Long-term effects of repetitive transcranial magnetic stimulation (rTMS) in patients with chronic tinnitus

Abstract

The pathophysiologic mechanisms of idiopathic tinnitus remain unclear. Recent studies demonstrated focal brain activation in the auditory cortex of patients with chronic tinnitus. Low-frequency repetitive transcranial magnetic stimulation (rTMS) is able to reduce cortical hyperexcitability. Fusing of the individual PET-scan with the structural MRI-scan (T1, MPRAGE) allowed us to identify exactly the area of increased metabolic activity in the auditory cortex of patients with chronic tinnitus. With the use of a neuronavigational system, this target area was exactly stimulated by the figure 8-shaped magnetic coil. In a prospective study, rTMS (110% motor threshold; 1 Hz; 2000 stimuli/day over 5 days) was performed using a placebo controlled cross-over design. Patients were blinded regarding the stimulus condition. For the sham stimulation a specific sham-coil system was used. Fourteen patients were followed for 6 months. Treatment outcome was assessed with a specific tinnitus questionnaire (Goebel and Hiller). Tertiary referral medical center. Increased metabolic activation in the auditory cortex was verified in all patients. After 5 days of verum rTMS, a highly significant improvement of the tinnitus score was found whereas the sham treatment did not show any significant changes. The treatment outcome after 6 months still demonstrated significant reduction of tinnitus score. These preliminary results demonstrate that neuronavigated rTMS offers new possibilities in the understanding and treatment of chronic tinnitus.