A prospective study of hearing preservation in untreated vestibular schwannomas

The authors previously published a systematic review of the English language literature regarding the natural history of untreated vestibular schwannomas (VSs). This analysis found that the best predictor of future hearing loss was tumor growth > 2.5 mm/year on serial imaging, a factor that doubled the rate of hearing loss. In this paper the authors present an analysis of prospectively collected outcomes in patients with untreated VS from their institution that confirms their previous findings.

Clinical, radiographic, and audiometric data for all patients evaluated for VS at the authors' institution over a 22-year period were prospectively collected in a database. All patients in this database who had serviceable hearing (American Academy of Otolaryngology-Head and Neck Surgery Grade A or B) on initial presentation were selected, and underwent serial observation. Magnetic resonance imaging and audiometric data were analyzed, and the time from presentation until hearing loss was analyzed using Kaplan-Meier analysis.

Fifty-nine patients with VS who initially presented with serviceable hearing were treated conservatively over this period. Consistent with the authors' previous findings, patients with a tumor growth rate > 2.5 mm/year at any point during follow-up lost their hearing at a much faster rate than those who had slower growing tumors. The median time to hearing loss was 7.0 years in those patients with tumor growth rate > 2.5 mm/year compared to 14.8 years in the other patients (p < 0.0001). The estimated median time to hearing loss in the 3 initial tumor size groups was 11.6 years in the intracanalicular group, 10.3 years in the group with 0.1-1 cm extension into the CPA cistern, and 9.3 years in the group with > 1 cm extension into the CPA cistern (p value nonsignificant). Initial tumor size, age at diagnosis, and neurofibromatosis Type 2 status did not affect the time to loss of serviceable hearing. Interestingly, many patients who were followed up for more than a decade eventually lost their hearing, regardless of whether the tumor displayed any documented interval growth.

The authors confirmed the findings of their systematic review of the literature using a prospectively followed group of patients with untreated VS. Collectively, these data suggest that the expectation for more rapid hearing loss should be communicated to patients, and the decision for surgical or other intervention should be made in the context of the known risk of continued observation of fast growing tumors.