Transcranial Magnetic Stimulation for Tinnitus: Influence of Tinnitus Duration on Stimulation Parameter Choice and Maximal Tinnitus Suppression *Dirk De Ridder, †Edwin Verstraeten, *Karolien Van der Kelen, *Gert De Mulder, ‡Stefan Sunaert, *Jan Verlooy, *Paul Van de Heyning, and §Aage Moller *Department of Neurosurgery and Otorhinolaryngology, University Hospital Antwerp, Belgium, †Department of Psychology, Free University Brussels, Belgium, ‡Department of Radiology, University Hospital Louvain, Belgium, and §School of Behavioral and Brain Sciences University of Texas at Dallas, U.S.A. Objective: Tinnitus is a distressing symptom for which few treatments exist. It leads to an important decrease in quality of life in 2 to 3% of the population. Tinnitus is considered a phantom sound, the result of cortical reorganization. Trans- cranial magnetic stimulation (TMS) is a noninvasive method to modulate cortical reorganization and has been shown to be able to influence tinnitus perception. Study Design: Retrospective analysis. Setting: Tertiary referral center. Patients: The effect of TMS of the contralateral auditory cortex in 114 patients with unilateral tinnitus is investigated as one of the selection criteria used for surgical implantation of electrodes on the auditory cortex. Intervention: TMS is performed at 90% of motor threshold at 1, 3, 5, 10, and 20 Hz, with each stimulation session consisting of 200 pulses. Results were classified as no effect (0–19% improvement), partial effect (20–79% improvement), and good effect (80–100 suppression). Main Outcome Measures: TMS had a good effect in 25% of the patients studied, partial effect in 28% patients, and no effect in 47%. Results: TMS at 200 pulses is capable of tinnitus suppression for seconds only. The results were influenced by tinnitus duration: the longer the tinnitus exists, the lower the stim- ulation frequency that yields maximal tinnitus suppression (p , 0.001). The maximal amount of tinnitus suppression decreases in time (p , 0.01), resulting in a 2% decrease of potential tinnitus suppression per year. Conclusion: TMS of the auditory cortex is capable of modifying tinnitus perception for a very short time. The max- imal amount of suppression and best stimulation frequency depends on the tinnitus duration. Key Words: Duration—High frequency stimulation—Low frequency stimulation—Tinnitus— TMS—Transcranial magnetic stimulation. Otol Neurotol 26:616–619, 2005. INTRODUCTION Tinnitus is a distressing symptom for which few treatments exist. An estimated 15% of the population is afflicted, and in 2 to 3%, it leads to a noticeable decrease in the quality of life (1). Tinnitus can vary in intensity where the variations are synchronous with the pulse (pulsatile tinnitus), or it can be constant or varying without relationship to the heartbeat (nonpulsatile tinnitus). It now generally is accepted that some forms of tinnitus are auditory phantom phenomena (2) similar to central neuropathic pain (3) or other forms of pain (4). These phantom phenomena are considered to be the result of reorganization of CNS structures (5,6). Re- cently, it has been shown that the normal tonotopic map is altered in tinnitus (6) and the subjective tinnitus strength is correlated with the amount of shift of the tinnitus frequency in the auditory cortex (6). This is similar to the phantom limb phenomenon where there is a strong correlation between the amount of reorganiza- tion of the somatosensory cortex and the amount of phantom limb pain (5). The tonotopic map can become reorganized in reaction to any abnormal (7,8) or even normal (9) pattern of neural activity from the periphery (8,9) through expression of neural plasticity. Functional imaging, using both fMRI (10) and PET scanning (11–14) have supported the hypothesis of cortical reorganization in tinnitus patients. Transcranial magnetic stimulation (TMS) is a non- invasive tool that makes it possible to stimulate specific Address correspondence and reprint requests to Dirk De Ridder, Department of Neurosurgery, University Hospital Antwerp, Wilrijkstraat 10, 2650 Edegem, Belgium; E-mail: dirk.de.ridder@uza.be Otology & Neurotology 26:616–619 Ó 2005, Otology & Neurotology, Inc. 616 JOBNAME: ajo 26#4 2005 PAGE: 1 OUTPUT: Wed June 15 10:19:42 2005 lww/ajo/99855/MAO200075 Prod. #MAO200075