Adjunctive Gamma Knife Surgery or Wait and Scan Policy After Optimal Resection of Large Vestibular Schwannomas: Clinical and Radiologic Outcomes.

OBJECTIVES: Patients with large vestibular schwannomas (VSs) will require surgical treatment owing to the potential consequences of long tract and cranial nerve compression. We assessed the long-term clinical and radiologic outcomes of patients harboring large VSs treated with a facial nerve (FN)-sparing technique.
METHODS: We performed a single-center retrospective cohort study of 169 consecutive large VSs treated surgically from January 2003 to May 2015. The postoperative volume of the tumor residue was assessed using thin-slice magnetic resonance imaging 6 months after surgery. Postoperatively, the patients were allocated to a wait and rescan (W&reS) or an upfront gamma knife surgery (GKS) policy.
RESULTS: At the last follow-up examination, FN function was good (House-Brackmann grade I or II) in 84% of the patients. Of the 169 patients, 11% had undergone gross total resection, 59% near total, 21% subtotal, and 9% partial resection. In the 143 patients without gross total resection, the overall median tumor residue volume was 0.39 cm3. Of these 143 patients, 66 had been allocated to the W&reS policy and 77 to upfront GKS. Overall tumor control was achieved in 83% of cases, with a mean follow-up of 62 months. Of the 27 growing residues, 17 required salvage treatment (11% failure rate). The 1-, 5-, and 7-year progression-free survival rate was 95%, 82%, and 76% in the W&reS group and 99%, 81%, and 78% in the GKS group, respectively (P = 0.57).
CONCLUSIONS: Functional nerve-sparing resection provides satisfactory FN preservation. The low probability of long-term regrowth of small remnants is an argument for a W&reS protocol. GKS is a legitimate option for salvage treatment.