How are intra- and postoperatively determined thresholds of objective measures comparable in cochlear implant patients

During and after cochlear implantation objective measures such as electrically evoked stapedial reflexes (ESRT) and electrically evoked compound action potentials (ECAP) are performed. Studies show that e.g. ECAP thresholds differ intra- and postoperatively. Given these differences, it's still debated in which way ESRTs and ECAPs may be used for fitting of cochlear implants (CI), which is especially important for children and patients who cannot communicate their perception.

For this retrospective data analysis we compared intra- and postoperative ESRTs and ECAP thresholds as well as electrode impedances (264 adults, 47 children, MED-EL, Cochlear). The postop measurements were derived during the initial fitting phase. Main question is whether one can infer postop ESRTs from intraop ESRTs by correlating individually matched intra- and postop thresholds in order to use also intraop ESRTs for CI adjustments e.g. in children. For further analysis only data sets with intra- and postop data pairs were selected in order to match intra- and postop values at individual electrode contact level.

Mean impedances are postoperatively 1.7  ± 3.0 kOhm (MED-EL) and 0.8  ± 3.0 kOhm (Cochlear) higher than intraoperatively. Mean ECAP thresholds and ESRTs are intraoperatively 3.2  ± 3.4 nC and 4.3  ± 5.6 nC, respectively, (MED-EL) or 2.2  ± 3.0 nC and 2.6  ± 5.8 nC, respectively, (Cochlear) higher than postoperatively. However, intraop ECAPs and ESRTs are not generally higher than postop thresholds but depend significantly on the level of the intraop threshold, meaning that differences between intra- and postop thresholds are larger for higher intraop thresholds (p<0.001, r²=0.49) and smaller for lower intraop thresholds with an intercept at around 17 nC for ESRTs.

Publikationsverlauf

Artikel online veröffentlicht:
24. Mai 2022