Pseudo- and segmental occlusion of the internal carotid artery: a new classification, surgical treatment and results

Feasibility and efficiency of a new classification based on high-resolution MRI for carotid artery pseudo-occlusion and occlusion: Hybrid revascularization pilot study

BACKGROUND AND PURPOSE

Studies on changes in the distal internal carotid artery based on high resolution magnetic resonance imaging (HRMRI) are scarce. Herein, we propose a histological classification system for patients with carotid artery pseudo-occlusion or occlusion based on preoperative HRMRI, for which we evaluated the feasibility and clinical implications.

MATERIALS AND METHODS

From January 2017 to June 2021, 40 patients with Doppler ultrasound, CTA or MRA suggesting carotid artery occlusion were enrolled in this study. A new classification system based on HRMRI was established and subsequently verified by postoperative specimens. We recorded and analyzed patient characteristics, HRMRI data, recanalization rate, requirements of additional endovascular procedures, complications, and outcomes.

RESULTS

Four histological classifications (type Ⅰ-Ⅳ) were identified. According to our classification system, 20 patients (50.00%) were type I, nine (22.50%) were type II, 7 (17.50%) were type III, and four (10.00%) were type Ⅳ. The success rate of recanalization was 88.89% (32/36) in type I-III patients. Four (44.44%) type Ⅱ patients and five (71.43%) type Ⅲ patients suffered from intraoperative dissection.

CONCLUSION

Patients identified as types I (pseudo-occlusion) and II (thrombotic-occlusion) were able to be treated via hybrid revascularization with relatively low risk, while patients identified as type III (fibrous-occlusion) required more careful treatment. Recanalization is not suitable for patients identified as type Ⅳ. Our proposed classification system based on HRMRI data can be used as an adjunctive guide to predict the technical feasibility and success of revascularization via a hybrid technique.

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.

Multimodal recanalization for subacute symptomatic internal carotid artery occlusion due to atherosclerosis: Outcomes and notes on hybrid techniques

OBJECTIVES

Subacute internal carotid artery occlusion (ICAO) is associated with ipsilateral recurrent stroke, and successful recanalization of ICAO can improve cerebral blood perfusion (CBP) and prevent stroke. However, the optimal treatment remains controversial.

METHODS

We conducted a retrospective analysis of patients with subacute symptomatic ICAO due to atherosclerosis treated at our center. The hybrid surgical procedures included carotid endarterectomy, Fogarty balloon catheter embolectomy, aspiration thrombectomy and percutaneous transluminal angioplasty/stenting. Recanalization rates, CBP improvement, stroke recurrence and restenosis/reocclusion were investigated.

RESULTS

Fourteen symptomatic atherosclerotic ICAO patients (type A, 4; type C, 10; men, 11; women, 3; average age, 68.1 ± 7.9 years) in the subacute phase were treated with a multimodal recanalization technique. Symptoms included mild cerebral infarction, transient ischemic attack (TIA) and amaurosis fugax. The average onset-to-treatment time was 18.1 ± 4.8 days. The successful recanalization (thrombolysis in cerebral ischemia grade 2 or 3) rate was 100%. The ipsilateral-to-contralateral mean transit time ratio was significantly lower at the 1-year follow-up than preoperatively (1.01 ± 0.05 vs. 1.26 ± 0.09, P < 0.0001). There was one case of restenosis detected 1 year after surgery and no cases of reocclusion. During the 28.3 ± 10.0 months of follow-up, only 2 cases of TIA occurred. The average modified Rankin Scale score and National Institute of Health Stroke Scale score were significantly lower at themost recent follow-up than before recanalization (1.21 ± 0.89 vs. 1.86 ± 0.66, P = 0.0003; 1.36 ± 1.55 vs. 2.00 ± 1.88, P = 0.0066).

CONCLUSION

Multimodal recanalization techniques performed in a hybrid operation theater can safely achieve high recanalization rates in atherosclerotic ICAO patients in the subacute phase, which can be beneficial for recovering CBP and preventing stroke.

Management of internal carotid artery near-occlusion: the need for updated evidence

Near occlusion of internal carotid artery (ICA) is a rare and easily misdiagnosed condition and the decision for revascularisation still remains controversial. We conducted an updated meta-analysis in order to investigate outcomes after carotid endarterectomy (CEA), carotid artery stenting (CAS) or best medical treatment (BMT) in patients with near-occlusion of the ICA. We also aimed to investigate the role of time as a potential moderator of the near-ICA occlusion-stroke rate association. A multiple electronic health database search on articles published up to November 2019 was performed. The pooled stroke rate after CEA, CAS and BMT were calculated. We also investigated transient ischemic attack (TIA), stroke-related death, myocardial infarction (MI), any cause of death and ICA restenosis crude rates (%). A total of 33 articles were finally deemed eligible. The pooled stroke rate was 1.52% [95% confidence interval (CI): 0.09-4.02%] after CEA, 1.80% (95% CI: 0.61-3.40%) after CAS and 8.39% (95% CI: 3.39-14.80%) after BMT. Out of 896 CEA patients, we recorded 22 TIAs (2.5%), 33 all-cause deaths (3.7%), 5 stroke-related deaths (0.6%) and 6 MIs (0.7%). Concerning outcomes after 603 CAS patients, we recorded 7 TIAs (1.2%), 56 all-cause deaths (9.3%), 4 stroke-related deaths (0.7%) and 22 MIs (3.6%). Among 263 patients who were treated with BMT, we found 16 TIAs (6.1%), 10 all-cause deaths (3.8%), no stroke-related death, and no MI. Crude restenosis rate during follow-up was 9.0% (54/601) for CEA and 4.1% (24/592) for CAS patients. No significant effect of publication year upon stroke rate after CEA was recorded. However, there was a significant reversed association between pooled stroke rate after CAS and publication year (P=0.05). A statistically significant reversed association between pooled stroke rate after BMT and publication year was also recorded (P<0.01). The results of this updated meta-analysis revealed high stroke rate for patients with near-occlusion of ICA who treated only with BMT, while intervention seemed to be safe and effective. A downward trend in the stroke rates over time after CAS and BMT was also discovered. These highlight that patients with near-occlusion of ICA should be included and investigated in future studies.

Interventional recanalization as a treatment of carotid stump syndrome caused by right internal carotid artery occlusion: A case report

RATIONALE

Carotid stump syndrome is a cerebral infarction caused by an embolus formed subsequent to the vortex of blood flow from the occluded stump, which then moves through the collateral vessels into the brain. The covered stent and stent-assisted coil embolization stump are the effective interventions for the carotid artery stump.

PATIENT CONCERNS

A 71-year-old man twice experienced left limb weakness; diffusion weighted imaging confirmed the diagnosis of cerebral infarction. Cervical computed tomography angiography, intracranial magnetic resonance angiography, and digital subtraction angiography were conducted to evaluate collateral circulation, intraluminal composition, and shape of the carotid stump.

DIAGNOSES

The patient was diagnosed with cerebral infarction and right carotid stump syndrome.

INTERVENTION

The patient underwent interventional recanalization of the occluded internal carotid artery, which relieved his symptoms and led to satisfactory therapeutic outcomes during the clinical follow-up.

OUTCOMES

A 9-month clinical follow-up revealed no stroke recurrence.

LESSONS

Interventional recanalization for the carotid artery stump syndrome is feasible. Accurate preoperative evaluation including collateral circulation, intraluminal composition, and shape of the carotid stump can assure a successful vascularization and guided management.

The risk of recurrent stroke at 24 months in patients with symptomatic carotid near-occlusion: results from CAOS, a multicentre registry study

BACKGROUND AND PURPOSE

The risk of recurrent stroke amongst patients with symptomatic carotid near-occlusion (SCNO) has not been clearly established, and its management remains controversial. The aim was to define the 24-month risk of recurrent stroke and to analyse the effect of the different treatment modalities (medical treatment and revascularization) in a population of patients with SCNO.

METHODS

A multicentre, nationwide, prospective study from January 2010 to May 2016 was performed. Patients with angiography-confirmed SCNO were included. The primary end-point was ipsilateral ischaemic stroke including periprocedural events within 24 months following the presenting event. Revascularization results and periprocedural complications, ipsilateral transient ischaemic attack, disabling or fatal stroke, and mortality were also noted.

RESULTS

The study population comprised 141 patients from 17 Spanish centres. Seventy patients (49.6%) were treated by revascularization (carotid stenting in 47, endarterectomy in 23). Complete revascularization was achieved in 58 patients (83%). Periprocedural stroke or death occurred in 5.7%. The 24-month cumulative incidence of the primary end-point was 11.1% (95% confidence interval 5.8-16.4; n = 15), 12% in the medical treatment group and 10.2% in the revascularization group, log-rank P = 0.817. The cumulative rates of ipsilateral ischaemic stroke or transient ischaemic attack, disabling or fatal stroke, and mortality, were 17%, 4.5% and 7.5%, respectively.

CONCLUSIONS

The rate of ipsilateral ischaemic stroke in patients with SCNO seems to be lower than the known rate associated with severe carotid stenosis without near-occlusion. The potential benefit of revascularization in the prevention of stroke in patients with SCNO may be influenced by the effectiveness and safety of the procedure.

Surgical Treatment of Proximal Segmental Occlusion of the Internal Carotid Artery

Purpose

To present the feasibility, safety, and efficacy of carotid endarterectomy in patients with type II internal carotid artery occlusions, including the long-term outcomes.

Methods

From March 2008 to August 2015, 74 consecutive patients (48 men with a mean age of 65.1 ± 8.06 years) underwent carotid endarterectomy because of internal carotid artery (ICA) segmental occlusions. These were verified with preoperative carotid duplex scans (CDS) and CT angiography (CTA). Also, brain CT scanning was performed in all these patients. The indication for treatment was made jointly by a vascular surgeon, neurologist, and an interventional radiologist in a multidisciplinary team (MDT) context. After successful treatment, all the patients were followed-up at 1, 3, 6, and 12 months, then every 6 months thereafter.

Results

The most common symptom at presentation was transient ischaemic attack (TIA) in 49 patients (66.2%), followed by stroke in the past six months in the 17 remaining patients (23%). Revascularisation of the ICA with endarterectomy techniques was performed successfully in all the patients with an average clamp time of 11.9 min. All the procedures were performed under general anaesthesia in combination with a superficial cervical block. The early complication rate was 8.1% and included two cardiac events (2.7%) (one rhythm disorder and one acute coronary syndrome), three TIAs (4.1%), and one intracerebral hemorrhage (1.3%). Only one patient with the intracerebral hemorrhage died 5 days after surgery giving a postoperative mortality of 1.3% for this series. During the follow-up period (mean 50.4 ± 31.3 months), the primary patency rates at 1, 3, 5, and 7 years were 98.4%, 94.9%, 92.9%, and 82.9%, respectively. Likewise, the survival rates were 98.7%, 96.8%, 89%, and 77.6%, respectively. Ultrasound Doppler controls during follow-up detected 8 ICA restenoses; however, only 3 of these patients required further endovascular treatment.

Conclusions

Carotid endarterectomy of internal carotid artery (ICA) segmental occlusion is a safe and effective procedure associated with acceptable risk and good long-term results. Therefore, the current guidelines which do not recommend carotid endarterectomy in this patient group should be reassessed, with the requirement for ongoing large-scale randomized controlled trials to compare CEA with best medical therapy in this patient cohort.

Carotid endarterectomy in patients with recurrent symptoms associated with an ipsilateral carotid artery near occlusion with full collapse

OBJECTIVE

Near occlusion (NO) of the internal carotid artery (ICA) with full collapse (NOFC) is a rare condition, with a prevalence of around 1%. Guidelines on carotid stenosis recommend a conservative treatment in patients with a single-event ipsilateral to a NOFC, but the optimal treatment for patients with recurrent symptoms associated with NOFC remains uncertain. We describe a consecutive series of patients with recurrent symptoms associated with NOFC (RSNOFC) who underwent carotid endarterectomy (CEA).

METHODS

From 2008 to 2017, 17 consecutive patients with RSNOFC were treated according to our standardized multidisciplinary work-up and protocol and included for this single-center cohort study. NO was defined according to the angiographic North American Symptomatic Carotid Endarterectomy Trial criteria. Only patients with NOFC were included in this study.

RESULTS

Standard longitudinal CEA was performed in 15 patients, whereas in 2 patients the ICA was ligated with concomitant endarterectomy of the ECA. Within 30 postoperative days, one patient died from a hemorrhagic infarction. During follow-up (median 23 months) one patient died of unknown cause 90 days after CEA. No TIA, stroke, myocardial infarction or re-stenosis occurred in the remaining patients.

CONCLUSION

In patients with RSNOFC, CEA may be considered a potential treatment option. Although procedural risks in this small subgroup may be higher as compared to patients with low-to-moderate risk anatomy, this risk may outbalance the natural course.

Angiographic Characteristics of Pseudo-occlusion of the Internal Carotid Artery Before and After Stenting

BACKGROUND

Various definitions of pseudo-occlusion and clinical outcomes after various treatments have been reported, but reports discussing the stenotic characteristics of pseudo-occlusion are rare.

OBJECTIVE

To analyze the angiographic characteristics of pseudo-occlusion of the internal carotid artery (ICA) before and after carotid artery stenting (CAS).

METHODS

We retrospectively reviewed the angiographic characteristics of 56 patients with pseudo-occlusion of the ICA treated with CAS. Angiographic changes were evaluated from digital subtraction angiography in terms of lesion characteristics of the stenosis and the diameter changes in the distal ICA before and after CAS.

RESULTS

Fifty-six patients were successfully treated. Based on angiographic findings of ICA stenosis, 33 and 23 patients were classified into the single-channel and multiple-channel group, respectively. Regarding the diameter changes in the distal ICA after CAS, 31 cases were classified as immediate dilatation and the other 25 as restricted dilatation. Immediate dilatation of the distal ICA beyond the stent and that at a follow-up examination were observed significantly less frequently in the multiple-channel group than in the single-channel group. The use of multiple stents and stent occlusion at a follow-up examination were significantly more prevalent in the multiple-channel group than in the single-channel group.

CONCLUSION

Stenotic lesions of pseudo-occlusion of the ICA were classified as single channel and multiple channel. Restricted dilatation of the distal ICA after CAS was more prevalent in the multiple-channel group. Because adverse events tended to be more frequent in the multiple-channel group than in the single-channel group, the indications for CAS should be determined carefully in multiple-channel patients.

ABBREVIATIONS

CAS, carotid artery stentingICA, internal carotid artery.

Endovascular Treatment for Near Occlusion of the Internal Carotid Artery : 30-Day Outcome and Long-Term Follow-Up

BACKGROUND

The treatment strategy and the correct incidence of near occlusion (NO) of the internal carotid artery (ICA) is still controversial. In routine radiological imaging NO can easily be misdiagnosed as complete occlusion and there is no consensus on the standard treatment strategy.

PURPOSE

To present our perioperative and long-term follow-up results of ICA NO patients treated with carotid artery stenting (CAS).

MATERIAL AND METHODS

Between 2004-2014 a total of 182 patients with ICA NO were evaluated for CAS. The study included 132 male (72.5 %) and 50 female (27.5 %) patients with a mean age of 70.2 years. Patients underwent a clinical neurological evaluation and radiological imaging of the carotid arteries before the CAS procedure. Of the patients 80 (44 %) were asymptomatic. The median clinical and carotid Doppler ultrasound (DUS) follow-up period was 64 months (range 18-124 months).

RESULTS

In 182 patients CAS were performed, 4 patients (2.2 %) developed minor stroke, 2 patients (1.1 %) developed myocardial infarction but no major stroke or death occurred in the following 30-day period. Asymptomatic restenosis was detected in seven patients (3.8 %) in the follow-up period.

CONCLUSION

With sufficient neurological evaluation during pretreatment and posttreatment periods and when the procedure is performed with technologically developed products by an experienced interventional team, CAS is beneficial in patients with ICA NO.

Carotid Near-Occlusion: A Comprehensive Review, Part 2--Prognosis and Treatment, Pathophysiology, Confusions, and Areas for Improvement

In Part 1 of this review, the definition, terminology, and diagnosis of carotid near-occlusion were presented. Carotid near-occlusions (all types) showed a lower risk of stroke than other severe stenoses. However, emerging evidence suggests that the near-occlusion prognosis with full collapse (higher risk) differs from that without full collapse (lower risk). This systematic review presents what is known about carotid near-occlusion. In this second part, the foci are prognosis and treatment, pathophysiology, the current confusion about near-occlusion, and areas in need of future improvement.

Carotid Near-Occlusion: A Comprehensive Review, Part 1--Definition, Terminology, and Diagnosis

Carotid near-occlusion is distal ICA luminal collapse beyond a tight stenosis, where the distal lumen should not be used for calculating percentage stenosis. Near-occlusion with full ICA collapse is well-known, with a threadlike lumen. However, near-occlusion without collapse is often subtle and can be overlooked as a usual severe stenosis. More than 10 different terms have been used to describe near-occlusion, sometimes causing confusion. This systematic review presents what is known about carotid near-occlusion. In this first part, the foci are definition, terminology, and diagnosis.

Stroke in patients with occlusion of the internal carotid artery: options for treatment

Ischemic stroke may occur in patients in whom vascular imaging shows the ipsilateral internal carotid artery (ICA) to be occluded. In younger patients this is often due to carotid artery dissection, while in older people this most likely results from cardiac embolism or thrombosis secondary to high-grade stenosis at the carotid bifurcation. Interventional techniques aim at recanalization of the carotid artery for early restoration of cerebral blood flow and secondary prevention of future strokes. In chronic ICA occlusion the ischemic infarct may be related to hemodynamic compromise. In this situation, extracranial-intracranial bypass surgery was introduced, but its role remains still unclear. Ischemic stroke may also occur in patients with a chronic occlusion of the contralateral ICA. This situation demands the usual stroke treatment, but surgical and neuroradiological interventions face a higher risk than unilateral vascular pathology. Medical treatment supports stroke prevention in carotid artery occlusion.

Carotid Endarterectomy for Pseudo-occlusion of the Cervical Internal Carotid Artery

OBJECT

This study described clinicopathological characteristics of pseudo-occlusion (PO) of the internal carotid artery (ICA) with regards to the pathological mechanism and the benefit of carotid endarterectomy (CEA).

METHODS

We retrospectively reviewed 17 PO patients who underwent CEA. Clinical presentation, angiographic findings, surgical outcomes and plaque components obtained from CEA were investigated.

RESULTS

PO plaques had more fibrous and two different pathological features, including total occlusion with recanalization and severe stenosis. Plaques of the total occlusion with recanalization (8 patients) were composed of thrombotic total occlusion and lumen recanalization by large neovascular channels, whereas those with severe stenosis (9 patients) were fibrous or fibroatheromatous plaque with severe stenosis of the original lumen. Of all the patients who underwent a carotid angiogram 2 weeks after surgery, 16 were successfully treated, but one showed complete occlusion of the ICA. At the follow-up period, two patients showed restenosis of the ICA. Three patients with complete occlusion or restenosis had histologically fibrous sclerotic plaques.

CONCLUSION

Patients with PO had more fibrous plaques and two different histological features, including total occlusion with recanalization or severe stenosis. The plaque histology may be related to the pathogenesis and the surgical outcome.

Clinical utility of echocontrast agents in neurosonology

INTRODUCTION

Neurosonological investigations of the extracranial and intracranial brain supplying arteries are helpful in the assessment of stroke and stroke-prone patients.

METHODS

In this paper we review the indications, application and advantages of second-generation (gas-filled) microbubble contrast agents such as SonoVue.

RESULTS

Gas-filled microbubbles have a strong echo enhancing effect and produce enhancement for several minutes, enabling the sonographer to perform the investigation with a single injection or two or three repeated injections without the need for continuous administration. Echocontrast agents provide better delineation of normal blood flow, occlusions, pseudo-occlusions, stenoses, and collaterals in the extracranial and intracranial vascular beds. They are of particular value during transcranial color-coded transcranial duplex investigations via the temporal and occipital window.

CONCLUSIONS

Echocontrast agents give additional information on the patient's vascular situation that is often crucial to planning further diagnostic and therapeutic steps. The use of second-generation gas-filled microbubbles, such as SonoVue in transcranial neurosonology, may help to avoid unnecessary, expensive and potentially harmful additional investigations such as intra-arterial DSA. Future applications include the visualization of brain tissue perfusion.

Long term follow-up of unilateral occlusion of the internal carotid artery including repeated tests of vasomotor reactivity by transcranial Doppler

BACKGROUND

Early study on pathological flow pattern in the ophthalmic artery (OA), connected with impaired vasomotor reactivity (VMR) and low pulsatility index (PI) in the anterior cerebral artery (ACA) on the occluded side, suggested collateral exhaustion. We undertook this study to evaluate whether the occurence of new strokes is predicted by special haemodynamic features.

METHOD

A total of 27 patients (22 men and five women), aged 63+/-15 years (mean+/-SD) with longstanding occlusion of the internal carotid artery (ICA), confirmed by duplex scanning were studied. They had minimal neurological deficit and were followed-up for mean 4.3+/-1.8 (mean+/-SD) years by repeated clinical and 3-D transcranial Doppler (3-D TCD) examinations with azetazolamide test of vasomotor reactivity (VMR).

RESULTS

During follow-up, seven patients had new strokes (five minor strokes and two major ones), two ipsilateral and four contralateral to the ICA occlusion and one in the posterior circulation. Four patients died, All patients experiencing a new stroke had previous symptoms and pathological flow patterns in the OA, i.e retrograde or isoelectric flow were noted in six of them. One patient with contralateral stroke experienced occlusion of the ICA located above the origin of the OA with anterograde flow; otherwise none of 11 patients with anterograde flow had a new stroke (p<0.05, Fisher exact text). During the follow-up, the initial mean velocity (MV) in the middle cerebral artery (MCA) on the occluded side in six patients with a new stroke in the anterior circulation, was 26.83+/-10.50 cm/s, which was significantly different from that of patients without a new stroke (45.80+/-12.8 cm/s) (p<0.01). MV in the ICA on the non-occluded side at the last examination was greater than that at the first examination (p<0.05) and increased after the use of acetazolamide only on this side (p<0.05), while PI decreased bilateraly (p<0.001 and 0.05). Resting MV both in the MCA on the occluded and ACA on the non-occluded side slightly decreased, while MV in the posterior cerebral artery (PCA) increased on the occluded side (p<0.083) compared with that at the start of the follow-up. VMR in the ACA decreased slightly both on the non-occluded and occluded side (Delta-6.9 and Delta-5.3 respectively), while impaired VMR<or=11% was not significantly connected with new strokes.

CONCLUSION

During the follow up, new strokes had appeared on both sides and in vertebrobasilar territory and were connected with pathological flow pattern in the OA and low MV in the MCA at the first examination.

Common carotid artery occlusion treatment: revealing a gap in the current guidelines

OBJECTIVE

To review the literature on the management of common carotid artery occlusion (CCAO).

METHODS

A review of English-language medical literature from 1965 to 2012 was conducted using the PubMed and EMBASE databases to find all studies involving management of CCAO. The search identified 21 articles encompassing 146 patients/arteries (73.2% men; mean age 65 ± 6.9 years).

RESULTS

The majority of the patients (93.8%) were symptomatic. Most of the patients (61.5%) had ipsilateral internal carotid artery (ICA) and external carotid artery (ECA) patent, while an occluded ICA and a patent ECA were found in 26.6% of the patients. Eighty per cent of the patients treated underwent a surgical bypass procedure, with the subclavian artery as the most common inflow vessel (64.1%). During the first 30 days of the procedure two strokes (1.5%) were reported. During a follow-up period spanning an average of 25.6 ± 11.2 months nine patients (6.6%) experienced a clinical cerebrovascular event. Seven restenoses (5.1%) and two reocclusions (1.5%) also occurred-eight after open surgical and one after endovascular repair.

CONCLUSION

The necessity to intervene to a CCAO remains controversial. This review shows that open surgical management of symptomatic CCA occlusive disease is a safe, durable, and effective therapeutic strategy with low perioperative cerebrovascular morbidity.

Spontaneous recanalization of the occluded internal carotid artery. A report of two cases

Spontaneous recanalization of the occluded internal carotid artery (ICA) is more frequent than is generally believed. The timing of spontaneous recanalization remains unclear but it may occur as either an early or a late event. The aim of this case report is to emphasize the importance of spontaneous recanalization and its consequences. From September 2008 to November 2010 we prospectively followed patients with old ICA occlusion. The diagnoses of an occlusion were based on duplex scan findings and were confirmed by CT angiography and digital subtraction angiography (DSA). ICA occlusions secondary to dissection, inflammatory process, like fibromuscular dysplasia, previous stenting or endarterectomy and trauma, were excluded from the study. All patients had a scheduled carotid duplex scan every six months. Overall 65 patients were enrolled. Two patients showed evidence of spontaneous recanalization. A 55-year-old man with a known history of transient ischemic attack had occlusion in the left side ICA. He presented with another TIA eight months later. Investigations showed evidence of rcanalization of occluded ICA. This artery underwent uneventful stenting. In another patient recanalization was heralded by global aphasia and right side hemiplegia. He was a 70-year-old man with a history of recurrent TIA. Carotid duplex scan and DSA showed recanalization of the occluded left ICA accompanied by occlusion of the ipsilateral middle cerebral artery. He remained profoundly disabled with severe neurological deficits. In conclusion, spontaneous recanalization of the occluded internal carotid artery is a potentially complicated event that may lead to severe neurological disability.

What is the real risk of dislodging thrombi during endovascular revascularization of a proximal internal carotid artery occlusion?

BACKGROUND

There is a theoretical concern that a thrombus may be dislodged distally when crossing the occluded segment during recanalization of a complete occlusion.

OBJECTIVE

To assess the immediate postprocedural brain diffusion-weighted image (DWI) findings following endovascular recanalization using an embolic protection device for proximal internal carotid artery (ICA) occlusion.

MATERIALS AND METHODS

We retrospectively identified 12 patients who underwent stent implantation for sudden symptomatic occlusion of the proximal ICA. In 8 patients, no additional intracranial occlusions were identified. In 4 patients, an additional intracerebral thrombus was detected in the middle cerebral artery. Distal protection devices were used in all cases. We evaluated the presence and amount of retrieved embolic fragments in the distal protection devices. The incidence and location of postprocedural emboli were determined using DWI.

RESULTS

Recanalization of the proximal ICA was achieved in all patients. After complete occlusion of the proximal ICA was demonstrated, primary passage of the embolic protection device through the occluded ICA was gently navigated in 7 patients. However, this was not possible in 5 patients. Three patients developed new lesions on postprocedural DWI. Of the 12 patients in which distal protection devices were used, debris was detected in 7 patients.

CONCLUSION

In endovascular revascularization of proximal ICA occlusion, postprocedural emboli occur less frequently than reported in a systematic review of the DWI literature. The real risk of dislodging thrombi appears to be from plaque fragment mobilization by angioplasty, rather than from crossing an occluded segment.

Internal carotid artery pseudo occlusion with embolic cerebral ischemia and low flow in the central retinal artery: a diagnostic challenge

We present a rare case of internal carotid artery pseudoocclusion (ICAPO) in a 60-year-old male Caucasian patient who experienced a reversible sudden loss of vision of the right eye for 10 min followed by recurrent blurring of vision as well as dysarthria and numbness in the left face. The referring ophthalmologist admitted the patient for suspicious occlusion of the internal carotid artery causing anterior ischemic optic neuropathy (AION).

Histopathological features with angiographic correlates of internal carotid artery pseudo-occlusion: impact of plaque compositions. Clinical article

OBJECT

This study describes clinicopathological characteristics of pseudo-occlusion of the internal carotid artery with regard to its possible mechanisms.

METHODS

The authors retrospectively reviewed 17 patients with pseudo-occlusion and 23 with high-grade stenosis (North American Symptomatic Carotid Endarterectomy Trial criteria ≥ 90%, but no collapsed distal internal carotid artery) who underwent carotid endarterectomy. Atherosclerotic risk factors, clinical presentation, angiographic findings, and histological features of plaque obtained from the carotid endarterectomy were investigated and comparisons were made between groups.

RESULTS

Plaques obtained in the pseudo-occlusion group were significantly more fibrous and less atheromatous than those in the high-grade stenosis group. Old, organized thrombi were more frequently found in pseudo-occlusion group plaques than in high-grade stenosis group plaques. Plaques acquired in the pseudo-occlusion group had 2 different histological features: the presence or absence of the original lumen. The pseudo-occlusion plaques with total occlusion and recanalization (8 patients) were composed of thrombotic total occlusion with lumen recanalization by large neovascular channels, whereas those with severe stenosis (9 patients) were fibrous or fibroatheromatous and had severe stenosis of the original lumen. In patients with pseudo-occlusion and total occlusion and recanalization, the authors observed a significantly higher incidence of transient ischemic attack and anterior communicating artery-posterior communicating artery collateral flow than those with high-grade stenosis and pseudo-occlusion with severe stenosis.

CONCLUSIONS

Plaques of the pseudo-occlusion group were more fibrous than those of the high-grade stenosis group and had 2 different histological features: pseudo-occlusion with total occlusion and recanalization or pseudoocclusion with severe stenosis. This difference in plaque histology may be related to the clinical features of pseudoocclusion, such as symptoms and collateral flow patterns.

Internal carotid artery stenting in patients with near occlusion: 30-day and long-term outcome

BACKGROUND AND PURPOSE

The natural history of the carotid NO is poorly characterized, and the management of patients remains controversial. We report the results and complications associated with CAS and follow-up.

MATERIALS AND METHODS

Between March 2000 and March 2009, 116 of 836 CAS procedures were performed in patients with carotid NO (13.9%). A total of 99 men (85.3%) and 17 women (14.7%) with a mean age of 65.8 years were included. Presenting symptoms were TIA in 44 patients (37.9%) and minor stroke or noninvalidating stroke in 61 (52.6%). One hundred five patients (90.5%) were symptomatic.

RESULTS

A distal filter was used for cerebral protection in 92 patients (79.3%). Transient hemodynamic alterations were frequent during balloon inflation: hypotension (37.1%), bradycardia (48.3%), and asystole in 24.1%. Four patients (3.4%) developed a TIA after CAS. Stroke in progression was arrested in the 1 patient (0.9%). The median follow-up period for patients was 36 months. Asymptomatic restenosis >70% occurred in 5 patients (4.3%); asymptomatic occlusion occurred in 3 patients (2.6%). During follow-up, 3 patients (2.6%) experienced a stroke, 1 ipsilateral (at 19 months) and 2 contralateral (at 6 and 30 months, respectively). Thirteen patients (11.2%) died, 7 from vascular causes.

CONCLUSIONS

Our study showed that carotid NO is an under-recognized condition, and CAS would seem to be beneficial when performed by an experienced neurointerventional team.

Contrast-enhanced MR angiography is not more accurate than unenhanced 2D time-of-flight MR angiography for determining > or = 70% internal carotid artery stenosis

BACKGROUND AND PURPOSE

Internal carotid artery (ICA) atheromatous disease is an important cause of ischemic stroke, and endarterectomy or stent placement is typically indicated for symptomatic patients with > or = 70% stenosis. Our purpose was to compare contrast-enhanced MR angiography (CE-MRA) with unenhanced 2D time-of-flight MR angiography (2D TOF MRA) in detecting hemodynamically significant ICA stenosis, by using CT angiography (CTA) as the reference standard.

MATERIALS AND METHODS

This was an institutional review board-approved retrospective study. We identified 177 consecutive patients (354 ICAs) who received correlative CE-MRA, 2D TOF MRA, and CTA. Two neuroradiologists blinded to the CTA data graded the degree of ICA stenosis according to a 5-point scale. Additionally, luminal signal-intensity characteristics including 1) signal intensity drop-out, 2) distal-vessel narrowing, and 3) distal-vessel signal-intensity reduction were recorded. MRA results were correlated with those of CTA, and receiver-operating-characteristic (ROC) curves were constructed.

RESULTS

On CTA, there were 55 ICAs with and 299 without > or = 70% stenosis. CE-MRA was 84% sensitive and 96% specific for detecting > or = 70% stenosis; 2D TOF MRA was 80% sensitive and 95% specific. The area under the ROC curve was 0.97 for CE-MRA and 0.95 for 2D TOF MRA (P = .51, not significant). For both MRA studies, each of the luminal signal-intensity characteristics had high specificity (> 98%) but poor-to-mild sensitivity (35%-66%) in detecting > or = 70% stenosis.

CONCLUSIONS

Although it is established that CE-MRA more accurately delineates neurovascular anatomy than does unenhanced 2D TOF MRA, the administration of gadolinium did not offer a significant advantage in distinguishing surgically treatable ICA stenosis. This conclusion may be important in patients with contraindications to gadolinium.

Imaging of the carotid arteries: the role of duplex ultrasonography, magnetic resonance arteriography, and computerized tomographic arteriography

Stenosis of the internal carotid artery represents a major cause of stroke, with atherosclerosis representing the major pathophysiology of this stenosis. It is estimated that over 700,000 Americans suffer a stroke annually. A prompt and accurate diagnosis of carotid artery disease is critical when planning a therapeutic strategy. Physical examination is inaccurate in determining the presence and severity of carotid artery disease. Therefore, reliable imaging tests which offer little risk to the patient are required.

Evaluation of carotid artery atherosclerotic plaque distribution by using long-axis high-resolution black-blood magnetic resonance imaging

Object

The goal of this study was to evaluate the usefulness of long-axis black-blood MR (BB–MR) imaging for assessing plaque morphology and distribution in patients with atherosclerotic carotid artery (CA) stenosis.

Methods

Sixty-eight carotid arteries in 67 patients who were scheduled to undergo CA endarterectomy or CA stent placement due to atherosclerotic stenosis were included in this study. The patients had undergone CA BB–MR imaging and digital subtraction (DS) angiography within 3 weeks of revascularization. The DS angiography studies were performed using the transfemoral artery approach with selective common CA catheterization. The BB–MR images were acquired using a 1.5-T whole-body MR imaging unit, and T1-weighted images parallel to the long axis of the artery at 1-mm intervals were obtained. Plaque distribution was evaluated by measuring the distance between the CA bifurcation and the point that appeared to be the distal extent of the plaque on BB–MR imaging (D–MR imaging) and DS angiography images (D–DS angiography).

Results

Plaque distribution was clearly shown in 88.2% of the cases using long-axis BB–MR images, except for 8 arteries with poor image quality. In 4 arteries, D–DS angiography could not be obtained because the distal plaque end could not be confirmed. In 56 vessels, both the D–DS angiography and D–MR imaging could be measured; the mean D–MR imaging (19.75 ± 6.85 mm [standard deviation]) was significantly longer than the average D–DS angiography (16.32 ± 7.07 mm).

Conclusions

Long-axis BB–MR imaging can provide a noninvasive and accurate way to show CA plaque distribution; it is of great use not only for stroke risk assessment in patients with CA atherosclerosis but also for preoperative evaluation in patients requiring CA endarterectomy or CA stent placement.

Assessment of apparent internal carotid occlusion on ultrasound: prospective comparison of contrast-enhanced ultrasound, magnetic resonance angiography and digital subtraction angiography

OBJECTIVES

Modern conventional ultrasound is sensitive to slow flow, but may misclassify some tight stenoses as occlusion. Symptomatic patients with tight proximal internal carotid artery stenoses may benefit from carotid endarterectomy but those with occlusion or long-segment disease do not.

DESIGN

A prospective study of the diagnostic accuracy of contrast-enhanced ultrasound (CE-US), 2D time-of-flight magnetic resonance angiography (2D-TOF MRA) and contrast-enhanced magnetic resonance angiography (CE-MRA) against a reference standard of digital subtraction angiography (DSA) in patients with apparent carotid occlusion on conventional ultrasound.

MATERIALS AND METHODS

Thirty-one patients with apparent carotid occlusion on conventional ultrasound and with recent ispilateral hemispheric transient ischaemeic attacks (TIAs) were studied. The primary endpoint was confirmation of occlusion with a secondary endpoint of identification of a surgically correctible lesion.

RESULTS

The sensitivity and specificity of CE-US, 2D-TOF MRA and CE-MRA for patency were 1 & 1, 0.33 & 1 and 0.6 & 1 respectively and for the detection of a surgically correctible lesion were 1 & 0.96, 0.67 & 1 and 1 and 0.96 respectively. CE-US was difficult to interpret, precluding confident diagnosis in 5 cases.

CONCLUSIONS

2D-TOF MRA had poor sensitivity for patency and cannot be recommended as a second-line investigation to assess vessels apparently occluded on conventional ultrasound. Confident diagnosis on CE-US and CE-MRA accurately identified occlusion. If occlusion is confirmed by either of these modalities, no further imaging is required. The relative advantages of CE-US or CE-MRA in this situation are uncertain.

[Segmental occlusion of the internal carotid artery with collateral reinjection downstream from the carotid sinus]

The preoperative evaluation before coronary bypass led to the discovery of complete atheromatous obstruction of the internal carotid artery sinus in a 79-year-old man free of any neurological symptom. Downstream from the carotid sinus, the patency of the internal carotid artery was ensured by a collateral branch fed by the ipsilateral external carotid artery. This exceptional anatomic variation can be explained by a persistent embryonic artery. The recognition of this atypical feature is clinically relevant because surgery may be possible in some cases, while it is not technically feasible in patients with total obstruction.

Feasibility of Endovascular Recanalization for Symptomatic Cervical Internal Carotid Artery Occlusion

OBJECTIVES

This study sought to report technical details and clinical results of the first series of endovascular recanalization for cervical internal carotid artery (ICA) occlusion.

BACKGROUND

Cervical ICA occlusion is associated with impaired cerebral perfusion, which may lead to ischemic cerebral symptoms and hemodynamic infarcts. Neither surgical nor endovascular revascularization has been shown to benefit this population.

METHODS

Endovascular recanalization was attempted in 30 patients with ICA occlusions (27 men; age 72.1 +/- 8.0 years, range 48 to 85 years). Recurrent neurologic deficit or cerebral ischemia by perfusion study, after known ICA occlusion, was noted in all patients. Strategies and devices for coronary occlusion intervention were applied, including microcatheter-supported tapered-tip stiff coronary guidewires. Contralateral ICA stenosis was found in 9 patients (30%). All patients underwent independent neurologic and duplex ultrasound follow-up.

RESULTS

The overall technical success rate was 73% (22 of 30). No neck hematoma, intracranial hemorrhage, or hyperperfusion was noted. One (3.3%) fatal brainstem infarction occurred 1 day after a successful ICA procedure, with angiographically proven acute basilar artery occlusion and patent ICA stent. Baseline ophthalmic artery flow was reversed in 15 of the 22 successfully recanalized patients, and was normalized in 12 after the procedure. There was no new cerebral ischemic event or neurologic death for a mean follow-up of 16.1 +/- 18.5 months.

CONCLUSIONS

Endovascular recanalization for cervical ICA occlusion is feasible with acceptable midterm clinical results.

Accuracy of Conventional plus Transoral Carotid Ultrasonography in Distinguishing Pseudo-Occlusion from Total Occlusion of the Internal Carotid Artery

BACKGROUND

To investigate the accuracy of conventional carotid ultrasonography (CCU) combined with transoral carotid ultrasonography (TOCU) for distinguishing pseudo-occlusion from total occlusion of the internal carotid artery (ICA).

METHODS

This study included 95 patients who were suspected of having an occlusion of the ICA on magnetic resonance angiography (MRA) and underwent both CCU and conventional digital subtraction angiography (DSA) in order to confirm the diagnosis. TOCU was also performed to observe the cervical portion of the ICA distal to the stenosis. We compared the ultrasonographic findings with the DSA findings.

RESULTS

Twelve of the 95 patients were defined as having an ICA pseudo-occlusion on DSA. On B-mode images with CCU color Doppler, slight residual flow signals in the ICA lumen were shown in 20 patients. Among them, 2 patients had a pulsed Doppler waveform of the distal ICA occlusion pattern. Among the remaining 18 patients, 4 had a pulsed Doppler waveform of the to and fro flow pattern, and 14 had a weak antegrade flow pattern in the ICA lumen. The conventional ultrasonographic method showed 100% sensitivity with 93% specificity for diagnosing an ICA pseudo-occlusion. The addition of TOCU findings increased the specificity to 98%. In 2 patients, who were overdiagnosed as having an ICA pseudo-occlusion even using TOCU, DSA revealed an occlusion of the ICA distal to the ophthalmic artery with a severe stenosis of the proximal ICA.

CONCLUSIONS

Using conventional and transoral carotid ultrasonography, an ICA pseudo-occlusion can be diagnosed with higher accuracy.

Carotid surgery in acute symptomatic patients

OBJECTIVES

evaluation of urgent carotid artery surgery with new diagnostic techniques and changing surgical considerations at a university hospital.

DESIGN, MATERIAL AND METHODS

prospective monitoring and assessment of outcome in 67 patients who underwent urgent carotid surgery because of symptomatic extracranial carotid artery involvement. Patients were examined via the stroke unit: duplex sonography was mandatory for diagnosis of extracranial carotid artery disease, as was proof of an open middle cerebral artery (MCA). Assessment of intracerebral damage followed CT or MR imaging procedures. Perioperative and surgical management was standardized. Neurological impairment was assessed pre-, postoperatively and at follow-up using the Rankin scale. "Urgent" was defined as "immediate" after the final diagnostic step had been performed.

RESULTS

within a period of 26 months 67 symptomatic patients (58% stroke, 42% TIA) underwent urgent carotid surgery. Median time from admission to surgery was 2 days. In all but five cases flow through the ICA could technically be restored (93%). Thirty-day mortality was 3% and disease-related morbidity 13%. The one and two year survival rates were 92 and 90%, respectively. No ipsilateral recurrent stroke occurred during follow-up.

CONCLUSIONS

clinical decision-making based on stratified diagnostic workup by means of extra- and intracranial as well as intracerebral hemodynamics using new imaging techniques may select patients who will benefit more from urgent surgery than from conservative management.

Reconstructive surgery of the extracranial arteries

The first carotid endarterectomy (CEA) is usually accredited to Eastcott who reported in 1954 the successful incision of a diseased carotid bulb with end-to-end anastomosis of the internal carotid artery (ICA) to the common carotid artery (CCA). During the following years surgeons were quick to adopt and improve the intuitively attractive procedure. But by the early to mid 1980s several leading neurologists began to question the growing number of CEAs performed at that time. Six major CEA trials were then designed which are now completed or nearing completion. Most conclusive data are available from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) for symptomatic carotid disease, and from the Asymptomatic Carotid Atherosclerosis Study (ACAS) for asymptomatic carotid disease. The key result of these studies is that CEA is beneficial to high grade symptomatic and asymptomatic carotid stenosis. While the benefit in symptomatic disease is clear, it may be negligible in asymptomatic patients suffering from other medical conditions, the most important being coronary artery disease. Since the conclusions from the different studies vary significantly, guidelines and recommendations with regard to CEA have been issued by a number of interest groups, so-called consensus conferences. The best known guidelines are published by the American Heart Association (AHA). However, the practice of interest groups to issue guidelines is currently being criticized, the main reason being that interest groups have different ideas and all claim the right to issue guidelines. At present we recommend CEA for symptomatic high-grade stenosis in patients without significant coincident disease. With regard to asymptomatic stenosis we suggest surgery to otherwise healthy patients if the stenosis is very narrow or progressive. Preoperative evaluation has changed over the years. Currently we recommend duplex sonography in combination with intra- and extracranial magnetic resonance angiography (MRA). Concurrent coronary artery disease is a major consideration in the perioperative management, and the use of a specific algorithm is recommended. Surgery is performed under general anaesthesia with intraoperative monitoring such as electroencephalography (EEG) and transcranial Doppler (TCD). A temporary intraluminal shunt is used selectively if after cross-clamping the flow velocity in the middle cerebral artery (MCA) falls to below 30 to 40% of baseline. For years we employed routine barbiturate neuroprotection during cross-clamping. At the present time we use barbiturate selectively, if the flow velocity in the MCA falls to below 30 to 40% of baseline and if the use of a temporary intraluminal shunt is not possible due to difficult anatomic conditions. The reason to abandon systematic barbiturate protection was to accelerate recovery from anaesthesia. Our patients are monitored overnight on the ICU or a surveillance unit. Routine hospitalization after surgery is 5 to 7 days with a control duplex sonography being performed prior to discharge. A number of details with regard to surgical technique and perioperative management are a matter of discussion. Our surgical routine is described here step by step. Such management resulted in 6 major complications among the 402 cases with 4 of cardiopulmonary and 2 of cerebrovascular origin. For the future we can expect the development of percutaneous transluminal techniques competing with standard carotid endarterectomy. At the present time several comparative studies are under way. Irrespective of the technical approach to treat carotid stenosis, several other issues have to be clarified before long. One of the major unresolved items is the timing of treatment after completed stroke. In this regard prospective trials need to be performed. Although numerically not as important as carotid stenosis, vertebral artery (VA) and subclavian artery (SA) stenoses are more and more accepted as indication for surgical

Reliability and validity of noninvasive imaging of internal carotid artery pseudo-occlusion

BACKGROUND AND PURPOSE

Our study evaluated noninvasive tests for the diagnosis of atheromatous internal carotid artery (ICA) pseudo-occlusion.

METHODS

Twenty patients (17 men, 3 women; mean age +/-SD, 64.3+/-11.6 years) with angiographically proven atheromatous ICA pseudo-occlusion (20 vessels) were prospectively examined with MR angiography (MRA; 2D and 3D time-of-flight techniques), color Doppler-assisted duplex imaging (CDDI) and power-flow imaging (PFI) with and without an intravenous ultrasonic contrast agent. As a control group, 13 patients (13 men; mean+/-SD age, 63.0+/-9.0 years) with angiographically proven ICA occlusion (13 vessels) were studied with the same techniques. For the determination of interobserver agreement (kappa statistics), the findings of each diagnostic technique were read by 2 blinded and independent observers who were not involved in patient recruitment and initial data acquisition. Specificity and sensitivity were calculated for all noninvasive techniques (observer consensus) in comparison to the standard of reference (intra-arterial angiography).

RESULTS

Interobserver reliabilities were kappa=0.86 for intra-arterial angiography, kappa=0.90 for unenhanced CDDI, kappa=0. 93 for enhanced CDDI, kappa=0.93 for unenhanced PFI, kappa=1.0 for enhanced PFI, kappa=0.93 for 2D MRA, and kappa=0.77 for 3D MRA, respectively (P<0.0001). Specificities and sensitivities were 0.92 and 0.70 for unenhanced CDDI, 0.92 and 0.83 for enhanced CDDI, 0.92 and 0.95 for unenhanced PFI, 1.0 and 0.94 for enhanced PFI, 1.0 and 0.65 for 2D MRA, and 0.89 and 0.47 for 3D MRA, respectively.

CONCLUSIONS

Advanced ultrasonographic techniques, especially PFI (with only 1 false-positive diagnosis of occlusion in the present series), can provide reliable and valid data to differentiate between ICA pseudo-occlusion and complete occlusion. In contrast, time-of-flight MRA at its present state is not capable of predicting minimal residual flow within a nearly occluded ICA.

Internal carotid artery patency following common carotid artery occlusion: management of the asymptomatic patient

Rarely, internal carotid artery (ICA) patency is maintained above a common carotid artery occlusion (CCAO) through collateral flow of the ipsilateral external carotid artery or an aberrant ICA branch. Several small series report excellent results of ICA revascularization in relieving cerebral ischemic symptoms in these patients. The natural history of CCAO with patent ICA in the asymptomatic patient, however, is unknown. The Greenville Memorial Hospital Vascular Teaching Service registry and all carotid duplex scans done in the Greenville Hospital System vascular laboratory from January 1994 through December 1997 were reviewed. Data collection included chart review, phone interviews, and the review of angiograms and duplex scans. This study suggests that carotid duplex is more sensitive for detecting ICA flow after CCAO than routine contrast angiography. It also suggests that while rare in presentation, asymptomatic patients with CCAO and a patent ICA appear to have a benign neurologic course and can probably be observed without a high risk of stroke.