Histopathologic Markers of Hearing Loss in Intralabyrinthine Schwannomas: Implications for Management

Objective: This study aimed to review the clinical history and management of patients with intralabyrinthine schwannomas and evaluate the histopathologic features of these tumors. Study Design: A retrospective case review of 24 patients and 7 temporal bone specimens. Setting: An otologic tertiary referral private practice. Patients: Patients with magnetic resonance imaging-confirmed intralabyrinthine schwannoma diagnosed after 1995 and non-Neurofibromatosis type 2 temporal bone specimens with schwannomas confined to the bony labyrinth. Main Outcome Measures: Clinical data including history, imaging and audiometry were evaluated. The histopathologic features of temporal bone specimens including tumor location and degenerative changes were analyzed. Results: The intralabyrinthine location of the tumor does not predict the degree or time to progression of hearing loss. Both sensorineural and conductive hearing loss can occur. Mechanisms of hearing loss include hair cell, spiral ganglion, and stria vascularis degeneration in addition to mechanical obstruction. Conclusion: Hearing loss is the most common symptom with intralabyrinthine schwannomas. Histopathology reveals that multiple mechanisms of degeneration may occur within the labyrinth to induce hearing loss. Observation provides the most reliable hearing preservation strategy.