Anatomical Study Of The Endoscopic Extended Transnasal Approach To The Clivus Region

Objective: This study aimed at by endoscopic anatomical study of endonasal approach to the clivus region via, for surgical treatment of clival lesions to provide anatomic parameters and morphological basis, and further study the surgical approach adaptation syndrome and complications prevention. Methods: Five formalin-fixed adult cadaveric heads specimens were used, a rigid endoscope(Karl Storz) was inserted into the bilateral nasal cavity for simulating the endoscopic extended transnasal approach to the clivus region. An extended endoscopic endonasal approach to the midline skull base and the clivus was made through two nostrils in all cases to measure the distance between main anatomical landmarks and area of exposure. Results: Average distance between the anterior nasal spina to ostia of sphenoidal sinus, tuberculum sellae, Carotid artery uplift, Optic canal uplift, anterior part of great occipital foramen were 55.78 ± 3.02 mm、72.74 ± 7.27 mm、67.98 ± 5.19 mm、68.33 ± 4.25 mm、90.75 ± 6.27 mm respectively. The length and height of clivus were 33.26 ± 3.61 mm、33.48 ± 4.58 mm respectively. Average distance between the nerve canal of the tongue 28.04 ± 4.12 mm, the distance between the two crotid arterys in the clivus was 17.82 ± 3.14 mm, the distance from sellae to the anterior margin of foramen magnum was 38.74 ± 3.84 mm. The Anatomic landmarks of the nasal cavity and nasopharynx: inferior turbinate, middle turbinate and nasal septum etc. The clivus was divided into three parts: the upper, the middle and the lower clivus. Bony landmarks of the clivals region were presented, such as parasellar internal carotid artery of tube bulge, adjacent to the slope segment of internal carotid artery of tube bulge, uplift of the optic canal etc; Inrtadural anatomic landmarks were the posterior cerebral artery, superior cerebellar artery, basilar artery, cranial nerve VI, pons, vertebral artery, cranial nerve IX- XII and medulla oblongata. Conclusions: The endoscopic extended transnasal approach to the clivus region was the appropriate surgical approach, with the endoscopic anatomy characteristic of this area and the relationship between the nerve and blood vessels had a more in-depth understanding, which provides anatomical basis for clinical surgery treatment of regional lesions.