gms | German Medical Science

Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

Diagnosing Implant Failures with the Nucleus Integrity Test System

Meeting Abstract

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  • corresponding author H. Mauch - Cochlear AG, Basel, Switzerland
  • C. Möller - Cochlear AG, Basel, Switzerland
  • B. Nevison - Cochlear Europe Ltd, Wimbledon, United Kingdom

Medical University of Hannover, Department of Otolaryngology. Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants. Hannover, 01.-04.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05omci073

The electronic version of this article is the complete one and can be found online at:

Published: May 31, 2005

© 2005 Mauch et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.




Any implant failure is a major event for the recipient and for the parents of young recipients. Cochlear has a track record of exceptional device reliability that shows continuous improvement over design generations. Current Cumulative Survival percentages for the Nucleus CI24R are 99.7% in adults and 99.0% in children after 4.5 years of implant use.

Materials and Methods

In case of a suspected failure objective testing is used to investigate if the implant is no longer functioning according to specification. The recipient is connected to the Nucleus ‘Crystal’ Integrity Test System, which allows to stimulate the implant with a known pulse pattern and to record the surface potential representation of the stimulus artifacts. A battery of tests is conducted to collect information about the implant’s telemetry function, stimulus morphology, stimulus continuity, loudness growth, pulse width variation, transmission range and stimulus mode. A biphasic stimulus artifact and specified amplitude growth needs to be observed during all measurements to confirm that there is no intermittent or unspecified output from the implant, and that all electrodes are functioning appropriately.


The implant test data obtained since the introduction of the Integrity Test System in the year 2000 has shown a high sensitivity to detect failure conditions. After the explantation of any faulty device, the root cause of failure is determined by exhaustive laboratory testing and the results of this analysis are compared with the symptoms and the results of the vivo testing.


The experience of the explanted device analysis to date with respect to the in vivo integrity test results will be discussed in order to demonstrate the test sensitivity but also to determine the limitations and potential improvements for the current test system.