Objective Measures of Electrode Discrimination With Electrically Evoked Auditory Change Complex and Speech-Perception Abilities in Children With Auditory Neuropathy Spectrum Disorder

Abstract

Objective: This study aimed to 1) determine the sensitivity of the electrically evoked auditory change complex (eACC) to changes in stimulating electrode position; and 2) investigate the association between results of eACC measures and behavioral electrode discrimination and their association with speech-perception performance in pediatric cochlear implant (CI) users who have auditory neuropathy spectrum disorder (ANSD). Design: Fifteen children with ANSD ranging in age between 5.4 and 18.6 yrs participated in this study. All subjects used Cochlear Nucleus devices. For each subject, open-set speech perception ability was assessed using the Phonetically Balanced Kindergarten (PBK) word lists presented at 60 dB SPL using monitored live voice in a sound booth. Behavioral and objective measures of electrode discrimination were made in a non-clinical test environment. The stimuli used to elicit these measures were 800-ms biphasic pulse trains delivered by a direct interface to the cochlear implant. Data were collected from two basic stimulation conditions. In the standard condition, the entire pulse train was delivered to a mid-array electrode (electrode 11 or 12) at the maximum comfortable level (C level). In the change condition, the stimulus was split into two 400-ms pulse train segments presented sequentially on two different electrodes. The stimulation level of the second 400-ms pulse train was loudness balanced to the C level of the mid-array electrode used in the standard condition. The separation between the pair of stimulating electrodes was systematically varied. For behavioral electrode discrimination measures, each subject was required to determine whether they heard one or two sounds for stimuli presented in different stimulation conditions. For the eACC measures, two replicates of 100 artifact-free sweeps were recorded for each stimulation condition. Results: The eACC in response to changes in stimulating electrode position was recorded from all subjects with ANSD using direct electrical stimulation. Electrode discrimination thresholds determined with the eACC and behavioral measures were consistent. Children with ANSD using cochlear implants who showed poorer speech performance also required larger separations between the stimulating electrode pair to reliably elicit the eACC than subjects with better speech-perception performance. There was a robust correlation between electrode discrimination capacities and speech-perception performances in subjects tested in this study. The effect of electrode separation on eACC amplitudes was not monotonic. Conclusions: These results demonstrate the feasibility of using the eACC to evaluate electrode discrimination capacities in children with ANSD. These results suggest that the eACC elicited by changes in stimulating electrode position holds great promise as an objective tool for evaluating spectral pattern detection in this population, which may be predictive of their potential speech-perception performance.

Development of electrophysiological and behavioural measures of electrode discrimination in adult cochlear implant users

“…The second is the spatial auditory change complex (ACC) -this is a cortical potential in response to a change in stimulating electrode during a continuous stimulus. Whilst both the spatial ACC and the MMN have been used to measure electrode discrimination (Brown et al, 2008;He et al, 2014;Wable et al, 2000), there is evidence to suggest that the ACC is a more sensitive marker of peripheral discrimination (Martin and Boothroyd, 1999).…”

“…It may be that the spatial ACC is a more strongly correlated with speech perception in experienced CI users in whom the the full potential for discrimination has been achieved. Indeed, He et al (2014) found that the EDL measured around a mid-array electrode with the spatial ACC was associated with speech perception when categorized as 'good' or 'poor'. Of note, most of the participants in their study had several years of CI experience.…”

Acoustically Evoked Auditory Change Complex in Children With Auditory Neuropathy Spectrum Disorder

“…Despite an absent or abnormal ABR, the auditory event-related potentials (ERPs), including the onset response and the auditory change complex (ACC), can often be recorded from patients with ANSD (Demitrijevic et al, 2011; Kraus et al, 2000; He et al, 2013a, 2013b; Michalewski et al, 2005, 2009; Narne & Vanaja, 2008; Pearce et al, 2007; Rance et al, 2002; Sharma et al, 2011; Starr et al, 1996). These two responses are cortically generated potentials that can be recorded from surface electrodes placed on the scalp.…”

The effect of development on cortical auditory evoked potentials in normal hearing listeners and cochlear implant users

“…They reported that the PBK word scores are correlated with the behavioral electrode-discrimination thresholds (r = -0.96), with good performers having significantly larger EACC than poor performers (p < 0.05). While these two studies (He et al, 2014) showed a broad range of variance in response morphologies of EACC in CI children with ANSD, authors did not discuss the changes in the EACC with age in this population. Martinez et al (2013) recorded ACCs in children with NH (n=5) and bilateral SNHL (n=5) aged from 2 to 6 years.…”

“…In the following study, He et al (2014) measured EACC in 15 CI children (between 5 and 17 years at the time of testing) who were diagnosed with ANSD, using the same method and stimuli. This time they presented the same biphasic pulses presented to the electrode 12 for 400 mses but then changed the second electrode, varying from electrode 13 to electrode 22.…”