Quantitive study on extradural anterior clinoidectomy for improving exposure of seller region

Aim : To investigate the effective method for improving exposure of seller areal structure in pterional approach. Methods: Ten formalin-fixed adult cadaver heads were dissected by right pterional approach, and measurement were made before and after anterior clinoidectomy. Twenty sets of pre- and post-anterior clinoidectomy measurements were collected, consisting of: optic nerve length from the optic chiasm to the optic canal (pre) and to the anulus of Zinn (post) ; internal carotid artery (ICA) length from the ICA bifurcation to the distal limit of the anterior clinoid process (pre) and to the ICA distal dural ring (post) ;opticocarotid triangle (OCT) width,the widest in situ distance between the optic nerve and ICA ( pre) and the analogous measurement with allowable retraction on the mobilized ICA and optic nerve (post) ; and OCT length from the point where the A1 segment crosses the optic chiasm to the optic canal (pre) and to the annulus of Zinn ( post) . Results:The mean values±standard errors of the data mentioned above before and after removal of the anterior clinoid process, repectively, were: optic nerve length 10.28±2. 30 mm and 22. 83±2.54 mm; ICA length 10.48±2.39 mm and 14.78±3.02 mm;OCT length 10.38±2.84 mm and 23.55±2.79 mm,OCT width 3.93±1. 16 mm and 12.95±2. 61 mm. Conclusion: Anterior clinoidectomy can provide a twofold increase in exposure of the optic nerve length and the Oct length,as well as a two- to three-fold increase in the maximum OCT width in the operative treatment of seller region tumors. Extra-dural anterior clinoidectomy is very important for improving exposure of seller region.