Long-term Outcomes of Radical Resection vs. Combined Subtotal Resection and Gamma Knife Radiosurgery for Large Vestibular Schwannomas

Objective: This study compares the long-term outcomes of radical resection versus subtotal removal followed by Gamma Knife (GK) radiosurgery for large vestibular schwannomas (VS), focusing on tumor control and neurological function preservation. Methods: A retrospective analysis of 87 patients with large VS (Koos grade III–IV) was conducted. Patients were divided into radical resection (Group R, n = 40) and subtotal removal followed by GK (Group C, n = 47). Tumor volume reduction, facial nerve function, hearing preservation, and other neurological outcomes were evaluated. Results: Group C had significantly larger tumor preoperatively (median: 10.8 cm³ vs. 7.9 cm³, p  = 0.002). Despite this, facial nerve function was better preserved in Group C than in Group R (House-Brackmann > 3: 19% vs. 30%), and the incidence of non-serviceable hearing (> 50 dB) was less frequent in Group C (72% vs. 88%) immediately after surgery. Trigeminal dysesthesia improved in Group C (32–26%) but worsened in Group R (28–38%). Ataxia was more common in Group C (final: 19% vs. 3%, p  < 0.001), likely due to larger tumor size. Tumor control was achieved in both groups, with a 95.7% reduction in Group R and a 69.5% reduction in Group C ( p  < 0.0001). VP shunt placement was more frequent in Group C than in Group R (19% vs. 5%). Failure of tumor control was observed only in Group C, where 4% of patients required salvage surgery and 2% underwent additional Gamma Knife treatment. Conclusion: Subtotal removal with GK balances tumor control and neurological preservation in large VS. Despite larger tumors, this treatment approach demonstrated better long-term facial nerve and hearing outcomes than radical resection.