2025 Poster Presentations
P476: CONTINUOUS FACIAL NERVE MONITORING WITH DIRECT BALL-TYPED ELECTRODE STIMULATION DURING THE VESTIBULAR SCHWANNOMA SURGERY
Wan-Soo Yoon, MD, PhD; Yeo Song Kim, MD; Dong-Sup Chung, MD, PhD; Incheon St. Mary's Hospital, The Catholic University of Korea
Introduction: Vestibular schwannoma surgery carries the risk of facial nerve injury, which is always the distress to the patients and surgeons. The several techniques have been tried to monitor the facial nerve, but it has not yet been confirmed which method is the best. Here, we present our experience with continuous facial nerve monitoring by the direct stimulation with ball-typed electrode for the resection of a series of vestibular schwannomas.
Method: During the last 2 years, a total 15 patients with vestibular schwannomas underwent the surgical resection. Ball-typed electrode was placed in the root exit zone of facial nerve near brain, the evoked facial nerve electromyograms was monitored in the real-time through a heads-up-display view of microscope.
Results: The application of ball-type electrode was tried to all included patients, but it was only applicable to 7 patients. The median diameter of this patients was 27 mm (range, 14 – 33), and Koos grades were II in 2 patients, III in 2, and IV in 3. Tumors were solid type and mixed type in 5 and 2 patients, respectively. And facial nerve locations were the ventral-inferior in 4 patients, the ventral-superior in 2, and the ventral-central in 1. Gross total resections were completed in all patients, and postoperative facial motor grades were favorable, except one patient with preoperative facial palsy with grade III. The ball-typed electrode was not applicable in the other 8 patients because of the limitation of fixation and facial nerve identification.
Conclusion: Ball-type electrode is a method worth trying for facial nerve monitoring during the vestibular schwannoma surgery. However, it has the limitation to the application in large tumors, ventral and central location of facial nerve, and fixation to facial nerve. Further studies are needed to determine whether the use of this electrode can reduce the postoperative facial palsy.