Factors Influencing Cortical Auditory Evoked Potentials in Cochlear Implantees

Abstract

Introduction: Cortical auditory evoked potentials (CAEPs) are a non-invasive tool that can provide objective information on the functioning of the auditory pathways. In our study, we study CAEP parameters like P1 latency, amplitude and morphology as tools of measure of auditory cortical maturation after electrical stimulation following cochlear implantation and compare the values in children implanted below 3 years (yrs) of age and between 3-6 years of age. Furthermore, in our study, we also recorded Category of Auditory Perception (CAP) and Speech Intelligibility Ratio (SIR) scores for subjectively assessing post-implantation outcomes and correlated the values with CAEP parameters. The results of our study are discussed. Materials and methods: 64 congenitally deaf children were enrolled for the study. They were divided into 2 groups (A-below 3 yrs of age and B-between 3 and 6 yrs). Observation and results: CAEP latency at 3 months, group 1 showed statistically significant difference when compared with group B. At 6 months post implantation there is no statistically significant mean difference between group 1 and 2 in SIR score whereas other variables were found to be significant. However at 12 months, the P1 latency alone was comparable in both groups indicating that intensive post implantation auditory-verbal habilitation plays significant newlinerole in both groups. Multiple logistic regression test was done to assess how well the model fitted the data. It resulted in a non significant value, which is an indication of a model that predicts the population fairly well. Conclusion: Overall CAEP P1 latency, amplitude, CAP and SIR scores in cochlear implantees show significant improvement following implantation and values improve with increased use of the implant, thus indicating ongoing cortical maturation. The earlier the implantation, the earlier the maturation of auditory cortex and stress on intensive auditory-verbal habilitation after implantation must be appropriately explained to the care-givers / parents.