Tinnitus can be described as the experience of sound in the ear or in the head. Subjective tinnitus is not heard by anyone else. The exact cause of tinnitus remains unknown. At present no particular treatment has been found effective in all patients. Recently, researchers have been able to image the brain using specialised techniques (such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET)). This has led us to believe that high spontaneous neuronal activity in the central auditory system and associated areas may responsible for the perception of tinnitus. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive means of inducing electrical currents in the brain and can decrease this neuronal activity. The purpose of this Cochrane Review was to assess the effectiveness and safety of rTMS for the treatment of tinnitus.
Our search for studies retrieved 283 articles. Of these, five trials comprising 233 tinnitus patients met our inclusion criteria and were included in the review.
The first study considered the use of 'complex waveform rTMS', the second looked at the use of high-frequency rTMS, and the other three studies considered the use of low-frequency rTMS. We found that the use of low-frequency rTMS resulted in 'partial improvement' in tinnitus severity and disability in one study, however these results were not replicated in two other studies that considered rTMS at the same frequency. Furthermore, this single positive finding should be taken in the context of the many different variables which were recorded at many different points in time by the study authors. We were able to demonstrate an improvement in tinnitus loudness in patients undergoing rTMS when we combined the results of two other studies.
rTMS is a safe treatment for patients with tinnitus in the short-term, however no data were available to verify safety in the long-term.