Aneurysms that form on the medial surface of the internal carotid artery’s (ICA) paraclinoid portion are difficult to treat surgically. The medial surface of the paraclinoid ICA can be partially exposed using the contralateral interoptic route, which utilises the space between the optic nerves. On 10 sides of 5 cadaveric heads, the contralateral interoptic pathway was investigated, and the medial paraclinoid ICA was discovered. The distance between the distal dural ring and the accessible area’s proximal and distal borders was measured. Preoperative measures and intraoperative data were evaluated in 8 clinical instances to validate these parameters.

The mean (SD) distances from the DDR to the proximal and distal extremities of the accessible area on the paraclinoid ICA in the sagittal plane were 2.5 (1.52) mm and 8.4 (2.32) mm, respectively, in the sagittal plane. The superior and inferior ends of the accessible region had mean (SD) angles of 21.7° (14.84°) and 130.9° (12.75°) relative to a vertical line in the coronal plane, respectively.

A contralateral interoptic trajectory was used to quantify the accessible region of the paraclinoid carotid artery. The technique can be used to determine if a paraclinoid aneurysm can be reached using a contralateral interoptic pathway. More clinical information for decision-making is provided by such data. The contralateral interoptic technique is a viable option for gaining access to aneurysms originating from the medial paraclinoid ICA. If 1) both the proximal and distal borders of the aneurysm neck are 2.5–8.4 mm distal to the DDR, and 2) at least one border of the aneurysm neck on the coronal clockface is 21.7°–130.9° medial to the vertex, an aneurysm can be clipped safely via the contralateral interoptic route.

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