Intralabyrinthine Schwannoma: Distinct Features for Differential Diagnosis

Abstract

Objectives: The aim of this study was to delineate the clinical and laboratory features suggestive of intralabyrinthine schwannoma (ILS). Methods: We compared the clinical features of 16 patients with ILS, who had been diagnosed at the Seoul National University Bundang Hospital from 2003 to 2018, with those of 18 patients with symptomatic unilateral intracanalicular schwannoma and randomly selected 20 patients with definite or probable unilateral Meniere's disease (MD). Results: Patients with ILS presented with either recurrent spontaneous dizziness/vertigo combined with auditory symptoms ( n = 8), isolated auditory symptoms without dizziness/vertigo ( n = 7), or recurrent spontaneous dizziness/vertigo without auditory symptoms ( n = 1). Most patients reported no improvement ( n = 11) or worsening ( n = 1) of the symptoms despite medical treatments including intratympanic ( n = 5) or intravenous steroids ( n = 2). Conventional brain MRIs failed to detect ILS in about a half of the patients (7/16, 44%). However, ILS showed a filling defect on 3-dimensional (3D) heavily T2-weighted MRIs ( n = 12), and nodular enhancement on 3D contrast-enhanced T1 ( n = 15) or FLAIR MRIs ( n = 13) targeted for the inner ear. Compared to MD or intracanalicular schwannoma, ILS showed mostly abnormal head-impulse tests (HITs, p = 0.001). In contrast, the incidence of canal paresis did not differ among the groups ( p = 0.513). Conclusion: ILS may mimic MD by presenting recurrent dizziness/vertigo and auditory symptoms. ILS should be suspected in patients with recurrent audiovestibulopathy especially when (1) the duration of the dizziness is not typical for MD, (2) the patients do not respond to medical treatments, or (3) HITs are abnormal.

Challenges of Cochlear Implantation in Intralabyrinthine Schwannoma Patients: Surgical Procedures and Auditory Outcome

“…A recently published study [29] describes 20 ILS cases, and in each of them, hearing loss was reported on the affected ear. In contrast, Lee et al [30] suggested that the most common symptom of ILS is dizziness/vertigo combined with auditory symptoms, followed by isolated hearing loss. The discrepancies between Lee's observations of ILS first symptoms and all other groups could likely reflect the patient recruitment procedure.…”

Cervical and Ocular Vestibular-Evoked Myogenic Potentials in Patients With Intracochlear Schwannomas

“…Only a few studies reported VEMP results in patients with intralabyrinthine schwannoma (ILS) and mostly described absent or decreased cVEMPs and/or oVEMPs in these patients (6,11,12). The exact tumor localization and description of VEMP results in patients with solely intracochlear schwannomas (ICS) was done by Dubernard et al (6) for 12 patients.…”

“…However, only few data are available on VEMPs in patients with an ILS. Lee et al (11) described absent or decreased cVEMPs and oVEMPs in patients with ILS without specifying the exact tumor location. Ralli et al (12) reported an absent oVEMP in a patient with an intravestibular ILS with presence of "a solid mass in the utricle" confirmed by magnetic resonance imaging (MRI).…”

Teaching Video NeuroImages: Intralabyrinthine schwannoma masquerading as Ménière disease

“…Intralabyrinthine schwannoma is a rare and underrecognized cause of recurrent audiovestibulopathy, masquerading as Ménière disease. 1 High-resolution MRIs allow antemortem diagnosis, 2 and labyrinthectomy may be attempted when refractory with medication. 1 This study followed the tenets of the Declaration of Helsinki and was performed according to the guidelines of the institutional review board of Seoul National University Bundang Hospital (1902/523-109).…”