Introduction: Endoscopic skull base surgery aims to reduce surgical morbidity by minimizing tissue manipulation and exposure. However, the anatomical constraints posed by the narrow surgical corridors and constrained operative workspace present technical challenges due to reduced dexterity. Previously, we evaluated a novel handheld robotic instrument in the context of endonasal skull base surgery. This study assesses the broader applicability, feasibility, and potential usefulness of this robotic technology for 360-degree skull base approaches.
Methods: The robotic system comprises of interchangeable articulated end-effectors coupled to a handheld controller. Two attending skull base neurosurgeons and two neurosurgery residents from two international units performed seven skull-base approaches on cadaveric specimens, spanning anterior, anterolateral, lateral, posterolateral, and posterior approaches. Conventional instruments were used to expose anatomical landmarks, followed by intraoperative tasks using the handheld robot. Participants were interviewed during the procedures to assess the robot's feasibility (ability to safely perform its objective of manipulating tissue at the operative site) and usefulness (ability to perform desired objectives well).
Results: The robot was interrogated across seven endoscopic skull base approaches. Feasibility was achieved in 7/7 approaches. The robot demonstrated superior workspace reach compared to standard instruments in 5/7 approaches. Tissue manipulation was satisfactory in 6/7 approaches.
In the endonasal approach, the robot demonstrated superior workspace reach and satisfactory tissue manipulation but was limited by its lower grasping forces and the lack of angled shafts. In the transorbital approach, the size of the handheld controlled and the lack of curved shafts resulted in impaired ergonomics, which hindered useful workspace reach and tissue manipulation.
In the supraorbital and pterional approaches, the device achieved varying results. For the former, the robot demonstrated superior workspace reach and satisfactory tissue manipulation. However, the diameter of the tooltip was too large and grasping forces were felt to be insufficient. For the pterional approach, whilst the device was feasible, its workspace reach was limited by instrument tips that were too large.
In the postero-lateral (retro-sigmoid) approach, the robot demonstrated superior workspace reach and satisfactory capability of tool-tissue manipulation. Limitations included insufficient delicacy of movement, conferred by relatively large instrument tips and the pistol-like design of the handheld controller.
In the suboccipital approach, the robot demonstrated a workspace reach superior to that of conventional instruments and satisfactory tissue manipulation capabilities. Device limitations included a longer than necessary shaft, the lack of availability of end-effectors, and a bulky handheld controller.
Discussion/Conclusion: This study evaluated a handheld robot designed for endoscopic neurosurgery across seven skull base approaches. The robot demonstrated feasibility for all approaches studied and improved workspace-reach in a majority of approaches. Limitations of the robot varied by approach and related to shaft length, grasping force, and controller and tooltip size. Design changes already in the pipeline, which include shorter, angled shafts, a wider variety of end-effectors, enhanced grasping force, and refined control interfaces, may address these limitations. Overall, this study supports the potential of handheld robots across endoscopic skull base surgery yet also highlights the need for iterative development to optimize instrument design and functionality.