Prognostic Factors of Hearing Outcome in Untreated Vestibular Schwannomas: Implication of Subdivision of Their Growth by Volumetric Analysis.

Abstract

Conservative wait-and-scan management for vestibular schwannomas (VSs) is an important treatment option, but its role is unclear because of discordance between tumor growth and hearing outcomes. The present study was a retrospective analysis of 97 patients with sporadic VSs without treatment who were followed-up between 2003 and 2012. Tumor volume was measured by 3-dimensional volumetry at each follow-up visit. The median follow-up duration was 47 months (range, 13-122 months). The relationship between the tumor growth rate and hearing outcome was compared according to stratification of the initial tumor volumes. Hearing impairment was related significantly to the initial hearing status (Gardner-Robertson grade ≥2), initial tumor volume (≥0.1 cm³), and tumor growth (≥0.10 cm³/year). During 4 years of follow-up, 26% and 42% of the patients with untreated VS showed rapid tumor growth and hearing impairment, respectively. For tumors with an initial volume of 0.1-3.0 cm³, hearing impairment during the conservative management period was inversely proportional to the tumor volume. Conservative management could be especially valid for small (<0.10 cm³), noncystic VSs in patients with Gardner-Robertson grade 1 at diagnosis. However, for tumors with a small-to-medium initial volume (0.10-3.0 cm³), future hearing impairment might be inversely proportional to tumor growth rate. Therefore, small-to-medium sized tumors should be followed-up more closely regardless of the initial hearing impairment.