Modulated Alpha Power as a Predictor of Tinnitus Alleviation

Pain associated with subjective tinnitus is known to be alleviated by treatments using a repetitive transcranial magnetic stimulation (rTMS). However, the mechanisms underneath are still on debate. We investigated the mechanism of tinnitus alleviation using time-frequency analyses. Twenty-four patients were randomly assigned to the dual-site stimulation group (temporal and frontal stimulation, TF), singlesite stimulation group (temporal stimulation, T), or sham stimulation group. An age-matched control group was also included (n = 12). Electroencephalography (EEG) was recorded and patient data were analyzed before and after treatment. A frontal increase in EEG power was observed in the alpha (8-12 Hz) frequency band domain after treatment; this increase was most pronounced in the TF group, followed by the T group. The TF and T groups showed increased alpha power in the fronto-central channels only in the silent period between paired-pulse tones. The TF and T groups showed decreases in alpha power in the temporal region, particularly in the neural response to the first of the paired-pulse tones. The difference in tinnitus handicap index between pre- and post-treatment was positively correlated with the alpha power of the silent period in the frontal and fronto-central channels. Dual-site stimulation showed the greatest alleviation of tinnitus-related discomfort, followed by single-site stimulation. Additionally, the modulation of alpha power was prominent in the active stimulation groups. Low frequency rTMS can alleviate tinnitus by increasing alpha band power and reducing hyperactivity.