Importance: This research examines the impact of 4 weeks of repetitive transcranial magnetic stimulation (rTMS) stimulation to the temporoparietal junction and compares the results of this longer duration of treatment with a similar stimulus protocol of only 2 weeks' duration.
Objective: To examine the effectiveness and safety of 4 weeks of low-frequency rTMS to the left temporoparietal junction in a cohort of patients with bothersome tinnitus.
Design: Crossover, double-blind, randomized controlled trial.
Setting: Outpatient academic medical center.
Participants: The study population comprised 14 adults aged between 22 and 59 years with subjective, unilateral or bilateral, nonpulsatile tinnitus of 6 months' duration or greater and a score of 34 or greater on the Tinnitus Handicap Inventory (THI).
Interventions: Low-frequency (1 Hz) 110% motor threshold rTMS or sham to the left temporoparietal junction for 4 weeks.
Main outcome and measure: The difference of the change in the THI score between active rTMS and sham rTMS.
Results: Active treatment was associated with a median reduction in THI score of 10 (range, -20 to +4) points, and sham treatment was associated with a median reduction of 6 (range, -24 to +12) points. The median difference in THI score between the change associated with active and sham rTMS was 4 (95% CI, -9 to 10; and range, -32 to +14) points.
Conclusions and relevance: Daily low-frequency active rTMS to the left temporoparietal junction area for 4 weeks was no more effective than sham for patients with chronic bothersome tinnitus. Possible explanations for this negative study include the failure of rTMS to stimulate deeper parts of auditory cortex within the sylvian fissure and more widespread cortical network changes not amenable to localized rTMS effects.
Trial registration: clinicaltrials.gov Identifier: NCT00567892.