Hybrid Cochlear Implant Outcomes and Improving Outcomes With Electric-Acoustic Stimulation

Electric-acoustic stimulation (EAS) provides cochlear implant (CI) recipients with preserved low-frequency acoustic hearing in the implanted ear affording auditory cues not reliably transmitted by the CI including fundamental frequency, temporal fine structure, and interaural time differences (ITDs). A prospective US multicenter clinical trial was conducted examining the safety and effectiveness of a hybrid CI for delivering EAS.

Fifty-two adults (mean age 59.9 yr) were enrolled in the study and followed up to 5 years postactivation. Testing included unaided and aided audiometric thresholds, speech perception (Consonant-Nucleus-Consonant [CNC] words in quiet and AzBio sentences +5 dB SNR), and patient-reported outcomes (Speech, Spatial, and Qualities of Hearing Scale).

Functionally aidable hearing, defined as low-frequency pure-tone average (125-500 Hz) <80 dB HL, was maintained for 77% of patients through 1 year, with 66.7% maintaining through 5 years. Speech perception was significantly improved at all postoperative timepoints compared with preoperative performance with hearing aid(s), and patient-reported outcomes indicated significantly improved subjective speech understanding, spatial hearing, and sound quality. Participants with preserved acoustic hearing using EAS reported significantly higher subjective spatial hearing and sound quality than participants with electric-only hearing in the implanted ear.

Patients with high-frequency hearing loss demonstrate significant long-term benefit with a hybrid CI including high rates of functional hearing preservation, significantly improved speech perception, and subjective patient-reported outcomes. EAS with binaural acoustic hearing affords benefit for subjective spatial hearing and sound quality beyond CI listening configurations using monaural acoustic hearing.