500 Section - Modulation of aperiodic cortical activity after virtual reality–based robotic upper limb rehabilitation in subacute stroke: a pilot randomized controlled trial

While post-stroke neurophysiology has classically been examined through oscillatory electroencephalographic (EEG) features, growing evidence indicates that aperiodic activity conveys complementary and clinically meaningful information. This pilot randomized controlled study investigated how virtual reality–assisted robotic rehabilitation of the upper limb influences aperiodic EEG dynamics in patients with subacute stroke, using the Spectral Exponent Index (SEI), quantifying the steepness of the EEG power spectral slowing.

Design:

Nineteen participants with subacute ischemic stroke completed a 30-session rehabilitation protocol using a bilateral upper limb robotic exoskeleton combined with non-immersive virtual reality. Subjects were randomly allocated to bilateral (n = 10) or unilateral (n = 9) training. Resting-state EEG recordings were obtained at baseline (T0), after the intervention (T1), and at one-week follow-up (T2). SEI values were extracted in both the affected (AH) and unaffected hemispheres (UH), in the 1–20Hz frequency range. Clinical performance was evaluated at T0 and T1 using the Fugl-Meyer Assessment for upper extremity (FMA-UE).

Results:

At T0, the SEI over the sensorimotor region of the AH was significantly lower than in the sensorimotor UH. Following the interventions, the SEI within the sensorimotor region of the AH at T1 was significantly higher than SEI within the same region at T0, regardless of the intervention group. This increase in SEI was accompanied by a significant FMA-UE improvement in both groups. At T2, SEI values in the AH declined again relative to the UH. No significant differences emerged between bilateral and unilateral groups.

Conclusion:

Our results indicate that upper limb robotic rehabilitation elicits a focal reduction of EEG slowing within the sensorimotor cluster of the AH in subacute stroke.