Flexible Endoscope Increases Surgical Freedom When Compared to a Rigid Endoscope in Endoscopic Endonasal Approaches to the Skull Base

Introduction: One challenge of performing endoscopic endonasal approaches is the instrument movement limitation and conflict caused by long working distances and a crowded operative nasal corridor. Such limitation and conflict decreases surgical freedom making it difficult to perform dissection maneuvers, increases surgeon frustration, and lengthens the learning curve for trainees. Instrument conflict occurs at several locations along the operative corridor, including along the shaft and back-end of the endoscope involving the light cable, camera, and surgeons' hands. We evaluated the impact of a new flexible endoscope, which can be configured to be out of the operative corridor, has on surgical freedom for endoscopic approaches to the pituitary gland.

Methods: Uninostril and binostril endoscopic transsphenoidal approaches to the sella turcica were performed on eight silicon-injected, formalin-fixed cadaveric heads using both rigid and flexible 3D endoscopes (Visionsense, Tel Aviv, Israel). Stereotactic CT scans were performed for anatomical correlation and measurements and surgical freedom area was assessed utilizing image guidance based on the scans (Stealth System, Medtronic). Surgical targets selected were the pituitary gland and bilateral cavernous internal carotid arteries. Standard statistical analyses were performed.

Results: Mean area of surgical freedom in the uninostril approach was 91.9 + / − 6.2cm2 and 107.8 + / − 7.3cm2, using the rigid and flexible endoscopes, respectively (p = 0.0001). Mean area of surgical freedom for the binostril approach was 115.5 + / − 10.4cm2 and 135.0 + / − 2.7cm2 using the rigid and flexible endoscopes, respectively (p = 0.0002). Experimental observations revealed that improved surgical freedom with the flexible endoscope was due to the avoidance of back-end collisions involving the hand controlling instruments and hand holding the endoscope camera when using the rigid endoscope.

Conclusions: In this setting, the flexible endoscope produced significantly better movement and use of instruments compared with the rigid endoscope system. The use of a flexible endoscope which can be contoured such that the camera and shaft are out of the surgical field increases surgical freedom by limiting back-end conflict that occur between the endoscope camera and surgeon's hands. Optimization of the optics, design and profile of endoscopic systems will produce improved ability and area within which to manipulate instruments.