Use of electrophysiologic measures in the management of children with cochlear implants: brainstem, middle latency, and cognitive (P300) responses.

The introduction of evoked potential techniques into standard clinical practice has revolutionized the early detection and diagnosis of hearing impairment in infants and young children. Therefore, it should come as no surprise that the same expectations exist relative to the evaluation of the electrical stimulability of the auditory system in the youngest cochlear implant patient population. At this time, special problems related to the recording of electrophysiologic responses evoked by electrical stimulation, such as response contamination by the stimulus artifact and the recognition of stimulus spread to other than the target system, still await resolution. Ideally, one would like to be able to determine preoperatively the extent and pattern of neural survival. One would also like to be able to use electrophysiologic measures to monitor implanted stimulability and as an aid to processor calibration, programming, rehabilitation, and training. The electric ABR (EABR) may be used in both pre- and postoperative applications in children to determine stimulability and implant stability. The electric MLR (EMLR), used successfully in adults and animal models, in not a suitable response in young children, due to maturational considerations. Cognitive endogenous evoked potentials (P300) have been used successfully postoperatively with adults in this laboratory and are currently being investigated in implanted children. This paper discusses current applications of electrically evoked auditory potentials in our cochlear implant program.