circle of Willis and Association with Vascular Anomalies on Cerebral CT Angiography

Background and Purpose

There is a wide variation in the anatomy of the CW in different individuals and population groups. The purpose of this study was to determine the proportion of variant anatomy of the circle of Willis (CW) and associated anomalies in patients with suspected cerebrovascular disease referred for cerebral computed tomography angiography (CTA) in two tertiary hospitals in Kenya.

Methodology

This was a cross-sectional descriptive study conducted on 94 patients referred for cerebral CTA at the Kenyatta and Nairobi hospitals from August 2017 to February 2018. MIP and 3D reformatted images were analyzed by two senior radiologists to determine the final configuration of the CW and presence of vascular pathology. Vessels with diameters <0.8 mm were considered to be absent or hypoplastic. Chen et al. classification was used to determine the final configuration of CW.

Results

Complete CW was seen in 37.2% (37.7% vs. 36.6% in males and females, respectively, p=0.909). Type A variant was the commonest anterior variant at 78.7%. Type E variant was the dominant posterior variant at 41.5%. Fetal PCA was demonstrated in 25.5%, unilateral > bilateral fetal PCA. Aneurysms were seen in 24.5% of patients. ACoA aneurysms were commonest at 43.6%. AVMs were seen in 8.5% of patients. Azygous ACA, fenestration, and duplication of vessels and persistent TA were not demonstrated. There is no significant association between aneurysms/AVMs and CW configuration.

Conclusion

The findings in this study demonstrate slight differences in the CW configuration. A higher proportion of complete anterior CW was seen in female patients. Type A anterior and type E posterior circulation variants were the commonest in both males and females. No significant association was demonstrated between CW configuration and occurrence of aneurysms/AVMs in this study. Various methods of classification of CW configuration have been proposed with no standardized method to date, thus the need for consensus building between neuroanatomists, neurologists, neurosurgeons, and neuroradiologists for ease of comparison between similar future studies on the CW.

Easily Screenable Characteristics Associated with Cognitive Improvement and Dysfunction After Carotid Endarterectomy

BACKGROUND

Carotid endarterectomy (CEA) is an effective treatment for the prevention of stroke in patients with carotid artery stenosis. We aimed to clarify the incidence and risk factors for early cognitive dysfunction (eCD) and early cognitive improvement (eCI), defined as change in cognitive performance ≤24 hours after surgery, using a battery of neuropsychometric tests.

METHODS

In total, 585 patients undergoing CEA were tested with neuropsychometric tests before and after surgery; 155 patients undergoing "simple" spine surgery were the reference group. Patient performance for each test was evaluated by z scores. Cognitive change was defined as eCD (or eCI) if: 1) patients had a z score ≤-2 (or ≥2) in ≥2 cognitive domains or 2) patients had mean z scores across all domains ≤-1.5 (or ≥1.5). Associations between the categorical cognitive outcomes and variables of interest were modeled using the proportional odds model.

RESULTS

Of the 585 subjects, 24% had eCD, 6% had eCI, and 70% had "no change." Patients who had eCD were more likely to be statin naïve (odds ratio [OR] 1.23 [1.03-1.48], P = 0.02) or women (OR 1.27 [1.06-1.53], P = 0.02). Those with eCI were less likely to have less formal education (OR 0.95 [0.90-1.00], P = 0.04) and less likely to have diabetes mellitus (OR 0.8 [0.65-0.99], P = 0.04).

CONCLUSIONS

Patients having CEA may develop eCD or eCI postoperatively. Medications likely to be associated with less eCD are statins and aspirin, which correlate most strongly in asymptomatic patients. In addition to confirming previous findings, we found that women were more likely than men to develop eCD. More sex-specific studies and analysis are needed to better explore these findings.

Safety of perioperative cerebral oxygen saturation during debranching in patients with incomplete circle of Willis

OBJECTIVES

The consequences of common carotid artery (CCA) cross-clamping during debranching before thoracic endovascular aortic repair are unclear. We examined the safety of a simple CCA cross-clamping procedure under regional cerebral oxygen saturation monitoring (rSO2) in patients with a complete or incomplete circle of Willis (CoW) anatomy.

METHODS

Twenty-eight patients with thoracic aneurysm underwent elective debranching thoracic endovascular aortic repair with bilateral frontal rSO2 monitoring at our institution between January 2012 and October 2015. Before CCA cross-clamping, we maintained a systemic mean arterial pressure of >100 mm Hg with a vasopressor. We recorded the bilateral frontal rSO2 before, during and after CCA cross-clamping.

RESULTS

The CoW was incomplete in 11 (39.3%) patients. Of these, 6 patients had a complication of ischaemic potential. The left frontal rSO2 was <50% in 3 patients but did not fall below 40%. Compared with baseline values (mean ± SD 64.6 ± 6.9%), the left frontal rSO2 showed no significant change perioperatively in those with a complete CoW on the left CCA cross-clamping (during: 61.0 ± 7.9%, P = 0.17; after: 65.1 ± 5.9%, P = 0.09). In patients with an incomplete CoW with ischaemic potential, the left frontal rSO2 did not change significantly after cross-clamping (baseline: 59.8 ± 3.2%, during: 55.5 ± 5.0%; P = 0.10) but increased significantly on declamping (62.8 ± 4.5%, P = 0.023). The extent of the changes in the mean left frontal rSO2 on clamping and declamping decreased and increased by 7.3% and 11.7%, respectively, in patients with an incomplete CoW, when compared with 5.3% and 5.8% in those with a complete CoW (P = 0.65 and 0.31, respectively). No perioperative cerebrovascular events were observed.

CONCLUSIONS

Simple CCA cross-clamping during debranching was safe when arterial pressure was supported and rSO2 was monitored, even with an incomplete CoW and ischaemic potential.

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.