Abstract: Objective To evaluate the feasibility of endoscopic transoral transpharyngeal approach to the atlantoaxial. Methods Endoscopic transoral approach was performed in 5 cadaveric heads and necks. The atlantoaxial was measured with CT. Results (1) The range from clivus to C3 could be exposed by this approach, including atlas, axis, lateral mass, odontoid process and vertebral artery. (2) The anterior tubercle of the atlas could serve as a landmark leading to the endoscopic transoral atlantoaxis surgery. The arch could be drilled either from the tubercle to the lateral side or broken from the junction to the lateral mass. Endoscopic odontoid dissection should begin at the apex of the odontoid, and proceeded inferiorly. There was a “safe zone” in the front of atlantoaxis of transoral-transpharyngeal approach. (3) CT results showed: length of anterior arch of atlas 19.5±2.8 mm, the thickness of anterior tubercle of atlas 8.0±0.4 mm, atlas lateral horizontal diameter(left/right)12.7±2.3mm/12.7±1.6 mm, atlas lateral sagittal diameter(left/right)15.0±2.5 mm/15.3±1.4 mm, spacing of atlas transverse process the inside hole 47.2±1.6 mm, spacing of atlas lateral transverse process hole 60.4±1.4 mm, angle of odontoid 10.2±1.3°, spacing of axis transverse process the inside hole 29.2±1.7 mm, spacing of axis lateral transverse process hole 44.3±1.6 mm. Conclusion Endoscopic transoral transpharyngeal approach to the atlantoaxial is technically feasible, which provides a good exposure and the same decompressing size as conventional transoral-transpharyngeal approach. It is safe and minimal invasive, and can be widely applied in clinical practice.

Key words: Endoscopic technique, Axis, Anatomy, Atlas