New Landmark for the Endoscopic Endonasal Transsphenoidal Approach of Pituitary Surgery

OBJECTIVE To clarify the anatomical correlations of the sphenoid sinus with surrounding structures in the normal Korean population, and to identify surgical landmarks for safe sellar floor dissection in the anterior skull base by endoscopy and microscopy. METHODS We reviewed the 196 brain magnetic resonance imaging findings showing a normal appearance, and measured the distances between anatomical landmarks. RESULTS The mean distances from the base of the columella to the anterior wall of the sphenoid sinus and the sellar floor were 69.71±4.25 mm and 86.26±4.57 mm, respectively in the over 15 age group, and showed the smallest degree of variation among the measurements. The mean angles between the floor of the nasal cavity and the straight line connecting the base of the columella and the sellar floor were 29.45±3.25° and 24.75±4.00° in the over 15 and under 15 age groups, respectively. The mean values of both distances and angles increased with age until 15 years after which no further increases were evident. There were no significant differences in the measurements between males and females or among subjects with different degrees of pneumatization in the over 15 age group. CONCLUSION The distances from the base of the columella to the sellar floor and the anterior wall of the sphenoid sinus, which were consistent among individuals, could be used as a surgical indicator to investigate the sellar floor in endoscopic or microscopic transsphenoidal approaches.