Analysis of Auditory Brainstem Response Change, according to Tinnitus Duration, in Patients with Tinnitus with Normal Hearing

OBJECTIVES: The purpose of this study was to analyze auditory brainstem response (ABR) waveforms of patients with tinnitus with normal hearing, according to tinnitus duration, and demonstrate the possible pathophysiological mechanisms of tinnitus. MATERIALS AND METHODS: From January 2016 to December 2017, patients who presented to our hospital with tinnitus as their chief complaint were enrolled and reviewed retrospectively. Pure tone audiometry and ABR tests were performed. The patients were classified into three groups according to tinnitus duration: acute (<1 month), subacute (1-6 months), and chronic (>6 months). The amplitudes of waves I and V and the latencies of waves I, III, and V were evaluated. In this study, 177 ears of 128 patients with tinnitus with normal hearing were evaluated. RESULTS: Wave V amplitude was significantly lower during the subacute phase than during the acute phase. The absolute latency value of wave V was greater during the subacute phase than during the acute phase. The interpeak latency I-V was significantly prolonged during the subacute phase compared with the acute and chronic phases. Wave V amplitude, wave V absolute latency, and interpeak latency I-V varied significantly between cases with a 1-month and 6-month tinnitus history. CONCLUSION: The compensatory response to tinnitus decreased sharply after 1 month of symptoms. Early tinnitus identification and treatment initiation are recommended.