Effects of tDCS on Language Recovery in Post-Stroke Aphasia: A Pilot Study Investigating Clinical Parameters and White Matter Change with Diffusion Imaging

Abstract

Objectives: In this pilot study we investigated the effects of transcranial direct current stimulation (tDCS) on language recovery in the subacute stage of post-stroke aphasia using clinical parameters and diffusion imaging with constrained spherical deconvolution-based tractography. Methods: The study included 21 patients with subacute post-stroke aphasia. Patients were randomly classified into two groups with a ratio of 2:1 to receive real tDCS or sham tDCS as placebo control. Patients received 10 sessions (5/week) bi-hemispheric tDCS treatments over the left affected Broca’s area (anodal electrode) and over the right unaffected Broca’s area (cathodal stimulation). Aphasia score was assessed clinically using the language section of the Hemispheric Stroke Scale (HSS) before and after treatment sessions. Diffusion imaging and tractography were performed for seven patients of the real group, both before and after the 10th session. Dissection of language-related white matter tracts was achieved, and diffusion measures were extracted. A paired Student’s t-test was used to compare the clinical recovery and diffusion measures of the dissected tracts both pre- and post- treatment. The partial correlation between changes in diffusion measures and the language improvements was calculated. Results: At baseline assessment, there were no significant differences between groups in demographic and clinical HSS language score. No significant clinical recovery in HSS was evident in the sham group. However, significant improvements in the different components of HSS were only observed in patients receiving real tDCS. Associated significant increase in the fractional anisotropy of the right uncinate fasciculus and a significant reduction in the mean diffusivity of the right frontal aslant tract were reported. A significant positive correlation was found between the changes in the right uncinate fasciculus and fluency improvement. Conclusions: Aphasia recovery after bi-hemispheric transcranial direct current stimulation was associated with contralesional right-sided white matter changes at the subacute stage. These changes probably reflect neuroplasticity that could contribute to the recovery. Both the right uncinate fasciculus and right frontal aslant tract seem to be involved in aphasia recovery.

Investigating NIBS for language rehabilitation in aphasia

“…Transcranial Direct Current Stimulation: Studies using tDCS for chronic non-fluent aphasia mainly used bilateral stimulation of left and right hemispheres for naming, comprehension, repetition, writing, and discourse even though unilateral anodal stimulation was the most commonly used tDCS modulation in the current scoping review (Costa et al, 2015;De Tomasso et al, 2015;Fiori et al, 2019;Manenti et al, 2015;Marangolo et al, 2016, Norise et al, 2017Pisano et al, 2021). The duration of all types of tDCS stimulation was about 20 minutes (Pisano et al 2021;Sebastian et al 2020;silva et al, 2018;Soliman et al, 2021, Zhao et al, 2021.…”

The effectiveness and safety of noninvasive brain stimulation technology combined with speech training on aphasia after stroke: A systematic review and meta-analysis

“…[ 5 ] Studies have shown that the combination of NIBS techniques based on speech training is expected to promote the recovery of speech function in PSA patients. [ 6 ] Although the results of several therapeutic studies of the NIBS technique combined with speech training for patients with PSA have generally been promising, [ 7 , 8 ] there have also been studies showing no significant therapeutic effect after intervention with NIBS combined with speech training. [ 9 ] It is yet to be possible to determine whether the combination of NIBS techniques and speech training is more effective due to the small-sample sizes of individual studies and differences in measurement methods and study designs.…”