Individual Hearing Preservation Cochlear Implantation Using the Concept of Partial Insertion.

OBJECTIVE: Aim of this study was to evaluate the method of partial insertion of flexible lateral wall electrodes in patients with residual hearing and potential electric-acoustic stimulation (EAS) users.

PATIENTS AND INTERVENTION: N = 6 patients with a high-frequency hearing loss were treated with a partial insertion using atraumatic lateral wall electrodes. In three cases, a electrode of 24 mm length was inserted with the aim to achieve a 16 mm insertion depth and in three cases a electrode of 28 mm length to achieve a 20 mm insertion depth.

MAIN OUTCOME MEASURE: Differences between the pre- and postoperative unaided air-conducted pure tone thresholds in low frequencies (125 Hz-1.5 kHz) were analyzed. Freiburg monosyllables (FBM) at 65 dB and Hochmair-Desoyer sentence test in noise (10 dB SNR) were performed. The pre- and postoperative cochlea images were analyzed.

RESULTS: Residual hearing could be preserved in all patients (n = 6) and is stable up to 6 months follow-up. All patients could use EAS with an average speech understanding score of 65% in monosyllables (FBM) and 76% in sentences in noise. All patients benefit significantly compared to the preoperative best aided situation.

CONCLUSION: First results of patients treated with partially inserted atraumatic lateral wall electrodes show good hearing preservation rates and very good speech perception results in EAS. Partial insertion appears to be a method for an individualized cochlea implantation. In case of postoperative hearing loss the electrode can be further inserted, so the patients can benefit from deeper insertion using electric stimulation only equivalent to larger electrodes.