Application of a Variable-Angle Endoscope Combined with the Three-Piece Set for IAC in the Resection of Residual Tumor at the Bottom of IAC during Acoustic Neuroma Surgery: A Report of 7 Cases

Background: The difficulty in acoustic neuroma surgery is the balance of complete tumor resection and the preservation of cranial nerve function. The treatment of the tumor component in internal auditory canal (IAC) is especially pivotal. Methods: This study introduces a novel surgical approach for managing tumors within the IAC during acoustic neuroma resection. We employed a variable-angle endoscope to visualize the entire length of the IAC and utilized a specialized three-piece set to remove tumors, including those at the fundus, under direct visualization, aiming to improve tumor resection and nerve preservation rates. The three-piece set for IAC consists of three instruments with varying shapes and blade orientations. First, we validated the anatomical feasibility of this approach using cadaveric head specimens. Subsequently, we applied this technique in acoustic neuroma surgeries to address IAC tumors. Results: Anatomical studies confirmed that the variable-angle endoscope provided comprehensive exposure of the entire IAC, and the three-piece set is effective in managing intracanalicular tumors. And then, we reported a 7 cases series of acoustic neuroma where this surgical approach was successfully implemented. Follow-up results demonstrated high tumor resection rates and facial nerve preservation within the IAC. Conclusion: The combination of a variable-angle endoscope and the three-piece set for IAC enhances tumor removal (especially in the resection of residual tumor at the bottom of IAC) efficiency while reducing the risk of cranial nerve injury, with a significant value for clinical promotion. Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany