Table 2.
Methodological characteristics of the studies analyzed
| Authors | Sample size | Intervention | Intervention duration (number of sessions) | Electrode position | ||
|---|---|---|---|---|---|---|
| Experimental group | Control group | Anode (position in the International System of Electrodes) | Cathode (reference electrode) | |||
| Ahn et al. [35] (2017) | 26 | tDCS + CDT | Sham tDCS + CDT | 2 weeks (10) | Bilaterally to the pharyngeal motor cortices, which were 15 cm from central electrode to A1 and 2 cm in the front direction on the right, and from central electrode to A2 in the front direction on the left | Contralateral supraorbital region |
| Farpour et al. [41] (2023) | 44 | tDCS + CDT | Sham tDCS + CDT | 5 days (5) | Undamaged hemisphere on the supra marginal gyrus (CP5 or CP6 according to 10–10 International Electroencephalogram System) | Contralateral supraorbital region |
| Kumar et al. [32] (2011) | 14 | tDCS + CDT | Sham tDCS + CDT | 1 week (5) | Undamaged hemisphere (C4-T4 right and C3-T3 left) | Contralateral supraorbital region |
| Mao et al. [36] (2021) | 40 | tDCS + CDT | CDT | 8 weeks (48) |
Sensory motor cortex, uninjured hemisphere (In the middle of C3-T3) |
Opposite shoulder |
| Pingue et al. [33] (2018) | 40 | tDCS + CDT | Sham tDCS + CDT | 10 days (10) | Injured hemisphere (C4-T4 right and C3-T3 left) | Contralateral hemisphere |
| Sawan et al. [34] (2020) | 40 | tDCS + CDT | Sham tDCS + CDT | 2 weeks (5) | Uninjured hemisphere (C4-T4 right and C3-T3 left) | Contralateral supraorbital region |
| Shigematsu et al. [37] (2013) | 20 | tDCS + CDT | Sham tDCS + CDT | 10 days (10) | Homolateral hemisphere (15 cm from the central electrode to A1 and 2 cm in the right frontal direction and central electrode to A2 in the left frontal direction) | Contralateral supraorbital region |
| Suntrup-Krueger et al. [38] (2018) | 60 | tDCS + CDT | Sham tDCS + CDT | 4 days (4) | Centre of the cortico-motor swallowing network (not described) | Contralateral supraorbital region |
| Wang et al. [39] (2020) | 28 | tDCS + CDT | Sham tDCS + CDT | 4 weeks (20) | Bilateral cerebral hemispheres (not described) | Contralateral supraorbital region |
| Wang et al. [42] (2023) | 40 | tDCS + CDT | CDT | 2 weeks (10) | Swallowing sensorimotor cortex of the unaffected side | Contralateral shoulder |
| Yang et al. [40] (2012) | 16 | tDCS + CDT | Sham tDCS + CDT | 2 weeks (10) | Pharyngeal motor cortex of the lesioned hemisphere (not described) | Contralateral supraorbital region |
tDCS: Transcranial direct current stimulation. CDT: Conventional dysphagia therapy