Repetitive transcranial magnetic stimulation (rTMS) for treatment of chronic tinnitus

Objective: There is compelling evidence that tinnitus is associated with functional alterations in the central nervous system. Repetitive transcranial magnetic stimulation (rTMS) is a potent tool for modifying neural activity at the stimulated area and at a distance along the functional anatomical connections. Depending on the stimulation parameters, cortical networks can be functionally disturbed or modulated in their activities. Low-frequency rTMS has been shown to result in a decrease in cortical excitability. The technique can alleviate tinnitus by modulating the excitability of neurons in the auditory cortex. We aimed to investigate the effects of low-frequency rTMS in patients and determine the factors that predict a beneficial outcome with rTMS treatment. Methods: Sixteen patients (male 10, female 6) with chronic tinnitus underwent low-frequency (1. Hz) rTMS (intensity: 110% motor threshold; number of stimuli: 1200) to the left auditory cortex. The treatment outcome was assessed with a visual analog scale (VAS) of loudness, annoyance and duration, loudness balance test, and tinnitus handicap inventory (THI). Therapeutic success was studied according to the patients' clinical characteristics. Results: A significant reduction in the VAS (loudness and annoyance) occurred immediately after rTMS, with a gradual return to pretreatment levels after 7 days. The tinnitus patients with sudden deafness were significant resistant to rTMS treatment compared with those diagnosed with age-related hearing loss. Conclusion: These results support the potential of rTMS as a new therapeutic tool for the treatment of chronic tinnitus. Because this study was performed with a small sample size and showed high interindividual variability in treatment effects, further development of the technique is needed before it can be recommended for clinical applications.