Fig. 1

Typical case 1; A 69-year-old female with a medical history of hypertension, diabetes, and hyperlipidemia presented with a 1-year history of a pulsatile neck mass and neck pain. Upon examination, bilateral pulsatile neck masses were observed (A-B), but the patient was neurologically intact. Further investigation through a CTA examination revealed an unruptured giant bilateral ECCA aneurysm (C). Cerebral angiography showed bilateral giant aneurysms of the extracranial internal carotid arteries (maximum diameter: 40.0 mm on the left and 34.0 mm on the right) (D-E). Firstly, the left ECCA aneurysm was surgically resected and underwent end-to-end anastomosis (F1). To ensure the patency of the parent artery, fluorescein angiography was performed during the operation (F2). The resected aneurysm specimen was also subjected to pathological examination (F3). Three days following the operation, angiography revealed complete disappearance of the aneurysm and smooth blood flow in the parent artery (F4). One year later, the patient underwent another neurosurgical resection and end-to-end anastomosis procedure to address the right aneurysm (G1). During this operation, fluorescein angiography was performed to verify the patency of the parent artery, and the resected aneurysm specimens were analyzed through pathological examination (G2-3). A year following the procedure, a CTA scan revealed that both aneurysms had vanished completely, and the blood flow in the parent artery was unobstructed (G4)