Sally M Rosengren1, James G Colebatch. 1. UNSW Clinical School, Prince of Wales Medical Research Institute, Randwick, Sydney, NSW 2031, Australia.
Abstract
OBJECTIVE: To confirm the exclusive vestibular dependence of the evoked potentials (P10 and N15) recorded in normal subjects, by recording the potentials evoked in response to bone-conducted sound stimulation in patients with bilateral hearing loss. METHODS: Fourteen patients with severe to profound bilateral hearing loss were stimulated via a B71 bone-vibrator above the mastoid with bone-conducted tone bursts (500 Hz, 6 ms) at fixed levels above their individual vestibular evoked myogenic potential (VEMP) thresholds. Surface potentials were recorded from scalp electrodes at F7, F3, Fpz, F4, F8, T3, Cz, and T4 and referred to linked earlobes. RESULTS: Seven of 14 patients had suitable VEMPs to the maximal stimulus. P10 and N15 potentials were present in each of these 7 patients, but were absent in patients with absent VEMP responses. The potentials were only detected above VEMP threshold, and were similar in size, shape and latency to those recorded in normal controls at a matched intensity above VEMP threshold. CONCLUSIONS: Normal P10 and N15 potentials can be recorded from patients with profound bilateral hearing loss using bone-conducted acoustic stimulation of the vestibular apparatus. SIGNIFICANCE: The P10 and N15 appear to be dependent purely upon vestibular activation.
OBJECTIVE: To confirm the exclusive vestibular dependence of the evoked potentials (P10 and N15) recorded in normal subjects, by recording the potentials evoked in response to bone-conducted sound stimulation in patients with bilateral hearing loss. METHODS: Fourteen patients with severe to profound bilateral hearing loss were stimulated via a B71 bone-vibrator above the mastoid with bone-conducted tone bursts (500 Hz, 6 ms) at fixed levels above their individual vestibular evoked myogenic potential (VEMP) thresholds. Surface potentials were recorded from scalp electrodes at F7, F3, Fpz, F4, F8, T3, Cz, and T4 and referred to linked earlobes. RESULTS: Seven of 14 patients had suitable VEMPs to the maximal stimulus. P10 and N15 potentials were present in each of these 7 patients, but were absent in patients with absent VEMP responses. The potentials were only detected above VEMP threshold, and were similar in size, shape and latency to those recorded in normal controls at a matched intensity above VEMP threshold. CONCLUSIONS: Normal P10 and N15 potentials can be recorded from patients with profound bilateral hearing loss using bone-conducted acoustic stimulation of the vestibular apparatus. SIGNIFICANCE: The P10 and N15 appear to be dependent purely upon vestibular activation.
Authors: Robin T Bigelow; Yevgeniy R Semenov; Eric Anson; Sascha du Lac; Luigi Ferrucci; Yuri Agrawal Journal: J Assoc Res Otolaryngol Date: 2016-07-22