Transcranial Electrical and Acoustic Stimulation for Tinnitus

Transcranial Electrical and Acoustic Stimulation for Tinnitus: A Randomized Double Blind Clinical Trial

Transcranial electrical stimulation (tES) is an umbrella term for non-invasive brain stimulation using weak currents. It comprises transcranial direct current stimulation (tDCS), which is the most established and used method applying constant direct current, transcranial alternating current stimulation (tACS) with sinusoidal current in a fixed frequency, and finally transcranial random noise stimulation (tRNS), which is a subform of tACS generating a random range of low and high frequency alternating currents.

A pilot study conducted by Shekhawat and colleagues in 2015 tested the effects of simultaneous electrical and acoustic stimulation. Using tDCS and bilateral broadband noise simultaneously, they found that more tinnitus patients report an improvement in tinnitus perception in comparison to conditions only using tDCS or sham. Further similar approaches very published in recent years, namely a pilot study conducted by Teissmann et al in 2014; study protocols of Rabau et al. in 2015 and Shekhawat et al. in 2015; and an experimental study by Lee et al. in 2017. Results were indicative of a superior efficacy of combined electrical and acoustic approaches, while large-scale controlled studies have not been performed. The need for extension and replication of these approaches is therefore timely.

The aim behind our proposed approach, similar to the bimodal approaches above, is to couple the effects of tRNS and acoustic stimulation (AS) for better temporary tinnitus suppression and possible reversal of maladaptive neuroplasticity related to tinnitus. We aim at targeting the (bilateral) auditory cortex with tRNS as in former studies and combine it with white noise (WN) stimulation. This specific combination is novel in its nature and is building on cortical excitability following tRNS.

Inclusion Criteria:

• Male and female patients 18 years to 75 years of age (younger age limit according to corona virus protection concepts and measures of the FOPH: Schutzkonzepte und -massnahmen (admin.ch))
• Persistent chronic tinnitus with duration of more than 3 months
• Signed Informed Consent after being informed about the study
• Fluent in German or English
• Tinnitus with a THI Grade 2 to 4 (18-76 points)
• Willing and able to attend the study visits

Exclusion Criteria:

• Actual neurological or psychiatric disorders
• Hyperacusis
• Regular intake of medication influencing the central nervous system (e.g. neuroleptics, hypnotics, sedatives, and anti-epileptics)
• Implanted pacemaker
• Surgical implants in the head region, such as cochlea implants
• Asymmetrical hearing (more than 20dB side difference), pantonal hearing loss > 40dB in any measured frequency up to 2kHz
• Women who are pregnant or breast feeding
• Intention to become pregnant during the course of the study
• Known or suspected non-compliance, drug or alcohol abuse
• Participation in another study with investigational drug within the 30 days preceding and during the present study,
• Enrolment of the investigator, his/her family members, employees and other dependent persons