title: ABR amplitude and dispersion variables. Relation to audiogram shape and click polarity.
abstract: ABR amplitude behaviour to condensation (C) and rarefaction (R) clicks was investigated in normal ears, ears affected by Ménière's disease and ears with high-frequency hearing loss (HF ears). The wave IV-V amplitude-intensity function was steeper in ABRs evoked by R than by C clicks. This may suggest that two different cochlear generator components, one intensity-dependent as well as one polarity-dependent, contribute to click-evoked ABRs. Wave IV-V amplitude was significantly higher in Ménière ears compared to HF ears in spite of comparable 2-4 kHz hearing loss in the two groups. Hence, audiometric steepness (which is lower in Ménière ears than in HF ears) seems to predict the wave IV-V amplitude decline more precisely than the 2-4 kHz perception threshold. The wave IV-V dispersion variable (SR IV-V) was close to normal in Ménière ears, while wave IV-V was more dispersed in HF ears. In general, C click ABRs were less affected than R click ABRs by 'peripheral' factors (i.e. intensity and audiometric steepness).
authors.affiliation: Department of Neurology, University Hospital of Trondheim, Norway.
authors.forename: T
authors.initials: T
authors.lastname: Sand
authors.forename: C
authors.initials: C
authors.lastname: Saunte
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001299:Audiometry; D001309:Auditory Threshold; D007758:Ear, Inner / Q000503:physiopathology*; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D006316:Hearing Loss, High-Frequency / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000150:complications / Q000503:physiopathology*; D008875:Middle Aged