Stuck in a dead-end diagnosis? Look for an external route! External carotid artery thrombosis and multiple strokes

We report a clinical case of recurrent embolism due to thrombosis related to external carotid artery (ECA) atherosclerosis with an ipsilateral patent internal carotid artery ICA in a patient with multiple cerebral infarcts in the same arterial territory at different time points. Serial CT-angiographic scans revealed endoluminal stenosis in the proximal ECA, with ipsilateral patent ICA, whose dimensions varied during a period of 9-months of recurrent ischemic events. Complete etiological assessment for other causes of recurrent embolism was negative. The patient was proposed for ECA endarterectomy without further stroke recurrence during more than a one-year follow-up. We argue that local hemodynamic changes in the carotid bifurcation, associated with thrombus fragmentation, may lead to recurrent paradoxical embolization through patent ICA, justifying multiple strokes in the same arterial distribution at different time points.