Department of Psychiatry, University of Regensburg, Germany.
Brain Stimul. 2008 Jul;1(3):192-205. doi: 10.1016/j.brs.2008.06.003. Epub 2008 Jul 1.
Tinnitus affects 10% of the population, its pathophysiology remains incompletely understood, and treatment is elusive. Functional imaging has demonstrated a relationship between the intensity of tinnitus and the degree of reorganization in the auditory cortex. Experimental studies have further shown that tinnitus is associated with synchronized hyperactivity in the auditory cortex. Therefore, targeted modulation of auditory cortex has been proposed as a new therapeutic approach for chronic tinnitus.
Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are noninvasive methods that can modulate cortical activity. These techniques have been applied in different ways in patients with chronic tinnitus. Single sessions of high-frequency rTMS over the temporal cortex have been successful in reducing the intensity of tinnitus during the time of stimulation and could be predictive for treatment outcome of chronic epidural stimulation using implanted electrodes.
Another approach that uses rTMS as a treatment for tinnitus is application of low-frequency rTMS in repeated sessions, to induce a lasting change of neuronal activity in the auditory cortex beyond the duration of stimulation. Beneficial effects of this treatment have been consistently demonstrated in several small controlled studies. However, results are characterized by high interindividual variability and only a moderate decrease of the tinnitus. The role of patient-related (for example, hearing loss, tinnitus duration, age) and stimulation-related (for example, stimulation site, stimulation protocols) factors still remains to be elucidated.
Even in this early stage of investigation, there is a convincing body of evidence that rTMS represents a promising tool for pathophysiological assessment and therapeutic management of tinnitus. Further development of this technique will depend on a more detailed understanding of the neurobiological effects mediating the benefit of TMS on tinnitus perception. Moreover clinical studies with larger sample sizes and longer follow-up periods are needed.
耳鸣影响了 10%的人群，其病理生理学仍然不完全清楚，且治疗方法难以捉摸。功能影像学已证明耳鸣的强度与听觉皮层的重组程度之间存在关系。实验研究进一步表明，耳鸣与听觉皮层的同步过度活跃有关。因此，靶向调节听觉皮层被提议作为慢性耳鸣的一种新的治疗方法。
重复经颅磁刺激（rTMS）和经颅直流电刺激（tDCS）是可以调节皮质活动的非侵入性方法。这些技术已以不同的方式应用于慢性耳鸣患者。颞叶皮层的高频 rTMS 单次治疗已成功地在刺激期间降低了耳鸣的强度，并可能对使用植入电极的慢性硬膜外刺激的治疗结果具有预测性。
另一种使用 rTMS 作为耳鸣治疗方法的方法是在多次重复疗程中应用低频 rTMS，以诱导听觉皮层中神经元活动的持久变化，超出刺激持续时间。几项小型对照研究一致证明了这种治疗的有益效果。然而，结果的特点是个体间变异性高，只有耳鸣的适度降低。患者相关（例如，听力损失、耳鸣持续时间、年龄）和刺激相关（例如，刺激部位、刺激方案）因素的作用仍有待阐明。
即使在这个研究的早期阶段，也有令人信服的证据表明 rTMS 代表了一种有前途的工具，可用于耳鸣的病理生理学评估和治疗管理。这项技术的进一步发展将取决于对介导 TMS 对耳鸣感知有益作用的神经生物学效应的更详细了解。此外，还需要进行具有更大样本量和更长随访时间的临床研究。
