Journal article
A Longitudinal Study of Electrode Impedance, the Electrically Evoked Compound Action Potential, and Behavioral Measures in Nucleus 24 Cochlear Implant Users
Ear and hearing, Vol.22(6), pp.471-486
12/2001
DOI: 10.1097/00003446-200112000-00004
PMID: 11770670
Abstract
OBJECTIVEThe primary goal of this study was to examine changes that may occur in electrode impedance, electrically evoked compound action potential (EAP) threshold and slope of the EAP growth function, and behavioral measures of threshold (MAP T-level) and maximum comfort (C-level) over time in both adult and child cochlear implant users. Secondary goals were to determine whether changes in these measures are consistent between children and adults, and to determine whether behavioral measures (MAP T- and C-levels) and electrophysiologic measures (EAP thresholds) exhibit the same trends over time.
DESIGNThirty-five children and 33 adults implanted with the Nucleus CI24M between November 1996 and August 1999 participated in this study. Subjects were included in this study if 1) they had used their implant for at least 1 yr after device connection, and 2) they had participated in the necessary data collection at a minimum number of the time intervals assessed in this study. EAP threshold, slope of the EAP growth function, and common ground electrode impedance measures were collected intraoperatively, at initial stimulation, and at several subsequent visits up to 2 yr post initial stimulation. MAP T- and C-levels were measured at initial stimulation and at the same time intervals as described above.
RESULTSChanges in electrode impedance, EAP thresholds, and slope of the EAP growth function from measures made intraoperatively, at initial stimulation, and at 1 to 2 mo post initial stimulation were similar in both children and adults. Beyond the 1- to 2-mo visit, children exhibited significant increases in electrode impedance, EAP thresholds, slope, and MAP T-levels, whereas these same measures in adults remained relatively stable. EAP thresholds in children stabilized by the 3- to 8-mo visit, and electrode impedance stabilized by the 6- to 8-mo visit, while slope of the EAP growth function, MAP T-levels, and MAP C-levels were stable by 1 yr post initial stimulation. C-levels in adults increased up to 1 yr post initial stimulation; however, the amount of increase was much smaller than that seen in children. In both children and adults, longitudinal trends in EAP thresholds mirrored T-level more closely than C-level.
CONCLUSIONSThe results of this study suggest that peripheral changes occur in many children that do not generally occur in adults within the first year of cochlear implant use. One implication of these results is that if EAP thresholds are to be used to assist in programming the speech processor for children, it is best to make those measures at the same time interval as device programming rather than using measures made intraoperatively or at the initial programming session to set MAP levels at later visits.
Details
- Title: Subtitle
- A Longitudinal Study of Electrode Impedance, the Electrically Evoked Compound Action Potential, and Behavioral Measures in Nucleus 24 Cochlear Implant Users
- Creators
- Michelle Hughes - Department of Otolaryngology–Head & Neck Surgery (M.L.H., C.J.B., P.J.A., D.M.R.K., H.F.B.T., M.W.L.), and Department of Speech Pathology & Audiology (K.R.V.W., C.J.B., P.J.A.), University of Iowa, Iowa City, IowaKathy Vander WerffCarolyn BrownPaul AbbasDanielle KelsayHolly TeagleMary Lowder
- Resource Type
- Journal article
- Publication Details
- Ear and hearing, Vol.22(6), pp.471-486
- Publisher
- Lippincott Williams & Wilkins, Inc
- DOI
- 10.1097/00003446-200112000-00004
- PMID
- 11770670
- ISSN
- 0196-0202
- eISSN
- 1538-4667
- Language
- English
- Date published
- 12/2001
- Academic Unit
- Communication Sciences and Disorders; Otolaryngology
- Record Identifier
- 9984002340902771
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