Research On Multimodal Physiological Information And Response Mechanism Induced By FES Of Lower Limb

Functional electrical stimulation(FES)applies certain-intensity low-frequency electrical pulses on one or more muscle groups through a pre-set program to induce functional movement or simulate voluntary movement,which aims to improve or recover the functions of the stimulated muscle or muscle groups.FES is widely considered as an effective clinical technique on function rehabilitation for patients suffering from spinal cord injury(SCI)or stroke.However,considering the current research status,kinematic parameter is still a main method to evaluate the response of human body during FES.And,the limitations of detection methods and referenced criteria have restricted the development and application of FES technique for a long time.The clinical application of FES included mainly two parts: stroke rehabilitation based on function reconstruction;SCI rehabilitation based on function substitution.Considering the technology bottleneck in clinical application of FES,this study developed a series of applied basic research on FES technique,including 1)for the lack of quantitative evaluation on neural plasticity in stroke patients,we sought effective evaluation parameters by comparing electroencephalography(EEG)oscillatory patterns during FES-induced movement with those during active/passive movement,and investigated the cortex activation differences by comparing EEG sources between different stimulation levels;2)we proposed a novel filtering algorithm to solve the extraction problem of electromyogrphy(EMG)signal,which is contaminated by stimulation artifact during FES.At the same time,we compared characteristic parameters of EMG signals from stimulated limb which was used as the active limb or passive limb during walking assisted with FES;3)for the muscle morphological changes during FES,we attempted to detect the changes of muscle activity and state by ultrasound images,which provided a novel detection method for the state of human body during FES;4)for that rapid fatigue restricts FES-based rehabilitation training,we compared the fatigue effect with different stimulation frequencies or modes in the SCI patients and healthy subjects.Results showed that 1)FES-induced movement can induce central event-related desynchronization(ERD)for both healthy subjects and a stroke patient;the EEG oscillatory pattern under FES-induced movement was proved for the first time to tend more towards active movement instead of passive movement which could be expected as a potential technique to evaluate the brain response during FES-induced movement;furthermore,motor area could be activated when the current strength reached a specific level even without joint movement,which could provide a theoretical basis for FES-based rehabilitation training;2)An adaptive matched filtering method based on genetic algorithm can effectively remove stimulation artifact from EMG of the stimulated muscle and its adjacent muscle to extract clean EMG signal,which provided key technical support for the EMG monitor in a future FES rehabilitation system and the improvement of an EMG-based FES feedback control system;3)Muscle thickness and texture characteristics were extracted for the first time from ultrasonic images during FES-induced movement,and these characteristic parameters were verified to be available to evaluate the muscle state during FES-induced movement;4)For SCI patients,DFT outperformed CFT and low frequency outperformed high frequency,which could optimize parameters for FES rehabilitation training;healthy subjects were found for the first time to present a contrary pattern of fatigue response to stimulation mode compared with SCI patients.In conclusion,this study aimed to investigate physiological state of lower limbs from EEG,EMG,ultrasound images,and force signal during FES.The work provides novel detection methods for FES system;establishes novel objective criteria for rehabilitation evaluation based on FES;lays a theoretical foundation for FES rehabilitation training,and offers key technical support for the development of a new FES rehabilitation system.