Assessment of Electrically Evoked Stapedius Reflex Threshold (eSRT) for Auditory Mapping in Pulse Width Modulation...

This study assesses the electrically evoked stapedius reflex threshold (eSRT) as an objective method for generating auditory maps in individuals with pulse-width-modulation cochlear implants (CIs). It investigates the impact of both single- and multiple-electrode stimulations on eSRT detection rates and their association with patients' comfort loudness levels (C-levels). Despite eSRT exploration by several CI brands incorporating pulse-amplitude-modulation stimulation technology, there is a lack of information on systems using pulse-width modulation.

The eSRT was measured in 19 ears ipsilaterally and contralaterally in response to stimulations in groups of 1, 3, and 5 electrodes across five distinct cochlear regions, spanning from apical to basal. For each group, the eSRT detection rate and its correlation with the C-levels were analyzed both regionally and overall.

In both contralateral and ipsilateral sides, higher electrically evoked stapedius reflex (eSR) detection rates were obtained for multielectrode (67%, 47%) than for single-electrode (41%, 23%) stimulation. Invoking eSR in the apical and basal regions was easier than in the middle region. The multiple stimulation just increased slightly the correlation coefficients between eSRT and C-levels from 0.73 to 0.77 and from 0.77 to 0.85 (p < 0.05) for the contralateral and ipsilateral ears, respectively.

Our research indicates that using a multielectrode stimulation approach enhances the detection rate of eSRT and slightly improves the correlation coefficient between eSRT and C-levels. It is found preferable to obtain measurements from the contralateral side due to its higher detection rate, although the ipsilateral side yields a marginally higher correlation coefficient. The findings suggest that eSRTs obtained from pulse width modulation implants could aid audiologists in programming the device.