Objective Planned subtotal resection followed by Gamma Knife surgery (GKS) in patients with large vestibular schwannoma (VS) has emerged during the past decade, with the aim of a better functional outcome for facial and cochlear function. Methods We prospectively collected patient data, surgical, and dosimetric parameters of a consecutive series of patients treated by this method at Lausanne University Hospital during the past 8 years. Results A consecutive series of 47 patients were treated between July 2010 and January 2018. The mean follow-up after surgery was 37.5 months (median: 36, range: 0.5-96). Mean presurgical tumor volume was 11.8 mL (1.47-34.9). Postoperative status showed normal facial nerve function (House-Brackmann I) in all patients. In a subgroup of 28 patients, with serviceable hearing before surgery and in which cochlear nerve preservation was attempted at surgery, 26 (92.8%) retained serviceable hearing. Nineteen had good or excellent hearing (Gardner-Robertson class 1) before surgery, and 16 (84.2%) retained it after surgery. Mean duration between surgery and GKS was 6 months (median: 5, range: 3-13.9). Mean residual volume as compared with the preoperative one at GKS was 31%. Mean marginal dose was 12 Gy (11-12). Mean follow-up after GKS was 34.4 months (6-84). Conclusion Our data show excellent results in large VS management with a combined approach of microsurgical subtotal resection and GKS on the residual tumor, with regard to the functional outcome and tumor control. Longer term follow-up is necessary to fully evaluate this approach, especially regarding tumor control.
Keywords: Gamma Knife; combined approach; radiosurgery; surgery; vestibular schwannoma.