Evaluation of factors that influence cochlear implant performance

Abstract

Background One of the primary goals of cochlear implantation is open-set auditory-only speech understanding in everyday listening environments. An understanding of the etiology and neurocognitive factors that contribute to a favorable outcome after cochlear implantation would potentially allow clinicians to predict the results for a cochlear implant patient. The ability to discriminate small acoustic differences is very important for the perception and processing of speech signals. The mismatch negativity (MMN) method is an objective tool that provides a measure of automatic stimuli discrimination. Objective of the study The aim of this study was to classify the communicative performance of children with cochlear implants and verify this outcome by means of electrophysiological biomarkers. Methods The study was carried out in three phases: phase I included completing an audiological data information sheet for all patients, with data taken from their records, which included demographic data, preoperative and postoperative audiological evaluation, operative detailed information, cochlear implant mapping data, and preoperative auditory verbal therapy details as regards regularity and benefit. Phase II involved classifying the patients’ communicative performance according to a phoniatric evaluation protocol into poor, fair, and good response, determining behavioral pure tone aided thresholds with their cochlear implants, and conducting electrophysiological studies ‘P1 and MMN’ for those with aided thresholds in the long-term average speech spectrum with their cochlear implant. Phase III entailed verification of factors that affect the outcome of all cochlear implant users. Results Age of cochlear implantation, cause of hearing loss, comorbidity, preoperative electrophysiological test results, and radiological findings are variables affecting cochlear implant performance and affecting the patient's communicative performance, whereas sex of the patient and number of stimulated electrodes are variables not affecting the cochlear implant performance. Conclusion Early cochlear implantation and good auditory verbal therapy have better outcomes as regards listening and communication skills. Cortical auditory evoked potential (P1) and MMN might provide a clinical tool to monitor aural rehabilitation outcome. These objective electrophysiological parameters may also be used as prognostic indicators for speech and language outcome.