Internal Carotid Artery and its Relationship with Structures in Sellar Region: Anatomic Study and Clinical Applications

BACKGROUND: Complications of the internal carotid artery (ICA) in surgery are rare but severe. This study aimed to locate the ICA with 5 stationary bony structures in the sellar region: the anterior clinoid process, the tuberculum sellae, the bottom of the hypophyseal fossa, the posterior edge of the hypophyseal fossa, and the postclinoid process and to do measurements to determine their anatomic relationship with the ICA. METHODS: After multiple planar reconstructions on computer tomographic angiography images of 120 ICA in 60 individuals, we defined the 5 bony structures as 5 origins in the horizontal, sagittal, and vertical planes with the 3D coordinate system and got the cross-sections of bilateral ICA on the coronal plane passing through each origin. We measured the distances between the cross-sections and the origins and angles between the horizontal plane and the line passing through the origin and the cross-sections on each coronal plane. We also measured the distances between the bilateral ICA on the 5 coronal planes. Besides, we measured the coordinate of the anterior edge of bilateral ICA, taking the anterior clinoid process as the origin. RESULTS: With the 3-dimensional coordinate system, we located the ICA to the bony structures in skull base. The distance between the bilateral ICA on coronal planes were 18.8 +/- 2.9 mm, 23.6 +/- 3.7 mm, 19.9 +/- 3.4 mm, 24.7 +/- 4.3 mm, and 23.5 +/- 3.5 mm, from anterior to posterior, respectively. CONCLUSION: The 3D coordinate system used in this study is of value in preoperational assessment, and data we obtained indicate the safety ranges avoiding damage to the ICA in surgery.