Effects of Single-Session High-Definition Transcranial Alternating Current Stimulation (HD-tACS) Combined with Robot-Assisted Hand Exercises on Corticospinal Excitability in Chronic Stroke
In brief
Brain stimulation raised hand-muscle response measures by 15% in healthy adults
In a crossover study, 12 healthy adults and 7 people with chronic stroke performed robot-assisted hand exercises during active or sham brain stimulation. Active stimulation increased a hand-muscle response by 15.3% in healthy adults; the stroke group showed a 22.3% increase, but that result was not significant on its own. The small, single-session study leaves unclear whether stimulation improves hand function.
- Journal
- American journal of physical medicine & rehabilitation (Q1)
- Published
- 12 October 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Hao Meng, Michael Houston, Ahmad Z Rao, Jinsook Rho, Gerard E Francisco, Sheng Li
- PMID
- 42886513
- DOI
- 10.1097/PHM.0000000000003108
Why clinicians should know about it
- Picked for Rehabilitation (paper of the day, 17 October 2026): HD-tACS increased corticospinal excitability compared with sham
Abstract
OBJECTIVE: This preliminary study investigated whether a single session of high-definition transcranial alternating current stimulation (HD-tACS) could improve corticospinal tract (CST) excitability compared with sham stimulation in healthy individuals and individuals with chronic stroke. DESIGN: Twelve healthy adults and 7 individuals with chronic stroke received active and sham HD-tACS over the primary motor cortex (M1) flexor digitorum superficialis (FDS) hotspot, ipsilesional in stroke subjects, for 30 minutes at 2mA and 21 Hz in a randomized crossover design. All subjects performed robot-assisted grasp-and-open hand exercises during active and sham stimulation. RESULTS: HD-tACS significantly increased FDS MEP amplitudes in the healthy group (15.3%). In the stroke group, FDS MEP amplitudes were increased by ∼22.3% after HD-tACS, but this change was not statistically significant. When MEP amplitudes were normalized as percentage change, HD-tACS significantly increased FDS MEP amplitudes in both groups compared with the sham condition. No significant extensor digitorum communis (EDC) modulation was observed in either group. CONCLUSION: HD-tACS combined with robot-assisted hand exercises may enhance CST excitability compared with robot-assisted hand exercises alone after a single session in both healthy and stroke subjects. However, larger studies are needed to confirm these findings.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.