Surgical Resection after Radiosurgery for the Management of Vestibular Schwannomas: A Systematic Review

Introduction: Multiple short series have evaluated the efficacy of salvage microsurgery after radiosurgery for the treatment of vestibular schwannomas; however, there is a lack of large patient data available for interpretation and clinical adaptation. Methods: The MEDLINE/PubMed, Web of Science, Cochrane Reviews, and EMBASE databases were queried. All English language and translated publications were included. Case studies of malignant transformation were excluded as were studies lacking adequate study characteristics and outcomes. Results: Twenty studies containing 319 cases met inclusion criteria. Three additional cases from Rush University were added for 322 total cases. Tumor growth with or without symptoms was the primary indication for salvage surgery (91% of cases), followed by worsening of symptoms without growth (5%) and cystic enlargement (4%). The average time to microsurgery after radiosurgery was 38.6 months. The average size and volume of tumor at surgery was 2.49 cm and 8.50 cm 3 , respectively. The surgical approach was retrosigmoid (44%) and translabyrinthine (56%). 60% of patients had a House–Brackman (HB) score of 1 or 2. The facial nerve was not preserved in 8.4% of cases. Facial nerve severance and HB scores were lower for retrosigmoid versus translabyrinthine approach ( p = 0.46, p = 0.18, respectively); however, fewer complications were noted in the translabyrinthine approach ( p = 0.09). Gross total resection (GTR) was completed in 56% of surgeries. Studies which used predominately STR were associated with a lower rate of facial nerve lesioning (5.7 vs. 11.2%, p = 0.09) and higher rate of HB 1 to 2 (67.6 vs. 51.1%, p = 0.005) versus majority of GTR. However, majority of STR was associated with a recurrence rate of 5.6% as compared with 1.4% for majority of GTR ( p = 0.07). Conclusion: Microsurgery following radiosurgery was universally considered more difficult than primary resection due to loss of surgical planes and greater adherence between tumor and cranial nerves. Concurrence among studies was to avoid surgery for the first 2 to 3 years following radiosurgery. There is disagreement among authors over whether to attempt GTR or use primarily STR for recurrent tumors. STR shows better facial nerve outcomes at the possible expense of tumor control. Longer follow-up times with more patients will be required to determine the true rate of tumor recurrence following STR. The trade-offs of each should be considered in patient counseling and treatment.