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chronic electrical stimulation of the vestibulocochlear nerve. Patients: Inclusion criteria were severe, chronic, therapeutically refractory, unilateral tinnitus and severe hearing loss at the ipsilateral site. Out of 6 patients, 4 patients were selected for long-term evaluation. Two patients were not evaluated because of premature dropout. Material and Methods: A stimulation electrode was placed around the vestibulocochlear nerve through a retrosigmoid approach and connected to a subcutaneously positioned pulse generator via an extensi- on cable. Follow-up was performed 3 months and 42.5 months after implantation. Three measures for treatment outcome were used. First, effect sizes were determined by means of the total Tinnitus Handi- cap Inventory (THI) score using Cohen‘s formula. Second, general and tinnitus-specific audiometric tests were performed in on and off conditions of the neurostimulation system. Third, recordings were noted for tinnitus severity and treatment success on a visual analogue scale. Results: All 4 patients reported successful treatment with neurostimulation. The effect size after 3 months was 0.7, indicating an average effect, while the effect size measured during long-term follow-up was 1.75, indicating a substantial effect with major clinical implications. No changes in hearing level for both ears were measured. The neurostimulation system did not change the tinnitus pitch in any of the patients, and resulted in a minimal reduction of tinnitus loudness in only 2 patients. In all 4 patients the original tinnitus sound was replaced by another, pleasantly perceived sound. The average VAS score of perceived tinnitus severity was reduced from 8 to 3.25. The average VAS score for treatment success was 7.25. Conclusions: The long-term follow-up of neurostimulation treatment for chronic tinnitus shows promising results. Long-term results were better than those determined after a 3-month follow-up. In all patients the tinnitus was replaced by another sound, which was perceived as pleasant. Further studies are needed before accepting neurostimulation as a treatment modality for chronic, therapeutically refrac- tory tinnitus. Copyright (c) 2007 S. Karger AG, Basel.

Moderate therapeutic efficacy of positron emission tomography-navigated repetitive tran- scranial magnetic stimulation for chronic tinnitus: a randomised, controlled pilot study. J Neurol Neurosurg Psychiatry. 2007 Feb;78(2):152-156. Plewnia C, Reimold M, Najib A, Reischl G, Plontke SK, Gerloff C Brain-Stimulation Laboratory, Department of Psychiatry, University of Tuebingen, Tuebingen, Germany. christian.plewnia@uni-tuebingen.de

Background: Tinnitus has been shown to respond to modulations of cortical activity by high-frequency and low-frequency repetitive transcranial magnetic stimulation (rTMS). Objective: To determine the tinnitus-attenuating effects of a 2-week daily regimen of rTMS, navigated to the maximum of tinnitus-related increase in regional cerebral blood flow. Methods: Six patients with chronic tinnitus were enrolled in this sham-controlled crossover study and treated with 2x2 weeks of suprathreshold 1 Hz rTMS (30 min) applied to the region with maximal tinnitus- related increase in regional cerebral blood flow delineated by functional imaging with [15O]H2O positron emission tomography and a control area. Tinnitus-related distress was assessed before and after each treatment and 2 weeks after the end of the 4-week course of stimulation using a validated tinnitus questi- onnaire. Additional self-assessment scores of tinnitus change, loudness and annoyance were obtained. Results: In five of six patients, rTMS induced greater reduction of the tinnitus questionnaire score than sham stimulation. In two patients, all parameters measured (tinnitus change score, tinnitus loudness, tinnitus annoyance) showed unequivocal improvement. At the group level, the degree of response in the tinnitus questionnaire score was correlated with tinnitus-associated activation of the anterior cingulate cortex. Two weeks after the final stimulation, tinnitus had returned to baseline in all patients but one. Conclusion: Tinnitus can be attenuated by low-frequency rTMS navigated to each person‘s maximum tinnitus-related cortical hyperactivity. The effects are only moderate; interindividual responsiveness varies and the attenuation seems to wear off within 2 weeks after the last stimulation session. Notably, tinnitus- related anterior cingulate cortex activation seems to predict the response to rTMS treatment.

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