The neurological basis of tinnitus is uncertain when there is no evidence of damage to the peripheral auditory system. However, neuroimaging studies of tinnitus patients show hyperactivity in several cortical regions, especially the auditory cortices and middle temporal regions. A potentially promising treatment modality for tinnitus is repetitive transcranial magnetic stimulation (rTMS). rTMS involves the application of frequent, repeated magnetic stimuli to the skull to induce electrical activity in the underlying cortical areas of the brain. When the magnetic device is placed on the skull, the resultant magnetic field passes through the skull and induces a small secondary current in the cortex. It has been hypothesized that the effect of the frequency used in rTMS differentially influences cortical activity with low-frequency (1Hz) stimulation decreasing and high-frequency stimulation (10-20 Hz) increasing cortical activity.
Currently, reports on treating tinnitus with rTMS have focused on low-frequency stimulation of the left auditory cortex, an area that has been demonstrated to be hyperactive in tinnitus. The benefits of low-frequency auditory cortex stimulation are time limited however. Converging data implicate structures of the brain that are important for mood and attention as playing a role in the maintenance of tinnitus; suggesting an alternative rTMS treatment approach that targets these structures. A growing number of studies demonstrate involvement of the prefrontal cortex in the generation and maintenance of tinnitus. rTMS stimulation in the dorsolateral prefrontal cortex in association with stimulation in the temporoparietal cortex has been shown to increase the durability of the TPC stimulation. The independent effect of rTMS stimulation to the DLPFC is not known. Studies in depression suggest that increasing the intensity and duration of stimulation has beneficial treatment effects. However, the field is new and more work is needed to assess the effectiveness of this treatment, predictors and correlates of response, and safety.
Herein, we propose an open-label pilot study investigating the effectiveness of rTMS stimulation of the dorsolateral prefrontal cortex, an area known to be important for mood and attention, in the treatment of tinnitus.
Study Start Date: June 2009
Study Completion Date: August 2010
Primary Completion Date: August 2010 (Final data collection date for primary outcome measure)