Electrically evoked auditory brainstem response: growth of response with current level

Area of Science:

• Audiology
• Biomedical Engineering
• Neuroscience

Background:

• Cochlear implants are vital for hearing restoration.
• Multichannel cochlear implants differ in electrode design and stimulation strategies.
• Understanding electrically evoked brainstem responses (EABR) is crucial for assessing implant function.

Purpose of the Study:

• To compare EABR characteristics between the Ineraid and Nucleus multichannel cochlear implant systems.
• To investigate the influence of different stimulation modes (monopolar vs. bipolar) and electrode spacing on EABR.
• To correlate EABR findings with word recognition performance.

Main Methods:

• EABR was measured in users of Ineraid and Nucleus cochlear implants.
• Stimulation modes included monopolar (Ineraid) and bipolar (Nucleus).
• Varied current levels were used to assess response amplitude and latency.

Main Results:

• ABR waveforms were similar across both implant groups.
• Both devices showed increased amplitude and decreased latency with higher current levels.
• Nucleus implants exhibited higher thresholds and more gradual amplitude growth compared to Ineraid implants under normal stimulation.
• Bipolar stimulation with closely spaced electrodes resulted in higher thresholds and slower amplitude growth for both implant types.

Conclusions:

• EABR thresholds and amplitude growth are influenced by cochlear implant design and stimulation parameters.
• Electrode configuration, particularly spacing in bipolar stimulation, plays a significant role in EABR characteristics.
• EABR results did not strongly correlate with word recognition scores in this study.