Abstract
Prominent theories of tinnitus suggest the functional connectivity between the auditory cortex and disparate brain areas involved in auditory memory and the self-percept have become maladaptive. Previous neuromodulation studies targeted this connectivity as a treatment avenue with negligible success. This pilot study investigated feasibility, safety, and trends of effect from a novel brain stimulation technique (high-definition transcranial infra-slow pink noise stimulation (HD-tIPNS)) for treatment of chronic tinnitus.
A double blinded randomised placebo-controlled trial was conducted, with clinical outcomes collected at baseline, 3-days, and 10-days post-treatment. Twenty participants were randomly allocated to a HD-tIPNS or sham stimulation group. Participants attended 12 stimulation sessions over four weeks. Baseline and follow-up assessments consisted of 10-minute resting-state electroencephalography recordings and several questionnaires. Friedman and Mann Whitney tests were performed on questionnaire data to assess changes within and between each group. Feasibility measures and trend of effect on clinical outcomes was assessed using descriptive statistics. No long-term adverse events were reported. Mild side effects included headache and dizziness, indicating the safety of this stimulation. Participants adhered to the study protocol with minimal difficulty, supporting the feasibility of the protocol.
Both sham stimulation and HD-tIPNS groups improved significantly on the Tinnitus Functional Index 10-days post-treatment. Both groups also significantly improved on the Depression, Anxiety, and Stress scale 10-days post-treatment. Standard low-resolution electromagnetic brain tomography revealed reduced beta-1 activity in the posterior cingulate cortex at 10-days post-treatment for the sham group. Whereas the treatment group found reduced beta-1 activity in the inferior parietal lobule at 3-days post-treatment.