[Image-guided endoscopic sinus surgery: a comparison of two navigation systems].

We evaluated the effectiveness of two navigation systems with optical tracking in endoscopic sinus surgery (ESS). The Signa SP/i Intraoperative navigation system (General Electric Co., Intraoperative NS) is advantageous in acquiring both real time and high-resolution images during surgery, compared to conventional image-guided navigation (Stealth Station TREON, Medtronic Inc., IGNS) that rely entirely on preoperative three-dimensional images. We studied the following in 14 patients treated with intraoperative NS and 19 treated with IGNS: 1) additional time for navigation system implementation, 2) available instrumentations in ESS, and 3) navigation system accuracy. Navigation systems required additional time to prepare ESS. The time lapse from admittance to the operating room to ESS onset was measured in patients under both systems and controls undergoing ESS without any image guidance. Preparation of the intraoperative NS required an additional 52 min and IGNS required 17 min compared to the control group. Based on operative instruments, the intraoperative NS has some limitations arising from the application of a high magnetic field. Surgical instruments must not be attracted by the magnetic field in the operating room. So those used in our study were thoroughly examined and some remanufactured using MR safe materials. All instruments in ESS could be used in surgical guidance during surgery in the IGNS. Anatomic landmarks were accurately visualized using intraoperative NS and IGNS. Intraoperative NS renews the image during surgery, so surgeons could confirm the surgical outcome during ESS. Since the average distant error in both systems was between 1 mm and 2.5 mm, we confirmed that accuracy obtained with both navigation system was suitable for ESS completion. The intraoperative NS renewed the image during navigation. In conclusion, both navigation systems are sufficient for accurate image navigation in ESS, but navigation systems must be selected based on the individual case.

[Endoscopic resection of benign and malignant tumors in the nasal cavity and paranasal sinus].

Endoscopic resection of nasal and paranasal sinus tumors is more aesthetic and less invasive than conventional resection, such as Luc's operation and lateral rhinotomy. We clarified the effect of radical endoscopic tumor excision and the control of local bleeding hazardous in endoscopic surgery. Subjects were patients with benign lesions in the nasal cavity, medial wall of the maxillary sinus, ethmoid sinus, and/or sphenoid sinus without concurrent malignant lesions. Although patients selection for malignant tumor excision was based on (1) possible en bloc resection, (2) low-grade malignant tumors, and (3) tumors in the nasal cavity and adjoining paranasal sinus, the final decision was made individual. Subjects were 23 patients with benign tumor (10 inverted papilloma, 9 hemangioma, 2 juvenile angiofibroma, and 2 other tumors) and 4 with malignant tumor (olfactory neuroblastoma, acinic cell carcinoma, squamous cell carcinoma, and chondroid chordoma) in the nasal and paranasal sinus. The tumor was resected en bloc except for patients with inverted papilloma (2 cases) and chondroid chordoma. Recurrence in benign tumors was zero during a mean observation of 21 months. One with chondroid chordoma, however, suffered a recurrent lesion 7 months after the initial operation. The lesion was successfully salvaged by a similar endoscopic procedure and subsequently treated with electron beam irradiation. Preoperative arterial embolization, laser coagulation, and ligation of the sphenopalatine artery were very useful in reducing blood loss during surgery and maintaining a clear endoscopic view. In intraoperative bleeding volume, less than 100 ml of bleeding occurred during surgery in 23 of 27 patients. The endoscopic excision of benign lesions in the nasal and paranasal sinus is thus as effective as conventional radical surgery. Endoscopic removal of malignant lesions remains controversial because of the small number of patients and short postoperative observation.