Donut-shaped partially thrombosed cavernous segment giant aneurysm treated under proximal flow control: Technical case report and literature review

•Dural AVF scalp feeders including OA and STA are very tortuous.•Reducing the shunt flow for TAE is essential for obliteration.•Bilateral ECA origin flow control technique is safe and effective. Donut-shaped aneurysms are rare subtypes of partially thrombosed aneurysms that can consist of partial intraluminal thrombus induced by preferential circular laminar flow within the aneurysms. Intraluminal thrombus in a donut-shaped aneurysm might be fragile and cause thromboembolic complications during endovascular treatment because its pathogenesis supposedly differs from common partially thrombosed aneurysms caused by intramural hemorrhage and vasa vasorum proliferation. Here, we describe a favorable outcome of treating a symptomatic, donut-shaped, partially-thrombosed giant aneurysm by endovascular intervention under proximal flow control. A 70-year-old woman presented with a four-month history of left oculomotor nerve palsy. Cerebral angiography revealed a donut-shaped, partially-thrombosed giant aneurysm in the cavernous segment of left internal carotid artery (ICA) and slow intra-aneurysmal circular blood flow because of severe stenosis of ICA near the aneurysm. After confirming ischemic tolerance with the balloon occlusion test, the parent artery was occluded without intra-aneurysmal coil deployment under proximal flow control to prevent perioperative thromboembolic complications due to specific intraluminal thrombus migration. No new neurological deterioration was found, and the patient recovered from the oculomotor nerve palsy. A donut-shaped, partially-thrombosed giant aneurysm on the cavernous segment of the ICA was safely treated by endovascular trapping under proximal flow control. Careful preoperative assessment and an optimal treatment strategy is required to prevent thromboembolism caused by the migration of intraluminal fragile thrombus.