Cochlear and brainstem audiologic findings in normal hearing tinnitus subjects in comparison with non-tinnitus control group.

While most tinnitus cases have some degree of hearing impairment, a small percent of the patients admitted to Ear, Nose and Throat Clinics or Hearing Evaluation Centers are those who complain of tinnitus despite having normal hearing thresholds. Present study was performed in order to better understanding of the probable causes of tinnitus and to investigate possible changes in the cochlear and auditory brainstem function in normal hearing patients with chronic tinnitus. Altogether, 63 ears (31 ears with tinnitus and 32 ears without tinnitus) were examined. The prevalence of transient evoked otoacoustic emissions and characteristics of the auditory brainstem response components including wave latencies and wave amplitudes was determined in the two groups and analyzed with appropriate statistical methods. There was no difference between the prevalence of transient evoked emissions in the two groups. The mean difference between absolute latencies of waves I, III and V was less than 0.1 ms between the two groups that were not statistically significant. Also, the interpeak latency values of I-III, III-V and I-V in both groups had no significant difference. Only the V/I amplitude ratio in the tinnitus group was significantly larger than the other group (p =0.04). The changes observed in amplitude of waves, especially in the later ones, can be considered as an Audiologic finding in normal hearing tinnitus subjects and its possible role in generation of tinnitus in these patients must be investigated.