Transcranial Direct Current Stimulation (tDCS) for the Treatment of Tinnitus

The purpose of this study is to determine if repeated sessions of transcranial direct current stimulation (tDCS) are effective for treating chronic subjective tinnitus. Previous studies have reported brief improvements in tinnitus after safe and noninvasive stimulation of the auditory cortex or limbic system. The investigators hypothesize that a greater improvement in tinnitus will be achieved following repeated sessions of tDCS that target both auditory and limbic systems.

Subjective tinnitus is a distressing condition characterized by the sensation of sound or noise in the absence of internal or external stimuli. Research indicates that tinnitus may develop due to maladaptive plastic changes in the auditory cortex and limbic system. These changes can be targeted using safe and noninvasive brain stimulation techniques like transcranial direct current stimulation (tDCS). TDCS alters the excitability of the cortex using a weak direct current and may lead to long-term plastic changes, making it a potential therapeutic tool for the treatment of tinnitus. Transient improvements in tinnitus have been reported after inhibitory stimulation of the auditory cortex and after excitatory stimulation of the prefrontal cortex, however the effects of a combined stimulation paradigm remain unknown. The investigators hypothesize that a cumulative effect will be observed following repeated sessions of tDCS by modulating both the excitability of the auditory cortex and prefrontal cortex.

Cathodal stimulation of the auditory cortex with an anode (reference electrode) over the prefrontal cortex. Stimulation will be applied for 20 minutes at 2 mA.

Tinnitus Handicap Inventory (THI; Newman, Jacobson, & Spitzer, 1996; French version: Ghulyan-Bédikian et al., 2010)

Inclusion Criteria: Age of at least 18 years Chronic tinnitus for at least 1 year Diagnosis of chronic subjective non-pulsatile tinnitus Age-adjusted normal (sensorineural) hearing Score of 25 or above on the Mini-mental state examination (MMSE) Must comply with use of contraceptives during interventions Exclusion Criteria: Objective tinnitus Concurrent treatment for tinnitus Prior exposure to transcranial direct current stimulation (tDCS) Electronic implants or metallic objects in body, including cardiac pacemakers, cochlear implants, implanted medical pump, metal plate in skull, metal implant in the skull or eyes (other than dental appliances or fillings) Skin conditions where electrodes will be applied Major neurological co-morbidities History of epilepsy and/or seizures Pregnancy and/or lactation