Endoscopic Endonasal Accessibility and Maneuverability Around the Internal Carotid Artery from Distal Dural Ring to Foramen Lacerum: Cadaveric Study

Background : Expanded-endoscopic endonasal approaches (eEEA) to surgical targets around the internal carotid artery (ICA) remain inspiring and necessitate a special learning curve. Materials and methods : Six formalin-fi xed heads were dissected to study the 360 (cid:1) accessibility and maneuverability around ICAs from the distal dural ring to the foramen lacerum on each side ( n ¼ 12) via eEEA. The ICA course was divided into three segments: ICA in cavernous sinus, paraclival-ICA, and lacerum-ICA. Following total exposure of each ICA, the three-dimensional (3D ¼ medial/lateral, super fi cial/deep, and above/below) anatomical targets ( n ¼ 35) around each ICA were evaluated. The data were collected and analyzed. Results : Distinctively, we included 35 anatomical targets (pertinent to ICA in cavernous sinus, paraclival-ICA, and lacerum-ICA were 16, 10, and 9, respectively) in 360 (cid:1) around every ICA ( n ¼ 12) from the distal dural ring to foramen lacerum. Although reasonable visual validation was possible for all targets, microdissections were safely achievable for 19 (54.3%) targets through full or limited surgical freedom in 73.7 and 26.3%, respectively. In the remaining 45.7%, the accessibility to targets was abandoned due to hazardous manipulation. The most unreachable targets were around the lacerum-ICA (55.6%) with extremely restricted maneuverability (75%). However, favorable accessibility (60%) and full surgical freedom (100%) were around the paraclival-ICA. Conclusion : This study delivers a distinctive view to appreciate the degree of complexity and invasiveness in relation to the degree of surgical freedom around ICA via eEEA.