Evaluation of Surgical Freedom for Four Microscopic and Endoscopic Transsphenoidal Approaches to the Sella

Introduction: Microscopic and endoscopic transsphenoidal approaches are utilized to address sellar pathology. Surgical freedom (the extent of movement of the surgeon's hands in the operative field) is an important skull base principle that can be measured objectively and used to compare approaches to assist in preoperative decision-making. In this study, we compared the surgical freedom of four transsphenoidal approaches to the sella turcica.

Methods: Four transsphenoidal surgical approaches to the sella (uninostril endoscopic, binostril endoscopic, uninostril direct microscopic, and microscopic sublabial) were performed on eight silicon-injected cadaveric heads. Surgical freedom was determined with image guidance (Stealth System, Medtronic) using previously established techniques published by our laboratory (Wilson et al., 2013). The center of the anterior face of the pituitary gland and bilateral ICAs were chosen as surgical targets. The results are presented as the 1) area of surgical freedom and the 2) angular surgical freedom in the axial and sagittal planes. Standard statistical analyses were performed (p < 0.05 considered significant).

Results: The mean area of surgical freedom was 25.73 cm2 ± 5.37, 21.83 cm2 ± 3.49, 19.71 cm2 ± 4.75, 14.16 cm2 ± 2.73 for the binostril endoscopic, microscopic sublabial, endoscopic uninostril, and microscopic uninostril approaches, respectively (p < 0.05). The mean angular surgical freedom for the same approaches in the sagittal plane was 16.6° ± 1.7, 14.8° ± 1.9, 14.7° ± 1.3, and 12.3° ± 1.7 (p < 0.05), and 12.9° ± 1.7, 14.7° ± 1.2, 9.25° ± 1.7 and 9.53° ± 1.06 (p < 0.05) in the axial plane.

Conclusion: The endoscopic binostril transsphenoidal approach provides superior total area of surgical freedom and angular surgical freedom in the sagittal plane for surgical targets in the sellar region compared with the other endoscopic and microscopic approaches studied. The microscopic sublabial approach provides the greatest angular surgical freedom in the axial plane. This data suggests that the endoscopic binostril approach for sella tumors is consistent with established skull base principles.