An unusual cause of cochlear implant failure

We present a cochlear implant failure previously unidentified and unreported. Following successful implantation and activation of a Cochlear Mini 22 system, a distressing barrage of crackling noises was heard by the patient despite repeated programming with threshold and comfort level adjustment. The implant soon became nonfunctional and integrity testing showed deficient electrical responses and abnormal surface measured wave forms. Investigation of the explant, following reimplantation with an identical system, showed a defective trim capacitor, an electric component of the internal circuit in the stimulator. Paired Student's t-test showed a marginally significant increase (p = 0.047) in effective threshold level and a highly significant decrease (p = 0.0002) in maximum comfort level for the second implant compared to the first implant.