Endoscopic endonasal transsphenoidal "above and below" approach to the retroinfundibular area and interpeduncular cistern - Cadaveric study and case illustrations

Objective: To evaluate the feasibility of reaching the interpeduncular cistern (IC) through an endoscopic endonasal approach that leaves the pituitary gland in place. Methods: In a series of 10 injected cadaver heads, the transtuberculum ("above") and transclival ("below") approaches were combined, without pituitary transposition. Using 0-degree, 30-degree, and 45-degree endoscopes, the extent of overlap and if a blind spot occurred were determined. Also, the visualization of the IC was compared with the transposition of the pituitary gland approach. Nonparametric statistics were used to evaluate the results. The approach was implemented in 2 patients. Results: For both the "above" and "below" views, there was a statistically significant increase in field of view when comparing the 0-degree endoscope with either the 30-degree endoscope (P < 0.05) or the 45-degree endoscope (P < 0.05). There was no difference between the 30-degree endoscope and the 45-degree endoscope (P > 0.05) in the "below" approach, but there was a difference (P < 0.05) in the "above" approach. There was no blind spot with any combination of endoscopes. There was no practical statistically significant difference between the transposition approach and the "above and below" approach. The "above and below" approach was used successfully in 2 surgeries. Conclusions: It is possible to work both "above" and "below" the pituitary gland to reach the IC through an endoscopic endonasal approach. The advantages are the maintenance of normal pituitary and parasellar anatomy and the minimization of the size of the skull base defect. There is no blind spot using this approach that would be revealed with a pituitary transposition. The feasibility of this approach has been confirmed in 2 patients.