Internal Carotid Artery Steno-occlusion Research Articles

The influence of contralateral circulation on computational fluid dynamics of intracranial arteries: simulated versus measured flow velocities

BackgroundThis study aimed to retrospectively evaluate the influence of contralateral anterior circulation on computational fluid dynamics (CFD) of intracranial arteries, by comparing the CFD values of flow velocities in unilateral anterior circulation with the measured values from phase-contrast magnetic resonance angiography (PC-MRA).MethodsWe analyzed 21 unilateral anterior circulation models without proximal stenosis from 15 patients who performed both time-of-flight MRA (TOF-MRA) and PC-MRA. CFD was performed with the inflow boundary condition of a pulsatile flow of the internal carotid artery (ICA) obtained from PC-MRA. The outflow boundary condition was given as atmospheric pressure. Simulated flow velocities of the middle cerebral artery (MCA) and anterior cerebral artery (ACA) from CFD were compared with the measured values from PC-MRA.ResultsThe velocities of MCA were shown to be more accurately simulated on CFD than those of ACA (Spearman correlation coefficient 0.773 and 0.282, respectively). In four models with severe stenosis or occlusion of the contralateral ICA, the CFD values of ACA velocities were significantly lower (< 50%) than those measured with PC-MRA. ACA velocities were relatively accurately simulated in the models including similar diameters of both ACAs.ConclusionIt may be necessary to consider the flow condition of the contralateral anterior circulation in CFD of intracranial arteries, especially in the ACA.Relevance statementIncorporating the flow conditions of the contralateral circulation is of clinical importance for an accurate prediction of a rupture risk in Acom aneurysms as the bidirectional flow and accurate velocity of both ACAs can significantly impact the CFD results.Key points• CFD simulations using unilateral vascular models were relatively accurate for MCA.• Contralateral ICA steno-occlusion resulted in an underestimation of CFD velocity in ACA.• Contralateral flow may need to be considered in CFD simulations of ACA.Graphical

Endovascular treatment in patients with middle cerebral artery occlusion of different aetiologies.

The purpose of this study was to evaluate differences in endovascular treatment (EVT) outcomes in M1 segment middle cerebral artery occlusion (MCAO) patients with different pathologic subtypes. Patients with MCAO who received EVT from July 2014 to December 2020 were categorized into three groups: embolism without internal carotid artery steno-occlusion (MCAO-E), in situ atherosclerotic thrombosis (MCAO-AS) and embolism from tandem ICA steno-occlusion (MCAO-T). Baseline characteristics, EVT-related factors and clinical outcomes were compared between groups. Multivariable regression analyses were performed to evaluate the relationship between aetiologic classification and outcomes at 90days after stroke. Among eligible patients (n = 220), MCAO-E (n = 129, 58.6%) was the most common aetiology, followed by MCAO-AS (n = 47, 21.4%) and MCAO-T (n = 44, 20.0%). Patients with MCAO-E were significantly older but had a lower rate of dyslipidaemia and smoking history than those with MCAO-AS. Although patients with MCAO-AS and MCAO-T more often required rescue balloon angioplasty and stenting (p < 0.001), no significant difference in the rate of final recanalization was found. Patients in the MCAO-AS group obtained better functional outcomes (90-day modified Rankin Scale score, 0-2) (p = 0.002) and lower mortality than in the MCAO-E group (p = 0.009). On multivariable logistic regression, we failed to find that stroke subtype was an independent predictor of functional outcomes and mortality. Patients with acute MCA M1 occlusion stroke due to different pathogeneses had comparable successful recanalization rates and functional independence at 90days. The optimal management for MCAO patients with different aetiologies requires further research.

Emergency Cervical Carotid Artery Stenting After Intravenous Thrombolysis in Patients With Hyperacute Ischemic Stroke.

BackgroundIntravenous recombinant tissue plasminogen activator (IV rtPA) is the mainstay of treatment for acute ischemic stroke to recanalize thrombosed intracranial vessels within 4.5 hours. Emergency carotid artery stenting for the treatment of acute stroke due to steno-occlusion of the proximal internal carotid artery (ICA) can improve symptoms, prevent neurological deterioration, and reduce recurrent stroke risk. The feasibility and safety of the combination therapy of IV rtPA and urgent carotid artery stenting have not been established.MethodsFrom November 2005 to October 2020, we retrospectively assessed patients who had undergone emergent carotid artery stenting after IV rtPA for hyperacute ischemic stroke due to steno-occlusive proximal ICA lesion. Hemorrhagic transformation, successful recanalization, modified Rankin Scale (mRS) score at 90 days, and stent patency at 3 and 12 months or longer were evaluated. Favorable outcome was defined as a 90-days mRS score of ≤ 2.ResultsNineteen patients with hyperacute stroke had undergone emergent carotid artery stenting after IV rtPA therapy. Their median age was 70 (67.5–73.5) years (94.7% men). Among 15 patients with an additional intracranial occlusion after flow restoration in the proximal ICA, a modified TICI grade ≥ 2b was achieved in 11 patients (73.3%). Hemorrhagic transformation occurred in five patients (26.3%); mortality rate was 5.7%. Eleven patients (57.9%) had favorable outcomes at 90 days. Stent patients (94.1%) maintained stent patency for ≥ 12 months.ConclusionWe showed that emergent carotid artery stenting after IV rtPA therapy for hyperacute stroke caused by atherosclerotic proximal ICA steno-occlusion was feasible and safe.

Successful Endovascular Thrombectomy in a Patient with Monocular Blindness Due to Thrombus of the Ophthalmic Artery Orifice

Background Retinal artery occlusion can lead to sudden visual loss without pain. The acute management of retinal artery occlusion remains unresolved. Case Report A 65-year-old male was hospitalized to an emergency room for visual loss on the left side within 6 hours of onset. Combined occlusion at retinal artery and ciliary artery was confirmed by an ophthalmologist and we assessed ophthalmic artery occlusion. However, MRA revealed no significant steno-occlusion of internal carotid artery. Transfemoral cerebral angiography was carried out immediately and showed a movable thrombus at the orifice of the ophthalmic artery. We decided on endovascular thrombectomy to prevent permanent visual loss. Finally, his visual acuity was improved after successful thrombectomy. Conclusions Although MRA is intact, small thrombus right at the orifice of the ophthalmic artery can cause a sudden monocular visual loss due to occlusion of the retinal artery. In this setting, urgent endovascular thrombectomy can offer visual improvement. Key Words: Monocular blindness; Ophthalmic artery; Thrombectomy

Clinical features and the degree of cerebrovascular stenosis in different types and subtypes of cerebral watershed infarction

BackgroundWhether there are differences in pathogenesis among different types and subtypes of cerebral watershed infarction (WSI) is controversial since they have been combined into a single group in most previous studies.MethodsWe prospectively identified 340 supratentorial WSI patients at Beijing Chao-Yang Hospital, Capital Medical University, China and classified them based on diffusion-weighted imaging(DWI) templates. Baseline characteristics, clinical courses and neuroradiological features were compared among patients with different types and subtypes of WSI.ResultsWe identified 92 patients with cortical watershed infarction (CWI), 112 with internal watershed infarction (IWI) and 136 with mixed-type infarction. Compared with CWI patients, more IWI patients had critical stenosis of internal carotid artery (ICA) (P < 0.001). For the CWI group, patients with anterior watershed infarction (AWI) were more prone to critical ICA stenosis than those with posterior watershed infarction (PWI) (P = 0.011). For the IWI group, critical ICA stenosis was more prevalent in patients with partial IWI (P-IWI) than in those with confluent IWI (C-IWI) (P = 0.026). IWI patients were more frequently found to have clinical deterioration during the first 7 days of hospitalization and a poor prognosis at the 90th day than in CWI patients (P = 0.003 and P = 0.014, respectively).ConclusionsIWI, especially the P-IWI subtype, is associated with hemodynamic impairment (HDI), whereas CWI has a weaker correlation with ICA steno-occlusion. Furthermore, IWI patients are more prone to poor prognosis.

Arterial Spin-Labeling Magnetic Resonance Perfusion Imaging with Dual Postlabeling Delay in Internal Carotid Artery Steno-occlusion: Validation with Digital Subtraction Angiography

Arterial spin-labeling magnetic resonance perfusion imaging (ASL-MRI) allows noninvasive measurement of cerebral blood flow (CBF) but depends on the arterial transit time (ATT). With the commonly used single postlabeling delay (PLD) of 1.5 seconds, slow flow through collateral vessels may be underestimated. We used both 1.5 and 2.5 seconds to overcome this problem. We validated these PLD settings by measuring the ATT and identifying the angiographic circulation using digital subtraction angiography (DSA). We retrospectively selected 5 patients with unilateral occlusion or stenosis of the internal carotid artery (ICA) in whom ASL-MRI showed low CBF with 1.5-second PLD in the target area and improved CBF with 2.5-second PLD. We then compared the ASL-MRI findings visually with DSA findings at 1.5 and 2.5 seconds after injection of the contrast. When arterial transit artifacts (ATAs), attributed to stagnant intravascular spin-labeled blood, were observed, DSA findings were analyzed visually at 4.5 seconds. DSA revealed that the hypovascular area seen at 1.5 seconds was improved via the primary and secondary collaterals and delayed anterograde flow at 2.5 seconds. Serpiginous or round-shaped ATAs, which appeared in nearly the same configuration on dual PLD ASL-MRI, were attributed to stagnant collaterals and flow in the M2 portion of the middle cerebral artery and ICA during the late venous phase. Use of dual PLD times was validated by the DSA findings. ATA detection using the dual PLDs also differentiated well-developed and stagnant collateral vessels from focal hyperperfusion.

Significance of Raised Flow Velocity in Basilar Artery in Patients with Acute Ischemic Stroke: Focal Stenosis, Coexistent Stenosis, and Collateral Flow.

Increased cerebral blood flow velocity of basilar artery (BA) is common but often neglected. By using digital subtraction angiography (DSA) to detect intracranial large artery stenosis, we performed transcranial Doppler (TCD) to evaluate cerebral hemodynamic changes of stroke patients. Acute stroke patients with TCD-detected raised peak systolic velocity (PSV) in BA (≥100 cm/second) were recruited. Among 91 recruited patients, BA stenosis (>50%) was confirmed by using DSA in 29 patients (32%), among which 20 patients (70.0%) had coexistent internal carotid artery (ICA) and vertebral artery (VA) stenoses. Among patients without BA stenosis (n = 62, 68%), severe stenosis or occlusion of ICA was evaluated in 22 patients (22/62, 35.4%) and severe stenosis or occlusion of VA was detected in 22 patients (22/62, 35.4%). Among the values of PSV (120, 140, 160, and 180 cm/second) and the stenotic-to-prestenotic ratio (SPR) (1.5, 2.0, 2.5, and 3.0), 160 cm/second was found to show the highest predictive value (area under the receiver operator characteristic curve: .75, 95% CI: .65-.86), with a sensitivity of .70 and a specificity of .81. Apart from an intrinsic BA stenosis, high-grade steno-occlusion of ICA or VA may contribute a lot to induce an elevated flow velocity in BA. A higher value of cutoff point may increase the accuracy of diagnosing BA stenosis.

Anterior Choroidal Artery Territory Infarction: Lesions Confined to versus beyond the Internal Capsule

Background: Studies investigating the clinical features and stroke mechanisms of anterior choroidal artery (AchA) infarction have reported inconsistent results. This may be partly due to different degrees of inclusion of patients with isolated posterior limb of the internal capsule (PLIC) lesions, which may be supplied by lenticulostriate arteries rather than AchA. The purpose of this study was to investigate clinical features and stroke mechanisms of AchA infarction, with particular attention to the above problem. Methods: We evaluated patients with AchA infarction assessed with diffusion-weighted imaging and magnetic resonance angiography, who were admitted to the Asan Medical Center from July 2001 to April 2011. Probable AchA (pAchA) infarction was diagnosed when the lesions were confined to the lower part of the PLIC, while definite AchA (dAchA) infarction was diagnosed when the lateral geniculate body, the uncus, or the cerebral peduncle were concomitantly involved. We assessed imaging findings, stroke mechanisms, and clinical features, and investigated the differences between patients with dAchA infarction and those with pAchA infarction. Results: We identified 127 patients with AchA infarction: 34 with dAchA infarctions, 90 with pAchA infarctions, and 3 without PLIC lesions. The most important stroke mechanism was small artery disease (SAD), followed by large artery disease (LAD). In patients with LAD, distal internal carotid artery (ICA) disease was a relatively important cause of stroke. The dAchA group, as compared with the pAchA group, was more frequently related to cardioembolism (12 vs. 2%, p = 0.03), distal ICA steno-occlusion (35 vs. 2%, p = 0.001), severe neurologic deficits (higher National Institute of Health Stroke Scale scores and more severe limb weakness), and less often associated with SAD (56 vs. 78%, p = 0.02). Conclusion: In general, SAD was the most important stroke mechanism for AchA infarction followed by LAD. However, dAchA infarction and pAchA infarction differ in that the former was more often associated with cardioembolism, distal ICA steno-occlusion, a worse clinical status and less often associated with SAD than the latter. The different proportion of patients with pure PLIC lesions included in previous studies may have led to inconsistent and confusing results, which should be considered to gain a proper understanding of AchA infarction.

Increased Pulsatility Index Is Associated with Intracranial Arterial Calcification

Background/Aims: An increase in the pulsatility index (PI) has been suggested to reflect distal vascular resistance. The purpose of the present study was to investigate the association between intracranial arterial calcification and intracranial PIs. Methods: Consecutive patients with acute ischemic stroke or transient ischemic attack were included. The PIs of both middle cerebral arteries (MCAs) were measured by transcranial Doppler ultrasonography. Intracranial carotid artery calcification (ICAC) was assessed on computed tomography angiography, and then compared with the mean PI of both MCAs. Patients with internal carotid artery steno-occlusion were excluded from this study. Results: A total of 156 patients were finally enrolled. The prevalence of diabetes increased as the PI value increased (p for trends; p = 0.025). PI was correlated with ICAC score (r = 0.413, p < 0.001) and age (r = 0.507, p < 0.001). Multiple linear regression analysis indicated that aging and ICAC were independent determinants of the PI of MCA after adjusting for sex, systolic blood pressure, smoking, and the presence of diabetes. Conclusions: This study shows that an increase in PI was correlated with the severity of ICAC, which suggests calcification-related vascular resistance might have a role in the elevation of PI.

Unruptured non-branching site aneurysms located on the anterior (dorsal) wall of the supraclinoid internal carotid artery: aneurysmal characteristics and outcomes following endovascular treatment

This study was undertaken to evaluate the aneurysmal characteristics and clinico-radiological outcomes of unruptured non-branching site aneurysms located on the anterior (dorsal) wall of the supraclinoid internal carotid artery (ICA). The data of 34 patients that underwent endovascular treatment for 36 unruptured ICA anterior wall aneurysms were reviewed. ICA anterior wall aneurysms were defined as aneurysms that projected superiorly from the anterior wall of the ICA ophthalmic (n = 35) or communicating (n = 1) segment on lateral angiograms, without any branch vessel relationship. In addition, aneurysmal characteristics and treatment outcomes were compared with those of 60 unruptured aneurysms originating from the posterior (ventral) wall of the ICA ophthalmic segment. Patients with an ICA anterior wall aneurysm frequently had a mirror aneurysm on the contralateral side (14.7 % versus 3.3 %) or another ICA aneurysm (35.3 % versus 15 %). Two of the 36 ICA anterior wall aneurysms exhibited ICA narrowing suggestive of dissection, and another five had dysplastic ICA dilatation around the neck. Stent-assisted embolization was more frequently performed for ICA anterior wall aneurysms (66.7 % versus 36.7 %) because of unfavorable dome/neck (mean, 1.21) and aspect (mean, 1.15) ratios, and because of microcatheter instability associated with superior aneurysmal projections against the abrupt curvature of the carotid siphon. Procedure-related thromboembolic complications occurred in three patients in the anterior aneurysm group, but no patient deteriorated clinically. Immediate radiological outcomes were more unfavorable for ICA anterior wall aneurysms (residual sac, 36.1 % versus 16.7 %). Nevertheless, rates of recanalization (2.9 % versus 5.2 %) and progressive occlusion (24.7 % versus 8.1 %) during follow-up slightly favored ICA anterior wall aneurysms. Two stent-treated ICA anterior wall aneurysms developed asymptomatic ICA steno-occlusion (8.3 %). Stent-assisted embolization is safe and effective for the treatment of unruptured ICA anterior wall aneurysms exhibiting unfavorable aneurysmal geometries and projections for coil embolization.

Blood flow velocities of cerebral arteries in lacunar infarction and other ischemic strokes

Blood flow velocity is an important determinant of vascular hemodynamics. The aim of the present study was to determine the mean flow velocities (MFVs) of cerebral arteries in patients with ischemic stroke, comparing lacunar and nonlacunar infarctions. 388 consecutive patients were examined for lacunar infarction, other subtypes of ischemic stroke, and the presence of underlying internal carotid artery steno-occlusion (ICS). MFVs were measured using transcranial Doppler along the full segments of each cerebral artery including both right and left middle cerebral arteries, basilar artery, and both of the vertebral arteries. The patients were categorized into two major groups: lacunar infarction, and nonlacunar infarction with or without underlying ICS. The characteristics of patients with lacunar infarction (n=83, 21.4%) were significantly different from those with nonlacunar infarctions: younger age, lower prevalence of type 2 diabetes, and lower concentration of plasma total homocysteine. The patients with lacunar infarction had lower MFVs in cerebral arteries than the patients with nonlacunar infarctions, especially in the posterior circulation vessels such as the basilar artery and both vertebral arteries. Different hemodynamics might be pathophysiologically associated with the lacunar infarction, compared with the other subtypes of ischemic stroke.

Association of Internal Border Zone Infarction with Middle Cerebral Artery Steno-Occlusion

Background: Demonstrating the precise anatomical area of the internal border zone (IB) by brain imaging has been unclear, and it is not well known which relevant arteries are associated with IB infarction. Methods: Patients with IB infarctions were selected from 748 consecutive patients with acute ischemic stroke. The IB infarctions were identified by coronal diffusion-weighted imaging, excluding lesions over the upper pole of the lateral ventricle. The angiographic findings of the internal carotid artery (ICA) and middle cerebral artery (MCA), on contrast-enhanced MRA, were evaluated in the patients with and without IB infarction. Results: Thirty patients met the criteria for an IB infarction: 7 had MCA steno-occlusion without ICA disease, and 23 had ICA steno-occlusion. Sixty-one patients had ICA steno-occlusion without IB infarction. The multiple logistic regression analysis showed that a more than moderate degree of steno-occlusion of the MCA was a significant factor (OR, 11.32; p = 0.006) associated with IB infarction; whereas that of the ICA was not significant (OR, 2.19; p = 0.298). Conclusion: The results of this study suggest that IB infarctions were associated with MCA steno-occlusion. ICA disease resulting in IB infarctions would be expected to have significant MCA steno-occlusion causing hemodynamic compromise.

Thyroid function and internal carotid artery stenosis in ischemic stroke

Thyroid dysfunction has been known to be closely associated with increased vascular events. The aims of the present study included determining the prevalence of subclinical thyroid disease and relationships between normal ranges of thyroid function and internal carotid artery steno-occlusion (ICS) in patients with ischemic stroke. From March 2007 to February 2008, 382 consecutive patients with ischemic stroke referred to the neurovascular ultrasound laboratory were analyzed. ICS was defined as greater than 50% luminal narrowing or complete obstruction in at least 1 internal carotid artery. Subclinical thyroid disease was determined by free thyroxine (fT4) and thyroid stimulating hormone (TSH) measurements. After the exclusion of patients with abnormal levels of thyroid hormones, normal ranges of fT4 were classified into 3 groups: low-normal (fT4, 11.0~12.3 pmol/L), mid-normal (12.4~15.4), and high-normal (15.5~24.0) thyroid groups. There were 17 patients (4.5%) with subclinical hypothyroidism and 6 (1.6%) with subclinical hyperthyroidism. There were 301 patients (78.8%) with normal fT4 and TSH levels, and among them, 67 patients (22.3%) had ICS. There was a significantly higher percentage of ICS in the low-normal thyroid group than in the other groups. By multivariate regression analysis, the low-normal fT4 group had an OR of 2.80 (95% confidence interval, 1.39-5.66) for ICS compared to the mid-normal group. In patients with ischemic stroke, the prevalence of subclinical thyroid disease was similar to the general population, and in euthyroid patients, low-normal thyroid function was independently associated with a higher percentage of ICS.