Long-term follow-up of hearing preservation in electric-acoustic stimulation patients.

Background: Hearing preservation (HP) surgery was initiated more than 10 years ago for combined electric and acoustic stimulation (EAS). Preserved residual low-frequency hearing has been demonstrated to improve speech perception in noise as well as music appreciation in EAS users up to 2 years. Multiple study groups aimed to evaluate initial loss of residual hearing (RH) as a consequence of HP surgery. However, after 1 year and 2 years of follow-up, further decline was reported. This study aimed to determine RH, speech perception, and the subjective benefits of EAS 10 years after HP surgery.

Subjects And Methods: Nine postlingual EAS partially deaf patients who underwent HP surgery at Antwerp University Hospital were included in this study (11 implanted ears). Hearing preservation (0% = loss of hearing; >0%-25% = minimal HP; >25%-75% = partial HP; >75% = complete HP), speech perception and subjective benefits were evaluated preoperatively; at 3, 6, 12, 18, and 24 months postoperatively; and annually thereafter.

Results: Complete HP was obtained in three of 11 ears; partial HP in five of 11 ears; and minimal HP in two of 11 ears, measured during their most recent follow-up. One subject lost his RH completely across time. The mean rate of HP was 48% (ranging from 6 months up to 10 years postoperatively). Speech perception analysis up to 10 years showed a continuous statistically significant improvement. The maximum subjective benefit was reached 3 months after implantation and subsequently remained statistically significant unchanged for the next 10 years.

Conclusion: Long-term HP in EAS users after HP surgery is feasible, although a small continuous decline of HP rate of 3% per year was observed (measured from first fitting up to 6 years postoperative). Nevertheless, a continuous improvement was found in the speech perception results of the EAS users across 10 years. Moreover, the positive subjective benefit, assessed 3 months postoperative, remained stable up to 10 years.