Effect of Gamma Knife Radiosurgery on Vestibular Schwannoma with Serviceable Hearing: A Single-Center Indian Study.

Objective: Gamma Knife radiosurgery (GKRS) is an established treatment modality for vestibular schwannomas (VSs). The tumor control and hearing preservation rates suggest that GKRS is a good alternative treatment for small- and medium-size VS. Data are lacking from India regarding GKRS for VSs. Our aim was to find the hearing preservation and tumor control rates and the factors contributing to these.

Methods: In a retrospective 9-year study period, 87 patients had undergone GKRS for unilateral VS with Gardner-Robertson (GR) class I or II serviceable hearing. All 87 had been evaluated with magnetic resonance imaging and audiometry before GKRS and during follow-up to assess for the factors influencing tumor control and hearing preservation.

Results: Of the 87 patients, 77 with a minimum follow-up of 2 years and magnetic resonance imaging and audiometry evaluations available were included in the present study. The median follow-up period was 30 months. The tumor control rate and hearing preservation rate was 96.1% and 79.2%, respectively. Hearing preservation was not affected by the tumor volume. However, age >40 years, pre-GKRS pure tone average <30 decibels, speech discrimination score >85%, pre-GKRS Gardner-Robertson grade I hearing, mean cochlear dose <4 Gy, and pre-GKRS Ohata class of laterality C, D, E were significant on univariate analysis. The multivariate analysis revealed that age >40 years (P = 0.017), pre-GKRS pure tone average <30 decibels (P = 0.002), and Gardner-Robertson class I (P = 0.001) were significant factors. No patient developed cranial nerve dysfunction, hydrocephalus, or malignant degeneration.

Conclusions: For most patients with small VSs, GKRS will be an effective alternative treatment to microsurgery with retained serviceable hearing and good tumor control.