A prospective cohort study of cochlear implantation as a treatment for tinnitus in post-lingually deafened individuals

Cochlear implants have helped over one million individuals restore functional hearing globally, but their clinical utility in suppressing tinnitus has not been firmly established. In a decade-long study, we examined longitudinal effects of cochlear implants on tinnitus in 323 post-lingually deafened individuals including 211 with pre-existing tinnitus and 112 without tinnitus. The primary endpoints were tinnitus loudness and tinnitus handicap inventory. The secondary endpoints were speech recognition, anxiety and sleep quality. Here we show that after 24 month implant usage, the tinnitus cohort experience 58% reduction in tinnitus loudness (on a 0–10 scale from 4.3 baseline to 1.8 = −2.5, 95% CI: −2.7 to −2.2, p = 3 x 10−6; effect size d’ = −1.4,) and 44% in tinnitus handicap inventory (=−21.2, 95% CI: −24.5 to −17.9, p = 1 x 10−15; d’=−1.0). Conversely, only 3.6% of those without pre-existing tinnitus develop it post-implantation. Prior to implantation, the tinnitus cohort have lower speech recognition, higher anxiety and poorer sleep quality than the non-tinnitus cohort, measured by Mandarin monosyllabic words, Zung Self-rating Anxiety Scale and Pittsburgh Sleep Quality Index, respectively. Although the 24 month implant usage eliminate the group difference in speech and anxiety measures, the tinnitus cohort still face significant sleep difficulties likely due to the tinnitus coming back when the device was inactive at night. The present result shows that cochlear implantation can offer an alternative effective treatment for tinnitus. The present result also identifies a critical need in developing always-on and atraumatic devices for tinnitus patients, including potentially those with normal hearing. Tinnitus is the perception that there is sound when it is not present. Cochlear implants are placed in the ears and can suppress tinnitus. However, the FDA do not yet recommend them as a tinnitus treatment. We evaluated 323 individuals with or without tinnitus before cochlear implantation and for over 2 years after implantation surgery. We investigated whether cochlear implantation is safe and effective for treating tinnitus and whether it causes tinnitus in people who did not have tinnitus previously. We found that cochlear implantation reduces tinnitus in 90% of those with pre-surgical tinnitus whilst causing tinnitus in only 3.4% of those without pre-surgical tinnitus. This finding confirms that cochlear implants are a safe and effective treatment for tinnitus. Wang, Kapolowicz, Li et al. investigate the effect of cochlear implantation on tinnitus in postlingually deafened individuals with or without pre-surgical tinnitus. There is a low risk of cochlear implants causing tinnitus but a high chance of them suppressing tinnitus, with a fast tinnitus suppression mechanism relating to device activation and a slow one that relates to brain plasticity.