Free Floating Thrombus of the Internal Carotid Artery: A Case Report

Carotid free floating thrombus is a rare vascular condition associated with a high risk of early cerebral embolisation. It may occur in the absence of significant carotid stenosis, which complicates therapeutic decision making. Owing to its rarity, optimal management remains controversial, with both medical and surgical strategies described.

A 66 year old woman presented with transient right upper limb paraesthesia consistent with a transient ischaemic attack. Computed tomography angiography and duplex ultrasound revealed a mobile free floating thrombus measuring 16-18 mm in the proximal left internal carotid artery, without associated stenosis, plaque ulceration, or dissection. Neurovascular imaging demonstrated a patent circle of Willis and normal intracranial perfusion. Given the thrombus mobility and recent neurological symptoms, urgent surgical thrombectomy was performed under general anaesthesia with cerebral monitoring. The thrombus was removed en bloc without complications. Post-operatively, the patient was treated with anticoagulant and statin therapy. At one year follow up, she remained asymptomatic, with imaging confirming sustained carotid patency and no recurrent thrombus.

This case highlights that carotid free floating thrombus can present without underlying carotid stenosis and still pose a significant embolic risk. Thrombus morphology, clinical presentation, and cerebrovascular anatomy are key factors guiding management. In selected symptomatic patients with favourable collateral circulation, urgent surgical thrombectomy may represent a safe and effective therapeutic option. Careful post-operative antithrombotic management and imaging surveillance remain important components of overall care.