Cerebral hemodynamics in patients with carotid artery occlusion and contralateral moderate or severe internal carotid artery stenosis

Transient ischemic attack and minor stroke as "surgeons affairs": a narrative review

OBJECTIVE

The scope of this paper is to review the subtypes of transient ischemic attack (TIA) and minor stroke (mS) in which a surgical treatment is needed, discussing the importance and the timing of a multidisciplinary approach, in order to achieve an optimized management and prevent major strokes or other critical complications.

MATERIALS AND METHODS

The keywords "transient ischemic attack," "minor stroke," "surgical treatment," "vascular surgery," "heart surgery," "neurosurgery," and "multidisciplinary" were searched using MEDLINE, EMBASE, and Scopus. Relevant search results were discussed by the authors for references inclusion.

RESULTS

Notwithstanding that best medical therapy is usually the first choice for the most part of cases, there are specific but recurrent etiologies that must be properly recognized because of a potential surgical approach, even in urgency. In fact, symptomatic carotid stenosis, or particular cases of hemodynamic cerebrovascular events, should be promptly referred to vascular surgeon, since increasing evidences highlighted a benefit from an early artery revascularization. In addition, beyond arrhythmic causes, cardioembolic events due to bacterial endocarditis and atrial myxoma should be quickly diagnosed, possibly in emergency department, because they are a presumptive urgency for heart surgery. In addition to the above-mentioned conditions, in patients suffering from vertebrobasilar TIA or mS, clinicians should keep in mind the Bow Hunter disease, because surgical artery decompression can represent the only suitable treatment in selected cases.

CONCLUSIONS

TIA and mS require a multidisciplinary in order to discuss therapeutic options, comparing risks and benefits and determining the best timing for an optimized management.

Multi-omics reveal neuroprotection of Acer truncatum Bunge Seed extract on hypoxic-ischemia encephalopathy rats under high-altitude

Hypoxic-ischemic encephalopathy (HIE) at high-altitudes leads to neonatal mortality and long-term neurological complications without effective treatment. Acer truncatum Bunge Seed extract (ASO) is reported to have effect on cognitive improvement, but its molecular mechanisms on HIE are unclear. In this study, ASO administration contributed to reduced neuronal cell edema and improved motor ability in HIE rats at a simulated 4500-meter altitude. Transcriptomics and WGCNA analysis showed genes associated with lipid biosynthesis, redox homeostasis, neuronal growth, and synaptic plasticity regulated in the ASO group. Targeted and untargeted-lipidomics revealed decreased free fatty acids and increased phospholipids with favorable ω-3/ω-6/ω-9 fatty acid ratios, as well as reduced oxidized glycerophospholipids (OxGPs) in the ASO group. Combining multi-omics analysis demonstrated FA to FA-CoA, phospholipids metabolism, and lipid peroxidation were regulated by ASO treatment. Our results illuminated preliminary metabolism mechanism of ASO ingesting in rats, implying ASO administration as potential intervention strategy for HIE under high-altitude.

Independent role of circle of Willis for peri-procedural evaluation of carotid endarterectomy in patients with severe carotid stenosis

OBJECTIVES

In patients with severe carotid stenosis (CS), collateral circulation via circle of Willis (CoW) is considered a compensatory response to maintain blood flow. The aim of this study was to evaluate the impact of CoW in patients with severe CS throughout carotid endarterectomy (CEA).

METHODS

A database of patients (n = 124) undergoing CEA was sampled from 2013 to 2020. Severe CS was defined as 90-99% caliber stenosis and collateral circulation was identified by CoW opening. Baseline characteristics, Age-related white matter change (ARWMC) score, immediate neurologic events (INEs) and manifestations were recorded and compared. Correlation and regression analysis for CoW were further investigated.

RESULTS

All patients enrolled were divided into two groups regarding to the visualized CoW opening and complete CoW was noticed in 57 patients. The prevalence of complete CoW was higher among asymptomatic patients (n = 39, 68.4%), while higher percentage of TIA or previous stroke were noticed in incomplete CoW (n = 45, 67.2%). Patients with incomplete CoW had a significantly higher median ARWMC score and remarkable cerebral perfusion deficit (P < 0.05*). Totally, 4 INEs (6.0%) were noted in patients with incomplete CoW after CEA. Cerebral hyperperfusion syndrome (CHS) was noticed in 10 patients and early-phase of postoperative hypertension (EPOH) in 15 ones with incomplete CoW versus patients with complete CoW (14.9% and 22.4% vs 3.5% and 7.0%, P < 0.05). Correlation analysis showed strong relationship between CoW opening and peri-operative factors like pre-operative symptoms, ARWMC, CHS and EPOH (P < 0.05*). Overall, CoW opening was an independent predictor of both CHS and EPOH (95% CI, 0.021-0.715 and 0.060-0.949, P < 0.05*) with logistic regression.

CONCLUSIONS

Sufficient collateral circulation via CoW may promote ipsilateral cerebral perfusion and mitigate WMC in patients with severe CS. In addition, collaterals may improve the predictive power of the risk scale for post-procedural complications after CEA.

Computed Tomography Perfusion Imaging Quality Affected by Different Input Arteries in Patients of Internal Carotid Artery Stenosis

BACKGROUND The aim of this study was to explore the influence of different input arteries on the parameters of computed tomography (CT) perfusion imaging for patients with different degree of stenosis of internal carotid artery (ICA). MATERIAL AND METHODS Forty patients were enrolled in the present study and divided into mild, moderate, severe stenosis and occlusion groups respectively with each 10 patients in each group. In reconstruction of cerebral CT perfusion (CTP) images, each raw perfusion image was reconstructed 3 times based on different reference input artery, including bilateral middle cerebral artery (MCA) and basilar arteries (BA). Region of interest (ROI) was drawn in the central territories of bilateral anterior cerebral artery, middle cerebral artery and posterior cerebral artery. And regional cerebral blood flow (rCBF) regional cerebral blood volume (rCBV), mean transit time (MTT), time to peak (TTP) and delay time (DT) were obtained from those ROI corresponding perfusion images. RESULTS In patients with mild and moderate ICA stenosis, there was no significant difference of perfusion parameters based on different input arteries (P>0.05). However, in severe ICA stenosis and occlusion CBF, MTT, and DT were significant different in affect side of the MCA group compared to the others (P<0.05). CONCLUSIONS Large intracranial artery can be selected as the input artery for patients with mild to moderate ICA stenosis, while for patients with severe stenosis and occlusion of ICA, the contra lateral middle cerebral artery or basilar artery would be better choice.

Management of Bilateral Carotid Occlusive Disease

BACKGROUND

Symptomatic bilateral internal carotid occlusive disease is a rare but potentially devastating entity. Medical therapy alone is associated with high rates of mortality and recurrent stroke. The optimal management of this disease remains poorly understood.

METHODS

A retrospective review of a prospectively maintained database was conducted for patients who presented with an acute stroke in the setting of bilateral carotid occlusive disease between May and October 2013.

RESULTS

We identified 3 patients. The admission National Institutes of Health Stroke Scale score ranged from 4 to 7. All patients had small- to moderate-sized infarcts in the anterior circulation on presentation. Angiography confirmed bilateral internal carotid occlusions with collateral filling via the posterior communicating artery and retrograde filling via external carotid artery supply to the ophthalmic artery. All patients were initially managed with permissive hypertension and anticoagulation followed by carotid angioplasty and stenting. At 1-year follow-up, all patients demonstrated a modified Rankin scale score of 0-1.

CONCLUSIONS

Carotid stenting may be a safe and effective therapy for patients presenting with symptomatic bilateral carotid occlusions.

Recovery of cerebrovascular reserves after stenting for symptomatic carotid artery stenosis

Although a decrease in cerebrovascular reserves (CVR) is known to enhance the risk of stroke, changes in this parameter after carotid artery stenting (CAS) have rarely been investigated. The present study is the first to compare CVR recoveries after applying CAS to patients with symptomatic carotid artery disease. CAS was performed for 31 consecutive patients with symptomatic carotid artery disease. They underwent acetazolamide-challenged single photon emission computed tomography (SPECT) before and after CAS to obtain data on resting stage cerebral blood flow (CBF(rest) values) in various regions of interest (ROIs) defined by a three-dimensional stereotactic ROI template. CVR values on ipsilateral and contralateral hemispheric sides were then calculated based on the CBF(rest) data. The 31 patients were dichotomized into unilateral (n=22) and bilateral (n=9) lesion groups, and no significant between-group differences were observed in CBF(rest) before and after CAS. In the unilateral group, there were no differences in CVR values before and after CAS. In the bilateral group, however, the CVR values significantly increased in nearly all the investigated ROIs on the contralateral side. Also, the hemispheric CVR values on both sides significantly increased after CAS in the bilateral group, while no such increase was observed in the unilateral group. CAS in patients with symptomatic bilateral carotid artery disease has the potential utility for their haemodynamic improvement even on the contralateral hemispheric side.

Cerebral hemodynamics after contralateral carotid endarterectomy in patients with symptomatic and asymptomatic carotid occlusion: a 10-year follow-up

We sought to investigate whether carotid endarterectomy (CEA) can achieve long-term cerebral hemodynamic improvement and reduce recurrence of cerebral ischemic events in symptomatic and asymptomatic patients with severe (>70%) carotid artery stenosis contralateral to carotid occlusion (CO). Thirty-nine patients with severe carotid lesion contralateral to CO were studied before (1 day) and after CEA (at 7 days, 1, 3 and 6 months, and then yearly thereafter). Collateral flow and cerebral vasomotor reactivity (VMR) were assessed by transcranial Doppler sonography (TCD). A total of 32 unoperated patients with severe carotid lesion contralateral to CO, who were comparable with respect to age and sex, served as a control group. The average period of TCD follow-up was 10 years and was obtained in all patients; during this period, major clinical events (stroke, acute myocardial infarction and death) were also recorded. The proportion of patients with collateral flow via the anterior communicating artery increased significantly from 61.5% before to 89.7% after CEA (P = 0.01). Cerebral VMR ipsilateral to CO improved in 85.7% of patients (30 of 35) within 30 days of CEA, and in all patients within 90 days. No significant spontaneous VMR recovery was recorded in the control group. After the initial recovery, no significant change in VMR was observed in the surgical group or the control group during the follow-up. In conclusion, in patients with severe carotid stenosis, CEA contralateral to symptomatic and asymptomatic CO determines a durable cerebral hemodynamic improvement not only on the side of the CEA but also on the contralateral side, with no difference between symptomatic and asymptomatic patients.

Cerebral vasomotor reactivity of bilateral severe carotid stenosis: is stroke unavoidable?

We evaluated the cerebral hemodynamic features of severe bilateral carotid stenosis by assessing and comparing cerebral vasomotor reactivity (VMR) in the middle cerebral (MCA) and vertebral arteries (VA) by transcranial Doppler and the Diamox (1 g acetazolamide i.v.) test. VMR was evaluated by recording the percentage differences in peak systolic blood flow velocity in each MCA and VA at baseline and by the Diamox test. Twenty-eight symptomatic (SCAS) and 31 asymptomatic (ACAS) patients with bilateral severe (>70%) internal carotid artery stenosis were studied. The mean MCA VMR% was 29 +/- 26.9% in SCAS and 43.2 +/- 26.8% in ACAS patients (P < 0.01). Their respective mean VA VMR% was 30.2 +/- 36.5% and 39.6 +/- 24.4% (P = NS). VMR% of the symptomatic MCA side in SCAS patients was significantly lower than the opposite side (20.5 +/- 31.1% and 39.2 +/- 37.9% respectively; P < 0.03). In contrast, the VA VMR% of both sides in SCAS patients remained similar (28.1 +/- 39.3% and 34.6 +/- 47.9% respectively; P = NS). VMR% of the MCA and VA in ACAS patients was also similar for both sides of bilateral carotid stenosis. The cerebral hemodynamic features differ between SCAS and ACAS patients with bilateral carotid occlusive disease in the anterior part of the circle of Willis. An independent cerebral vascular reserve capacity of the posterior circulation is proposed.

Heterogeneity of cerebral blood flow in symptomatic patients undergoing carotid endarterectomy

There is still controversy concerning which patients with asymptomatic carotid stenosis or symptomatic moderate stenosis are likely to benefit from carotid endarterectomy. The surgical candidates for carotid endarterectomy should have a high risk for stroke, but a low risk for operative complications. Therefore, new effective patient selection strategies, including haemodynamic testing, schemes of risk stratification and pre-operative cardiac testing, are under investigation. To improve haemodynamic assessment of patients with carotid artery stenosis, we evaluated a novel global cerebral blood flow (CBF) heterogeneity index at rest and after acetazolamide injection in patients undergoing carotid endarterectomy. CBF heterogeneity index was measured in 15 patients by using basal and acetazolamide enhanced 99mTc-HMPAO SPET both before and 1 month after surgery. CBF heterogeneity index was calculated as the coefficient of variation of a total of 44 cerebral regions representing mainly both ipsi- and contralateral grey matter. A high linear correlation was observed between CBF heterogeneity index and ipsilateral carotid stenosis degree (r=0.74, P=0.003). Before surgery, CBF heterogeneity index increased significantly after acetazolamide injection when compared to the basal condition (from 7.0+/-1.5 to 8.3+/-1.7%, P=0.008). This response disappeared after carotid endarterectomy. When compared to pure asymmetry of CBF (ipsi/contralateral CBF ratio), the CBF heterogeneity index seemed to reflect, more sensitively, the haemodynamic effects of carotid endarterectomy. The CBF heterogeneity index after acetazolamide injection is a sensitive marker of the haemodynamic consequences of carotid artery stenosis and its operative treatment.