Enhancement of Visual Feedback Ownership in Hand Mirror Therapy Using Automated Control of Electrical Muscle Stimulation Based on Healthy Hand Movement

Abstract

Mirror therapy (MT) has been recognized for its potential to harness neuroplasticity and improve recovery in post-stroke patients. In MT, a mirror tricks the brain into thinking that the weak or paralyzed side of the body is moving when the healthy side moves, thereby helping to stimulate healing and relearn movement after a stroke or injury. However, MT is limited in addressing the sensory impairment and visual feedback ownership on the affected hand. A combination of MT and electrical muscle stimulation (EMS) is believed to enhance muscle strength and sensory perception, but lacks synchronization with the movement intention of the healthy hand. This study aims to advance MT to further promote neuroplasticity through movement synchronization in both hands. A stretch-sensor glove was used on the unaffected hand to capture finger movement kinematics, controlling the electrical intensity of an EMS device on the assumed affected hand. Thereby, a proportional control of electrical intensity and synchronous movement of both hands was achieved. This study compared four types of electrical intensities, spanning from baseline (no stimulation) to higher intensities (S0–S4). As a result, body representation perception showed an overall negative correlation with the level of comfort associated with the stimulus. Enhancements in body representation perception were significantly confirmed (p < 0.01) in stronger stimulus types, notably S4 and S4F of the spontaneous movement scheme, compared to the baseline stimulus S0 and the weak intensity S1. There may be a possibility of enhancing neuroplasticity by strategically using various electrical intensities. The proposed system shows promising performance by enhancing body representation through improved visual feedback ownership at higher electrical intensities.