Is Salvage Surgery for Large Vestibular Schwannomas After Failed Gamma-knife Radiosurgery More Challenging?

Abstract Objectives: In order to verify whether a previous Gamma-Knife surgery (GKS) treatment could influence the oncological and functional outcome in large vestibular schwannoma (VS) surgery, we have compared group of patients operated on for large VS after failed-GKS to a group of genuine VS that underwent the same functional nerve-sparing resection technique regimen in the same period.Methods: Single center retrospective cohort study of 23 consecutive GKS-failure and 170 genuine VS patients operated on between April 2003 and March 2019. After resection, patients were allocated to a Wait-&-rescan or an upfront GKS policy.Results: At last follow-up examination, the facial nerve function was good (House-Brackmann Grades I or II) in 95% of the GKS-failure and 84% of the genuine VS patients (p=.25). The median volume of tumor residue was .56cc in the GKS-failure group, and .62cc in the genuine VS group (p=.70). Tumor control was achieved in 91% and 83% of cases with a mean follow-up of 74 and 63 months in the GKS-failure and the genuine VS populations, respectively. The 1-, 5- and 7-year progression free survival were 100%, 95% & 85% respectively in the GKS-failure group, and 97%, 80% & 81% in the genuine VS group (p=.27).Conclusion: Despite significant modifications of the microsurgical environment associated to salvage surgery after GKS-failure, a functional nerve-sparing resection is an effective strategy to optimize the results on facial nerve function, with similar long-term tumor control to those observed in the genuine VS population.