Intracanalicular Vestibular Schwannomas: Initial Clinical Manifestation, Imaging Classification, and Risk Stratification for Management Proposal

Introduction: There is no consensus about the use of observation as a therapeutic modality for intracanalicular vestibular schwannoma (ICVS). The objective of this study was to describe tumor evolution, its correlation with initial size, stage of vestibular schwannoma, clinical presentation and to propose a risk classification for tumor growth with a therapeutic decision algorithm.

Methods: Fifty-three patients with ICVS were followed prospectively from 2010 to 2015. The mean follow-up was 32 months. Patients underwent clinical examination, audiogram, magnetic resonance imaging at 6, 12, and then 12 months intervals within the first 5 years of initial diagnosis. We analyzed the patient's clinical course, audiologic changes, initial tumor location, and correlation of different parameters with ICVS growth.

Results: Fourteen patients (26%) deteriorated their hearing level and 17 patients (27%) showed tumor growth during the follow-up period. Growth was noted during the first year of observation in 13 patients (76.5%). Considering initial presentation: tumor size, intracanalicular staging, and hearing level, patients with larger vestibular schwannoma, extension to the fundus regardless of tumor size, higher initial pure-tone average, and speech recognition test showed a significantly higher rate of tumor growth. ICVS evolution was not correlated with hearing deterioration with time.

Discussion: We should consider observation a therapeutic modality. We valid the intrameatal staging as prognostic factor and propose a stratification of patients into low, moderate, or high risk for potential tumor growth to guide the initial management of ICVS.