Magnetic and electrical stimulation of the auditory cortex for intractable tinnitus

Abstract

Tinnitus is a distressing symptom that affects up to 15% of the population for whom no satisfactory treatment exists. The authors present a novel surgical approach for the treatment of intractable tinnitus, based on cortical stimulation of the auditory cortex. Tinnitus can be considered an auditory phantom phenomenon similar to deafferentation pain, which is observed in the somatosensory system. Tinnitus is accompanied by a change in the tonotopic map of the auditory cortex. Furthermore, there is a highly positive association between the subjective intensity of the tinnitus and the amount of shift in tinnitus frequency in the auditory cortex, that is, the amount of cortical reorganization. This cortical reorganization can be demonstrated by functional magnetic resonance (fMR) imaging. Transcranial magnetic stimulation (TMS) is a noninvasive method of activating or deactivating focal areas of the human brain. Linked to a navigation system that is guided by fMR images of the auditory system, TMS can suppress areas of cortical plasticity. If it is successful in suppressing a patient's tinnitus, this focal and temporary effect can be perpetualized by implanting a cortical electrode. A neuronavigation-based auditory fMR imaging-guided TMS session was performed in a patient who suffered from tinnitus due to a cochlear nerve lesion. Complete suppression of the tinnitus was obtained. At a later time an extradural electrode was implanted with the guidance of auditory fMR imaging navigation. Postoperatively, the patient's tinnitus disappeared and remains absent 10 months later. Focal extradural electrical stimulation of the primary auditory cortex at the area of cortical plasticity is capable of suppressing contralateral tinnitus completely. Transcranial magnetic stimulation may be an ideal method for noninvasive studies of surgical candidates in whom stimulating electrodes might be implanted for tinnitus suppression.

The mechanisms of tinnitus: Perspectives from human functional neuroimaging

“…However, if the subsequent rTMS applied to the site of maximal TI-related activity is successful in reducing TI, then this finding increases confidence that this cortical site plays a causal role in TI." We provide only two examples of this approach (Plewnia et al, 2007 andde Ridder et al, 2004). We conclude this section on page 20 by saying "Although requiring replication, these two rTMS studies point to the essential role of auditory cortex and regions of multisensory integration in the perception of TI."…”

“…When rTMS was subsequently targeted to this site, six patients reported TI relief. In an earlier case study, de Ridder et al (2004) reported a relative reduction in the right auditory cortical response to music presented binaurally. While this result is consistent with the left-sided laterality of the hearing loss, de Ridder and colleagues claim that the result also supports the conclusion that TI-related activity was greater on the side contralateral to (leftsided) TI.…”

“…Fortunately many patients are able to voluntarily modify their TI, for example by eye gaze or facial movement (Levine, 1999b). In others, the TI level can be modulated in other ways, for example by a noise masker (Mirz et al, 1999;Melcher et al, 2000), by the administration of pharmacological treatments such as lidocaine (Staffen et al, 1999;Andersson et al, 2000) or by the application of neural stimulation using a TMS coil (de Ridder et al, 2004;. TI-related activity can be identified by taking advantage of these manipulations to create experimental paradigms that lend themselves to statistical subtraction.…”

Hearing suppression induced by electrical stimulation of human auditory cortex

“…Years later Sinha et al (2005) observed, in a single chronically implanted patient, that electrical stimulation of the surface of the left posterolateral STG resulted in reversible, moderate hearing loss in the right ear. In what may be a related phenomenon, it has also been reported that tinnitus is suppressed by electrical stimulation of posterolateral STG (de Ridder et al, 2004) and by repetitive transcranial magnetic stimulation (rTMS) directed toward temporal-parietal cortex (Plewnia et al, 2003). These observations raise the possibility that temporal lobe cortical stimulation might be an effective treatment for patients with intractable tinnitus.…”

Surgical treatment by electrical stimulation of the auditory cortex for intractable tinnitus

“…Drouot et al 8 suggested a sequential pattern between 1 and 3 V for the analgesic stimulation. De Ridder et al 9 proposed continuous mode and long stimulation for the tinnitus treatment. The programming for the stimulation, at first, followed our experience in analgesic stimulation.…”