Outcomes of Cochlear Implantation for Single-Sided Deafness and Asymmetric Hearing Loss: Quality of Life, Tinnitus, and the Effect of Deafness Duration.

OBJECTIVES.: To evaluate multidimensional outcomes of cochlear implantation (CI) in adults with single-sided deafness (SSD) or asymmetric hearing loss (AHL), and to examine how duration of deafness influences speech perception, tinnitus severity, and hearing-related quality of life. METHODS.: This retrospective cohort study included 124 adults with SSD or AHL who underwent unilateral CI at a tertiary referral center (September 2019-October 2024) with at least 12 months of postoperative follow-up. The primary outcome, hearing-related quality of life, was assessed using the Speech, Spatial, and Qualities of Hearing Scale (SSQ); secondary outcomes included the Hearing Handicap Inventory for the Elderly (HHIE), Tinnitus Handicap Inventory (THI), Short Form-36 (SF-36), and open-set speech perception (n = 61). The association between duration of deafness and postoperative outcomes was evaluated using duration as a continuous predictor in linear regression. RESULTS.: Significant postoperative improvements occurred in SSQ Speech (+0.97; d = 0.53; p < 0.001) and Spatial domains (+1.60; d = 0.88; p < 0.001), HHIE (- 13.0; d = 0.50; p < 0.001), THI (-15.8; d = 0.61; p < 0.001), and SF-36 (+4.2; d = 0.27; p = 0.031). Speech perception improved markedly under CI-only conditions (monosyllabic d = 1.98; bisyllabic d = 2.92; sentence recognition d = 3.59). Longer duration of deafness was significantly associated with smaller THI improvement (β = 1.13 points/year, 95% CI 0.43-1.84; p = 0.002; adjusted β = 0.98, 95% CI 0.18-1.78; p = 0.017), whereas quality-of-life and sentence recognition outcomes were not associated with deafness duration. CONCLUSION.: Unilateral CI produces clinically meaningful improvements in hearingrelated quality of life, tinnitus severity, hearing handicap, and speech perception in adults with SSD and AHL. Quality-of-life and speech outcomes were preserved regardless of deafness duration, whereas tinnitus suppression declined with increasing deaf duration. These findings support earlier CI for candidates with bothersome tinnitus.