Primary inner ear schwannomas: a case series and systematic review of the literature

Abstract

Objectives/hypothesis: To describe the natural history of primary inner ear schwannomas (PIES) and evaluate management outcomes and relationship between PIES location, clinical presentation, and time to diagnosis.

Study design: Retrospective chart review and systematic review of the literature.

Methods: Vestibular schwannoma confined to or arising from the inner ear were included. PIES classification was based on anatomic subsite(s) involved. Detailed clinical history and outcomes were recorded.

Results: In a systematic review (1933-2011), including 14 patients from the authors' institution (1999-2009), a total of 72 studies comprising 234 patients were evaluated. Mean follow-up was 32.8 ± 39.1 months (range, 0-183 months). The cochlea was the most commonly involved subsite (51%). Hearing loss was the most frequent presenting symptom (99%). Vertigo and abnormal balance were more common among tumors involving the vestibular system (P < .01). Average delay between symptom onset and diagnosis was 7.0 ± 8.0 years (median, 5 years; range, 0-40 years). Recent onset hearing loss was more likely to elicit an earlier diagnosis (P = .01). The majority of patients were observed without treatment (53%). Tumor progression was seen in 52% of patients.

Conclusions: PIES are rare tumors and most commonly involve the cochlea. Tumor location is often associated with clinical presentation and correlates with delay between symptom onset and diagnosis. A watch-and-scan approach is the management strategy of choice in the absence of intractable vertigo or extensive tumor growth. The majority of patients report stable or improved symptoms over time, regardless of treatment.

Keywords: Intralabyrinthine schwannoma; acoustic neuroma; delay to diagnosis; hearing loss; magnetic resonance imaging; primary inner ear schwannoma; tinnitus; vertigo; vestibular schwannoma.