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Abstract

People suffering from chronic tinnitus continuously experience auditory noise in the absence of any auditory stimulation. This agonising phantom perception has been related to an enhanced activation of the auditory cortex. Low-frequency transcranial magnetic stimulation (TMS) is a convenient tool that can effectively inhibit this hyperactivity and attenuate the severity of tinnitus. Yet, it has been shown that theta burst stimulation (TBS) inhibits cortical activation more effectively than conventional low-frequency TMS. Hence, TBS might likewise be more effective in relieving tinnitus patients’ distressing auditory perceptions. We aimed to evaluate the effect of two weeks of TBS treatment on tinnitus severity and cortical activation using a placebo controlled design. During each session, two trains of 200 theta bursts (one burst = 3 pulses, 50Hz) each were applied, resulting in a total of 1200 pulses. By means of a neuronavigation device, the TMS coil could be located exactly above the auditory cortex. Tinnitus severity was assessed using the tinnitus questionnaire, the tinnitus handicap inventory (THI) and a visual analogue scale. To evaluate the cortical activation, we depicted the hemodynamic response using near infrared spectroscopy (NIRS) at baseline and immediately after the last session. Lastly, the cortical excitability of the motor cortex was assessed using a double pulse TMS paradigm. In order to be able to depict immediate and long term effects of TBS on the cortical excitability, the paradigm was carried out six times: before and after session one, six and ten. Preliminary results reveal that TBS can effectively improve tinnitus severity. In some patients, the score on the tinnitus questionnaire and on the tinnitus handicap inventory declined by maximally 50. The effect of TBS on hemodynamic response (NIRS) and on cortical excitability (double pulse TMS) will be discussed and related to changes in tinnitus severity.