Abstract Number: Esoc2026a563 a Jailed Free-Floating Cavernous Internal Carotid Artery Thrombus Causing Recurrent Amaurosis Fugax

Abstract Background and aims Free-floating thrombus of the internal carotid artery (ICA) is an uncommon high-risk stroke mechanism. Formation of a thrombus “jailed” between two independent ICA occlusions and sustained solely by retrograde collateral flow is rare. We report a case of monocular visual loss caused by a jailed cavernous ICA thrombus supplied by external carotid–ophthalmic collateralization. A 59-year-old man with recurrent venous thromboembolism on lifelong anticoagulation, prior transient ischemic attacks, and patent foramen ovale closure presented with episodes of transient right monocular vision loss. Ophthalmologic examination showed normal retina. Computed tomography angiography revealed a new complete occlusion of the right cervical ICA, previously patent. MRI demonstrated punctate acute infarcts in the right precentral gyrus. Digital subtraction angiography demonstrated a free-floating thrombus within the proximal cavernous ICA extending toward the ICA terminus, jailed between proximal cervical and distal ICA occlusions. This isolated segment was perfused exclusively by retrograde flow from the external carotid artery via the ophthalmic artery. Given the low NIHSS score and vascular anatomy, no endovascular intervention was pursued. Subtherapeutic rivaroxaban dosing was identified and corrected, with escalation to full-dose anticoagulation and addition of aspirin. The patient experienced complete resolution of visual symptoms without recurrence. Conclusions This case highlights a rare mechanism of ischemic stroke and ocular ischemia caused by a jailed cavernous ICA thrombus sustained by retrograde ophthalmic collateral flow. Recognition of this anatomy is critical, as management may favor optimized antithrombotic therapy over intervention and requires angiographic evaluation in patients with recurrent monocular visual symptoms and incongruent noninvasive imaging. Conflict of interest Curtis Amankwah: nothing to disclose