AN UNUSUAL CAUSE OF COCHLEAR IMPLANT FAILURE

We present a cochlear implant failure previously unidentified and unre ported. Following successful implantation and activation of a Cochlear Mini 22 system, a distressing barrage of crackling noises was heard b y 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 mea sured wave forms. Investigation of the explant, following reimplantati on with an identical system, showed a defective trim capacitor, an ele ctric component of the internal circuit in the stimulator. Paired Stud ent's t-test showed a marginally significant increase (p = 0.047) in e ffective threshold level and a highly significant decrease (p = 0.0002 ) in maximum comfort level for the second implant compared to the firs t implant.