EP 50. High frequency stimulation of the rat dorsal cochlear nucleus inhibits tinnitus

• Published in: Clinical neurophysiology Vol. 127; no. 9; p. e197
• Main Authors: van Zwieten, G, Smit, J, Jahanshahi, A, Stokroos, R, Temel, Y
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2016
• Subjects: Neurology
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/j.clinph.2016.05.242

Introduction Tinnitus can cause a serious burden on patients and remains often treatment-resistant. Up to date no standard effective treatment is available. Deep brain stimulation (DBS) has been widely applied for various neurological disorders, most often in patients with Parkinson’s disease. There is growing evidence that deep brain stimulation might be able to interrupt the local altered neuronal activity found in tinnitus and hereby inhibit tinnitus perception. Multiple preclinical and clinical studies suggest that the dorsal cochlear nucleus (DCN) plays an important role in the development of tinnitus and could therefore be a target for DBS in tinnitus. We hypothesized that tinnitus can be treated with high-frequency DBS of the DCN. Objectives In this study we assessed treatment of experimental tinnitus with high-frequency and low-frequency DBS in the DCN in an animal model with behavioral signs of tinnitus in an intra-individual controlled experimental design. Materials and methods In ten Sprague Dawley rats the startle reflex using the pre-pulse inhibition (PPI) paradigm was measured as a pretest. Tinnitus was defined as an increase in the gap/no-gap ratio. After bilateral DBS implantation in the DCN the sham situation was assessed including screening of hearing using the auditory brainstem response (ABR). Unilateral tinnitus was induced using a 16 kHz octave-banded noise and the PPI and ABR were again measured. The effect of high-frequency (100 Hz, 60 ms pulse with, 100 mA) and low-frequency (10 Hz, 60 ms pulse with, 100 mA) DBS of the DCN on tinnitus was assessed after noise trauma. Results Histological examination showed that the electrodes were correctly positioned within the DCN. After noise trauma the gap/no-gap ratio was increased at 16 and 20 kHz ( p < 0.01). Hearing in the contralateral ear was not impaired by noise trauma as measured with ABR. Only during high-frequency DBS the gap/no-gap ratio normalized to baseline ( p < 0.01). Conclusion This study shows that high-frequency DBS of the DCN is effective in reducing experimental tinnitus in a validated animal model. Optimal parameters for stimulation and side effects should be further investigated. It is worthwhile to investigate the effect of DBS in other more accessible brain structures within the auditory pathway for human application.