Differentiating intralabyrinthine schwannoma from perilymphatic fistula

Abstract

Objectives: Intralabyrinthine schwannoma (ILS) is rare, with fewer than 60 cases reported in the literature. Historically, ILS has been diagnosed during total labyrinthectomy for intractable vertigo, but increasing use of MRI for assessment of hearing loss and vertigo has substantially increased detection rates of ILS at early stages. Despite nonspecific audiovestibular symptoms, ILS is associated with rapidly progressive hearing loss and vertiginous complaints and is often confused with Meniere’s disease, or less commonly, perilymphatic fistula. The differentiation between ILS and other neurotologic disorders is essential, as the treatment of each is distinct. The work-up and treatment of intralabyrinthine schwannoma will be discussed, with particular attention to differentiating ILS from perilymphatic fistula. Methods: A retrospective case review at a tertiary medical center. Results: We present 2 patients with histologically confirmed diagnoses of ILS. Both patients presented with unilateral sensorineural hearing loss and vestibulopathy. Their vestibular symptoms were characterized by early periods of recurrent vertigo attacks followed by later stage of chronic imbalance. Both patients experienced transient dizziness when positive pressure was applied to the ipsilateral ear. MRI scan revealed enhancing lesions in the vestibule consistent with ILS. The patients underwent a transmastoid labyrinthectomies for tumor removal, and their vestibular symptoms improved postoperatively. Conclusion: Although the audiovestibular presentations of ILS are nonspecific, their clinical features can mimic those of labyrinthine fistulas. MRI scan is required to rule out ILS in patients with fistula-like symptoms in order to facilitate and expedite appropriate treatment.