Comparison of two configurations of transcranial direct current stimulation for aphasia treatment

To compare 2 configurations of transcranial direct current stimulation (tDCS) for treatment of aphasia.

Randomized cross-over study.

Patients with chronic post-stroke aphasia (n = 13).

tDCS was combined with word-finding therapy in 3 single sessions. In session 1, sham-tDCS/pseudo-stimulation was applied. In sessions 2 and 3, 2 active configurations were provided in random order: anodal tDCS over the left inferior frontal gyrus (l-IFG) and anodal tDCS over the left posterior superior temporal gyrus (l-STG). The optimal configuration was determined per individual based on a pre-set improvement in naming trained (> 20%) and untrained picture items (> 10%).

Overall, participants improved on trained items (median = 50%; interquartile range = 20-85) and post-treatment performance was highest in the active l-IFG condition (p = 0.040). Of the 13 participants, 6 (46%) showed relevant improvement during active tDCS; either in the l-IFG condition (n = 4; 31%) or in both the l-IFG and l-STG conditions (n = 2; 15%). On the untrained items there was no improvement (median = 0%; interquartile range  = 0-0).

This randomized cross-over single-session protocol to determine an optimal tDCS configuration for treatment of aphasia suggests that only performance on trained items can be used as guidance for configuration, and that it is relevant for half of the patients. For this subgroup, the l-IFG configuration is the optimal choice.