Audiological Outcomes in Growing Vestibular Schwannomas Managed either Conservatively, or with Stereotactic Radiosurgery

Introduction: Management strategies for patients with vestibular schwannomas include ‘watchful waiting’, stereotactic radiosurgery (STRS) or microsurgery. Traditionally, treatment with STRS has been considered a significant risk to hearing. However, recent studies have suggested good hearing preservation following STRS, particularly in those with functional hearing (Gardner-Robertson class I-II) prior to treatment. This study aims to assess audiological outcomes in patients with growing acoustic neuromas treated either with STRS, or managed conservatively.

Methodology: A retrospective cohort study was conducted in 69 patients with growing vestibular schwannomas, treated either conservatively (n = 24) or with STRS (n = 45). Vestibular schwannomas were considered growing if they demonstrated >15% increase in tumor volume during one year of watchful waiting. Serial pure tone audiograms (PTA) were classified according to Gardner-Robertson criteria and average audiological thresholds were obtained according to American Association of Otolaryngology – Head and Neck Surgery (AAOHNS) guidelines. AAOHNS threshold deterioration and Gardner-Robertson class deterioration were utilized as the primary outcome measures. Rate of progression to loss of functional hearing (Gardner-Robertson class I-II) was also determined between cohorts.

Results: Mean length of follow up was similar in STRS and conservatively managed patients (69.6 and 71.7 months, respectively). There was no significant difference in AAOHNS deterioration (t = 1.05, df = 53, p = 0.301) or Gardner-Robertson deterioration (χ ² = 0.47, df = 1, p = 0.492) between STRS and conservatively managed patients. Furthermore, rate of progression to loss of functional hearing was also similar between cohorts (HR = 0.704, 95% CI: 0.287–1.728, p = 0.44).

In STRS patients, AAOHNS deterioration was significantly greater in those patients with lower AAOHNS thresholds at diagnosis (t = −2.683, df = 28, p = 0.0121). Similarly, Gardner-Robertson deterioration was significantly more likely in STRS patients with functional hearing (Gardner-Robertson class I–II) (Adj. OR = 32.14, 95% CI: 3.15–328, p = 0.0034).

Conclusion: Stereotactic radiosurgery for vestibular schwannomas results in similar audiological outcomes compared with patients managed conservatively. Furthermore, hearing loss does not seem to be accelerated by the use of STRS. However, in contrast to recent studies, patients with preserved hearing at diagnosis have significantly greater audiological deterioration when undergoing STRS.