Article
Electrophysiologic Measures of Binaural Interaction in Bilateral Cochlear Implant Recipients
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Published: | May 31, 2005 |
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Outline
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Introduction
One of the goals of our laboratory is to examine the utility of electrically evoked potentials to study the effects of bilateral compared to unilateral cochlear implant function. The purpose of this study was to investigate electric binaural interaction by measuring brainstem and cortically evoked auditory potentials in subjects who have received bilateral cochlear implants.
Materials and Methods
Subjects were bilateral cochlear implant (CI) recipients. Electrophysiologic measures included the auditory brainstem response (ABR) and cortical N1-P2 complex elicited with electric stimulation. Auditory evoked potential measures were examined for monaural (right ear, left ear) and binaural conditions. The binaural interactions were assessed within the evoked-potential measures and between subjects. A normal hearing (NH) control group was also studied with acoustic stimulation.
Results
Latency and amplitude measures suggest that binaural interaction occurs at several time periods following the onset of the stimulus for both bilateral CI subjects and NH controls. In some CI subjects, ABR latencies are shorter for binaural stimulation compared to those for monaural stimulation of either ear. In addition, measures of amplitude are smaller in the binaural condition compared to the sum of the monaural conditions. CI subjects demonstrate greater binaural interaction compared to NH controls.
Conclusions
Binaural interaction is present in subjects with bilaterally implanted devices and can be assessed via electrically evoked auditory potentials. Binaural interaction measures that extend from the brainstem to the cortex will be discussed.