Thrombi at the site of carotid stenosis. Radiographic diagnosis

Intraluminal Thrombus of the Extracranial Cerebral Arteries in Acute Ischemic Stroke: Manifestations, Treatment Strategies, and Outcome

Background

Intraluminal thrombus (ILT) of the cervical arteries is an uncommon finding that can lead to acute or recurrent ischemic stroke. Currently, antithrombotic therapy in the form of antiplatelet and/or anticoagulation is considered the mainstay of treatment, but evidence of which one has a better outcome is lacking.

Methods

A retrospective cohort study included 28 patients diagnosed with acute stroke or transient ischemic attack with ILT of the extracranial arteries from 2013 to 2022. The primary efficacy outcome was assessed as recurrent stroke, and the primary safety outcome was assessed as hemorrhagic complications. Secondary outcomes were assessed as the resolution of thrombi by CT angiography (CTA) and clinical improvement by the Modified Rankin Scale (mRS) and NIH Stroke Scale (NIHSS).

Results

Out of 28 patients, more than half (57.1%; n = 16) were males with a mean age of 57.8 ± 9.5 years and an average BMI of 26.9 ± 4.5 kg/m2. As initial treatment, twenty-four patients received anticoagulation and four received antiplatelet agents. Recurrent strokes were found in four patients (14.29%), and all were initially treated with anticoagulation. One patient in the anticoagulation group had a significant retroperitoneal hemorrhage. None of the patients in the antiplatelets group had a recurrent stroke or bleeding event. Initial treatment with antiplatelet agents significantly improved the NIHSS on day 7 (P = 0.017). A significant improvement in NIHSS on day 90 was observed in the anticoagulant group (P = 0.011). In the follow-up CTA performed on 24 patients, 18 (75%) showed complete resolution (3 out of 3 (100%) in the antiplatelet group and 15 out of 21 (71.43%) in the anticoagulant group).

Conclusion

Initial treatment with anticoagulants improves neurologic outcomes in patients with ILT-induced acute ischemic stroke but carries the risk of recurrent stroke and bleeding. However, initial treatment with dual antiplatelet agents appears to have comparable efficacy without sequelae, particularly in atherosclerosis-induced ILT.

Symptomatic carotid artery intraluminal thrombus: risk of medical management failure and distal embolization

BACKGROUND

Carotid artery intraluminal thrombus (ILT), or free-floating thrombus, is an uncommon cerebrovascular entity with considerable equipoise regarding its clinical management. Likewise, in patients treated with medical management (MM), distal embolization and/or intracranial hemorrhage (ICH) may still occur.

METHODS

All patients with symptomatic ILT from 2016 to 2023 were identified from our tertiary care institution. Patients with MM failure (recurrent cerebral ischemia and/or symptomatic ICH) were compared with patients with MM non-failure. Differences in ILT volume and length were calculated. Receiver operator characteristic (ROC) curve analysis was used to identify the cut-off volume and length for risk of MM failure.

RESULTS

In total, 45 patients with ILT were identified with 41 treated with frontline MM. Of these 41 patients treated with MM, seven (17%) had MM failure with six (14.6%) having new embolic stroke and one (2.3%) with symptomatic ICH. Patients with MM failure had a significantly higher mean thrombus volume than MM non-failure patients (257 mm3 vs 59.6 mm3, P=0.0006). Likewise, patients with MM failure had significantly longer thrombus on average (21 mm vs 6.6 mm, P=0.0009). ROC curve analysis showed that an ILT volume of 90 mm3 resulted in a sensitivity of 71.4% and specificity of 85.3% for MM failure (AUC 0.775; CI 0.55 to 1.0, P=0.023).

CONCLUSIONS

Carotid ILTs that fail MM are significantly larger and longer. These findings suggest that a thrombus volume of 90 mm3 may serve as a guide for intervention with good sensitivity and specificity for risk of MM failure.

Intraluminal Thrombi in the Cervico-Cephalic Arteries

Background and Purpose- Intraluminal thrombus (ILT) is an uncommon finding among patients with ischemic stroke. We report clinical-imaging manifestations, treatment offered, and outcome among patients with ischemic stroke/transient ischemic attack and ILT in their cervico-cephalic arteries. Methods- Sixty-one of 3750 consecutive patients with acute ischemic stroke/transient ischemic attack (within 24 hours of onset) and ILT on initial arch-to-vertex computed tomography angiography from April 2015 through September 2017 constituted the prospective study cohort. Functional outcome was assessed using the modified Rankin Scale score with functional independence at discharge defined as modified Rankin Scale score ≤2. Results- Prevalence of ILT on computed tomography angiography was 1.6% (95% CI, 1.2%-2.1%). Median age was 67 years (interquartile range, 56-73), and 40 subjects (65%) were male. The initial clinical presentation included transient ischemic attack in 12 (20%) and stroke in 49 patients (80%); most strokes (76%) were mild (National Institutes of Health Stroke Scale ≤5). The most common ILT location was cervical carotid or vertebral artery (n=48 [79%]) followed by intracranial (n=11 [18%]) and tandem lesions (n=2 [3%]). The most common initial treatment strategy was combination antithrombotics (heparin with single antiplatelet agent) among 57 patients (93%). Follow-up computed tomography angiography (n=59), after a median 6 days (interquartile range 4-10 days), revealed thrombus resolution in 44 patients (75% [completely in 27%]). Twenty four of 30 patients (80%) with >50% residual carotid stenosis underwent carotid revascularization (endarterectomy in 15 and stenting in 9 patients) without peri-procedural complications a median of 9 days after symptom onset. In-hospital stroke recurrence occurred in 4 patients (6.6%). Functional independence was achieved in 46 patients (75%) at discharge. Conclusions- Patients presenting with acute stroke/transient ischemic attack with ILT on baseline imaging have a favorable clinical course in hospital with low stroke recurrence, high rate of thrombus resolution, and good functional outcome when treated with combination antithrombotic therapy.

Asymptomatic free-floating thrombus of the internal carotid artery

Free-floating thrombus (FFT) of the internal carotid artery, which is almost always symptomatic and is usually discovered by ultrasound or angiography performed after a transient cerebrovascular event, is a highly uncommon diagnosis. Here, we report a case of an asymptomatic freefloating internal carotid artery thrombus most probably caused by an atherosclerotic plaque rupture. It was detected by carotid ultrasound and was treated with eversion endarterectomy without any neurologic complications. Six weeks after surgery, the patient is doing well.

Floating thrombus as a marker of unstable atheromatous carotid plaque

Floating thrombus in a carotid artery is an uncommon pathology with a high risk of embolism. We present three patients diagnosed with acute stroke, with a floating thrombus complicating an atheromatous plaque, who were treated with anticoagulants and statins. Although two patients had satisfactory results, one patient suffered a stroke related to plaque progression nearly 3 years after initial presentation. Medical treatment seems to be a good initial option, although late cerebral ischemic complications may be seen due to carotid plaque instability. Delayed carotid endarterectomy or stenting should be considered in cases with subsequent plaque progression.

Free-floating thrombus of the carotid artery: Literature review and case reports

BACKGROUND

Free-floating thrombus (FFT) of the carotid artery is an uncommon entity that usually presents as an acute emergency. Management is based on case reports and series because the natural history and optimal treatment are unknown. This study was conducted to systematically review the world literature in an attempt to better understand FFT, its presentation, distribution, management, and outcome.

METHOD

A literature search in all languages was performed of the PubMed database (> or =1950s) and Medline database (1966-November 2004). All relevant articles were reviewed and their references analyzed in a similar manner for further literature. Cases from the authors' institutions were reviewed as well. All cases within the reports were individually assessed for inclusion or exclusion. Inclusion required that the FFT originate or anchor within the carotid artery (ie, excluding emboli, arch thrombi with extensions into the carotid artery), be partially occluding (ie, excluding occlusions, "string-sign," microscopic thrombus), and ideally have an elongated or protrusive morphology, circumferential flow around the distal portion, and cyclical motion with the cardiac cycles.

RESULTS

There were 61 reports reviewed, of which 43 contained FFT cases. These reports had 342 cases (including the current series) that were reviewed, of which 145 met our inclusion criteria. A database was created for qualitative and quantitative assessment of all cases. When data were pooled, appropriate statistical analysis was performed. A limitation of the study is that FFT is under-reported and ill defined, which limited the analysis in quantity and quality. In addition, reporting is not uniform, and therefore, significant data were not always present. In attempting to define FFT and include or exclude cases, subjectivity is inherent.

CONCLUSIONS

FFT is more frequently reported in men than women, with a ratio of nearly 2:1 (P < .0001), and at a younger age than in most patients with carotid disease (P < .0001 when compared with North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial, and Asymptomatic Carotid Surgery Trial). Symptoms are present in 92% of patients. There was a trend for patients with FFT to be hypercoagulable (47% of those serologically tested). The internal carotid artery was the most commonly affected (75%), with atherosclerosis being the most common associated pathology. Medical and surgical management have both been used, with neither clearly superior to the other. Medical management for stabilizing neurologic deficits has less risk and less benefit than surgical intervention.

Angioplasty of symptomatic high-grade internal carotid artery stenosis with intraluminal thrombus: therapeutic approach

Intraluminal thrombus in the internal carotid artery (ICA) is usually found in patients with severe atheromatous stenosis. Having reviewed 300 carotid angioplasties for symptomatic >70% ICA stenosis, we found three patients (1%) with intraluminal thrombus. Conservative treatment with anticoagulants and double antiplatelet coverage can result in lysis of the thrombus without severe risks. Percutaneous transluminal angioplasty and stenting, preferably with distal protection, can be an excellent alternative to carotid endarterectomy.

Does the angiographic appearance of a carotid stenosis predict the risk of stroke independently of the degree of stenosis?

We aimed to determine whether the angiographic characteristics of recently symptomatic carotid stenosis predict risk of subsequent ischaemic stroke independently of the degree of stenosis. First, two observers compared the angiographic characteristics of patients who subsequently suffered a carotid distribution ischaemic stroke ipsilateral to the stenosis (n = 50) with those of stroke-free controls (n = 100) matched for the degree of stenosis of the symptomatic internal carotid artery. No significant differences were found. Secondly, seven independent observers attempted to identify the angiograms of 50 patients who subsequently suffered a stroke from those of 50 stroke-free controls matched for degree of stenosis, age and sex. None of the observers identified the stroke case more often than was expected by chance alone. We conclude that clinicians cannot differentiate between 'high risk' and 'low risk' carotid stenoses on the basis of angiographic characteristics other than the degree of stenosis.

Free-floating thrombus of the extracranial internal carotid artery

Free-floating clots of the extracranial internal carotid artery are generally considered as surgical emergencies. This retrospective study analyzes six free-floating clots diagnosed by arteriography. Three of these patients had a fixed stroke while the other three had an evolving stroke. Three patients had antecedent ocular or hemispheric transient ischemic attacks. The causes of free-floating clots in the internal carotid artery were atheromatous stenosis in two cases, ulcerated plaque in three cases, and carotid artery dissection in one. All six patients were seen late, approximately 15 hours after their neurologic accident. They were treated with intravenous heparin over a two to five week period. Repeat arteriograms demonstrated complete clot lysis in four instances, while partial lysis was seen in one case. Moderate extension of thrombus occurred in one case only. No further neurologic complications were noted during the treatment by heparin. As indicated by follow-up arteriographic findings, secondary surgery was performed for major carotid lesions and residual clots in five cases. The free-floating thrombus syndrome of the carotid artery should not be considered as a surgical emergency when discovered late in the wake of an acute neurologic accident.

Intraluminal thrombus in the cerebral circulation. Implications for surgical management

Thrombi defined as intraluminal filling defects detected by angiography were identified in 30 patients (29 in the carotid system, one in the vertebral artery). Stroke was the presentation ipsilateral to the thrombus in 22 patients (12 had previous transient ischemic attacks), transient ischemic attacks occurred alone in seven cases, and one patient was asymptomatic. Angiography revealed a severe stenosis in association with the thrombus in 23 patients, a moderate stenosis in four patients, and, in the three patients with only minimal stenosis presumably due to atherosclerosis, there was evidence for a coagulopathy. Sixteen of the 30 patients were operated on urgently, 10 within 24 hours of detection of the thrombus. Twelve of these 16 surgical patients were given anticoagulation before surgery. At endarterectomy, thrombus was identified in 11 of the 14 surgical patients in whom the thrombus was accessible; the other two surgical patients had intracranial thrombus only. In this group, four of 11 surgical patients with accessible thrombi suffered perioperative episodes of new or larger infarction. Fourteen of the 30 patients initially received medical management with no complication. Eight of these 14 medical patients had repeat angiography; seven exhibited complete resolution of thrombus, and six of these seven patients subsequently underwent delayed endarterectomy for the stenosis. No thrombus was identified at surgery in any of the six. One of the six delayed surgery patients suffered a perioperative stroke. Although these numbers are small, reflecting the rarity of thrombus demonstrated by angiography, undetected thrombus is often found at endarterectomy. Its presence may increase operative risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraluminal clot of the carotid artery. A clinical-angiographic correlation of nine patients and literature review

Between March 1980 and March 1985, intraluminal thrombi of the carotid artery were noted in 9 of 2250 patients undergoing arteriography for symptoms of cerebral ischemia. Five patients had transient ischemic attacks, and four had acute cerebral infarctions. Six patients had surgery, but a thrombus was only found in five. Two patients had new neurological deficits after surgery. Three patients received only medical therapy, and all remained stable. Intraluminal thrombus is an uncommon radiographic finding in patients with cerebral ischemia. Not all clots are confirmed at operation. The optimal treatment of this situation is not known. Both surgical and medical treatments deserve further investigation.

Cerebral embolism from septal fibromuscular dysplasia of the common carotid artery

A rare type of fibromuscular dysplasia of the common carotid artery, in the form of a septum, was observed in a patient suffering from recurrent cerebral infarctions. Angiography demonstrated growth of the lesion and documented the presence of an intraluminal thrombus attached to it. Comparison with reported cases of the more common "string of beads" lesion of fibromuscular dysplasia suggests that the risk for development of ischemic neurological problems is higher for this type of fibromuscular lesion. Surgical correction is recommended, especially for symptomatic patients.

Disappearing carotid defects

Large intraluminal cervical carotid artery filling defects consistent with mural thrombi were angiographically demonstrated during acute hemispheric neurologic episodes. These thrombi disappeared benignly as shown by serial angiography in 2 patients treated with intravenous heparin and spontaneously in 1 patient treated surgically. Thus, partially obstructing cervical carotid artery thrombi may lyse either with the use of anticoagulant therapy or else spontaneously. The etiology of the thrombi may partly be related to underlying atheromatous disease.

[Follow-up studies of subtotal carotid artery stenosis (author's transl)]

Angiographic and/or operative follow up studies on 19 patients with angiographically demonstrated subtotal carotid artery stenosis showed the following results: In 3 out of 16 cases where no immediate operation of the stenosis was performed, complete occlusion followed within a week of the angiographic demonstration of the stenosis. Though intramural artifacts did not occur, this could be a consequence of the angiographic procedure (temporary fall of blood pressure?). In 4 out of 7 cases with subtotal stenosis where the diagnosis was known for at least 6 months, no occlusion occurred. The blood flow through a subtotal carotid artery stenosis might not be as small as is usually assumed, as illustrated by 2 out of 3 cases where a definite increase in the symptoms occurred on complete occlusion of the the vessel. The results indicate that cases of subtotal stenosis should be promptly treated by disobliteration.

Lysis of thrombus in internal carotid artery in the neck. Report of a case

A case report is presented demonstrating spontaneous lysis of clot in the internal carotid artery in the neck with surgical and angiographic documentation. The possible factors promoting thrombus formation and lysis are discussed. Spontaneous lysis of a carotid thrombus occurred in 72 hours.