Revealing Pathological Auditory Central Inhibition in Tinnitus Using Cortical Auditory Evoked Potentials Responses to Contralateral Acoustic Stimulation.

OBJECTIVE: To test the hypothesis that auditory central inhibition is reduced in tinnitus patients and explore whether improving this inhibitory function could alleviate tinnitus severity. METHODS: We recruited 16 chronic tinnitus patients and 14 age-matched healthy controls, all of whom exhibited clinically normal audiometric thresholds. Electroacoustic measures, cortical auditory evoked potentials (CAEP), were used to assess neural activity. Contralateral noise stimulation was employed to evaluate contralateral suppression (CS) of CAEP amplitude. RESULTS: Significant differences in CS of N100 and P300 amplitude were observed between tinnitus patients and healthy controls, indicating impaired central inhibition in tinnitus. After 3 months of tinnitus masking therapy, patients showed significant improvements in CS of N100 and P300 amplitudes, which correlated with a reduction in tinnitus handicap inventory scores. Receiver operating characteristic curve analysis confirmed that changes in CS, especially in the P300 amplitude, reliably reflect treatment efficacy. CONCLUSIONS: This study highlights the critical role of central auditory inhibition in tinnitus pathophysiology and suggests that neurophysiological markers, particularly changes in CS of P300 amplitude, could serve as reliable biomarkers for evaluating treatment outcomes. SIGNIFICANCE: These findings pave the way for developing targeted therapies aimed at restoring central auditory inhibition, offering more effective and personalized treatment strategies for tinnitus patients.