Safety and Efficacy of Hypo Fractionated Stereotactic Radiosurgery in Facial Nerve Schwannoma: a Single Institution Retrospective Case Series

Background: In the current era of modern neurosurgery, the treatment strategies have been shifted to “nerve-preservation approaches” for achieving a higher facial and hearing function preservation rate following facial nerve tumors.Objective: We have conducted this novel report on determining the outcome of patients with facial nerve schwannomas (FNS) treated with hypo fractionated stereotactic radiosurgery (hfSRS).Methods: Retrospective chart review of a prospectively maintained database search was conducted. Patients who underwent hfSRS CyberKnife (Accuray Inc, Sunnyvale, California., USA) for FNS were included. Outcomes consisted of tumor control, facial and hearing nerve function as graded by House-Brackmann (HB) and Gardner-Robertson scale, and adverse radiation effects. SPSS 23 was used to perform statistical analysis.Results: With an institutional board review approval, we retrospectively identified 5 patients with FNS [4 intracranial (80%) and 1 extracranial (20%)] treated with hfSRS (2011-2019). Patients received definitive SRS in 3 patients (60.0%) wile adjuvant to surgical resection in 2 patients (40.0%). A median tumor volume of 7.5 cm3 (range, 1.5-19.6 cm3) received a median prescription dose of 23.2 Gy (range, 21-25 Gy) administered in median of 3 fractions (range, 3-5 session). With a median radiographic follow-up of 31.4 months (range, 13.0-71.0 months) and clinical follow-up of 32.6 months (range, 15.1-72.0 months), the local tumor control was 100.0%. At last clinical follow-up, the facial nerve function improved or remained unchanged HB I-II in 80.0% of the patients, while the hearing nerve function improved or remained stable in 100.0% (Gardner-Robertson I-II) of the patients. Temporary clinical toxicity was seen in 3 patients (60.0%) which resolved. None of the patient developed adverse radiation effect.Conclusion: From our case series, hfSRS in FNS seems to be safe and efficacious in terms of local tumor control, and improved facial and hearing nerve function.