Table 3.
Summary of clinical trials from the last 10 years (2013–2022) investigating transcranial direct current stimulation (tDCS) for various chronic pain conditions
| Study | Country | Study design | Sample size | Chronic pain condition | Main results | Adverse events |
|---|---|---|---|---|---|---|
| De Souza 2021 [105] | Brazil | RCT | 58 | CHIK | Significant pain reduction was observed in the tDCS group compared to the sham group (n=14.303); no significant difference in functional capacity was observed (n=2797). | N/A |
| Ahn 2017 [104] | USA | RCT | 40 | Knee OA pain | Active tDCS significantly reduced Numeric Rating Scale of pain compared to sham tDCS after completion of the five daily sessions, and remained up to 3 weeks (n=20). | N/A |
| Chang 2017 [112] | Australia | RCT | 57 | Knee OA pain | All participants in the AT+EX group (n=13) and in the ST+EX group (n=12) reported an improvement in their knee OA symptoms following treatment. | Headache (n = 1); pain during primary stimulation (n = 1) |
| Harvey 2017 [113] | Canada | RCT | 14 | OA (n = 4); CLBP (n = 4); spinal cord injury (n = 1); other chronic neuropathic pain (n = 5) | Active but not sham tDCS significantly reduced pain (p >0.05). No change was observed in sleep parameters, in both the active and sham tDCS groups (all p ≥0.18). | N/A |
| Hazime 2017 [114] | Brazil | RCT | 92 | CLBP | The results suggest that tDCS + PES (mean reduction [MR] = −2.6, CI95% = −4.4 to −0.9) and PES alone are effective in relieving CLBP in the short term. However, only tDCS + PES induced a long-lasting analgesic effect. tDCS alone showed no clinical meaningful pain relief. | N/A |
| Khedr 2017 [106] | Egypt | RCT | 40 | Fibromyalgia | The effect of treatment differed in the two groups with higher improvement in the experimental scores of the patients in the real tDCS group (p = 0.001 for WPI, SS, VAS, pain threshold, and 0.002, 0.03 for HAM-A, HAM-D respectively). Ten sessions of actual tDCS over an M1 may induce pain relief and mood enhancement in patients with fibromyalgia. | N/A |
| Lagueux 2018 [115] | Canada | RCT | 22 | CRPS | GMI+tDCS induced no statistically significant reduction in pain compared with GMI+sham tDCS (n=22). | N/A |
| Thibaut 2017 [116] | USA | RCT | 33 | Spinal cord injury | Baseline comparisons between stimulation conditions showed no significant a priori differences except for gender (chi-square: 4.90; p =0.009). | N/A |
| Ayache 2016 [108] | France | RCT | 16 | Multiple sclerosis | Compared to sham, active tDCS yielded significant analgesic effects according to VAS and BPI global scales. The mean VAS0−100 pain ratings 7 days before and 7 days after stimulation showed significant decrease after active tDCS (p = 0.024), but no change after sham tDCS (p = 0.66). Analogously, the mean VAS0−100 pain ratings for days 1–3 before and after stimulation showed significant decrease after active tDCS (p = 0.021), and no improvement after sham tDCS (p = 0.56). | N/A |
| Brietzke 2015 [117] | Brazil | RCT | 28 | HCV | tDCS decreased VAS scores (p < 0.003), with mean decrease of 56%. | N/A |
| Mendonca 2016 [118] | Brazil | RCT | 45 | Fibromyalgia | This study has demonstrated that neuromodulation with tDCS, in association with aerobic exercise training, in fibromyalgia patients effects greater decreases in pain intensity than the individual techniques. The improvement from baseline was: for the tCDS group = 20.8%, for the AE group = 19.1%, for the tCDS/AE group = 31.5%. | Headache (n = 3); neck pain (n = 1); tingling (n = 5); skin redness (n = 11); somnolence (n = 5); concentration issues (n = 1) |
| Volz 2016 [119] | Germany | RCT | 20 | Chronic abdominal pain | The analgesic effects observed are unrelated to inflammation and disease activity, which emphasizes central pain mechanisms in CAP (n=20). | N/A |
| Donnell 2015 [120] | USA | RCT | 24 | Chronic myofascial pain | There were significant improvements for clinical pain and motor measurements in the active HD-tDCS group compared to the placebo group: responders with pain relief above 50% in the VAS at four-week follow-up (p=0.04); pain-free mouth opening at one-week follow-up (p<0.01); and sectional pain area, intensity and their sum measures contralateral to putative M1 stimulation during the treatment week (p<0.01). | N/A |
| Luedtke 2015 [109] | Germany | RCT | 135 | CLBP | This results of this trial on the effectiveness of transcranial direct current stimulation for the reduction of pain and disability do not support its clinical use for managing non-specific chronic low back pain (n=135). | N/A |
| Ngernyam 2015 [121] | Thailand | RCT | 20 | Spinal cord injury | Research revealed a significant decrease in pain intensity from pre- to post-session for active tDCS treatment (0.800, 95% CI = 0.410 to 1.190; p < 0.001) but no statistically significant change in pain intensity for the sham condition (0.025, 95% CI = −0.049 to 0.549; p = 0.096). The active treatment condition (anodal tDCS over M1) but not sham treatment resulted in significant decreases in pain intensity. | N/A |
| Sakrajai 2014 [122] | Thailand | RCT | 31 | Myofascial pain syndrome | After 4 weeks, 15 (94%) of the participants in the tDCS group reported a 50% or greater reduction in average pain intensity, while only 7 (47%) of the sham group participants reported these levels of pain reduction. | N/A |
| Hagenacker 2014 [123] | Germany | RCT | 17 | TN | Anodal tDCS over 2 weeks ameliorates intensity of pain in TN. RS (verbal rating scale) decreased after anodal stimulation from baseline by 18% (±SD 29%), while sham stimulation led to an 11% (±30.8%) increase of VRS. Attack frequency was not significantly decreased between sham or anodal stimulation (p = 0.123). One patient was completely pain free after anodal stimulation. | N/A |
| Souto 2014 [124] | USA | RCT | 20 | Chronic pain HTLV-I infected patients | There were 8 (80%) responders (reduction of 50% or more in pain intensity) in the tDCS group and 3 (30%) in the sham group (p =0.03). Both groups demonstrated improvements for most associated factors evaluated. However, there was no difference in between-group comparison analyses. | Mild adverse events were reported by 100% of patients in the tDCS group and 90% in the sham group. |
| Wrigley 2013 [125] | Australia | RCT | 10 | Spinal cord injury | In this trial, tDCS did not provide any pain relief in subjects with neuropathic SCI pain (n=10). A similar lack of effect was also seen after sham treatment. | N/A |
| Jensen 2013 [126] | USA | RCT | 31 | Spinal cord injury | Very weak and mostly non-significant associations were found between changes in EEG-assessed brain activity and pain (n=31). | N/A |
| Kim 2013 [127] | Korea | RCT | 60 | PDPN | The reduction in VAS (visual analog scale) for pain was sustained after 2 and 4 weeks of follow-up in the M1 group compared with the sham group (p<0.001, p=0.007). Significant differences were observed among the three groups over time in VAS for pain (p<0.001), CGI score (p=0.01), and PT (p<0.001). No significant difference was observed among the groups in sleep quality, anxiety score, or BDI score immediately after tDCS. | N/A |
| Villamar 2013 [107] | USA | RCT | 18 | fibromyalgia | Found that both active stimulation conditions led to significant reduction in overall perceived pain as compared to sham (n=18). | N/A |
CHIK chikungunya disease, OA osteoarthritis, TN trigeminal neuralgia, CLBP chronic low back pain, CRPS complex regional pain syndrome, PDPN painful diabetic neuropathy, HTLV-I human T lymphotropic virus type I, VAS visual analog scale