Spontaneous thrombosis of a giant cavernous-carotid aneurysm with simultaneous ipsilateral complete parent artery occlusion: a rare phenomenon and review of the literature.

Cavernous-carotid artery (CCA) aneurysms represent about 3-5% of all intracranial aneurysms. Spontaneous thrombosis of a CCA aneurysm with simultaneous occlusion of its parent vessel is an extremely rare phenomenon with few reported cases in the literature offering different management strategies. A 54-year-old Asian female presented with a one day-history of painless left eye conjunctival injection, proptosis, and features of cavernous sinus syndrome (cranial nerve III, IV, V1, V2, and VI palsies). Imaging revealed a giant thrombosed CCA aneurysm measuring 3.6cmx3.4cm with complete thrombosis of the left cervical internal carotid artery (ICA) and adequate collaterals from the anterior and posterior communicating artery and branches of the left external carotid artery. Management was conservative with antiplatelet therapy and close clinical-radiological follow-ups. The outcome was satisfactory. Data in the literature on this condition is limited due to its exceedingly rare occurrence. The majority of patients do well via a conservative approach and surgery is rarely indicated. For clinically stable patients, especially those with adequate collateral circulation and tolerance to Balloon Test Occlusion, we advocate for a conservative approach and initiation of anti-platelet therapy to treat these patients. Emphasis is needed on close serial clinical-radiological surveillance in these cases to monitor the propagation of the thrombus as well as the development of new and/or enlarging pre-existing aneurysms in the contralateral ICA circulation.