Electrophysiological Detection of Scalar-Changing Perimodiolar Cochlear Electrode Arrays: A Six-Month Follow-Up Study

The position of the cochlear electrode array within the scala tympani is essential for optimal hearing benefit. An intraoperative neural response telemetry ratio (NRT ratio; a threshold ratio of pairs of apical and basal electrodes) has been established, which can provide information about the intracochlear electrode array position. Out of a previous collective of 85 patients, the 6-month follow-up electrophysiological NRT data of 37 patients have been included in this study. Comparing the intraoperatively estimated NRT ratio with the 6-month follow-up NRT ratio, it remained unchanged intraindividually in 92% of cases. Within this group the NRT ratio and the intracochlear position of the electrode array matched in all cases. There were two newly occurring mismatches and one new match was observed. After a period of 6 months the NRT ratio remained unchanged in most cases and showed a good correlation with the intracochlear position of the electrode array.