METHODOLOGIC PERSPECTIVES Toward an Endovascular Internal Carotid Artery Classification System

SUMMARY: Does the world need another ICA classification scheme? We believe so. The purpose of proposed angiography-driven classification is to optimize description of the carotid artery from the endovascular perspective. A review of existing, predominantly surgically-driven classifications is performed, and a new scheme, based on the study of NYU aneurysm angiographic and cross-sectional databases is proposed. Seven segments – cervical, petrous, cavernous, paraophthlamic, posterior communicating, choroidal, and termi-nus – are named. This nomenclature recognizes intrinsic uncertainty in precise angiographic and cross-sectional localization of aneurysms adjacent to the dural rings, regarding all lesions distal to the cavernous segment as potentially intradural. Rather than subdividing various transitional, ophthalmic, and hypophyseal aneurysm subtypes, as necessitated by their varied surgical approaches and risks, the proposed classification emphasizes their common endovascular treatment features, while recognizing that many complex, trans-segmental, and fusiform aneurysms not readily classifiable into presently available, saccular aneurysm-driven schemes, are being increasingly addressed by endovascular means. We believe this classification may find utility in standardizing nomenclature for outcome tracking, treatment trials and physician communication. Until now, the ICAwas subdivided into various segments, pri-marily on the basis of surgical considerations. Fischer’s orig-inal classification (Fig 1),1 with C1–C5 segments, in retrograde fashion, addressed the then-existing need for localization of re