Noninvasive and Invasive Neuromodulation for the Treatment of Tinnitus: An Overview

Objective: Nonpulsatile tinnitus is an auditory phantom percept characterized as a tone, or a noise-like sound such as a hissing or buzzing sound or polyphonic, in the absence of any objective physical sound source. Although advances have been made in symptomatic pharmacologic and nonpharmacologic treatments, these treatments are unable to eliminate the tinnitus sensation in most patients. A novel approach using noninvasive and invasive neuromodulation has emerged as an interesting and promising modality for tinnitus relief. Methodology: We review noninvasive neuromodulation techniques including transcranial magnetic stimulation, transcranial direct current stimulation, transcutaneous electrical nerve stimulation, and cortical neurofeedback, as well as invasive neuromodulation techniques including auditory cortex stimulation, dorsolateral prefrontal cortex stimulation, subcutaneous occipital nerve stimulation, and deep brain stimulation, as potential treatments of tinnitus. Conclusion: Although the different techniques introduced revealed promising results, further research is needed to better understand how these techniques work and how the brain responds to neuromodulation. More sophisticated stimulation regimens and parameters should be developed to dynamically stimulate various regions at different frequencies and intensities, physiologically tailored to the patient's brain state in an attempt to maximize efficacy.