Growth Patterns of Small Intracanalicular Vestibular Schwannomas

Objective: Describe the natural history of small intrameatal vestibular schwannomas. Study design: Retrospective case series. Setting: Tertiary referral center. Patients: Patients diagnosed with small (5 mm or less) intrameatal vestibular schwannoma with at least 3-year surveillance magnetic resonance imaging studies. Intervention(s): Observational study. Main outcome measure(s): Tumor growth and conversion from active surveillance to surgical or radiotherapy treatment during observation. Results: Of the 74 patients identified, 36% (n=27/74) of tumors grew over a median surveillance time of 79 months (IQR: 71). Twelve percent (n=9/74) of cases with small intrameatal vestibular schwannomas who entered a period of active imaging surveillance went on to receive surgical or radiotherapy treatment at a median time of 77 (IQR: 30) months post-diagnosis. Conclusions: The findings support an ongoing recommendation for small intrameatal vestibular schwannomas to be followed with the same magnetic resonance imaging protocols as larger tumors.