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Case description
A right-handed man in his 40s presented to a local hospital after 2 days of progressively worsening episodes of aphasia. He had hypertension and prior nicotine dependence. He was not eligible for acute stroke therapies owing to his delayed presentation. MR scan of the brain showed left frontal and parietal infarcts (figure 1). Subsequent CT angiogram of the head and neck showed an extensive intraluminal thrombus involving the extracranial left internal carotid artery with an associated non-stenotic plaque (figure 2A–D). Haemoglobin A1c was elevated at 7.1%, indicating a new diagnosis of diabetes. Laboratory studies, including lipid and coagulation profiles, were unrevealing. Transthoracic echocardiogram was normal. He was started on low-dose aspirin and heparin infusion (later changed to apixaban for anticoagulation) and statin therapy. There were no further neurological episodes. One month later, he was assessed in our cerebrovascular clinic. Neurological examination identified mild residual aphasia but was otherwise unremarkable. Repeat vessel imaging showed complete resolution of the thrombus (figure 2E).
MR scan of the brain showing acute frontal and parietal infarcts. Axial diffusion weighted images (A and C) and apparent diffusion coefficient images (B and D) showing areas of restricted diffusion in the left frontal lobe (A and B) and parietal lobe (C and D), consistent with acute infarctions.
Imaging features of an intraluminal internal carotid artery thrombus on CT angiogram of the neck: axial images (A and B) and reformatted sagittal images (C and D) show a predominantly low-density plaque (curved arrow in (A) and asterisk in (C)) at the left internal carotid artery origin. Thrombus extends from the superior surface of the plaque (dashed arrow in (C)), along most of the lumen of the extracranial left internal carotid artery (straight arrows in (B–D)). MR cerebral angiogram 1 month later (E) shows complete resolution of the intraluminal thrombus and substantial reduction is the size of the atherosclerotic plaque.
Discussion
Intraluminal carotid thrombus, defined as an elongated thrombus attached to the arterial wall,1 is identified in about 1.6% of strokes cases.2 Though uncommon, it carries a high risk of recurrent stroke.3 The primary underlying cause is atherosclerosis, although carotid aneurysms or arterial dissections may be associated less commonly .1–3 If vessel imaging does not identify any underlying vascular pathology, and particularly in younger people or those without conventional vascular risk factors, a hypercoagulable workup is recommended, including search for thrombocytosis, inherited thrombophilia disorders, antiphospholipid antibody syndrome or (as appropriate) for an occult neoplasm.1–3 The prothrombotic state of COVID-19 infection may also cause intraluminal carotid thrombus.4 5
There are no current guidelines for optimal management of non-occlusive intraluminal thrombus.6 A few small studies suggest that it is successful and safe to start antithrombotic therapy promptly and to consider delayed revascularisation in selected patients.1–3 7 Unfractionated or low-molecular-weight heparin has been used as a first-line treatment, though weight-based intravenous unfractionated heparin nomograms may be preferred acutely, given the ability to titrate activated partial thromboplastin time.2 3 6 7 Combination antithrombotics may give favourable outcomes.2 3 7 Concern for underlying atherosclerosis and added protection from further thromboembolic events may be the rationale for including antiplatelet agents. We need further research to establish safety and efficacy of a preferred treatment regimen.
Most patients (75%–86%) treated with antithrombotics have partial to complete thrombus resolution on follow-up imaging, even as early as 1–2 weeks.2 3 For this reason, a suggested approach is initial medical management followed by repeat vessel imaging (perhaps within 7–10 days), with consideration of delayed revascularisation procedures when necessary.3 The duration of initial antithrombotic regimen remains uncertain, but reports range from several weeks to several months.1–3 The need for long-term anticoagulation should be excluded before anticoagulant withdrawal. Balancing risks and benefits, maintenance antithrombotic regimens must be tailored on an individual level based on any identified cause for the underlying thrombus.
Key point
There is no optimal evidence-based treatment for intraluminal carotid thrombus; however, antithrombotic therapy (anticoagulation with or without antiplatelet agent) appears to reduce the stroke recurrence risk and have a high rate of thrombus resolution, obviating need for delayed surgical intervention.
Data availability statement
Data sharing not applicable as no datasets generated and/or analysed for this study.
Ethics statements
Patient consent for publication
Ethics approval
Not applicable.
Acknowledgments
We thank Dr Giuseppe Lanzino and Dr John Benson for providing expert opinion and for assistance with figure preparation.
Footnotes
Contributors Both authors have contributed equally to this work.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned. Externally peer reviewed by David Werring, London, UK.
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