Resting-State Theta Oscillations as Biomarkers of Adaptive Neuroplasticity in Chronic Stroke: A Pilot EEG Study

Background Stroke-related motor deficits persist in many patients despite rehabilitation, highlighting the need for objective biomarkers of brain recovery. Resting-state EEG offers a non-invasive window into functional reorganization and cortical network dynamics. Objective To investigate changes in resting-state EEG following upper limb rehabilitation in chronic MCA stroke patients and to evaluate qEEG parameters as biomarkers of adaptive neuroplasticity. Methods Ten chronic left MCA stroke patients and seven healthy controls underwent 64-channel EEG before and after a 15-session occupational therapy program. EEG spectral power (delta, theta, alpha, beta) and composite indices (Delta/Alpha Ratio [DAR], Delta+Theta/Alpha+Beta Ratio [DTABR], Brain Symmetry Index [pdBSI]) were calculated. Motor function was assessed with the Fugl-Meyer Upper Extremity scale (FM-UE). Results Patients showed higher delta and theta and lower alpha and beta power versus controls. DAR, DTABR, and pdBSI were elevated. Post-treatment, FM-UE scores improved (p = 0.008) and relative theta power increased (p = 0.038), with a trend toward reduced delta (p = 0.051). Theta and alpha power correlated with motor outcomes. Conclusion Theta power increased after therapy and was associated with motor improvement, suggesting a role in adaptive cortical reorganization.