Symptomatic carotid near-occlusion causes a high risk of recurrent ipsilateral ischemic stroke

Carotid Near-Occlusion: Surgical or Conservative Management? Retrospective Multicenter Study

BACKGROUND

Carotid near-occlusion (CNO) represents an anatomical-functional condition characterized by severe (more than 90%) internal carotid artery stenosis which can lead to a distal lumen diameter greater or less than 2 mm. CNO can be divided into a less severe subgroup (without lumen full collapse: diameter >2 mm) and a more severe subgroup (with lumen full collapse: diameter <2 mm). The decision for revascularization is still highly debated in Literature. The aim of the present multicenter retrospective study is to analyze the incidence of perioperative (30 days) and follow-up complications in 2 groups of patients with or without distal internal carotid lumen full collapse.

METHODS

Between January 2011 and March 2023, in 5 Vascular Surgery Units, 67 patients (49 male, 73% and 18 females, 27%) with CNO underwent carotid endarterectomy: 28 (41.7%) with lumen diameter <2 mm and 39 (58.3%) with diameter >2 mm. 19 patients were symptomatic and 48 asymptomatic. The outcomes considered for comparative analysis were: perioperative neurological and cardiac complications, carotid restenosis or occlusion at follow-up. Both groups were homogeneous in terms of risk factors, morphological features and pharmacological treatments.

RESULTS

In the group with lumen <2 mm, 3 perioperative major events (10.7%) occurred (1 ischemic stroke, 1 hemorrhagic stroke, 1 myocardial infarction) and 2 (7.1%) at follow-up (average 11 ± 14.5 months; 1 asymptomatic carotid occlusion, 1 hemodynamic restenosis treated with stenting). No event was recorded in the group with lumen >2 mm.

CONCLUSIONS

According to our results CNO patients show different complication risk according to the presence or not of distal lumen collapse. The later seems to play a significant role in perioperative and follow-up complication rate. These results therefore support a surgical treatment only in patients with CNO without lumen full collapse.

High risk of early recurrent stroke in patients with near-occlusion with full collapse of the internal carotid artery

We aimed to validate the prognostic ability and assess interrater reliability of a recently suggested measurement-based definition of near-occlusion with full collapse (distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42). 118 consecutive patients with symptomatic near-occlusion were prospectively included and assessed on computed tomography angiography by 2 blinded observers, 26 (22%) had full collapse. At 2 days after presenting event, the risk of preoperative stroke was 3% for without full collapse and 16% for with full collapse (p = 0.01). At 28 days, this risk was 16% for without full collapse and 22% for with full collapse (p = 0.22). Interrater reliability was perfect (kappa 1.0). Thus, near-occlusion with full collapse should be defined as distal ICA ≤ 2.0 mm and/or ICA ratio ≤ 0.42 in order to detect cases with very high risk of early stroke recurrence.

Diagnostic separation of conventional ⩾50% carotid stenosis and near-occlusion with phase-contrast MRI

INTRODUCTION

The aim of this study was to assess sensitivity, specificity and interrater reliability of phase-contrast MRI (PC-MRI) for diagnosing carotid near-occlusion.

PATIENTS AND METHODS

Prospective cross-sectional study conducted between 2018 and 2021. We included participants with suspected 50%-100% carotid stenosis on at least one side, all were examined with CT angiography (CTA) and PC-MRI and both ICAs were analyzed. Degree of stenosis on CTA was the reference test. PC-MRI-based blood flow rates in extracranial ICA and intracranial cerebral arteries were assessed. ICA-cerebral blood flow (CBF) ratio was defined as ICA divided by sum of both ICAs and Basilar artery.

RESULTS

We included 136 participants. The ICAs were 102 < 50% stenosis, 88 conventional ⩾50% stenosis (31 with ⩾70%), 49 near-occlusion, 12 occlusions, 20 unclear cause of small distal ICA on CTA and one excluded. For separation of near-occlusion and conventional stenoses, ICA flow rate and ICA-CBF ratio had the highest area under the curve (AUC; 0.98-0.99) for near-occlusion. ICA-CBF ratio ⩽0.225 was 90% (45/49) sensitive and 99% (188/190) specific for near-occlusion. Inter-rater reliability for this threshold was excellent (kappa 0.98). Specificity was 94% (29/31) for cases with ⩾70% stenosis. PC-MRI had modest performance for separating <50% and conventional ⩾50% stenosis (highest AUC 0.74), and eight (16%) of near-occlusions were not distinguishable from occlusion (no visible flow).

CONCLUSION

ICA-CBF ratio ⩽0.225 on PC-MRI is an accurate and reliable method to separate conventional ⩾50% stenosis and near-occlusion that is feasible for routine use. PC-MRI should be considered further as a potential standard method for near-occlusion detection, to be used side-by-side with established modalities as PC-MRI cannot separate other degrees of stenosis.

Risk of Stroke Recurrence After Intravenous Thrombolysis in Patients with Symptomatic Carotid Stenosis

OBJECTIVE

To assess if intravenous thrombolysis (IVT) affects the risk of recurrent preoperative cerebrovascular events before carotid surgery or stenting in patients with symptomatic ≥ 50% carotid stenosis.

METHODS

Three cohorts of symptomatic ≥ 50% carotid stenosis patients were merged. To make the control group relevant, we excluded patients not presenting with stroke on the day of symptom onset. The risk of preoperative cerebrovascular events up to 30 days was compared between the IVT-treated and non-IVT-treated.

RESULTS

In total, 316 patients were included, 64 (20%) treated with IVT. Those treated with IVT had similar risk of recurrent ipsilateral ischemic stroke or retinal artery occlusion (12% at day 7, 12% at day 30) as those not treated (9% at day 7, 15% at day 30; adjusted HR 0.9, 95% CI 0.4-2.2). There was a tendency (p = 0.09) towards time-dependency in the data where the recurrence risk was higher in IVT-treated at day 0 (6% in IVT-treated, 1% in non-IVT-treated, OR 5.5, 95% CI 1.2-25.4, p = 0.03). This was not significant when adjusting for co-factors (adjusted OR 4.4, 95% CI 0.9-21.8, p = 0.07) and was offset by a later risk decrease, with no remaining risk difference between IVT-treated and non-IVT-treated at day 7.

CONCLUSIONS

Intravenous thrombolysis treatment does not seem to affect the risk of recurrent ipsilateral ischemic stroke in patients with symptomatic ≥50% carotid stenosis: The risk is high in both IVT-treated and non-IVT-treated. However, there might be a risk increase on the day of IVT treatment that is offset by a risk decrease during the first week.

Poststenotic Distal Caliber Reduction Predicts Very High-Grade Proximal Internal Carotid Artery Stenosis

BACKGROUND

Angiography relates the residual lumen to the poststenotic distal lumen (NASCET criterion) and expresses the result in percent lumen reduction. This method is not applicable when there is a collapse of the distal lumen, as seen in severe stenosis. The purpose of this study was to evaluate whether the reduced poststenotic caliber could be an additional sonographic criterion for estimation of the degree of stenosis.

METHODS

We measured the caliber of the distal lumen of the extracranial internal carotid artery (ICA) in 57 patients with low-grade stenosis <50% (NASCET criterion), and in 57 patients with unilateral stenosis of ≥ 50 %. All were classified following international recommendations. The criteria used included the poststenotic velocity to discriminate moderate to high-grade stenosis (50-70%) from very high-grade (≥ 80 %) stenosis. In addition, we measured the interrater reliability of the ultrasonic measurement of the lumen in the distal ICA.

RESULTS

In the group of patients with 50% to 70% stenosis, the distal lumen was 4.3 ± 0.6 mm. In the group with very high-grade stenosis ≥ 80%, the distal lumen was 2.6±0.5mm (p<0.0001). A distal lumen of 3.2 mm or less predicted a very high-grade stenosis with a sensitivity of 0.92 and a specificity of 0.96 (AUC 0.986; 95% CI 0.97-1.00; p=0.0001).

CONCLUSION

The distal poststenotic lumen is an additional ultrasonic criterion to discriminate a very high-grade ICA stenosis from a lesser degree of ICA stenosis. It can help avoid misinterpretation due to the high variability of intrastenotic peak systolic velocities (PSV) in very high-grade ICA stenoses.

Prevalence and Incidence of Carotid-Fetal-Posterior Syndrome

INTRODUCTION

Carotid-fetal-posterior (CFP) syndrome is a posterior cerebral artery (PCA) territory ischemic stroke/TIA caused by symptomatic ≥50% carotid stenosis or occlusion via fetal posterior communicating artery. We aimed to assess the incidence of CFP syndrome and prevalence of CFP syndrome among symptomatic ≥50% carotid stenosis or occlusion as these are unknown.

METHODS

We reassessed consecutive CTAs from 4,042 persons and included locally admitted patients with ≥50% carotid stenosis or occlusion. These were assessed for symptoms and signs of possible posterior circulation stroke/TIA (suspicion of CFP syndrome). Among these, those with unilateral PCA territory stroke/TIA, ipsilateral stenosis, and fetal/fetal-type PCA were considered CFP syndrome.

RESULTS

We included 208 locally admitted patients with ≥50% carotid stenosis or occlusion; 33 (16%) patients had suspicion of CFP syndrome, of which 3 (9%) had CFP syndrome. The prevalence of CFP syndrome was 2.9% of symptomatic ≥50% carotid stenosis or occlusion; incidence was 4.23 per 1,000,000 person-years. Also, we found a lower prevalence of CFP syndrome (0.9%, p = 0.047) among referred patients with symptomatic ≥50% carotid stenosis or occlusion than among locally admitted patients with symptomatic ≥50% carotid stenosis or occlusion.

DISCUSSION/CONCLUSION

CFP syndrome has a low incidence and low prevalence among symptomatic carotid stenosis cases. Given lower prevalence of CFP syndrome among referred cases than local, CFP syndrome seems susceptible to underdiagnosis. On the other hand, few cases with suspicion of CFP syndrome had CFP syndrome, why CFP syndrome also seems susceptible to overdiagnosis if detailed assessment is not employed.

Dilation of proximal internal carotid artery collapse due to severe distal stenosis after angioplasty for distal stenosis: A case report

Background

We report a case of proximal internal carotid artery (ICA) collapse due to severe distal stenosis that dilated after angioplasty for distal stenosis.

Case Description

A 69-year-old woman underwent thrombectomy for the left ICA occlusion due to stenosis of C3 portion and was discharged home with a modified Rankin Scale score of 0. One year later, she developed cerebral infarction due to progressive stenosis of the C3 portion of the left ICA with proximal ICA collapse and underwent emergency percutaneous transluminal angioplasty (PTA) for distal stenosis. Device guidance to the stenosis was difficult due to proximal ICA collapse. After PTA, blood flow in the left ICA increased, and proximal ICA collapse dilated over time. Due to severe residual stenosis, she underwent more aggressive PTA followed by Wingspan stenting. Device guidance to the residual stenosis was facilitated because proximal ICA collapse had already dilated. Six months later, proximal ICA collapse further dilated.

Conclusion

PTA for severe distal stenosis with proximal ICA collapse may result in dilation of proximal ICA collapse over time.

Clinical value of microemboli combined with cerebrospinal fluid inflammatory factor level monitoring in predicting recurrent stroke of middle cerebral artery stenosis

OBJECTIVE

To evaluate the clinical value of microemboli combined with cerebrospinal fluid inflammatory factor level monitoring in the prediction of recurrent stroke in middle cerebral artery stenosis.

METHODS

This is a retrospective study. Patients (n=170) who were hospitalized in the Department of Neurology of the First People's Hospital of Jiangxia District from June 2019 to January 2021 with cerebral infarction or transient ischemic attack were included in the study. Among them, 85 patients with ischemic attack were divided into the non-recurrent stroke group (primary onset, n=40) and the recurrent stroke group (history of cerebral infarction or transient ischemic attack within 5 years prior to the onset, n=45). Routine blood biochemical tests were performed using the Olympus 5800 automated chemical analyzer. Cerebrospinal fluid levels of inflammatory factors (TNF-α, IL-6) were detected by ELISA kits. Special Doppler hyperintensities for microemboli in cerebral blood flow were tested by transcranial Doppler ultrasound.

RESULTS

The mean age, statins and LDL-C were higher in the recurrent stroke group than the non-recurrent stroke group (P<0.05). The levels of cerebrospinal fluid TNF-α, PCT, CRP and IL-6 in the recurrent stroke group were higher than the non-recurrent stroke group (P<0.05). The proportion of grade 0 microemboli in the recurrent stroke group was lower than the non-recurrent stroke group (P<0.05), and the proportion of grade 1, 2, 3, 4 and 5 microemboli was higher than the non-recurrent stroke group (P<0.05). The positive rate of microemboli in the recurrent stroke group was higher than the non-recurrent stroke group (P<0.05). The accuracy rate of microemboli combined with cerebrospinal fluid inflammatory factor level monitoring in the recurrent stroke group for the prediction of recurrent stroke due to middle cerebral artery stenosis was higher than that in the non-recurrent stroke group (P<0.05). Increased age, statin use, microembolization, and increased LDL-C, TNF-α, PCT, CRP and IL-6 levels were independent risk factors.

CONCLUSION

Microemboli combined with cerebrospinal fluid inflammatory factor level monitoring can increase the detection rate of recurrent stroke in middle cerebral artery stenosis and prevent vascular events to a great extent.

Effect of Risk-Focused Diversified Safety Management Mode in Patients with Major Artery Stent Implantation

Background

Intracranial atherosclerotic stenosis (ICAS) causes a series of neurological symptoms, such as vertigo, impaired consciousness, limb weakness, ataxia, dysphagia, ocular motility disorders, and visual impairment. With the improvement of people's living standards, there are higher requirements for nursing care. Nursing, as an indispensable part of medical care, is closely related to achieving the goal of patient's safety and the overall quality of nurses, quality of care, and nursing management methods.

Objective

To explore the effect of risk-centered diversified safety management in patients undergoing aortic stenting.

Methods

Eighty patients with cerebral infarction were selected and treated with percutaneous transluminal angioplasty and stent implantation (PTAS). Then they were divided into a control group (40 cases) with routine monitoring and an experimental group (40 cases) with risk-focused intervention of a diversified safety management model according to the mode of care. Patient satisfaction and blood index test results were compared after the intervention.

Results

Patients in the experimental group had 6 falls, 3 bed falls, 3 phlebitis, 4 tube slips, and 10 deep vein thrombosis, all significantly fewer than those in the control group. Thirty-eight patients in the experimental group expressed satisfaction with safe management, which was substantially better than the control group (P < 0.05). The levels of tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PA1-1), and von Willebrand factor (vWF) in the experimental group were (13.5 ± 1.3) ng/mL, (60.1 ± 9.9) ng/mL, and (2.1 ± 0.2), respectively, which were substantially lower than those in the control group ((14.6 ± 2.4) ng/mL, (64.2 ± 10.7) ng/mL, and (2.8 ± 0.3)), respectively (P < 0.05).

Conclusion

The risk-centered diversified safety management model can effectively reduce the probability of adverse events in patients, improve patient satisfaction with nursing services, and promote faster postoperative recovery, which has clinical application value.

Symptomatic and asymptomatic carotid near-occlusions have very similar angiographic appearance on CT-angiography

The aim of this study was to compare the angiographic appearance of symptomatic and asymptomatic carotid near-occlusion. We have found no such previous study. The study hypothesis was that among symptomatic patients with ≥ 50% carotid stenosis, near-occlusion is more common and near-occlusions are more severe than among asymptomatic persons with ≥ 50% carotid stenosis. We reassessed consecutive CTAs from 4042 persons, 645 had ≥ 50% carotid stenosis, and 385 (60%) symptomatic. Near-occlusion was similarly common in symptomatic (105, 27%) and asymptomatic (56, 24%) cases. Among near-occlusions, the angiographic appearance was very similar between symptomatic and asymptomatic cases: mean stenosis lumen diameter (0.7 mm), distal ICA diameter (2.1 mm), and ECA ratio (0.79) were the same in both groups. Mean ICA ratio (0.46 and 0.48) and share of full collapse was very similar (45% and 42%). These findings add to the pathophysiological understanding of carotid near-occlusion.

Endarterectomy, Stenting, or Medical Treatment for Symptomatic Carotid Near-Occlusion: Results from CAOS, a Multicenter Registry Study

BACKGROUND AND PURPOSE

The treatment of symptomatic carotid near-occlusion is controversial. Our aim was to analyze the results of carotid endarterectomy and carotid artery stent placement in patients with symptomatic carotid near-occlusion and to identify factors related to technical failure, periprocedural complications, and restenosis.

MATERIALS AND METHODS

We conducted a multicenter, prospective nonrandomized study. Patients with angiography-confirmed carotid near-occlusion were included. We assessed the revascularization rate and periprocedural stroke or death. Twenty-four-month clinical and carotid imaging follow-up was performed, and rates of carotid restenosis or occlusion, ipsilateral stroke, and mortality were analyzed. Carotid artery stent placement, carotid endarterectomy, and medical treatment were compared.

RESULTS

One hundred forty-one patients were included. Forty-four carotid artery stent placement and 23 carotid endarterectomy procedures were performed within 6 months after the event. Complete revascularization was achieved in 83.6%, 81.8% in the carotid artery stent placement group and 87% with carotid endarterectomy (P = .360). Periprocedural stroke or death occurred in 6% (carotid artery stent placement = 2.3%; carotid endarterectomy = 13%; P = .077) and was not related to revascularization failure. The carotid restenosis or occlusion rate was 8.3% (5% restenosis, 3.3% occlusion); with carotid artery stent placement it was 10.5%; and with carotid endarterectomy it was 4.5% (P = .419). The 24-month cumulative rate of ipsilateral stroke was 4.8% in the carotid artery stent placement group, 17.4% for carotid endarterectomy, and 13.1% for medical treatment (P = .223). Mortality was 12%, 4.5%, and 5.6%, respectively (P = .422). Revascularization failure and restenosis occurred more frequently in patients with full collapse compared with patients without full collapse (33.3% versus 5.6%, P = .009; 21.4% versus 2.9%, P = .032, respectively).

CONCLUSIONS

Carotid artery stent placement and carotid endarterectomy are associated with high rates of failure and periprocedural stroke. Carotid near-occlusion with full collapse appears to be associated with an increased risk of technical failure and restenosis. Carotid near-occlusion revascularization does not seem to reduce the risk of stroke at follow-up compared with medical treatment.

CT angiography for diagnosis of carotid near-occlusion: a digital subtraction angiography validation study

INTRODUCTION

Carotid near-occlusion (CNO) is a variant of severe stenosis where there is a distal luminal collapse of the internal carotid artery (ICA) beyond a tight stenosis. This study aimed to validate new visual extracranial diagnostic CT angiography (CTA) criteria, for the diagnosis of CNO. The new criteria include distal ICA diameter smaller than contralateral ICA and distal ICA diameter less than or equal to the ipsilateral external carotid artery (ECA). We also assessed the previously described CTA criteria: stenosis ≤ 1.3 mm, ipsilateral distal ICA ≤ 3.5 mm, ipsilateral distal ICA/contralateral distal ICA ratio ≤ 0.87, ipsilateral distal ICA/ipsilateral ECA ≤ 1.27.

METHODS

Fifty-eight patients with ICA stenosis (including the near-occlusion variant) or occlusion on digital subtraction angiography (DSA) were included. These patients had DSA and CTA studies completed within 30 days of each other. DSA was considered the reference test. Two neuroradiologists blinded to the DSA results assessed the CTA images and evaluated the new and previously published CNO diagnostic criteria.

RESULTS

Twenty-eight CNO were identified with DSA. The "distal ICA diameter less than or equal to the ipsilateral ECA" criterion had 79% sensitivity and 83% specificity with excellent interobserver agreement (kappa = 0.80), while three or more of the previously published criteria reached 82% sensitivity and 90% specificity, with a good interobserver agreement (kappa = 0.64).

CONCLUSIONS

CT angiography may be useful for CNO diagnosis. The new visual diagnostic criteria provide acceptable results of sensitivity and specificity with an excellent interobserver agreement. However, false-negative and positive results persist.

Carotid Endarterectomy for the Treatment of Carotid Near-Occlusion With Recurrent Symptoms

Objective

Report our preliminary experience of carotid endarterectomy (CEA) for the treatment of carotid near-occlusion (CNO) with recurrent symptoms.

Materials and Methods

Retrospectively analyze the demographics, treatment detail, and outcomes data of 122 patients with CNO from 2014 to 2020. According to whether distal full collapse exists, patients were classified into the full collapse group and the non-full collapse group. The incidence of death, myocardial infarction, stroke, and other variables were compared between the two groups.

Results

A total of 122 patients with CNO and recurrent symptoms were enrolled. The demographics were comparable between the two groups. Thirty-day incidence of primary endpoints was 1.85% in the full collapse group and 4.41% in the non-full collapse group. Twelve-month incidence of primary endpoints was 7.41% in the full collapse group and 4.41% in the non-full collapse group. One re-stenosis occurred in the non-full collapse group 8 months after CEA.

Conclusion

For patients with CNO with recurrent symptoms, CEA is not worse than the results described in historical control groups, despite whether distal full collapse exists. The shunt is important to avoid intraoperative hypoperfusion and postoperative hyperperfusion. The long-term results should be further evaluated.

The periprocedural and 30-day outcomes of carotid stenting in patients with carotid artery near-occlusion

The safety of endovascular revascularization in patients with carotid artery near occlusion (CANO) is unknown. We aimed to evaluate the peri-procedural risk in CANO patients receiving carotid artery stenting (CAS). A prospective data base with retrospective review was performed to identify patients who underwent CAS with CANO from July 2006 to July 2020, and had at least 1-month clinical follow-up data. The primary endpoints were stroke, hyperperfusion syndrome, and death within 30 days after CAS. A total of 198 patients with carotid artery stenosis were enrolled including 92 patients with CANO and 106 age and sex-matched patients with 70–99% conventional carotid stenosis. Full distal carotid collapse was found in 45 CANO patients (45/92, 49%). The technical success rate was 100%. The CANO patients had significantly longer lesion lengths compared with those of the non-CANO group. The incidence of hyperperfusion syndrome was comparable (CANO: 2.2%, non-CANO: 0.9%, P = 0.598). The risks of ischemic stroke and death within 30 days were 1.1% and 0% in the CANO group; and 1.9% and 0.9%, in the non-CANO group, respectively, without statistical difference. In conclusion, CAS is safe for patients with CANO, with a similar low 30-day peri-procedural event rate comparable to those of non-CANO.

Mapping Cerebrovascular Reactivity Impairment in Patients With Symptomatic Unilateral Carotid Artery Disease

Background

Comprehensive hemodynamic impairment mapping using blood oxygenation‐level dependent (BOLD) cerebrovascular reactivity (CVR) can be used to identify hemodynamically relevant symptomatic unilateral carotid artery disease.

Methods and Results

This prospective cohort study was conducted between February 2015 and July 2020 at the Clinical Neuroscience Center of the University Hospital Zurich, Zurich, Switzerland. One hundred two patients with newly diagnosed symptomatic unilateral internal carotid artery (ICA) occlusion or with 70% to 99% ICA stenosis were included. An age‐matched healthy cohort of 12 subjects underwent an identical BOLD functional magnetic resonance imaging examination. Using BOLD functional magnetic resonance imaging with a standardized CO₂ stimulus, CVR impairment was evaluated. Moreover, embolic versus hemodynamic ischemic patterns were evaluated on diffusion‐weighted imaging. Sixty‐seven patients had unilateral ICA occlusion and 35 patients unilateral 70% to 99% ICA stenosis. Patients with ICA occlusion exhibited lower whole‐brain and ipsilateral hemisphere mean BOLD‐CVR values as compared with healthy subjects (0.12±0.08 versus 0.19±0.04, P=0.004 and 0.09±0.09 versus 0.18±0.04, P<0.001) and ICA stenosis cohort (0.12±0.08 versus 0.16±0.05, P=0.01 and 0.09±0.09 versus 0.15±0.05, P=0.01); however, only 40 (58%) patients of the cohort showed significant BOLD‐CVR impairment. Conversely, there was no difference in mean BOLD‐CVR values between healthy patients and patients with ICA stenosis, although 5 (14%) patients with ICA stenosis showed a significant BOLD‐CVR impairment. No significant BOLD‐CVR difference was discernible between patients with hemodynamic ischemic infarcts versus those with embolic infarct distribution (0.11±0.08 versus 0.13±0.06, P=0.12).

Conclusions

Comprehensive BOLD‐CVR mapping allows for identification of hemodynamically relevant symptomatic unilateral carotid artery stenosis or occlusion.

Near-Occlusion is a Common Variant of Carotid Stenosis: Study and Systematic Review

BACKGROUND

Symptomatic carotid near-occlusion is often described as rare. Recent studies have shown that near-occlusions are overlooked, especially near-occlusion without full collapse (with a small but normal-appearing distal internal carotid artery).

OBJECTIVE

To assess the prevalence of near-occlusion among symptomatic ≥50% carotid stenosis, incidence of symptomatic near-occlusion, and review the literature.

METHODS

Prospective controlled single-center cross-sectional study. Consecutive cases with symptomatic ≥50% carotid stenosis were examined with computed tomography angiography (CTA). The CTAs were assessed for near-occlusion by two observers. A systematic literature review was performed with emphasis on how study design affects prevalence estimate.

RESULTS

Totally, 186 patients with symptomatic ≥50% carotid stenosis were included, 34% (n = 63, 95% CI 27, 41) had near-occlusion. The incidence of symptomatic near-occlusion was 3.4 (95% CI 2.5, 4.2) per 100,000 person-years. Inter-rater κ was 0.71. The average prevalence of near-occlusion among symptomatic ≥50% carotid stenosis was higher in studies with good design (30%, range 27%-34%) than studies without good design (9%, range 2%-10%).

CONCLUSIONS

Near-occlusion is common variant of symptomatic ≥50% carotid stenosis, both in the current study and in all previous studies of good design. Studies that suggest that near-occlusion is rare have had methodological issues.

Defining carotid near-occlusion with full collapse: a pooled analysis

Purpose

Create a new definition of near-occlusion with full collapse to predicting recurrent stroke.

Methods

Pooled analysis of two studies. Patients with symptomatic ≥ 50% carotid stenoses were included. Outcome was preoperative recurrent ipsilateral ischemic stroke or retinal artery occlusion within 28 days of presenting event. We analyzed several artery diameters on computed tomography angiography and stenosis velocity on ultrasound.

Results

A total of 430 patients with symptomatic ≥ 50% carotid stenosis were included, 27% had near-occlusion. By traditional definition, 27% with full collapse and 11% without full collapse reached the outcome (p = 0.047). Distal internal carotid artery (ICA) diameter, ICA ratio, and ICA-to-external carotid artery ratio were associated with the outcome. Best new definition of full collapse was distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42. With this new definition, 36% with full collapse and 4% without full collapse reached the outcome (p < 0.001).

Conclusions

Defining near-occlusion with full collapse as distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42 seems to yield better prognostic discrimination than the traditional appearance-based definition. This novel definition can be used in prognostic and treatment studies of near-occlusion with full collapse.

Diagnosing Carotid Near-Occlusion with Phase-Contrast MRI

Carotid near-occlusion is a frequently overlooked diagnosis when CTA examinations are assessed in routine practice. To evaluate the potential value of phase-contrast MR imaging in identifying near-occlusion, we examined 9 carotid near-occlusions and 20 cases of conventional ≥50% carotid stenosis (mean stenosis degree, 65%) with phase-contrast MR imaging. Mean ICA flow was lower in near-occlusions (52 mL/min) than in conventional ≥50% stenosis (198 mL/min, P < .001). ICA flow of ≤110 mL/min was 100% sensitive and specific for near-occlusion. Phase-contrast MR imaging is a promising tool for diagnosing carotid near-occlusion.

Near-occlusion is difficult to diagnose with common carotid ultrasound methods

Purpose

To assess the sensitivity and specificity of common carotid ultrasound method for carotid near-occlusion diagnosis.

Methods

Five hundred forty-eight patients examined with both ultrasound and CTA within 30 days of each other were analyzed. CTA graded by near-occlusion experts was used as reference standard. Low flow velocity, unusual findings, and commonly used flow velocity parameters were analyzed.

Results

One hundred three near-occlusions, 272 conventional ≥50% stenosis, 162 <50% stenosis, and 11 occlusions were included. Carotid ultrasound was 22% (95%CI 14–30%; 23/103) sensitive and 99% (95%CI 99–100%; 442/445) specific for near-occlusion diagnosis. Near-occlusions overlooked on ultrasound were found misdiagnosed as occlusions (n = 13, 13%), conventional ≥50% stenosis (n = 65, 63%) and < 50% stenosis (n = 2, 2%). No velocity parameter or combination of parameters could identify the 65 near-occlusions mistaken for conventional ≥50% stenoses with >75% sensitivity and specificity.

Conclusion

Near-occlusion is difficult to diagnose with commonly used carotid ultrasound methods. Improved carotid ultrasound methods are needed if ultrasound is to retain its position as sole preoperative modality.

Ultrasonographic and hemodynamic characteristics of patients with symptomatic carotid near-occlusion: results from a multicenter registry study

PURPOSE

The ultrasonographic and hemodynamic features of patients with carotid near-occlusion (CNO) are still not well known. Our aim was to describe the ultrasonographic and hemodynamic characteristics of a cohort of patients with CNO.

METHODS

A prospective, observational, nationwide, and multicenter study was conducted from January/2010 to May/2016. Patients with digital subtraction angiography (DSA)-confirmed CNO were included. We collected information on clinical and demographic characteristics, carotid and transcranial ultrasonography and DSA findings, presence of full-collapse, collateral circulation, and cerebrovascular reactivity (CVR).

RESULTS

One hundred thirty-five patients were analyzed. Ultrasonographic and DSA diagnosis of CNO were concordant in only 44%. This disagreement was related to the presence/absence of full-collapse: 45% of patients with CNO with full-collapse were classified as a complete carotid occlusion, and 40% with a CNO without full-collapse were interpreted as severe stenosis (p < 0.001). Mean velocities (mV) and pulsatility indexes (PIs) were significantly lower in the ipsilateral middle cerebral artery compared with the contralateral (43 cm/s vs 58 cm/s, p < 0.001; 0.80 vs 1.00, p < 0.001). Collateral circulation was identified in 92% of patients, with the anterior communicating artery (73%) being the most frequent. CVR was decreased or exhausted in 66% of cases and was more frequent in patients with a poor or absent collateral network compared with patients with ≥ 2 collateral arteries (82% vs 56%, p = 0.051).

CONCLUSION

The accuracy of carotid ultrasonography in the diagnosis of CNO seems to be limited, with significant discrepancies with DSA. Decreased ipsilateral mV, PI, and CVR suggest a hemodynamic compromise in patients with CNO.

Carotid near-occlusion is often overlooked when CT angiography is assessed in routine practice

Objective

Assess the sensitivity and specificity of computed tomography angiography (CTA) for carotid near-occlusion diagnosis interpreted in clinical practice against expert assessment.

Methods

CTAs were graded by two expert interpreters for near-occlusion. Findings were compared with clinical reports in 383 consecutive cases with symptomatic ≥ 50% carotid stenosis. In addition, 14 selected CTA exams (8 near-occlusions and 6 controls) were analyzed in a national effort by 13 radiologists experienced with carotid CTA.

Results

In clinical practice, imaging reports were 20% (95% CI 12–28%) sensitive for near-occlusion, ranging 0–58% between different radiologists; specificity was 99%. Among the 13 radiologists reviewing the same 8 near-occlusions, the average sensitivity was 8%, ranging 0–75%; specificity was 100%.

Conclusions

Carotid near-occlusion is systematically under-reported in clinical routine practice, caused by limited application of grading criteria when assessing CTA.

Key Points

• Carotid near-occlusion is severe stenosis with distal artery collapse; this collapse is often subtle.

• A fifth of near-occlusions were detected in routine practice. Many readers mistake near-occlusion for stenosis without distal artery collapse, either by not actively searching for subtle collapses or by not interpreting the collapse correctly when noticed.

• On the other hand, the novice diagnostician should be cautioned to not over-diagnose near-occlusion; other causes of extracranial ICA asymmetry also exist such as distal disease and Circle of Willis anatomical variants.