Optimizing the efficiency of ECAP measurements due to interpolation

ABSTRACT:

Background

Thresholds of electrically evoked compound action potentials (TECAP) may serve as starting points for electrophysiologically based fitting of cochlear implants. Absent TECAP data at single electrodes reduces the number of data points available for fitting and can be substituted by interpolation of measured data points.

Aim

To compare complete TECAP profiles with interpolated TECAP profiles of 5/22 (∼22.7%) and 11/22 (50%) electrode contacts.

Material and methods

Single-centre, retrospective, observational study of data from 624 ears implanted with a Slim Modiolar (CI ×32) or Contour Advance (CI ×12, CI24RE(CA)) electrode array (Cochlear Ltd). The deviation of the complete measured TECAP profile from the same profile with missing and therefore interpolated TECAP values was quantified.

Results

Interpolated TECAP profiles significantly differ from complete measured profiles especially at the basal and apical electrodes. Reference data for Slim Modiolar and Contour Advance electrodes mean profiles are provided.

Conclusions and significance

Reducing the number of measured TECAP electrodes has to be weighted against losses in the TECAP accuracy of interpolated values. A clinically acceptable compromise may be a reduction from 22 to 11 even non-equidistant data points. While reducing ECAP measurement time, it is accompanied by a minimal loss of accuracy of the TECAP threshold profile.

Chinese Abstract

背景：电诱发复合动作电位 (TECAP) 的阈值可作为基于电生理学的人工耳蜗植入的起始点。 单电极TECAP 数据的缺乏减少了可用于拟合的数据点的数量, 这可以通过对所测数据点进行插值来代替。

目的：将完整的 TECAP 概况与 5/22 (∼22.7%) 和 11/22 (50%) 电极触点的插值 TECAP 概况进行比较。

材料和方法：对 624只植入Slim Modiolar (CI ×32) 或Contour Advance (CI ×12, CI24RE (CA)) 电极阵列 (Cochlear Ltd)的耳朵的信息进行单中心、回顾性、观察性研究。将完整测量的 TECAP 概况和缺失的而因此插值的 TECAP 值的相同概况之间的偏差进行量化。

结果：插值 TECAP 概况与完整测量概况显著不同, 尤其是在基底电极和顶端电极。 提供了Slim Modiolar 和 Contour Advance 电极平均概况的参考数据。

结论及意义：减少被测TECAP电极的数量需考虑插值 TECAP 精度的减少。 临床上可接受的折衷方案可能是, 将非等距数据点从 22 个减少到 11 个。 在减少ECAP测量时间的同时, 伴有 TECAP 阈值概况精度的最低损失。

Keywords:

• Cochlear implant
• eCAP
• electrically evoked compound action potential
• TECAP
• interpolation

Acknowledgments

Our special thanks go to Martin Olesch for managing the data export.

Disclosure statement

No potential conflict of interest was reported by the author(s).