Microsurgical Management for Aneurysm Arising from a Low-Lying Internal Carotid Artery-Posterior Communicating Artery Bifurcation through the Anterior Temporal Approach.

A low-lying internal carotid artery (ICA) running closer to the skull base than in usual cases prevents use of the standard transsylvian approach (TSA) to view an aneurysm through the retrocarotid space. A 75-year-old male had a 10-day history of headache and left eyelid ptosis. Initial computed tomography (CT) showed no evidence of subarachnoid hemorrhage. Emergency three-dimensional CT angiography showed a saccular aneurysm with bleb arising from the left horizontally projecting ICA. The aneurysm was approached through the TSA but could not be visualized well. We used the anterior temporal approach (ATA) followed by the TSA, offering a more lateral line of vision and allowing the surgeon to visualize the aneurysmal neck. The aneurysm was successfully obliterated. The ATA provided a better lateral view than the standard TSA for the ICA aneurysm. We emphasize the effectiveness of ATA for aneurysm arising from a low-lying IC-posterior communicating artery bifurcation.