Cochlear implant device failure: diagnosis and management.

Complete, irreversible failure of the implanted receiver-stimulator of the Cochlear Corporation multichannel implant are relatively rare. However, as the implanted patient population grows, malfunctions may be expected. From the over 200 patients implanted at the University of Michigan Medical Center, 6 patients with a complete and irreversible cochlear implant receiver-stimulator failure have been identified and treated. This represents a 3% failure rate. The amount of time between initial implantation and device failure ranged from 6 months to 3.5 years. Determination of device failure was made using psychophysical, electrophysiologic, and averaged electrode voltage measurements. The measurement of the average electrode voltages proved to be useful in determining the condition of the implant. Physiologic changes causing reduced electrical excitability were ruled out using psychophysical or electrophysiologic promontory testing. All patients were successfully explanted and reimplanted.