THE RELATION BETWEEN ELECTRIC AUDITORY BRAIN-STEM AND COGNITIVE RESPONSES AND SPEECH-PERCEPTION IN COCHLEAR IMPLANT USERS

Electrically evoked brainstem responses (EABR) and event-related corti cal potentials were recorded in seven postlingually deaf adults who we re experienced users of a Nucleus multichannel cochlear implant. The p atients were divided into two subgroups: good performers and moderate performers. Poor EABR were found in two of the moderate performers. Th e latencies and amplitudes of the cortical N1-P2 complex in the good p erformers were within the same range as those of subjects with normal hearing, but were deviant in the group of moderate performers. This ma y indicate disturbed cochleotopical organization of the auditory corte x in the latter group. P300 measurements in the good performers showed normal latencies, whereas in the moderate performers they were prolon ged. The results suggest that the outcomes of electrophysiological mea surements to assess the integrity of a patient's auditory neural syste m on a brainstem and. a cortical level, are related to the patient's p erformance with the cochlear implant.