Microscopic Anatomic And Imaging Anatomic Study Of Neuronavigation-assisted Transoral Approach To The Inferior Clivus

Objective With the application of a StealthStation neuronavigation, to measure some anatomic data, to quantify and compare the length of the anatomic structures, the exposure angles and the clivus areas available for 10 cadaveric heads instrument manipulation in transoral approach to the inferior clivus before and after the soft palates split for a clinical scientific basis.Methods The study of transoral approach to the inferior clivus before and after the soft palates split were respectively carried out on filled with red silion in the arteries, following by dissecting to the medulla and the upper cerical cord. The related anatomical structures such as vertebral artery, basal artery and the cranial nerves were observed and measured. With application of a navigation system, quantitation of the length of the anatomic structures, extracranial periclival exposure angles, and areas for instrument manipulation were evaluated.Results (1) Posterior pharyngeal wall consisted of 5 layers and two interspaces: mucosa, submucosa, superficial muscular layer, anterior fascia of vertebrae, anterior muscular layer of vertebrae and posterior interspace of pharynx, anterior interspace of vertebrae. (2)The operative exposure position through TOA ranged from inferior part of the clivus to the superior part of the C3 vertebral body.(3)The distances from anterior tubercle of atlas, anterior and posterior dens, dura mater , medulla oblongata , axis are respectively, (69.2～88.1)mm, (74.8～96.2)mm, (84.7～107.4)mm, (87.6～ 111.5)mm, (91.3～116.0)mm, (76.2～93.1)mm. (4)The values for the length of the anatomic structures, the maximal operation field angles and periclival exposure, respectively, for the surgical approaches studied were as follows:simple transoral=(51.9±3. 4)mm , (36.7±3.3)°and (490.1±227.2)mm~2 , transoral with a soft palate splitting=(60.7±3.6)mm, (54.1±1.0)°and (745.7±315. 8)mm~2.Conclusions This study revealed that it had the advantages of short operative distance, good exposure and sufficient decompression in dealing with the ventro lesions from the upper cervical to the lower clivus through the transoral approach.The maximal operation field length,angles and periclival exposure can be increased after the soft palates split.neuronavigation is more valuable and efficient for exploring anatomic structures of the tranoral approach.