Towards a Steerable Neurosurgical Robot for Debulking of Brain Mass Lesions.

Minimally invasive surgery is regarded as a safer approach than open craniotomy to removing deep intracerebral mass lesions such as hematomas. It is usually performed by introducing a straight suction tool, sometimes combined with accessories for tissue debridement and irrigation, into the brain. Since collateral trauma to healthy tissue is proportional to the diameter of the tools, slender tools with small diameters are desired. However, current minimally invasive tools are inadequate for removal of large, multi-focal, and fibrous mass lesions. In this work, we present a new robotic surgical device for removing intracerebral mass lesions. The device consists of four concentric tubes. From outermost to innermost, they include a straight rigid stainless steel tube, a precurved superelastic nitinol tube with asymmetric notches, a braid-reinforced composite tube with tissue cutting holes at the tip, and a suction tube connected with a suction machine. A Pebax sleeve covers the notched area of the outer tube except the two most distal notches. By rotating and translating the notched nitinol tube, the robot tip can be manipulated inside a mass lesion. By concurrently rotating the cutting tube and applying negative pressure, tissues can be cut and removed through the suction tube. In this paper, we present our design and fabrication of this robotic device, kinematic modeling of the robot in terms of the rotation and translation of the notched tube and rotation of the cutting tube, and the results of feasibility studies show 540% improvement of mass lesion removal efficiency.