Newswise — Subjective tinnitus, the perception of ringing or rushing sounds within the ear, is a common phenomenon disturbing millions of individuals worldwide. The causes of these debilitating disorders remain unclear; numerous investigations have revealed that chronic tinnitus is associated with increased activity in primary auditory cortex (PAC).
A team of German researchers have completed a study that suggests that Transcranial Magnetic Stimulation, which induces an electrical current in nearby regions of the brain to diagnose brain abnormalities may be an effective inhibitor of tinnitus. Their theory reflects past research findings which established that low frequency (1Hz) rTMS reduces activation in the directly stimulated brain area as well as in other functionally connected brain areas. In this context,low frequency rTMS reduces auditory hallucinations in patients with schizophrenia after application to the left temporoparietal cortex .
The aim of their study was to investigate whether low frequency rTMS of increased metabolic activity in the PAC is able to cause longer lasting inhibitory effects in tinnitus perception. To assure reliable stimulation of the individual target area they used a neuronavigational system based on patient-specific neuroimaging data.
The authors of "Treatment of Chronic Tinnitus with Repetitive Transcranial Magnetic Stimulation (rTMS)" are T. Kleinjung, J. Strutz, and P. Jacob, P. Eichhammer, B. Langguth, G. Hajak, J. Marienhagen, and S. R. Wolf, all from the University of Regensburg, Germany.
Their findings will be presented at the American Academy of Otolaryngology-Head and Neck Surgery Foundation http://www.entnet.org Annual Meeting and OTO EXPO, being held September 21-24, 2003, at the Orange County Convention Center, Orlando, FL.
Methodology: The design of the study was a prospective placebo-controlled cross-over treatment schedule. Ten patients suffering from mild to extreme chronic tinnitus underwent a FDG- PET study (positron emission tomography with 18F deoxyglucose) to detect areas of increased metabolic activity in the cortex. After fusioning these PET scans with structural MRI-scans an anatomical correlation could be performed. The area of increased metabolic activation within the auditory cortex was selected as target for repetitive Transcranial Magnetic Stimulation (rTMS).
The exact position of the figure 8-shaped magnetic coil on the subjects' head in relation to the target was monitored with a neuronavigational system\ adapted for TMS positioning. rTMS (110 percent motor threshold; 1 Hz; 2000 stimuli/ day over five days) was performed in a placebo controlled cross-over design. Patients were blind regarding stimulus condition. For sham stimulation a specific sham-coil system was used. Treatment outcome was assessed with a standard tinnitus questionnaire.
Results: In all patients PET-scan showed remarkable focal increase of FDG-uptake in the region of the primary auditory cortex (nine on the left, one on the right side). The fusion with structural MRI-data demonstrated that this hyperactive area was located within the superior temporal gyrus (Brodmann area 41) in all patients. All patients tolerated rTMS well. No serious adverse- or side effects were noticed. After five days of verum rTMS a remarkable improvement of the tinnitus score was found. This effect could not be seen after sham stimulation.
Conclusions: This study suggests that TMS should be explored as a viable, long-term inhibitor of tinnitus.
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