Tinnitus affects about 10% of population worldwide. Most patients present with some degrees of hearing impairment, while others remain normal. The aim of this study was to analyze the latency and amplitude of auditory brain stem response (ABR) waveforms in patients with unilateral tinnitus. The tinnitus ears and non-tinnitus ears were compared for each patient. Sixty-seven patients with single-sided tinnitus were enrolled, including 26 male and 41 female patients with a mean age of 54.4 (age ranged from 22 to 79). Eighteen patients had bilateral normal hearing, while 49 patients had some degree of sensorineural hearing. The ABR waveforms were retrospectively analyzed in terms of waves I, III, and V absolute latency, as well as waves I-III, waves II-V, and waves I-V latency intervals, amplitude, and amplitude ratio (III/I, V/I). Statistical analyses were performed within patients. There was no significant ABR difference between the tinnitus and non-tinnitus ears with regard to all the wave latencies and amplitudes in our patients (all P values >0.1). Our result that ABR changes were not found between tinnitus and non-tinnitus ears implies that tinnitus does not simply originate from the defect of the peripheral auditory system. It conforms to the contemporary theory that a higher level of the brain is involved in the generation of tinnitus.
Keywords: auditory brain stem responses (ABR); unilateral tinnitus; within subject.