title: Tuning of the ocular vestibular evoked myogenic potential (oVEMP) to air- and bone-conducted sound stimulation in superior canal dehiscence.
abstract: Recent studies have demonstrated the frequency selectivity of air-conducted (AC) and bone-conducted (BC) stimuli in eliciting ocular vestibular evoked myogenic potentials (oVEMPs). In this study, frequency tuning of the oVEMP was assessed in patients with superior canal dehiscence (SCD) and compared with responses previously reported for healthy subjects. Six (five unilateral) SCD patients were stimulated using AC sound (50-1,200 Hz) and BC transmastoid vibration (50-1,000 Hz). Stimuli were delivered at two standardized intensities: one the same as previously used for healthy controls and the other at 10 dB above vestibular threshold (a similar relative intensity to that used in controls). For AC stimulation, SCD patients had larger oVEMP amplitudes across all frequencies tested for both stimulus intensities. Normalized tuning curves demonstrated greater high-frequency responses with the stronger stimulus. For BC stimulation, larger oVEMP amplitudes were produced at frequencies at and above 100 Hz using standard intensity stimuli. For the matched intensity above vestibular threshold, enhancement of the oVEMP response was present in SCD patients for 500-800 Hz only. We conclude that SCD causes greater facilitation for AC than BC stimuli. The high-frequency response is likely to originate from the superior (anterior) canal and is consistent with models of inner ear changes occurring in SCD.
authors.affiliation: Prince of Wales Clinical School, University of New South Wales, Randwick, Sydney, NSW, 2031, Australia.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Zhang
authors.forename: Sendhil
authors.initials: S
authors.lastname: Govender
authors.forename: James G
authors.initials: JG
authors.lastname: Colebatch
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D001844:Bone Conduction / Q000502:physiology*; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D007759:Labyrinth Diseases / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012665:Semicircular Canals / Q000503:physiopathology*; D012684:Sensory Thresholds; D058585:Vestibular Evoked Myogenic Potentials / Q000502:physiology*; D014724:Vestibular Function Tests; D055815:Young Adult