Accuracy of Surgeon's Estimation of Sella Margins during Endoscopic Surgery for Pituitary Adenomas: Verification Using Neuronavigation.

We assessed the accuracy of a surgeon's localization of sella margins during endoscopic transsphenoidal surgery for pituitary adenomas, as verified using a neuronavigational system, and we identify types of pathology in which neuronavigation is of most benefit. We performed a prospective cohort study of 32 consecutive patients undergoing image-guided endoscopic transsphenoidal surgery for pituitary adenomas. We assessed the margin of error in the surgeon's localization of the superior and inferior margins of the sella and the lateral margins as determined by the medial border of left and right carotid arteries, using a magnetic resonance-based neuronavigational system. The overall mean error of localization of sella margins by the surgeon was 4.5 ± 3 mm. Localization of the inferior sella margin was more accurate (3.1 ± 2 mm mean error) compared with localization of the left (4.8 ± 3 mm) or right carotid arteries (4.6 ± 3 mm). Giant adenomas (> 2.5 cm), more invasive adenomas (Hardy grade IV), and those with parasellar extension (Hardy grades D and E) were associated with larger errors in localization of the carotid arteries. There was no significant difference when stratifying for recurrent surgery, nostril of approach, and sella morphology. During endoscopic transsphenoidal surgery, the margin of error in the surgeon's estimation of the sella margins for adenomas less than 2.5 cm located predominantly within the sella is relatively small. The margin of error increases for giant adenomas, with greater invasiveness and parasellar spread, and the use of neuronavigation can be especially useful in such cases.