Feasibility of robotic posterior fossa skull base surgery.

Objective: Despite its potential advantages, robotic surgery has yet to be applied to skull base procedures. Complex anatomy and restricted access have limited the development of robotic skull base surgery. The authors' aim was to conduct a feasibility study of robotic surgery for posterior fossa skull base lesions.

Methods: Six silicone-injected postmortem human heads were prepared for the robotic surgery. Because there was no drilling tool with the robot, specimens were dissected in advance using an endoscope and microscope. The following approaches were investigated: 1) supracerebellar-infratentorial; 2) retromastoid; and 3) posterior occipitocervical junction surgeries. For each approach specific anatomical landmarks were identified, and the surgical freedom (vertical distance angle between the tools) was measured.

Results: In the case of the supracerebellar-infratentorial approach, the authors used 3 burrs with 1.5 cm of diameter: 1 paramedian and 2 laterally. The view of the pineal region was visualized, and sufficient surgical freedom of both tools was secured. The median vertical distance was 1.2 cm (range 1.1-1.8 cm), and the median angle between the tools was 105° (range 92°-110°). On the other hand, in the retromastoid approach, with a single burr 2.5 cm in diameter, the root exit zone of the facial nerve was barely visible, and a space for tools to access was not secured. The median vertical distance was 0.8 cm (range 0.6-1.0 cm), and the median angle between the tools was 10° (range 6°-12°). In the case of the posterior occipitocervical junction approach, the authors used the 3 tubular retractors, 1 in the middle and 2 laterally. Even though the space was narrow, the medulla and adjacent nerves could be identified, and a moderate level of surgical freedom could be obtained for tool mobilization. The median vertical distance was 1.6 cm (range 1.2-2.5 cm), and the median angle between the tools was 90° (range 88°-95°).

Conclusions: Although robotic surgery has yet to be applied to neurosurgery, it is expected to be helpful in posterior fossa skull base surgery if appropriate tools can be developed.