Effect of age, electrode array, and time on cochlear implant impedances

Abstract

Objectives: To determine the impact of age, electrode array, and time on impedance patterns in cochlear implant (CI) patients.

Methods: A retrospective case review was performed on 98 patients implanted with the CI24RE perimodiolar (PM) and CI422 lateral wall (LW) arrays between 2010 and 2014 to assess impedances at the 1 week and 3–6 month visit after initial stimulation (IS).

Results: With respect to age, impedances were higher in young patients compared to older patients in the middle and apical turns. With time, there were significant reductions in impedances across most electrodes. Electrode array type also had a significant impact on impedance measurements with PM and LW arrays having higher impedances in the basal turn and apical turns, respectively. Furthermore, PM arrays demonstrated significantly lower impedances in the middle and apical turn with time, when compared to LW arrays.

Conclusions: Age, electrode array, and time can independently affect CI impedances. Moreover, we show that PM arrays may be advantageous to LW arrays, due to demonstrated lower impedances in the middle and apical turns long term. Understanding the impact of impedance on speech discrimination and determining the intracochlear processes that contribute to differences in impedance are future research directions.

Keywords:

• CI
• Cochlear Implantation
• Electrode Array
• Impedance
• Age
• Fibrosis
• Cochlea
• Electrode Design

Notes on contributors

Sandra Velandia, Au.D. is an audiologist, assistant professor and the Director of Operations of the Audiology Department at the Ear Institute. UHealth University of Miami Health System.

Diane Martinez, Au.D. is a senior audiologist and assistant professor at UHealth University of Miami Health System.

Stefania Goncalves, M.D. is a resident and research track fellow in Otolaryngology at the University of Miami Health Systems.

Stefanie Pena, M.S. is a medical student at the University of Miami Miller School of Medicine.

Esperanza Bas, Ph.D. is a research assistant professor in Otolaryngology at Uhealth University of Miami Health System.

Liliana Ein, M.D. is a resident in Otolaryngology at the University of Miami Health Systems.

Sandra Prentiss, Ph.D. is a clinical research audiologist and assistant professor at UHealth.

Fred Telischi, M.D. is the James R. Chandler Chairman, Department of Otolaryngolgy.

Simon Angeli, M.D. is the Director of the Uhealth Ear Institute.

Christine T. Dinh, M.D. is an asssitant professor and the Ear Institute Director of Education at the University of Miami Health System.