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Intralabyrinthine Schwannomas Mimic Cochleovestibular Disease: Symptoms From Tumor Mass Effect in the Labyrinth

Objective To describe symptoms from intralabyrinthine schwannomas specific from more common vestibular schwannomas of the internal auditory canal or cerebellopontine angle resulting from mass effect from the tumor within the labyrinth. Patients Eight patients diagnosed as having intralabyrinthine schwannomas from 2000 to 2014 were examined retrospectively from two tertiary neurotologic centers. Interventions Diagnosis of intralabyrinthine schwannoma was made with gadolinium-enhanced magnetic resonance imaging scans. Heavily T2-weighted sequences were used to verify mass within the fluid-filled labyrinth. Patients then underwent audiometric and vestibular testing when appropriate. Treatment consisted of observation or surgical resection. Main Outcome Measures Clinical symptoms, magnetic resonance imaging scans, audiometric and videonystagmography data, and operative findings were reviewed. Results Five of the eight patients had positional vertigo or nystagmus on testing. One patient’s only complaint was positional vertigo without auditory symptoms. Three of the patients demonstrated mixed hearing loss. Two patients underwent resection of their tumors, one because of tumor growth and the other because of intractable vertigo. Conclusion These data show that a high proportion within our series displayed symptoms of positional vertigo and mixed hearing loss, which are symptoms not typical of nonintralabyrinthine schwannomas. One patient’s only reported symptom was positional vertigo. These symptoms may arise from the effect of the tumor’s mass exerted on the cochlear and vestibular end organs.