Cochlear Implant Device Failure – The Value of Available Objective Diagnostic Tool in Diagnosing a Soft Failure

Introduction: Device failure is the most common cause for revision cochlear implantation (CI). The aim of the study was to compare results of objective diagnostic tool for cochlear implant mal-function (in situ integrity testing) to post re-implantation functional outcomes.
Methods: 63 device failure events occurred in a population of 1113 primary implantations performed between 1998-2016 were reviewed (11 in adults and 52 in children).
Results: In 50% of the soft failure cases (15/32), in situ integrity test failed to reveal abnormal function, while after re-implantation 100% of those who had auditory symptoms improved, pain symptoms improved in 86%, and facial stimulation was solved in 83%. The smallest improvement (77%) was observed in those who were diagnosed with device failure due to a “failure to achieve expected benefit”. Mean interval between CI and re-implantation was 5.38±3.82 years (range, 0.6-13.2) and 4.51±3.35 years (range, 0.7-14.9), for the soft and the hard failures respectively. Mean interval between initial symptoms of what eventually led to the re-implantation in the soft failure group was 1.8±1.9 years between 1998-2003 and 1.4±1.0 years after 2003 (difference was not significant). Number of soft failures had decreased over the years from 1998 to 2016.
Conclusions: In order to replace only failed devices and to shorten the time to re-implantation in cases of suspected device failure, manufacturers should develop more sensitive objective in-situ diagnostic tools for the diagnosis of a device failure.