Comparisons between Neural Response Imaging thresholds, electrically evoked auditory reflex thresholds and most comfortable loudness levels in CII Bionic Ear users with HiResolution™ sound processing strategies

Abstract

For 8 patients (53 stimulating electrodes) the correlation between tNRI threshold and M level was r=0.675 (p=0.000) and that between first NRI thresholds and M level was r=0.741 (p=0.000). On average the M-level value was 20 CU (Current Unit) lower than the first NRI threshold value and 12 CU higher than the tNRI threshold value. The M-level patterns across the electrode array overall were similar to the tNRI or first NRI threshold patterns. For 7 patients (112 stimulating electrodes) the correlation between EART and M levels was r=0.710 (p=0.000). On average the EART value was 14 CU higher than the M-level value.

Effects of stimulus manipulation on electrophysiological responses of pediatric cochlear implant users. Part II: Rate effects

“…Electrically evoked electrophysiological measures to single pulses tend to occur at higher levels than behavioral thresholds to pulse trains, falling closer to the most comfortably loud level (Gordon et al, 2004). Indeed, responses from the auditory nerve and brainstem can be as much as 40 current units above behavioral measures Gordon et al, 2004;Han et al, 2005;Cafarelli Dees et al, 2005) and alone do not provide sufficiently accurate predictions of behavioral thresholds to use in individual implant users Brown et al, 1999Brown et al, , 2000Gordon et al, 2004).…”

Electrophysiological Correlates of Behavioral Comfort Levels in Cochlear Implantees: A Prospective Study

“…Investigators have also assessed the efficacy of ESRT in predicting comfort levels for optimal programming and they found ESRT to be of greater predictive value than ECAP for estimation of behavioral comfort levels [8,10,11]. Postoperative ESRT thresholds show high correlations with behaviorally obtained comfort levels and help predict the maximum comfort level pattern across electrodes [8].…”

“…In the past, correction factors proposed to predict threshold and comfort levels from objective measures, were based on the difference between objective thresholds and at least one behavioral measure (Abbas et al [6], Zimmerling and Hochmair [15], Brown and Carolyn [7]). Subsequent literature suggests that correction factors based on ECAP, ESRT and EABR thresholds are needed to predict behavioral levels required for programming in difficult situations (Di Nardo et al [13], Han et al [10], Caner et al [11]). These studies suggested extrapolation of the averaged value calculated by these correction factors, across the array in order to set behavioral levels.…”

“…Electrophysiological measurements are performed at default stimulation parameters that are different from the stimulation rates eventually used during cochlear implant programming. Sensitivity and neural reactions recorded to electrophysiological stimuli are different from the behavioral reactions recorded at higher rates of stimulation, used while programming [9,10,13].…”

“…The higher thresholds for electrophysiological responses at the basal electrodes are due to the physical current distribution; (2) neural preservation and excitability of the nerve fibers and (3) cortical and behavioral reactions to the excitation patterns in the higher auditory pathways as influenced by the age at onset of deafness, cognition, intellect, hearing aid usage and duration of hearing deprivation prior to implantation. All electrophysiological measures like ECAP, EABR and ESRT are the measures of the phenomena occurring at levels 1 and 2, yet take no account of the variability present at level 3 [9,10,13].…”