Introduction: The present study evaluates whether hearing deterioration during observation reduces serviceable hearing preservation rates after stereotactic radiosurgery (SRS) in vestibular schwannoma (VS) patients with useful hearing.
Methods: We retrospectively analyzed 1447 VS patients who underwent SRS between 1992 and 2017. We identified 100 VS patients who had Grade I Gardner- Robertson (GR) hearing at initial diagnosis but were observed without surgery or SRS. We compared hearing after SRS in 67 patients who retained GR Grade I hearing from initial diagnosis to SRS (the hearing maintenance or HM group) to 33 patients whose hearing worsened from GR grade I to grade II (the hearing deterioration or HD group). We also investigated whether a decline in pure tone average (PTA) or speech discrimination score (SDS) before SRS affected hearing preservation after SRS.
Results: The serviceable hearing (GR I and II) preservation in HM patients was 80%s, 63%, and 51% at 3, 5, and 10 years, respectively. The serviceable hearing preservation in HD patients was 40%, 33%, and 20% at 3, 5, and 10 years, respectively. In multivariate analysis, younger age (< 55 years, p = 0.045) and HM during observation (p = 0.001) improved serviceable hearing preservation rates. Patients whose PTA increased ≥ 15 dB (p = 0.024) or whose SDS declined ≥ 10% (p = 0.019) had reduced serviceable hearing preservation rates.
Conclusions: Hearing deterioration during observation before SRS reduced long term hearing preservation rate in VS patients with GR grade I hearing at initial diagnosis. SRS before hearing deterioration was recommended for hearing preservation.
Keywords: Gamma knife surgery; Gardner-Robertson grade; Hearing preservation; Pure tone average; Speech discrimination score; Vestibular schwannoma.