# Stimulating the cochlear apex without longer electrodes

> **NIH NIH R21** · NEW YORK UNIVERSITY SCHOOL OF MEDICINE · 2022 · $211,875

## Abstract

PROJECT SUMMARY
 Cochlear implant (CI) electrode arrays are only partially inserted into the cochlea, in most cases leaving
more than half of the cochlea unstimulated. In the normal hearing ear, the cochlear region left unstimulated by
most CIs represents frequencies below approximately 800Hz. Providing electrical stimulation to a broader
region of the cochlea with a CI has the potential to enhance performance. For example, increasing apical
coverage has been shown to improve speech perception and accelerate CI patients’ adaptation to their device.
These benefits may be due to representation of low-frequency information closer to the normal cochlear place.
Furthermore, stimulation deeper than one cochlear turn may provide better perception of temporal information
and better sound quality. However, using longer electrode arrays to access deep apical regions has several
disadvantages. First, because the scala tympani diameter decreases with increasing cochlear depth, the
likelihood of an incomplete insertion increases with electrode array length. Second, if deeper insertion is
achieved, the probability of damage to cochlear structures increases as the walls of the cochlear duct become
closer to the electrode. Third, even the longest electrodes only stimulate ~70% of the cochlear length.
 To address these shortcomings, we developed a novel approach to stimulate the cochlear apex
without increasing the electrode array length. Moreover, our approach uses existing FDA-approved
CIs, speech processors, and commercial fitting software without modification. In Cochlear CI devices,
two extra-cochlear electrodes (ECEs) are used for grounds: ECE1 (usually placed under the temporalis
muscle) and ECE2 (located on the implant case). In the novel approach, ECE1 is placed into the cochlear
helicotrema via an apical cochleostomy and the electrode array is inserted from the basal end of the cochlea
through a traditional cochleostomy. When an electrode from the array is grounded to ECE1 in the cochlear
helicotrema, the electric field is driven towards the cochlear apex, stimulating residual neural tissue at sites
deeper than available with the standard configuration of electrode arrays and ground electrodes. Using ECE2
as the ground provides monopolar stimulation, which is the clinical standard. Thus far, we have successfully
implanted three patients using this novel surgical approach and implemented novel signal processing
using the ECE1 electrode. All reported a lower pitch when using ECE1 instead of ECE2 as a ground.
 This new approach provides a unique opportunity to answer important scientific questions and to
evaluate a new clinical intervention. It provides the first opportunity to directly stimulate the cochlear
helicotrema (apex) in humans. We can now study if such stimulation improves temporal coding (Aim 1) and
extends the tonotopic pitch range (Aim 2). Additionally, we can study if the intervention improves clinical
outcomes (Aim 3). We propose to implant...

## Key facts

- **NIH application ID:** 10461862
- **Project number:** 5R21DC019743-02
- **Recipient organization:** NEW YORK UNIVERSITY SCHOOL OF MEDICINE
- **Principal Investigator:** David M Landsberger
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $211,875
- **Award type:** 5
- **Project period:** 2021-08-04 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10461862

## Citation

> US National Institutes of Health, RePORTER application 10461862, Stimulating the cochlear apex without longer electrodes (5R21DC019743-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10461862. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*