Improving motor imagery practice with synchronous action observation in stroke patients

Background: Action observation (AO) has the potential to improve motor imagery (MI) practice in stroke patients. However, currently only a few results are available on how to use AO effectively. Objective: The aim of this study is to investigate whether MI practice can be improved more effectively by synchronous AO than by asynchronous AO. Methods: Ten patients with upper limb motor dysfunction following stroke were selected as the participants. They were divided into two groups to perform MI practice combined with a daily conventional rehabilitation for four consecutive weeks. The control group was asked to perform MI guided by asynchronous AO (MIAAO), and the experimental group was asked to perform the same MI but guided by synchronous AO (MISAO). The event-related power decrease (ERD) in sensorimotor rhythms of electroencephalograph was calculated to reflect the sensorimotor cortex activation and to assess the cortex excitability during MI. Fugl-Meyer assessment (FMA) and pinch strength test (PST) were used to assess the limb motor recovery. Results: The ERD pattern of the experimental group not only had greater amplitude and longer duration, but also included more frequency components. Furthermore, the effect sizes of ERD values between the two groups continuously increased (d(ES) > 0.8) during the course of treatment. Moreover, the FMA and PST scores achieved with MISAO were also significantly higher than those achieved with MIAAO (p < 0.05). Conclusions: Compared with MIAAO, MISAO can enhance the excitation of sensorimotor cortex more effectively and lead to a more rapid neurorehabilitation of stroke patients.