The mismatch negativity test in ears with and without tinnitus-a path to the objectification of tinnitus

The mismatch negativity (MMN) test evaluates neural responses to unexpected sounds, providing objective data on the neural plasticity of the auditory system.

In this study, we assessed whether the MMN test could identify failure of neural habituation of the auditory pathway in patients with severe tinnitus.

Patients with normal hearing were compared to tinnitus patients, via the MMN test. The Tinnitus Handicap Inventory (THI) and a visual analog scale (VAS) were used to evaluate tinnitus-derived annoyance. The Hospital Anxiety and Depression (HAD) scale was used to assess anxiety and depression.

The average MMN amplitudes in the tinnitus group were -0.88 uV in the right ear (RE), and -1.13 uV in the left ear (LE), while in control group the corresponding amplitudes were 1.01 uV and -1.19 uV. Mean latencies in the tinnitus group were 208.34 ms in the RE, and 209.92 ms in the LE, while in the control group the corresponding latencies were 217.38 ms and 215.69 ms. The differences in mean latencies between the groups were statistically significant.

The MMN test may be useful for evaluating the habituation process of the central auditory pathways in tinnitus patients.