Combined Endovascular and Microsurgical Treatment for a Giant Thrombosed Posterior Cerebral Artery Aneurysm: A Case Report.

Giant thrombosed aneurysms of the posterior cerebral artery are rare and pose significant challenges in both diagnosis and management. We present a case of a 61-year-old woman who had been under observation for 5 years because of a partially thrombosed posterior cerebral artery aneurysm. The aneurysm gradually enlarged to 50 mm, resulting in left hemiparesis and homonymous hemianopsia. Magnetic resonance imaging revealed cerebral edema and contrast enhancement of the aneurysmal wall and intraluminal space. Digital subtraction angiography demonstrated a slowly perfused aneurysm located at the P1-P2 segment, with a medial posterior choroidal artery branching from the short P1 segment. Given the limited microsurgical exposure and the presence of critical perforators, a hybrid approach was selected. Endovascular parent artery occlusion was first performed using coils and n-butyl cyanoacrylate, targeting both the intraluminal space and the vasa vasorum. Seven days later, microsurgical proximal clipping and partial thrombectomy were carried out via a subtemporal approach. Although transient neurologic deterioration occurred postoperatively, significant improvement was observed with rehabilitation. Follow-up imaging showed marked reduction in aneurysmal size and localized infarction in the posterior cerebral artery territory. This case illustrates the effectiveness of a combined endovascular and microsurgical strategy for treating giant thrombosed posterior cerebral artery aneurysms. Individualized treatment planning based on anatomic complexity, collateral flow, and perforator preservation is essential for achieving successful outcomes in such challenging cases.