Tinnitus outcomes after unilateral and bilateral cochlear implantation

Background The effect of cochlear implantation (CI) on tinnitus, particularly unilateral versus bilateral implantation, remains unclear.Aims To evaluate the effect of CI on tinnitus by comparing unilateral and bilateral implantation using tinnitus scores and objective hearing performance data.Materials and methods This retrospective observational study was conducted at a single tertiary center in Japan. Sixty-one patients with hearing loss underwent unilateral or bilateral CI and preoperative and postoperative tinnitus evaluations. Tinnitus was measured using the tinnitus handicap inventory (THI) and Visual Analog Scale (VAS).Results Of 61 patients, 10 with THI scores of 0 both preoperatively and postoperatively were excluded from the tinnitus change analysis; none developed new-onset tinnitus. Among the remaining 51, 36 had preoperative THI scores ≥7; 32 showed clinically meaningful improvement and four showed no change. Of 15 with THI scores <7, 14 showed no change and one showed worsening. No significant differences were found for THI or loudness, whereas the improvement group showed significantly longer daily device use time for distress (p < 0.05). Listening-environment exposure did not differ consistently between groups.Conclusions In the tinnitus change analysis, tinnitus improved significantly after CI, but neither bilateral implantation nor longer daily device use demonstrated a clear exposure–response relationship with tinnitus reduction.