title: The relationship between electrically evoked compound action potential and speech perception: a study in cochlear implant users with short electrode array.
abstract: OBJECTIVE
  To determine the extent to which electrically evoked compound action potential (ECAP) measurements were related with speech perception performance in implant users with a short electrode array and to investigate the relationship between ECAP measures and performance according to specific devices.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Tertiary referral center.
  
  
  METHODS
  Seventeen Hybrid cochlear implant users were tested in this study. Subjects were divided into 2 groups: 8 using the Nucleus Hybrid M and 9 using the Nucleus Hybrid RE. In addition, 21 Nucleus Freedom long electrode implant (CI24RE) users also were tested to compare with the results of the old device (CI24M).
  
  
  METHODS
  ECAP growth functions were recorded using either an interphase gap (IPG) of 8 or 45 mus. We then calculated the slope of the growth function and changes in sensitivity with IPG. For each subject, these measures were compared with performance on tests of word recognition.
  
  
  RESULTS
  The changes in sensitivity using 2 IPGs showed no correlation with the results of word recognition test in Hybrid cochlear implant users. In contrast, relatively strong correlations have been found between the slope of ECAP growth functions and performance on word recognition test. Additionally, when we separate the results of Hybrid M and RE, the slopes of ECAP growth functions from only Hybrid RE CI recipients were significantly correlated with speech performance. The slopes of ECAP growth function in CI24RE users with long electrode also were significantly correlated with performance. However, comparing between 2 independent correlations in RE devices, correlation was higher in Hybrid RE group.
  
  
  CONCLUSIONS
  The results presented in this article support the view that slope of the ECAP growth can show significant correlation to performance with a cochlear implant. Furthermore, these results suggest that the strength of the correlation may be related to the specific device. These results suggest that ECAP measures may be useful in developing a test to predict outcomes with the implant.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa, U.S.A. jrkim53@hanmail.net
authors.forename: Jae-Ryong
authors.initials: JR
authors.lastname: Kim
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Abbas
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Brown
authors.forename: Christine P
authors.initials: CP
authors.lastname: Etler
authors.forename: Sara
authors.initials: S
authors.lastname: O'Brien
authors.forename: Lee-Suk
authors.initials: LS
authors.lastname: Kim
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D003054:Cochlear Implants; D003638:Deafness / Q000503:physiopathology / Q000628:therapy; D004558:Electric Stimulation; D004566:Electrodes; D004581:Electronics; D004867:Equipment Design; D005260:Female; D006320:Hearing Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013067:Speech Perception / Q000502:physiology*; D013686:Telemetry