ABSTRACT NUMBER: ESOC2026A1845 BEYOND ATHEROSCLEROSIS: WATERSHED STROKE REVEALING INTERNAL CAROTID ARTERY HYPOPLASIA AND ANTERIOR CEREBRAL ARTERY AGENESIS

Abstract Background and aims Internal carotid artery hypoplasia (ICAH) is a rare congenital vascular anomaly, characterized by diffuse narrowing of the arterial lumen, typically 1–2 cm above carotid bifurcation. Although many patients remain asymptomatic due to circle of Willis collateral circulation, ICAH can lead to cerebral ischemia and increased risk of aneurysm formation. Methods Clinical case of a 49-year-old patient, with medical history of multiple autoimmune diseases (myasthenia gravis, psoriasis vulgaris), as well as associated cardiovascular risk factors (dyslipidaemia, hypertension), admitted for left-sided motor weakness. Symptoms started a week prior to admission. Brain-MRI performed at an outpatient clinic, showed subacute ischemic lesions in the right superior frontal lobe, with a watershed distribution. Results At the admission, neurological examination revealed left-sided hemiparesis and left lower limb tactile hypoesthesia. Brain computed tomography (CT) described cortical-subcortical hypodensities in the right superior frontal lobe, displaying watershed distribution pattern. Based on the imaging aspect of the ischemic lesions, an atherothrombotic cause was initially considered. Further supra-aortic trunks CT-angiography revealed: right internal carotid artery hypoplasia, agenesia of right anterior cerebral artery (A1-segment) with compensatory supply from the left side and superimposed stenoses of the A2 and A3 segments of the anterior cerebral artery. Thus, stroke etiology was attributed to cerebral hypoperfusion secondary to internal carotid artery hypoplasia and ipsilateral anterior cerebral artery stenoses. Dual antiplatelet therapy and maximum dose statin was instituted, with favourable outcome. Conclusions We chose to present this case in order to highlight the role of rare vascular anomalies in stroke etiology. Conflict of interest Alexandra Pavel: nothing to disclose