Electrode failure and device failure in adult cochlear implantation

To determine the prevalence of cochlear implant electrode failure and the relationship with overall device failure.

Electrode status was analyzed in 322 functioning and in-use devices from 366 adult cochlear implant patients currently followed at our center. An additional 21 devices that had been explanted were also analyzed. Electrode failure was defined as unacceptably high impedance alone or in combination with aberrant percepts.

At least one electrode had been turned off in 173 devices (54%). Most deactivated electrodes were the basal-most and had been turned off to improve sound quality. Of 437 deactivated electrodes, 33 were considered to have failed and were represented in 22 devices. These 22 devices are still in use (mean: 43.0 ± 29.8 months) without further electrode failures or device failure. There were no statistically significant differences in electrode failure rates among device manufacturers. There were 21 devices explanted of which 10 were due to device failure. One of five hard failures and two of three soft failures had deactivated electrodes prior to explantation. Two failures had no electrode data available.

An inherent risk of cochlear implantation, as with all implanted electrical prostheses, is device failure. Failure of individual electrodes has been postulated to represent an early indicator of impending device failure. Our data demonstrate that electrode failure does not necessarily predict impending device failure. Although maps containing deactivated electrodes are fairly common, electrode failure as a reason for bypassing an electrode is rare and is often manageable with programming.