Is salvage surgery for large vestibular schwannomas after failed gamma knife radiosurgery more challenging?

Lucas Troude,Guillaume Baucher,Pierre-Hugues Roche,Mohamed Boucekine,Jean-Pierre Lavieille,Anne Balossier,Jean Régis

doi:10.1007/s10143-021-01604-3

Abstract

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. 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. 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 63months in the GKS failure and the genuine VS populations, respectively. The 1-, 5-, and 7-year progression-free survival were 100%, 95%, and 85% respectively in the GKS failure group and 97%, 80%, and 81% in the genuine VS group (p = .27). 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.

Highlights

The invasiveness and reported tumor growth control of 92 to 98% tend to propose the Gamma-knife surgery (GKS) as one of the established standard treatments for small to middle vestibular schwannomas (VS) [6,12,15,21,22,23]
In order to verify whether a previous Gamma-Knife surgery (GKS) treatment could hamper the oncological and functional outcome, we conducted a comparative study between patients operated on for large VS after failed-GKS to a consecutive group of genuine VS that underwent the same functional nervesparing resection technique regimen in the same period
Twenty-three consecutive patients who underwent salvage surgery for large VS after GKS failure were enrolled in this study, including 12 females and 11 males, with a mean age of 56 years

Summary

Introduction

The invasiveness and reported tumor growth control of 92 to 98% tend to propose the Gamma-knife surgery (GKS) as one of the established standard treatments for small to middle vestibular schwannomas (VS) [6,12,15,21,22,23]. Salvage surgery after failed GKS have been reported in only 1.57 to 5% of cases [6,12,15,2123]. Some authors asserted that previous radiosurgery may significantly complicate this resection due to post-GKS fibrosis and severe adhesion to the neurovascular structures, which lead to additional morbidity [14,19,28,29]. Radical resection of those tumors are associated to a higher risk of permanent postoperative facial nerve (FN) deficit [2,20]. In order to verify whether a previous GKS treatment could hamper the oncological and functional outcome, we conducted a comparative study between patients operated on for large VS after failed-GKS to a consecutive group of genuine VS that underwent the same functional nervesparing resection technique regimen in the same period

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