Development and Preclinical Trials of a Surgical Robot System for Endoscopic Endonasal Transsphenoidal Surgery

In endoscopic endonasal transsphenoidal surgery, for the treatment of deep brain tumors, such as craniopharyngiomas, an endoscope and surgical instruments are inserted through a nasal cavity into the lesion to remove the tumor. This has recently become the preferred technique because there is less likelihood of neural damage and a low complication rate. Manually controlled rigid surgical instruments are available for this procedure, but they provide limited dexterity and field of view. Therefore, some areas remain inaccessible when these surgical instruments are used. To solve these problems, we propose a surgical robot system for endoscopic endonasal transsphenoidal surgery. We defined a target surgical space based on an analysis by a surgeon and designed surgical instruments to reach this target space. The system consists of two robot arms, end-effectors, surgical instruments, a master device, a control device, and a robot base. The robot arm has an end-effector exhibiting two degrees of freedom (DOFs) and an inner channel, into which flexible surgical instruments are inserted. The flexible surgical instrument can reach the target space by steering the robot arm and end-effector. The outer diameter of the end-effector is 4 mm, and the diameter of the instrument channel, into which commercial surgical instruments can be integrated, is 2 mm. We motorized the motion of the robot arms, end-effectors, and instruments and included motion capability with the necessary precision, and developed a master device and control device to operate them. The surgical robot base is used to place the surgical robot before the operation and allow for manual operation. In a cadaver experiment, it was confirmed that the robot system can reach a larger area than is accessible with current surgical instruments, and it can support or remove tissues in the target surgical space. We received productive feedback from the surgeon conducting the experiment, and further research is underway to improve the robot system.