The Effects of Compensatory Auditory Stimulation and Transcranial Direct Current Stimulation on Tinnitus Perception

Tinnitus refers to persistent "ringing in the ears" in absence of external sound. For some individuals tinnitus can be disabling. Most tinnitus is of idiopathic origin and currently there are no reliable treatment options available. Existing approaches, such as hearing aids, counseling, and noise masking typically provide only partial relief and only for a minority of patients. Newer exploratory methods include tailored auditory stimulation and various brain stimulation techniques. While these techniques show great promise in a subset of subjects (maybe about 1/3), it is hard to anticipate which, if any, will benefit a given patient.

Transcranial Direct Current Stimulation (tDCS) has been explored for a number of neurological conditions, and it is most effective when paired with some form of training (e.g. motor rehab after stroke). For tinnitus however this treatment modality has only been tested in isolation. The purpose of this pilot study is to explore the benefits of combining tailored compensatory auditory stimulation with tDCS.

There is widespread consensus in the research community that tinnitus originates with some peripheral hearing deficit, and that maladaptive central plastic mechanisms subsequently lead to the tinnitus percept. Most individuals with tinnitus have audiometric evidence of hearing loss. Our hypothesis is that reduced input to the auditory pathway leads to increased sensitivity (auditory gain) and finally aberrant activity in the frequency band with hearing loss. In this view, auditory stimulation that compensates for the reduced input can potentially revert the maladaptive plasticity.This is consistent with the reported benefits of hearing aids and tailored auditory stimulation. Our hypothesis is that tDCS can boost adaptation induced by compensatory auditory stimulation to reduce the strength of the phantom percept.