Effect of Cochlear Implant Electrode Array Design on Electrophysiological and Psychophysical Measures: Lateral Wall versus Perimodiolar Types

ABSTRACT

BACKGROUND AND OBJECTIVES: The present study aims to investigate whether the cochlear implant electrode array design affects the electrophysiological and psychophysical measures. SUBJECTS AND METHODS: Eighty five ears were used as data in this retrospective study. They were divided into two groups by the electrode array design: lateral wall type (LW) and perimodiolar type (PM). The electrode site was divided into three regions (basal, medial, apical). The evoked compound action potential (ECAP) threshold, T level, C level, dynamic range (DR), and aided air conduction threshold were measured. RESULTS: The ECAP threshold was lower for the PM than for the LW, and decreased as the electrode site was closer to the apical region. The T level was lower for the PM than for the LW, and was lower on the apical region than on the other regions. The C level on the basal region was lower for the PM than for the LW whereas the C level was lower on the apical region than on the other regions. The DRs on the apical region was greater for the PM than for the LW whereas the DR was narrower on the apical region than on the other regions. The aided air conduction threshold was not different for the electrode design and frequency. CONCLUSIONS: The current study would support the advantages of the PM over the LW in that the PM had the lower current level and greater DR, which could result in more localized neural stimulation and reduced power consumption.