Investigating the Effect of Blurring and Focusing Current in Cochlear Implant Users with the Panoramic ECAP Method

Area of Science:

• Neuroscience
• Biomedical Engineering
• Audiology

Background:

• Cochlear implants (CIs) use electrical stimulation to restore hearing.
• Optimizing CI performance involves controlling electrical current spread and neural responsiveness.
• Panoramic ECAP (PECAP) offers a method to assess these parameters along the CI electrode array.

Purpose of the Study:

• To investigate how electrical current "sharpening" (partial tripolar stimulation) and "blurring" (simultaneous multi-electrode stimulation) affect current spread and neural responsiveness.
• To evaluate the utility of PECAP in estimating these stimulation effects.

Main Methods:

• PECAP measurements were taken in 12 Advanced Bionics CI users at their most comfortable listening levels.
• Stimulation modes included standard, partial tripolar (pTP), and simultaneous multi-electrode ("blurred") stimulation.
• Current spread and neural responsiveness were estimated along the CI electrode array using PECAP data.

Main Results:

• Blurred stimulation consistently increased estimated current spread towards the cochlear apex.
• Partial tripolar stimulation showed variable effects on current spread, with a small group-level increase observed in some participants.
• PECAP successfully detected localized changes in current spread.

Conclusions:

• Simultaneous multi-electrode stimulation effectively increases current spread toward the cochlear apex, as detected by PECAP.
• Partial tripolar stimulation's effect on current spread is inconsistent.
• These findings align with speech perception data and offer insights for improving CI programming and device design.