[Endoscopic endonasal surgery with image-guidance].

We evaluated the advantages and disadvantages of image-guided endoscopic endonasal surgery for various diseases. Thirty-three patients, including 8 with chronic sinusitis, 14 with paranasal cysts, 1 with paranasal tumor (biopsy), 1 with sellaturcial cyst (Rathke's cleft cyst) and 9 with pituitary tumors were endonasally operated on from September 1998 to May 1999, with an electromagnetic navigation system, The Insta Trak (Visualization Technology Inc. USA). The Insta Trak system is composed of a computer, a metal probe with a nonmetallic suction tube attachment, and a soft-type headset with an electromagnetic sensor. This freehand, armless system compensates well for patient's head movement during surgery, and precludes the need for head fixation. Either straight or curved suction tube (probe) can be used to access almost of all pathological sites in the sinus cavity. Location of the metal probe is displayed on the computer moniter as an intersection point on the axial, coronal and sagital CT images. In all cases, Insta Trak showed the surgeon the appropriate location and direction of each lesion. The Insta Trak also indicated the location of the orbit, optic canal, nasolacrimal duct and/or skull base, thus, preventing intraoperative complications. When the anatomy was distorted by previous surgery and/or when there was uncontrollable bleeding from a severe lesion so that the surgeon had difficulty finding the proper orientation, the usefulness of image-guided surgery was sufficiently recognized. However, the following disadvantages were also pointed out. An additional 15 to 20 minutes is needed for equipment set up and operation, unless the surgeon and the operation room staff are familiar with the machine. The patient's CT image used for navigation relies on data obtained preoperatively, that is to say, it can not reflect morphological changes produced during surgery. Moreover, the surgeon must consider possible errors of the navigational point that may result in the headset during surgery, as well as, errors the machine may originally possess. The image-guided system successfully integrated the most up-to-date computer technology with a surgeon's anatomical knowledge for improved treatment of endoscopic endonasal surgery. However, we also concluded that the system should be used as a surgical supporting device for safer and more adequate procedures.