Auditory brainstem implant: electrophysiologic responses and subject perception

Area of Science:

• Neuroscience
• Biomedical Engineering
• Audiology

Background:

• Auditory Brainstem Implants (ABIs) bypass the cochlea to directly stimulate the auditory brainstem.
• Understanding the relationship between electrical stimulation parameters, evoked responses, and patient perception is crucial for optimizing ABI function.

Purpose of the Study:

• To compare perceptual sensations from bipolar auditory brainstem implant (ABI) electrode stimulation with electrically evoked response morphology.
• To examine the relationship between bipolar and monopolar stimulation sensations.
• To correlate evoked potential morphology with monopolar stimulation sensations.

Main Methods:

• Recorded early and middle-latency auditory evoked responses to bipolar stimulation in four ABI patients.
• Categorized perceptual sensations (auditory, mixed, side effect, none) for bipolar and monopolar stimulation.
• Compared evoked response morphology (e.g., P3 wave, eMLR) with categorized sensations.

Main Results:

• Auditory or mixed sensations from bipolar stimulation correlated with the presence of P3 waves in electrically evoked auditory brainstem responses (eABR) and electrical early middle-latency responses (eMLR).
• Non-auditory sensations were not consistently distinguished by other eABR waves.
• Monopolar stimulation sensations also showed correlations with the presence of P3 and eMLR when compared to bipolar-elicited evoked potentials.

Conclusions:

• ABI electrodes eliciting auditory sensations via bipolar stimulation are more likely to produce evoked responses with P3 or middle-latency waves.
• The absence of auditory sensation from either electrode in a bipolar pair during monopolar stimulation reduces the likelihood of P3 and eMLR presence.