Enhanced 40 and 80 Hz Auditory Steady State Responses in Patients with Idiopathic Tinnitus.

PURPOSE: This study aimed to investigate changes in auditory processing using auditory steady state responses (ASSR) in patients with idiopathic tinnitus. METHODS: 19 tinnitus patients (7 females) and 24 control subjects (9 females) without tinnitus were examined with multiple ASSRs. Three modulation frequencies of 20, 40, and 80 HZ were tested, and the steady state responses were compared between tinnitus and control group. Further, the thresholds in ipsi- and contralateral side to ear with tinnitus were compared. RESULTS: Our findings showed no significant difference in ASSR thresholds in ipsi- and contralateral side in tinnitus patients. However, we observed enhanced ASSRs at 40 and 80 Hz modulations in patients with idiopathic tinnitus compared to no-tinnitus control subjects. CONCLUSION: The results of this study suggest possible sensory deficits along higher order auditory regions in patients with idiopathic tinnitus. Further, our data indicates a bilateral involvement of auditory pathway in these regions in patients with lateralized tinnitus.