Table 2: Overview of study parameters of tDCS studies.
Main author and year | Instrument | Stimulation (anodal) | Sample | Time (minutes) | Intensity (mA) | Session (active + sham) | Improvement (perception or distress) | Sustained effect |
Randomized clinical trials | ||||||||
Shekhawat, et al., 2013 [63] | CGI, VAS | LTPC | 25 | 10, 15, and 20 with each current | 1 and 2 | 6 | Drop of 0.2 to 0.9 mean points on VAS | overnight relief |
Forogh, et al., 2015 [64] | THI, VAS, CGI | LTPC | 22 | 20 | 2 | 5 | No improvement | none |
Pal, et al., 2015 [65] | THI, STSS, HADS, VAS, CGI | prefrontal cortex | 42 | 20 | 2 | 5 | No improvement | none |
Shekhawat, et al., 2015 [58] | MML, VAS | LTPC | 10 | 20 | 2 | 4 | Drop of 1.2 point on VAS. No change in MML | transient |
Shekhawat, et al., 2013 [63] | TFI, MML, TCHQ, TSNS, HADS, THQ, HHI, CGI, VAS | LTPC (followed by hearing aids for 6 months) | 40 | 20 | 2 | 5 | No improvement | none |
Teismann, et al., 2014 [15] | THI, VAS, THQ, TQ | LAC (plus tailor made notched music training) | 34 | 30 | 2 | 5 | Drop only on THQ, but not on THI or VAS | 5 to 31 days |
Randomized crossover clinical trials | ||||||||
Vanneste, et al., 2011 [32] | VAS | RDLPFC | 12 | 20 | 1.5 | 2 | Drop of perception (41.67% on VAS) and distress (43.20% on VAS) | 18 to 62 hours (mean = 24h) |
Garin, et al., 2011 [66] | VAS | LTPC | 20 | 20 | 1 | 3 | Significant drop of VAS score | < 1 hour |
Faber, et al., 2012 [67] | VAS, HADS | RDLPFC | 15 | 20 | 1.5 | 6 | Significant drop of VAS score. No changes in HADS scores | not mentioned |
Legend: AC: Auditory Cortex; CGI: Clinical Global Improvement; DLPFC: Dorsolateral Prefrontal Cortex; HADS: Hospital Anxiety and Depression Scale; HHI: Hearing Handicap Inventory; LTPC: Left Temporoparietal Cortex; MML: Minimal Masking Level; RDLPFC: Right Dorsolateral Prefrontal Cortex; STSS: Subjective Tinnitus Severity Scale; TCHQ: Tinnitus Case History Questionnaire; TFI: Tinnitus Functional Index; THI: Tinnitus Handicap Inventory; THQ: Tinnitus Handicap Questionnaire; TPC: Temporoparietal Cortex; TSNS: Tinnitus Severity Numeric Scale; and VAS: Visual Analogue Scale.