Efficacy of non-invasive neuromodulation for chronic tinnitus: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Chronic tinnitus affects approximately 14% of adults worldwide, with nearly 2% experiencing severe, persistent symptoms that impair daily functioning. Non-invasive neuromodulation techniques, such as repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and acoustic or nerve stimulation, have emerged as potential therapies, yet their clinical effectiveness remains uncertain. This systematic review and meta-analysis synthesized evidence from randomized controlled trials (RCTs) evaluating the efficacy of neuromodulation for chronic tinnitus. METHODS: PubMed, Scopus, and Web of Science were searched through September, 2025. Eligible studies were RCTs assessing non-invasive neuromodulation versus sham in adults with chronic tinnitus. The primary outcome was change in Tinnitus Handicap Inventory (THI) scores. Secondary outcomes included the Tinnitus Functional Index (TFI), Tinnitus Questionnaire (TQ), loudness measures, and anxiety and depression scales. RESULTS: A total of 32 trials comprising 1,561 participants were included. Neuromodulation significantly improved tinnitus severity at short-term, with a pooled THI reduction of - 6.96 points (95% CI - 10.67 to - 3.26). rTMS showed a significant benefit (MD - 4.35, 95% confidence interval [CI] - 7.36 to - 1.33), as did acoustic/nerve stimulation (MD - 8.70, 95% CI - 15.81 to - 1.60), whereas tDCS demonstrated a nonsignificant effect (MD - 9.14, p = 0.10). Benefits were most pronounced immediately post-treatment and at 1-3 months, with effects diminishing by 6 months (MD - 3.93, p = 0.06). Secondary outcomes showed no significant improvements in TFI, TQ, objective loudness, or mood scales. Subjective loudness on visual analogue scale (VAS) showed a small borderline improvement (standardized mean difference [SMD] - 0.38, 95% CI - 0.75 to 0.00). CONCLUSION: Non-invasive neuromodulation provides modest, clinically meaningful short-term reduction in tinnitus severity, particularly with rTMS at dorsolateral prefrontal cortex area and acoustic/nerve stimulation. However, effects are inconsistent across modalities and decrease over time. Future studies should prioritize standardized protocols, optimized stimulation parameters, and personalized targeting to enhance therapeutic efficacy.