CANS Navigator for Skull Base Surgery: Usefulness of Successive Localizations and Surgical Track

Detection of surgically manipulated extension is sometimes difficult during skull-base surgery. It is, however, essential to preserve important structures and to excise the lesion precisely. To solve this problem we developed a frameless, armless neurosurgical navigational system (“CANS navigator”). The CANS navigator utilizes electromagnetic coupling technology and detects the spatial position and orientation angle of a suction tube attached to a magnetic sensor. It displays the tip of the suction tube as well as its direction at a real-time basis on the preoperative images. Because the suction tube is continually directed toward the point of surgical manipulation, the navigator is able to demonstrate the extent of the surgical manipulation by accumulating the manipulation points on the display (“surgical track”). Before the skin incision is made, this system is useful in optimizing the patient’s head-position and the microscope angle and in determining the extent of the skin incision. After the craniotomy, this system assists the operator in clarifying surgical orientation, in preserving important structures encased in the tumors, and in confirming the dissectable range of neoplasms with unclear or irregular margins. Surgical track display is especially powerful in recurrent surgery or staged surgery in which the normal anatomy has been destroyed. The CANS navigator introduces precise localization of CT or MR to conventional skull-base surgery without limiting the operative field or interfering with the surgical procedures and assists the surgeon in reducing surgical invasion.