BCI-controlled ankle robot training improves lower extremity function in stroke patients

BACKGROUND: Persistent post-stroke ankle impairment hinders functional recovery. Brain-computer interface (BCI)-controlled ankle robot show rehabilitation potential, but their efficacy and underlying neuroplasticity remain unclear. OBJECTIVE: To assess BCI-controlled ankle robot training on post-stroke lower-limb motor recovery and neuroplasticity using quantitative EEG (qEEG). METHODS: Thirty-two stroke patients were randomized to BCI (n = 16, 40-minute BCI-robot training) or control (n = 16, 40-minute ankle-robot training) groups, receiving 5 sessions/week for 2 weeks. Outcomes included Fugl-Meyer Assessment-Lower Extremity (FMA-LE), Berg Balance Scale (BBS), Functional Ambulatory Category (FAC), Modified Ashworth Scale (MAS), active range of motion (AROM), and muscle strength. QEEG assessed the relative power of the delta (rδ), theta (rθ), alpha (rα), beta (rβ) bands, spectral power ratios, pairwise-derived Brain Symmetry Index (pdBSI), and functional connectivity. RESULTS: Both groups showed significant within-group improvements in dorsiflexion AROM, dorsiflexor strength, FMA-LE, BBS, and FAC ( < .05). The BCI group demonstrated significantly greater FMA-LE improvement than controls (∆FMA-LE,  = .007) and reduced calf spasticity (MAS;  = .038). QEEG analysis in the BCI group revealed decreased rδ ( = .005), increased rα ( = .017), reduced DAR and DTABR ( < .05), reduced interhemispheric asymmetry (pdBSI-δ;  = .018), and enhanced Cz-parietal connectivity in α and β bands ( < .05). CONCLUSION: BCI-controlled ankle robot training significantly improved lower-limb motor function and reduced spasticity post-stroke. Associated neurophysiological changes, characterized by reduced slow-wave power and asymmetry, increased alpha power, and functional connectivity, indicated beneficial neuroplastic reorganization. China Clinical Trail Registry (ChiCTR2300074381; URL: http://www.chictr.org.cn).