Standard Cochlear Implantation of Adults With Residual Low-Frequency Hearing: Implications for Combined Electro-Acoustic Stimulation

Objective: This study compared preoperative and postoperative cochlear implant benefit in subjects with steeply sloping high-frequency hearing losses (HLs) who were implanted with standard long cochlear implant electrodes to: 1) determine the effect of etiology, 2) compare outcomes in studies exploring the use of combined electrical and acoustic stimulation, and 3) compare outcomes in patients implanted using standard criteria. Study Design: Retrospective case review. Setting: Tertiary referral center. Patients: Nine adults with steeply sloping high-frequency congenital (n = 2) or acquired (n = 7) bilateral sensorineural HL. All pure-tone audiograms fit the criteria for trials of a short electrode aimed at preserving low-frequency acoustic hearing. Intervention: Subjects received full insertion of a standard cochlear implant long electrode in the poorer ear. Main Outcome Measures: Preoperative versus postoperative audiograms, word and sentence recognition in quiet and noise. Results: Patients with progressive acquired HLs experienced significantly improved speech understanding in quiet and in noise with the cochlear implant, especially when combined with hearing aid use in the contralateral ear. Patients with congenital HLs experienced little or no improvement in the implanted ear when tested with the implant alone, but achieved some benefit when the implant was combined with a hearing aid in the nonimplanted ear. Conclusion: Based on this small sample, patients with acquired steeply sloping high-frequency HLs obtain significant benefit from cochlear implantation with standard long electrodes. In progressive losses, full insertion of a long electrode would be preferable to a short electrode because acoustic hearing may diminish over time. In contrast, patients with congenital losses may not benefit from long electrodes, and might be better served by implanting a short electrode, thereby allowing use of low-frequency acoustic stimulation.