2026 Proffered Presentations
S194: ACQUISITION OF SURGICAL SKILLS IN VESTIBULAR SCHWANNOMA SURGERY: A FOUR-HAND MICROSURGICAL TRAINING MODEL AND TRAINEE LEARNING CURVE
Ana Sofia Alvarez, MD; Celine Hounjet, MD; Yoojin Choi, MD, PhD; Brian Westerberg, MD; Serge Makarenko, MD; Ryojo Akagami, MD; University of British Columbia
Vestibular schwannoma resection represents a cornerstone of skull base surgery, integrating fundamental microsurgical principles such as arachnoid dissection, vascular and neural preservation, and tumor removal techniques. Optimal strategies for training residents and fellows in this technically demanding procedure remain undefined. Traditional teaching models, based on passive observation from a side-arm microscope and limited opportunities to perform isolated portions of the operation, often restrict hands-on experience and contribute to the long learning curve.
At our institution, we have implemented a structured four-hand training approach. By orienting the operating microscope binoculars 180 degrees apart, both the attending neurosurgeon and the trainee operate simultaneously from opposite sides of the patient’s head. The attending scrubs in all cases, maintaining full ability to intervene at any stage. This model ensures that the trainee has instruments in the field throughout the entire procedure and actively participates in every surgical step with task delegation possible on a granular basis instead of during selective steps.
This technique enables real-time feedback on tissue handling and microsurgical technique, promotes joint intraoperative decision making between attending and trainee, and allows immediate intervention in the event of intraoperative complications without the need of change positions or reposition the microscope.
We reviewed 734 vestibular schwannoma surgeries performed with resident and/or fellow participation, analyzing the number of resections performed per trainee per year, their progression along the learning curve and surgical outcomes. Stages of training were defined based on technical complexity and risk of vascular or neural injury, with each stage recommended for mastery before progressing to higher levels.
For the standard retrosigmoid approach in non-purely intracanalicular tumors (Koss grade II–IV), we defined four levels of difficulty: (1) exposure and approach, including cisterna magna opening, cerebrospinal fluid release, and cerebellopontine angle exposure with basic arachnoid dissection; (2) tumor debulking and capsule management, including microsurgical dissection of the capsule from the brainstem; (3) facial nerve identification and dissection along the tumor and in the internal acoustic canal; and (4) advanced cases such as recurrences after surgery or radiosurgery and giant tumors (> 4 cm)with significant brainstem compression.
We believe this methodology accelerates skill acquisition through graded task delegation under continuous attending oversight, establishing the foundation for mastery of fundamental skull base surgical techniques early in training while maintaining patient safety.