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Impedance, Neural Response Telemetry, and Speech Perception Outcomes After Reimplantation of Cochlear Implants in Children

Birman, Catherine S.*†‡∥; Sanli, Halit†‡; Gibson, William P. R.†‡§; Elliott, Elizabeth J.*†

doi: 10.1097/MAO.0000000000000362
Cochlear Implants

Objective To compare mean impedance levels, neural response telemetry (NRT), and auditory perception after initial and explant-reimplant pediatric cochlear implants.

Study Design Retrospective case review.

Setting Tertiary referral hospital and cochlear implant program.

Patients Children 0 to 16 years inclusive who have undergone explant-reimplant of their cochlear implant.

Intervention Impedance levels, NRT, and speech perception performance.

Main Outcome Measures Impedance, NRT, and auditory perception at switch on, 3 months, 12 months, 3 years, and 5 years after initial cochlear implant and reimplantation.

Results The explant-reimplant group receiving Cochlear contour array had significantly (p < 0.001) raised impedance at switch on, 3 months, 12 months, and 3 years, compared with their initial implant. The explant-reimplant group receiving Cochlear straight array had marginally significant (p = 0.045) raised impedance at switch on, 3 months, 12 months, and 3 and 5 years. Infection was associated with greater increases in impedance in the reimplant Contour group. NRT was increased in the explant-reimplant group but not significantly (p = 0.06). Auditory perception returned to preexplant levels within 6 months in 61% of children.

Conclusion Impedance is higher after explant-reimplant and remains increased for years after explant-reimplant with Cochlear contour and to a lesser degree the straight array device.

*Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney; †Sydney Children’s Hospital Network (Children’s Hospital at Westmead); ‡The Sydney Cochlear Implant Centre; §Emeritus Professor, Sydney Medical School, University of Sydney; and ∥Department of Linguistics, Faculty of Human Sciences, Macquarie University, Sydney, New South Wales, Australia

Address correspondence and reprint requests to Catherine S. Birman, M.B.B.S., FRACS, Suite 402, Macquarie University Clinic, 2 Technology Place, Macquarie University, NSW 2109; E-mail:

The authors have no conflict of interest and received no funding for this research.

E. J. E. holds a Practitioner Fellowship from the National Health and Medical Research Council of Australia (No. 1021480).

Copyright © 2014 by Otology & Neurotology, Inc. Image copyright © 2010 Wolters Kluwer Health/Anatomical Chart Company