Low Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) in Brain Hyperexcitability Disorders Like Tinnitus and Auditory Hallucinations

Abstract

(from the chapter) Chronic tinnitus, the perception of sound or noise in the absence of acoustical stimulation, is a debilitating condition affecting some 0.5-1% of the population of the western world. At the present time there is no satisfactory treatment and no objective method for diagnosis and evaluation of treatment effects (Dobie, 1999). Like auditory hallucinations, tinnitus is considered as an auditory phantom perception, related to plastic alterations in the auditory cortex (Muhlnickel, 1998). Electrophysiologic (Kaltenbach, 2000) and functional neuroimaging studies (Arnold, 1996; Mirz, 2000) demonstrated, that chronic tinnitus is associated with excessive spontaneous activity in the central auditory system. Repetitive transcranial magnetic stimulation (rTMS) offers a noninvasive method for altering excitability of the brain (George, 1996). Involving the production of intermittent magnetic fields in the range of 1,5 - 2 T (tesla), rTMS is powerful enough to cause neuronal depolarisation in the cortex of humans, taking advantage of the fact that magnetic fields pass largely undistorted through the scalp and scull. Electrophysiological as well as functional imaging studies have demonstrated that repetitive transcranial magnetic stimulation induces alterations of excitability in distinct cortical areas that outlast the stimulation period. Low frequency rTMS (