A Rare Giant Dissecting Internal Carotid Artery Aneurysm With Middle and Fetal-Type Posterior Cerebral Artery Origins: A Case Report

Giant dissecting aneurysms of the internal carotid artery (ICA) >20 mm are rare and associated with risks of rupture, mass effect, and thromboembolism, particularly when branch vessels originate from the sac. A 46-year-old woman presented with headaches and blurred vision due to a giant dissecting aneurysm originating from the ophthalmic segment of the left internal carotid artery (ICA). Endovascular treatment using a flow-diverter stent (4.5×38 mm) was deployed from the left middle cerebral artery to the cavernous part of the ICA, with adjunctive balloon angioplasty for incomplete expansion due to vessel kinking. Immediate post-procedure angiography showed thrombosis with preserved branch perfusion. Symptoms resolved completely by one month, with dual antiplatelet therapy continued for six months and monotherapy for the next six months. This case highlights the efficacy of flow-diverter stents in complex anatomies, achieving rapid thrombosis and symptom relief.