IMAGE-GUIDED ENDOSCOPIC ENDONASAL SURGERY WITH A POWERED INSTRUMENT FOR PARANASAL CYSTS

Abstract

Between July and August 1999, we performed image-guided endoscopic endonasal sinus surgery using a powered instrument on seven patients with paranasal cysts. Four of these surgeries were for postoperative maxillary cysts, one was for a postoperative ethmoidal cyst, one for a primaly frontal cyst, and one for a postoperative front-ethmoidal cyst. The advantages of using an optical 3-dimensional navigation system (EVANS III ; Tomiki Corp., Japan) with a powered instrument (XPS Drill-System ; Xomed Corp., USA) for intranasal surgery were then evaluated. The EVANS III is composed of a workstation, CCD camera, a metal probe with three mirror markers, and a headsensor with four light-emitting diodes (LEDs). The optical digitizer is mounted on a stand located 1.5-2 : 5 meters away from the patient's head. This system uses the patient's preoperative image data sets (CT/MRI) to create a 3-dimensional reconstruction. The position of the probe's tip is visualized using triplanar (axial, coronal and sagittal) views of the 2 -dimensional images and/or a 3-dimensional reconstruction at the center of the crosshairs. The 3-dimensional navigation system allows the surgeon to determine the approximate location and direction of each cyst wall and the appropriate point of incision into the nasal cavity. The XPS Drill-System can be used to drill through bone and was used in five cases to open the bony portion of cysts. Anatomical structures such as the frontal sinus and the maxillary sinus are difficult to reach using a straight blade, but can be easily reached using a curved blade (40 degree angle cutter, 55 degree angle drill bar). The curved blade cutter and drill bar enables maxillary, ethmoidal and frontal cysts to be easily resected.