Is electric acoustic stimulation better than conventional cochlear implantation for speech perception in quiet?

Objective: To assess whether combined electric acoustic stimulation (EAS) provides a significant hearing-in-quiet advantage over ipsilateral electrical stimulation alone, ipsilateral acoustic stimulation alone, or full-length cochlear implantation without preserved hearing. Setting: Tertiary care academic referral center. Patients: Two matched groups of cochlear implant (CI) patients that were implanted with either an EAS or full-length device and use similar speech processing strategies. Intervention: EAS cochlear implantation and hearing preservation (n = 10, EAS group) or conventional CI (n = 10, conventional CI group) without hearing preservation. Main Outcome Measures: Status of residual hearing and speech perception data in quiet at 3 and 6 months after fitting. Results: Preoperatively, the mean aided Consonant Nucleus Consonant Word Test word score was 24.2 ± 8.3% for the EAS group and 20.7 ± 11.36% for the conventional CI group (p = 0.14). In the conventional CI group, hearing was not preserved after surgery in any subject, whereas 9 of the 10 subjects in the EAS group had hearing preservation. Mean CNC word scores at 6 months after activation using electrical stimulation alone were 50.3 ± 11.53% in the EAS group and 53.8 ± 17.32% in the conventional CI group (p = 0.81). Between-condition comparisons among the EAS subjects revealed that combined stimulation was significantly better than either the electrical or acoustic stimulation condition alone (p < 0.05). When compared with the conventional CI group, combined stimulation in EAS subjects was again superior (p < 0.05). Conclusion: Limited length CI with ipsilateral hearing preservation provides comparable speech perception performance results to conventional CI when electric stimulation alone is used. The addition of ipsilateral acoustic stimulation in ears with preserved residual hearing provides an additional benefit over electrical stimulation alone.