Evaluation of medium-term cochlear implant use in patients with asymmetric hearing loss

Cochlear implant (CI) effectiveness in asymmetric hearing loss (AHL) is well established, but CI use over time and daily usage are rarely monitored by health care systems. Continued use of the CI after the first year could be considered an indirect indicator of subjective benefit. The objective of this study was to evaluate CI use with a follow-up period of 5 years.

Sixty-four patients were included in this retrospective study. AHL candidates included patients with an aided speech perception score (SPS) < 50% at 60 dB in the ear to be implanted. The better ear had to have a non-fluctuating HL, and an aided SPS ≥ 60% for disyllabic words in quiet, with an interaural SPS gap ≥ 40%.

Ninety-seven percent of patients still used their CI all day at 1-year and 93% at 5-years post-implantation. Only four patients discontinued use. The mean duration of daily use at 5-years assessed using data-logging was 12 ± 3.2 h. Aided SPS for the implanted ear improved at 1-year post-implantation, for both mono- and disyllabic words in quiet and sentences in noise (p < 0.0001), and remained stable at 5-years. Unaided and aided SPS of the acoustic ear decreased over time. However, SPS in bimodal conditions improved at 1-year for both mono- (p < 0.0001) and disyllabic words (p < 0.005) and sentences in noise (p < 0.0005) and the scores remained stable at 5-years.

The low percentage of non-users and the long duration of daily use at 5 years post-implantation are an additional strong argument to recommend cochlear implantation in patients with asymmetric hearing aid benefit.