Development of a snake-like dexterous manipulator for skull base surgery.

Petrous apex lesions constitute considerable surgical challenges due to their location in the skull base and close relationship with critical structures such as inner ear, carotid arteries, facial nerves and jugular bulb. These lesions often cannot be treated completely with rigid tools due to the limited accessibility. We are aiming to develop a snake-like manipulator to assist surgeons with the infralabyrinthine treatment of petrous apex lesions with increased dexterity. This snake-like dexterous manipulator (SDM) with 3.3 mm outer diameter and 40 mm working length was designed including a tool channel with a diameter of 1.8 mm and an endoscope channel with a diameter of 0.7 mm. The SDM can be actuated in one plane and two directions enabling the C- and S-shaped bends and rotated around its longitudinal axis. The constant curvature modeling was implemented to predict the deflection in one direction. Experiments were carried out with optical microscope to find out different bending modes. Experimental bending modes were in a good agreement with the theoretical ones in terms of the bending behavior. However tip position prediction showed discrepancies up to 1 mm in X and 2 mm in Z axes.