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

Laura Fröhlich; Ian S Curthoys; Sabrina Kösling; Dominik Obrist; Torsten Rahne; Stefan K Plontke

doi:10.3389/fneur.2020.549817

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

Front Neurol. 2020 Oct 27:11:549817. doi: 10.3389/fneur.2020.549817. eCollection 2020.

Authors

Laura Fröhlich¹, Ian S Curthoys², Sabrina Kösling³, Dominik Obrist⁴, Torsten Rahne¹, Stefan K Plontke¹

Affiliations

¹ Department of Otorhinolaryngology, Head and Neck Surgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
² Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW, Australia.
³ Department of Radiology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
⁴ ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.

Abstract

Objective: To evaluate ocular and cervical vestibular evoked myogenic potentials (oVEMPs and cVEMPs) in patients with solely intracochlear localization of an intralabyrinthine schwannoma (ILS). Study Design: Retrospective analysis of a series of cases. Setting: Monocentric study at a tertiary referral center. Patients: Patients with intracochlear schwannoma (ICS) and VEMP measurements. Outcome Measures: Signed asymmetry ratio (AR) of cVEMPs and oVEMPs to air conducted sound with AR cut-offs considered to be asymmetrical when exceeding ±30% for cVEMPs and ±40% for oVEMPs with respect to the side affected by the tumor (reduced amplitudes on the affected side indicated by negative values, enhanced amplitudes by positive values); VEMP amplitudes and latencies; tumor localization in the cochlear turn and scala. Results: Nineteen patients with a solely intracochlear tumor (ICS patients) [10 males, 9 females, mean age 57.1 (SD: 13.4) years] were included in the study. On the affected side, cVEMPs were absent or reduced in 47% of the patients, normal in 32%, and enhanced in 21%. Ocular VEMPs on the affected side were absent or reduced in 53% of the patients, normal in 32% and enhanced in 15%. Latencies for cVEMPs and oVEMPs were not significantly different between the affected and non-affected side. In all patients with enhanced VEMPs, the tumor was located in the scala tympani and scala vestibuli. Conclusions: As a new and unexpected finding, VEMP amplitudes can be enhanced in patients with intracochlear schwannoma, mimicking the third window syndrome.

Keywords: VEMP; asymmetry; intracochlear; intralabyrinthine; secondary hydrops; semicircular canal dehiscence; third window; vestibular schwannoma.