ABSTRACT
Objective To evaluate the feasibility of endoscopic transoral-transpharyngeal approach to the upper cervical. Methods Anatomic characteristics were observed and measured in the anterior column of 50 dry atlas and axis specimens. Conventional and endoscopic methods to decompress the spinal cord and excise the cartilage surface of the atlantoaxial joint by transoral-transpharyngeal approach were taken respectively in two groups of cadaveric heads and necks. All the cadaveric specimens were then open dissected to evaluate endoscopic operation methods, decompression size and the "safe zone". Results The anterior arch of atlas was of a length of (19.8?2.3) mm, the height of odontoid was (15.9?1.9) mm, the width (10.5?0.6) mm, and the thickness (11.5?1.9) mm; the maximal transverse diameter of superior facet of axis was (15.1?1.6) mm, and the anteroposterior one was (17.7?1.3) mm. The anterior tubercle of the atlas could be acted as landmark leading to the endoscopic 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 proceed inferiorly. It was necessary to move or slope the working tube to explore atlantoaxial lateral joint and dissect its cartilage, but the width and depth of cartilage dissection should be limited to 12 mm and 10 mm in order to avoid damage to vertebral artery and spinal cord. Measurements after postoperative open dissection showed that endoscopic decompression size were not significantly different from that of conventional method. There was a "safe zone" in the front of atlantoaxis of transoral-transpharyngeal approach, with (45.9?3.6) mm wide and (29.4?2.5) mm high. Conclusion Endoscopic transoral-transpharyngeal approach to the upper cervical is technically feasible, which had a good exploration and could get the same decompressing size with conventional transoral-transpharyngeal approach.