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Conclusion: Significant amount of patients either experience no change in their tinnitus or a decrease. Level of tinnitus handicap overall is not marked in this population. However, tinnitus could be a significant problem in some CI patients.

III Brain stimulation

Dose-dependent attenuation of auditory phantom perception (tinnitus) by PET-guided repetitive transcranial magnetic stimulation. Hum Brain Mapp. 2007 Mar;28(3):238-46. Plewnia C, Reimold M, Najib A, Brehm B, Reischl G, Plontke SK, Gerloff C Department of Psychiatry, Neurophysiology Section, University of Tuebingen, Tuebingen, Germany.

Recent data suggest that chronic tinnitus is a „phantom auditory perception“ caused by maladaptive neu- roplasticity and subsequent hyperactivity in an extended neuronal network including the primary auditory cortex, higher-order association areas, and parts of the limbic system. It was suggested that attenuation of this tinnitus-associated hyperactivity may offer a rational option for lasting tinnitus reduction. Here, we tested the hypothesis that tinnitus loudness can be attenuated by low-frequency repetitive transcranial magnetic stimulation (rTMS) individually navigated to cortical areas with excessive tinnitus-related activi- ty as assessed by [(15)O]H(2)O positron-emission tomography (PET). Nine patients with chronic tinnitus underwent this combined functional imaging and rTMS-study. Group analysis of the PET data showed tinnitus-related increases of regional cerebral blood flow in the left middle and inferior temporal as well as right temporoparietal cortex and posterior cingulum. Repetitive TMS was performed at 1 Hz and 120% of the motor threshold for 5, 15, and 30 min, navigated to the individual maximum of tinnitus-related corti- cal hyperactivity. A noncortical stimulation site with the same distance to the ear served as sham control. Tinnitus loudness was reduced after temporoparietal, PET-guided low-frequency rTMS. This reduction, lasting up to 30 min, was dependent on the number of stimuli applied, differed from sham stimulation, and was negatively correlated with the length of the medical history of tinnitus in our patients. These data show the feasibility and effectiveness of rTMS guided by individual functional imaging to induce a lasting, dose-dependent attenuation of tinnitus. Of note, these effects were related to stimulation of cortical asso- ciation areas, not primary auditory cortex, emphasizing the crucial role of higher-order sensory proces- sing in the pathophysiology of chronic tinnitus. Hum Brain Mapp, 2007. (c) 2006 Wiley-Liss, Inc.

Effects of repetitive transcranial magnetic stimulation on chronic tinnitus. A randomised, cross over, double blind, placebo-controlled study. J Neurol Neurosurg Psychiatry. 2007 Feb 21. Rossi S, De Capua A, Ulivelli M, Bartalini S, Falzarano V, Filippone G, Passero S Universita di Siena, Italy.

Background: chronic tinnitus is a disabling, almost untreatable, condition usually accompanied by psy- chiatric distress. In patients with complex neuropsychiatric diseases as chronic pain, with whom tinnitus shares pathophysiological similarities, placebo effects may be pronounced. Moreover, it may be difficult to distinguish actual rTMS-induced clinical benefits beyond placebo effects in neuropsychiatric patients. Methods: 16 patients with chronic tinnitus underwent a randomized, double-blind, cross-over, placebo controlled trial of 1 Hz rTMS (120% of motor threshold; 1200 stimuli/day for 5 days) of the left temporo- parietal region. Patients were screened for psychiatric comorbidity; additionally, anxiety and depression were monitored throughout the study. Moreover, an original placebo rTMS procedure produced the same activation of ipsilateral face muscles (a condition which may per se change tinnitus subjective rating) of the real rTMS.

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