Electrically evoked stapedial reflex threshold assessment among malaysian cochlear implant users: Comparisons between different stimulus rates

Abstract

Background and Objective: Cochlear implant (CI) mapping can be carried out using subjective or objective assessments. Electrically evoked stapedial reflex threshold (ESRT) measurement is one of the valuable objective assessments to establish appropriate CI maps. As such, more research efforts are required to determine the most optimum recording protocols when recording ESRT. In the present study, the effect of stimulus rate on ESRT among CI users was determined. It was also of interest to know which stimulus rate would produce the optimum correlation with the behavioral most comfortable level (MCL) results. Materials and Methods: In this study that employed a repeated measures design, 12 Malaysian CI users were enrolled (mean age = 22.3 ± 13.3 years, ranging from 14 to 51 years). MCL and ESRT (measured in charge units, qu) were measured for three representative electrodes (electrode 2, electrode 6, and electrode 11) using 1000 pps and 2000 pps rates. Results: ESRT was 100% recordable for electrodes 2 and 6. For electrode 2, the mean ESRT values were 20.5 qu and 20.4 qu for 1000 pps and 2000 pps, respectively. While for electrode 6, the mean ESRT was 25.4 qu for 1000 pps and 25.7 for 2000 pps. Excellent correlations were found between ESRT and MCL for both stimulus rates (intraclass correlation ≥0.90). Conclusion: Both stimulus rates were found to produce comparably good ESRT results. Since ESRT and MCL values were highly correlated with each other, the objective ESRT testing can be used conveniently to predict the behavioral MCL, particularly among difficult-to-test patients.