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

Abstract

Indications for cochlear implantation have expanded today to include very young children and those with syndromes/multiple handicaps. Programming the implant based on behavioral responses may be tedious for audiologists in such cases, wherein matching an effective MAP and appropriate MAP becomes the key issue in the habilitation program. In 'Difficult to MAP' scenarios, objective measures become paramount to predict optimal current levels to be set in the MAP. We aimed, (a) to study the trends in multi-modal electrophysiological tests and behavioral responses sequentially over the first year of implant use, (b) to generate normative data from the above, (c) to correlate the multi-modal electrophysiological thresholds levels with behavioral comfort levels, and (d) to create predictive formulae for deriving optimal comfort levels (if unknown), using linear and multiple regression analysis. This prospective study included ten profoundly hearing impaired children aged between 2 and 7 years with normal inner ear anatomy and no additional handicaps. They received the Advanced Bionics HiRes 90K Implant with Harmony Speech processor and used HiRes-P with Fidelity 120 strategy. They underwent, Impedance Telemetry, Neural Response Imaging, Electrically Evoked Stapedial Response Telemetry and Electrically Evoked Auditory Brainstem Response tests at 1, 4, 8 and 12 months of implant use, in conjunction with behavioral Mapping. Trends in electrophysiological and behavioral responses were analyzed using paired t test. By Karl Pearson's correlation method, electrode-wise correlations were derived for NRI thresholds versus Most Comfortable Levels (M-Levels) and offset based (apical, mid-array and basal array) correlations for EABR and ESRT thresholds versus M-Levels were calculated over time. These were used to derive predictive formulae by linear and multiple regression analysis. Such statistically predicted M-Levels were compared with the behaviorally recorded M-Levels among the cohort, using Cronbach's Alpha Reliability test method for confirming the efficacy of this method. NRI, ESRT and EABR thresholds showed statistically significant positive correlations with behavioral M-Levels, which improved with implant use over time. These correlations were used to derive predicted M-Levels using regression analysis. Such predicted M-Levels were found to be in proximity to the actual behavioral M-Levels recorded among this cohort and proved to be statistically reliable. When clinically applied, this method was found to be successful among subjects of our study group. Although there existed disparities of a few clinical units, between the actual and predicted comfort levels among the subjects, this statistical method was able to provide a working MAP, close to the behavioral MAP used by these children. The results help to infer that behavioral measurements are mandatory to program cochlear implantees, but in cases where they are difficult to obtain, this study method may be used as reference for obtaining additional inputs, i...

Effect of Cochlear Implant Electrode Array Design on Electrophysiological and Psychophysical Measures: Lateral Wall versus Perimodiolar Types

“…Clinical studies in human CI users have been also conducted on electrophysiological and behavior measurements. The electrically evoked compound action potential (ECAP) has been widely used as a valuable objective tool in mapping the CI, especially for those who have difficulty in showing the reliable behavioral response [12]. Whereas some studies reported that the ECAP threshold, T level, and C level were lower for the PM than the LW, and were lower on the apical region than on the basal and medial regions [13-15], other studies showed different results [16,17].…”

Utilidad de mediciones objetivas para la programación en implantes cocleares

“…Uno de los problemas principales en la realización del ePEATC en pacientes pediátricos es la cooperación ya que este examen requiere de más tiempo 11 . Aun con estas limitaciones, el ePEATC puede ser de gran utilidad en casos de mapas erróneos que han sido pasados por alto con mediciones de ECAP o del eREE 6 , en casos de disfunción/ disincronía de la vía auditiva 11,20 , o en casos en los cuales no fue posible detectar un ECAP 19 . Es decir, casos para los cuales la programación puede ser más dificultosa.…”

“…Para los pacientes pediátricos de menor edad (i.e. lenguaje limitado, experiencia inadecuada con el sonido y no pueden dar respuestas conductuales confiables), y los pacientes con dificultades para proporcionar una retroalimentación adecuada, la programación del implante puede ser más dificultosa 6 . Una buena programación del implante es crucial y se realiza de forma individualizada, esto permite que el paciente implantado pueda: -Detectar y discriminar los sonidos de la voz humana en relación al lenguaje oral, -lograr niveles de audición óptimos, -evitar experiencias desagradables que propicien el rechazo del implante, y -evitar una percepción acústica alterada que impacte el desarrollo del lenguaje oral 7 .…”

Correlation between Preoperative Auditory Steady-State Response and Postoperative Electrically Evoked Auditory Brainstem Response and T Level in Cochlear Implantation for Child Patients with Inner-Ear Malformations

“…With origins of waves similar to those in ABR, EABR can theoretically reflect the functional state of the auditory pathway in the acoustic nerve of the brainstem, and it has a high extraction rate. Furthermore, as the objective indicator of audiometry, the EABR threshold can be used to assess the efficacy of implantation [20][21][22][23]. The cerebral cortex is involved in testing the subjective threshold (T-level values).…”