Facial Nerve Schwannoma Treatment with Stereotactic Radiosurgery (SRS) versus Resection followed by SRS: Outcomes and a Management Protocol

Abstract

Background: Stereotactic radiosurgery (SRS) and resection are treatment options for patients with facial nerve schwannomas without mass effect. Objective: To evaluate outcomes of patients treated with SRS Vs resection+SRS. Method: We retrospectively compared 43 patients treated with SRS to 12 patients treated with resection+SRS. The primary study outcome was unfavorable combined endpoint, defined as worsening or new clinical symptoms, and/or tumor radiological progression. SRS (38.81+ 5.3) and resection+ SRS (67.14+ 11.8) groups had similar clinical follow ups. Results: At the time of SRS, the tumor volumes of SRS (mean+ standard error; 1.83cc+ 0.35CC) and resection+ SRS (2.51cc+ 0.75CC) groups were similar. SRS (12.15+0.08 Gy) and resection+ SRS (12.16+ 0.14 Gy) groups received similar radiation doses. SRS group (42/43, 98%) had better local tumor control than the resection+SRS group (10/12, 83%, p=0.04). Most of SRS (32/43, 74%) and resection+SRS (10/12, 83%) group patients reached a favorable combined endpoint following SRS (P=0.52). Considering surgical associated side effects, only 2/10 patients of resection+SRS group reached a favorable end point (P<0.001). Patients of SRS group, who are >34 years old (p=0.02), have larger tumors (>4cc, 0.04), internal auditory canal (IAC) segment tumor involvement (p=0.01) were more likely to reach an unfavorable endpoint. Resection+SRS group patients did not show such a difference. Conclusions: While resection is still needed for larger tumors, SRS offers better clinical and radiological outcomes compared to resection followed by SRS for facial schwannomas. Younger age, smaller tumors, and non-IAC situated tumors are factors that portend a favorable outcome.