Comparison of the 3D-Exoscope and Operating Microscope in Mastoidectomy.

OBJECTIVES: The operating microscope (OM) commonly used in ear surgeries has several disadvantages, including a low depth of field, a narrow field of view, and unfavorable ergonomic characteristics. The exoscope (EX) was developed to overcome these disadvantages. Herein, we compared OM and EX during mastoidectomy and found out the feasibility of the EX. STUDY DESIGN: Prospective randomized comparative study. SETTING: Tertiary academic medical center. PATIENTS: Patients who had mastoidectomy for chronic otitis media with or without cholesteatoma between January 2022 and April 2022. INTERVENTION: Canal wall-up mastoidectomy (CWUM) or canal wall-down mastoidectomy (CWDM) using OM or EX without endoscope. MAIN OUTCOME MEASURES: Operative setting time (the time between the end of general anesthesia and incision), operative time (from incision to suture), postoperative audiologic outcomes, perioperative complications, and the decision to switch from EX to OM. RESULTS: Of 24 patients who were diagnosed with chronic otitis media or cholesteatoma, 12 each were randomly assigned to the OM or EX group. The mean operation time was 175 ± 26.5 minutes and 172 ± 34.6 minutes in the EX and OM group, respectively, which was not significantly different ( p = 0.843). The procedures in the EX group were successfully completed using a three-dimensional (3D)-EX without conversion to OM. All surgeries were completed without any complications. The postoperative difference in the air and bone conduction was 11.2 and 12.4 dB in the EX and OM groups, respectively, which was not significantly different ( p = 0.551). CONCLUSIONS: EX is comparable to OM in terms of surgical time, complications, and audiologic outcomes following mastoidectomy. The EX system is a potential alternative to OM. However, further improvements are required to overcome some drawbacks (deterioration of image resolution at high magnification, requirement of an additional controller for refocusing).

Application of an Intraoperative Neuromonitoring System Using a Surface Pressure Sensor in Parotid Surgery: A Rabbit Model Study.

OBJECTIVES: Facial nerve monitoring (FNM) can be used to identify the facial nerve, to obtain information regarding its course, and to evaluate its status during parotidectomy. However, there has been disagreement regarding the efficacy of FNM in reducing the incidence of facial nerve palsy during parotid surgery. Therefore, instead of using electromyography (EMG) to identify the location and state of the facial nerve, we applied an intraoperative neuromonitoring (IONM) system using a surface pressure sensor to detect facial muscle twitching. The objective of this study was to investigate the feasibility of using the IONM system with a surface pressure sensor to detect facial muscle twitching during parotidectomy. METHODS: We evaluated the stimulus thresholds for the detection of muscle twitching in the orbicularis oris and orbicularis oculi, as well as the amplitude and latency of EMG and the surface pressure sensor in 13 facial nerves of seven rabbits, using the same stimulus intensity. RESULTS: The surface pressure sensor detected muscle twitching in the orbicularis oris and orbicularis oculi in response to a stimulation of 0.1 mA in all 13 facial nerves. The stimulus threshold did not differ between the surface pressure sensor and EMG. CONCLUSION: The application of IONM using a surface pressure sensor during parotidectomy is noninvasive, reliable, and feasible. Therefore, the IONM system with a surface pressure sensor to measure facial muscle twitching may be an alternative to EMG for verifying the status of the facial nerve.