Detailed analysis of auditory brainstem responses in patients with noise-induced tinnitus.

The role of the auditory brainstem in tinnitus is questionable. This study aimed comprehensively to assess auditory brainstem responses (ABRs) in patients suffering from noise-induced tinnitus (NIT). ABRs were recorded from 13 chronic NIT patients (21 ears) and 11 (21 ears) age and hearing matched control subjects without tinnitus. ABRs were recorded with scalp electrodes placed ipsilateral and contralateral to the stimulated ear, and in three orthonormal differential configurations. The ABRs were analyzed as a function of time, frequency and voltage space. A significantly enhanced ipsilaterally recorded, time domain wave III amplitude was observed for the tinnitus patients. This finding was not confirmed by any of the other ABR measures, which were indistinguishable between subject groups. Although this may be a spurious result, it nonetheless may point to an alteration in the functioning of the putative wave III auditory brainstem generator, which deserves further study.