Relation between cortical auditory evoked potentials and behavioral auditory discrimination in cochlear implant children

Abstract

Abstract Background Cochlear implants (CI) can partially or totally revert the effects of sensory deprivation; thus enabling the development of auditory abilities. However, there remains a large amount of variability in speech perception outcome among CI users. Such variability may be attributed to the children’s diverse capabilities in detecting amplitude, temporal and spectral changes in the incoming complex speech signals in quiet and in difficult listening situations. Objective To study whether the newly introduced Acoustic Change Complex (ACC) cortical potential using short duration can be used to document such variability. If used as a tool for cortical discrimination, it will aid in evaluating young children who cannot be tested using behavioral measures. Patients and Methods Cortical auditory evoked potentials were recorded in forty five unilaterally-implanted children ranging in age from 6 to 12 years. Stimuli used to elicit ACC were short duration (500 msec.) speech and tonal stimuli. Spectral change was done using /i/ to /u/ vowels, while temporal change was done using variable gaps-in-1000 Hz tone, ranging from 5 msec. to 200 msec. Auditory evoked responses were compared to behavioral tests which included speech perception test (PBKG) and psychophysical test for temporal resolution. Results ACC potentials were successfully recorded in most of the children evaluated. Generally, ACC were significantly highly detected in temporal changes than spectral change. Individual data showed that poor behavioral performance was associated with higher ACC detection thresholds to gap in tone and poorer % detection to vowel change. Conclusion: ACC potential using short duration stimuli can be recorded in young implanted children in an ordinary clinical setting. However, more research is needed to document the complex behavioral-objective relationship and its ultimate link to speech perception and language development in young CI recipients.