[Correlation between stimulation levels und ECAP thresholds for audiometry-based fitting of cochlear implants. German version].

Abstract

Background: Persons whose speech recognition with hearing aids at 65 dB_SPL, WRS₆₅(HA), is inadequate but whose maximum monosyllabic word recognition score (WRS_max) is still measurable may benefit from a cochlear implant (CI). Using a validated prediction model, one can estimate word recognition with a CI, WRS₆₅(CI), for these patients. The aim of this study was to investigate the relationship between electrically evoked compound action potentials (ECAP) and stimulation parameters of the CI system.

Patients and methods: In this prospective study, 37 patients were included. The WRS₆₅(CI) was determined after 6 and 12 months and compared with the predicted WRS₆₅(CI). The correlation of minimum and maximum electrical stimulation with the ECAP was investigated.

Results: All patients showed a significantly better WRS₆₅(CI) after 12 months compared with the preoperatively determined WRS₆₅(HA). The proportion of patients whose WRS₆₅(CI) fell short of the predicted value by more than 20 percentage points was 19% after 6 months and 5% after 12 months. In the patient population, there was a closer correlation of the ECAP thresholds with the maximum than with the minimum electrical stimulation.

Conclusion: For patients whose speech understanding with hearing aids is inadequate-even with a very high preoperative WRS_max in moderately severe hearing loss-CI fitting appears to be a promising treatment option. The predictive model enables individual treatment planning. Its application contributed to a quality of care that was higher than was found in an earlier retrospective study. The correlation found between stimulation intensity and ECAP in a cohort of patients with achieved predicted values supports the hypothesis that a fitting procedure based on ECAP and audiometry is a promising approach.