Radiosurgery versus Resection for Residual Vestibular Schwannomas

Background: Either by design or due to anatomical constraints, vestibular schwannomas are sometimes incompletely removed on first attempt. To remove the entirety of the tumor, reoperation or stereotactic radiosurgery is indicated. Herein we analyze facial nerve preservation, hearing nerve preservation, and tumor control between patients who underwent either double surgery for vestibular schwannomas or surgery followed by radiosurgery.

Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed. A literature search across 5 databases was conducted to look for outcomes of residual tumors following stereotactic radiosurgery versus resection or staged surgery. Outcomes of interest included facial nerve function following the House–Brackman (HB) scale, hearing function using the Gardner-Robinson (GR) scale, and tumor recurrence. To compare differences between the two groups SPSS (IBM) was used with an α level set to 0.05. Heterogeneity analysis was conducted using τ², Cochran’s Q, and I² statistics

Results: In total, there were 1,089 patients and 1,096 tumors. Group A, which was surgery followed by radiosurgery for vestibular schwannoma, had 137 of the tumors (17.3%) undergo gross-total resection and 657 (82.7%) subtotal resection. Radiosurgery for residual tumors included Gamma-Knife (91.3%), Cyberknife (1.3%), and LINAC (7.18%). Within this group, 778 (90.8%) of the tumors were controlled. On the HB scale, 326 (97.6%) provided good facial nerve function and 328 (95.9%) provided serviceable facial nerve function. 68 (79.1%) of patients experienced preserved serviceable hearing on the GR scale.

In group B, there were 239 patients with a second surgery after primary resection. 159 (83.3%) underwent a retrosigmoid approach for the primary resection, 28 (14.7%) underwent a translabyrinthine approach, and 4 (2.1%) patients had a middle fossa approach. 147 patients had subtotal resections (77.4%) with 43 (22.6%) patients having gross-total resection. Of the 239 patients who had a secondary surgery, the majority, 139 (58.2%) had a translabyrinthine approach, with 99 (41.4%) retrosigmoid, and 1 (0.4%) middle fossa. In group B, 124 (91.2%) of the tumors were controlled with 96 (71.1%) reporting good Facial nerve function on the HB scale and 88 (67.2%) reporting serviceable facial nerve function. Data on preserved serviceable hearing was not available.

Significant study heterogeneity was found for good (p = 0.02) and serviceable (p = 0.03) facial nerve function in the double surgery group. Heterogeneity was also found in the surgery-radiosurgery group with serviceable FNF (p = 0.03) and tumor regrowth (p < 0.01). However, when it came to secondary surgery for treatment of residual vestibular schwannomas, it was found that good serviceable facial nerve function was better preserved in the surgery-radiosurgery group (p < 0.01), with no heterogeneity ([Fig. 1]).

Conclusion: When considering treatment options for patients with residual vestibular schwannomas, systematic review shows that despite similar tumor growth control and hearing preservation rates between double surgery and surgery-radiosurgery groups, the latter has better preservation of facial nerve function up to grade II on the HB scale. Limitations include possible heterogeneity in the double surgery group. This information will help facilitate patient discussion in the future.