Paraclinoid Segment Aneurysms of the Internal Carotid Artery

Abstract

Background: Paraclinoid segment aneurysms arise from the internal carotid artery (ICA) between the distal dural ring and the origin of the posterior communicating (PComm) artery. Objective: This pictorial study presents videos showing clipping of paraclinoid segment aneurysms. Materials and Methods: The various subtypes of these aneurysms, the nuances in the technique of clinoidectomy, and methods of proximal control are presented. Results: Cavernous ICA is designated as C4, clinoidal segment (between the proximal and distal dural rings) as C5, and supraclinoid segment (between the distal dural ring up to the PComm artery as C6 segment. The techniques used for clipping various aneurysms are based upon their subtypes and location. In the first case, in a giant superior hypophyseal artery aneurysm directed toward the suprasellar region, an intradural clinoidectomy helped in accessing the neck of the aneurysm encroaching into the clinoidal segment of ICA. In the second case, concurrent bilateral “kissing” paraclinoid segment aneurysms were clipped using a unilateral approach. In the third case, clipping of a dissecting paraclinoid segment aneurysm is demonstrated. Conclusions: Surgery still represents the most definitive form of treatment. It may also be used to evacuate an intracerebral hematoma, with an extremely tortuous proximal vessel or in an aneurysm with complex anatomy, with blister aneurysms, or following aneurysm regrowth following a failed endovascular procedure. Assessing the three-dimensional anatomy of various segments of ICA is an important step.