The Relationship between Thresholds of Electrically Evoked Compound Action Potential and Speech Perception in Children with Cochlear Implants

Abstract

Background and ObjectivesZZNeuropathology around the cochlea could create variation from site to site in physiological thresholds of cochlear implant users. This variability would be detrimental to speech recognition with a cochlear implant for a variety of reasons, including distortion of the place code and variation in the number of neurons. The purpose of this study is to examine the relationship between thresholds of electrically evoked compound action potential (ECAP) and speech perception in children implanted with the Nucleus Freedom devices. Subjects and MethodZZFifty-seven children implanted with the Nucleus Freedom device participated in this study. ECAP thresholds were recorded using the automated neural response telemetry test protocol. We then calculated mean threshold and three metrics to assess acrosssite variation within subjects: 1) the variance of T levels for all tested sites, 2) the range of T levels (highest minus lowest) across all tested sites and 3) site-to-site variation. For each subject, these measures were compared with performance on tests of word recognition. ResultsZZThere was considerable across-site (within-subject) and across-subject variability in thresholds. However, we found no significant correlation between speech recognition and across-site variation of thresholds as well as mean threshold levels. ConclusionZZThese data suggest that the ECAP measures of thresholds may not be an accurate predictor of speech perception ability. � Korean J Otorhinolaryngol-Head Neck Surg 2011;54:688-92 Key WordsZZCochlear implant ㆍElectrically evoked compound action potential ㆍ Key WordsZZThreshold ㆍSpeech perception.