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Results: responders were 8 out of 14. Two patients dropped out for transient tinnitus worsening. Active rTMS induced an overall significant, but transient, improvement (35% of the basal score) of subjective tinnitus perception, that was independent either by tinnitus laterality or by mood or anxiety changes. No correlations were found between response to rTMS and tinnitus duration, initial subjective score or patients‘ age. When asked after the study was over, 71.4% of patients failed to identify the temporal se- quence of the real or sham rTMS interventions. Conclusions: beneficial effects of rTMS on tinnitus are independent by mood changes. Moreover, they appear in the context of an original placebo stimulation designed to more closely replicate somatic sensation of active stimulation. Due to the limited temporal duration of the clinical benefit, these neuro- modulatory effects could be mediated by transient functional changes taking place in the neural circuits underlying tinnitus processing.

Effect of vagal nerve stimulation on a rat tinnitus model. (Abstract of ARO Meeting Denver, Colorado) Joseph Ursick1, Dianne Durham1, Hinrich Staecker1, Phillippe Lefebvre2, Jean Schoenen3, Martin Scholsem4, Thomas Imig5 1Department of Otolaryngology Head and Neck Surgery, Kansas University Medical Center, 2Department of Otolaryngology, University of Liege, Belgium, 3Department of Neurology, University of Liege, Belgium, 4Department of Neurosurgery, University of Liege, Belgium, 5Department of Molecular and Integrative Physiology, Kansas University Medical Center

Vagal nerve stimulation (VNS) has been used to treat a variety of disorders including epilepsy and de- pression. Recently, VNS has been shown to decrease neuronal spontaneous activity (SA) associated with chronic facial pain in a rat model. Several animal models suggest that tinnitus may be associated with changes in SA in the dorsal cochlear nucleus (DCN), inferior colliculus, and auditory cortex. Using a rat model of noise-induced tinnitus (Durham and Imig, JCN 490:391-413, 2005), we examined the effects of VNS on 2-deoxyglucose (2DG) uptake in the DCN of three groups of Long Evans rats. Rats were anesthetized and exposed to 15-20 kHz band pass noise at 115 dB SPL for one hour. Five days later, the VNS group (n=4) was implanted with a vagal nerve stimulator (Cyberonics, Inc.). On day 6, the stimulators were activated and on day 7, 2DG was injected. A non-VNS group (n=8) received acoustic trauma and 2DG injection after 7 days, but no VNS stimulation. A control group (n=9) recei- ved neither noise exposure nor VNS. Animals were placed in a quiet sound attenuated chamber for 45 minutes during 2DG uptake. Rats were sacrificed and brainstem sections were prepared for 2DG film autoradiography. Optical density (OD) measurements were used to determine 2DG uptake in the high frequency (HF) and low frequency (LF) regions of the DCN. These OD values were used to calculate a symmetry ratio (ipsi HF/LF)/(contra HF/LF). In the control group, the symmetry ratio was near one. Noise exposure decreases 2DG uptake in the high frequency region of the ipsilateral DCN. Thus, both noise trauma groups showed a decreased symmetry ratio. However, the VNS group had a symmetry ratio that was intermediate to those in control and non-VNS groups. VNS stimulation may reduce the alteration of SA caused by noise trauma and thus warrants further study as a potential tinnitus therapy (Supported by the Tinnitus Research Consortium and the Dept. of Otolaryngology Head and Neck Surgery, KUMC).

Long-Term Evaluation of Treatment of Chronic, Therapeutically Refractory Tinnitus

by Neurostimulation. Stereotact Funct Neurosurg. 2007 Jan 26;85(4):150-157. Bartels H, Staal MJ, Holm AF, Mooij JJ, Albers FW Department of Otorhinolaryngology, University Medical Center Groningen, Groningen, The Netherlands

Objective: Long-term evaluation of treatment of chronic, therapeutically refractory tinnitus by means of

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