Cortico-muscular interaction to monitor the effects of neuromuscular electrical stimulation pedaling training in chronic stroke.

Neuromuscular electrical stimulation (NMES) has been widely utilized in post-stroke motor restoration. However, its impact on the closed-loop sensorimotor control process remains largely unclear. This is the first study to investigate the directional changes in cortico-muscular interactions after repetitive rehabilitation training by measuring the noninvasive electroencephalogram (EEG) and electromyography (EMG) signals. In this study, 10 subjects with chronic stroke received 20 sessions of NMES-pedaling interventions, and each training session included three 10-min NMES-driven pedaling trials. In addition, pre- and post-intervention assessments of lower limb isometric contraction were conducted before and after the whole NMES-pedaling interventions. The EEG (128 channels) and EMG (3 bilateral lower limb sensors) signals were collected during the isometric contraction tasks for the paretic and non-paretic lower limbs. Both the cortico-muscular coherence (CMC) and generalized partial directed coherence (GPDC) values were analyzed between eight selected EEG channels in the central primary motor cortex and EMG channels. The results revealed significant clinical improvements. Additionally, rehabilitation training facilitated cortico-muscular interaction of the ipsilesional brain and paretic lower limbs (p = 0.004). Moreover, both the descending and ascending cortico-muscular pathways were altered after NMES-training (p = 0.001, p < 0.001). Therefore, the results implied potential applications of EEG-EMG in understanding neuromuscular changes during the post-stroke motor rehabilitation process.

Effects of Electromyographically-driven Neuromuscular Stimulatio Cycling System on the Lower-Limb of Stroke Survivors.

This paper describes the design of an Electromyographically(EMG)-driven Neuromuscular Electrical Stimulation (NMES) cycling system. It utilises real-time EMG from actively participating stroke survivors as feedback control to drive the cycling system for rehabilitation. The user controls the speed of the cycling system using muscle activities of the side affected recorded by EMG electrodes. Additionally, adaptable NMES stimulations; also EMG based, were provided in cyclic pattern to the respective muscle groups in order to improve muscle coordination. The targeted muscle groups used to control the system were the Hamstring (HS), Tibialis Anterior (TA), Quadriceps (QC), Gastrocnemius Lateralis (GL) of the leg on the affected side. Using the system, 20 30-minutes sessions were conducted with chronic stroke survivors (n=10) at frequency of 2-4 sessions per week. Clinical assessment scores, namely FMA_LE, BBS and 6MWT were calculated before the first session and after the completion of 20 sessions. All the assessment scores showed significant improvement after using the system; FMA_LE(P=0.0244), BBS(P=0.0156), 6MWT(P=0.0112), and SI (P=0.0258), showing that the EMG-driven NMES cycling system provides effective rehabilitation for stroke survivors in terms of muscle strength and balance.

Design of Functional Electrical Stimulation Cycling System for Lower-Limb Rehabilitation of Stroke Patients.

The active participation of the stroke survivor during Functional Electrical Stimulation (FES) cycling system is an interesting question that we would like to investigate, since active rehabilitation can promote a better motor function recovery than passive training. In this pilot study, a smart FES cycling system which can assess the participants cycling effort was proposed to record real-time Electromyography (EMG) and torque during lower limb training for chronic stroke survivors. The rehabilitation goals were to increase the lower-limb muscle strength and enhance the muscle coordination. Chronic stroke patients (n=6) with gait impairment and moderate motor disability were recruited to evaluate the functionality of the system. The system was composed of a modified station bike with an adjustable chair, a programmable functional electrical stimulator, a step motor, a torque sensor, and a surface electromyography (EMG) amplifier. Four-channel FES and EMG electrodes were placed at quadriceps (QC), hamstrings (HS), tibialis anterior (TA) and gastrocnemius (GL) to exert stimulation. We adopted two measurements, clinical assessment scores and symmetric index (SI), to evaluate the training effects. The experimental results showed the proposed cycling system could improve the participants walking ability (p=.046) and enhance balance of the muscle coordination (p=.042) after training.

The Effectiveness of Functional Electrical Stimulation (FES) in On-Off Mode for Enhancing the Cycling Performance of Team Phoenix at 2016 Cybathlon.

In this study we designed a Functional Electrical Stimulation (FES) trike for a female subject with spinal cord injury to exercise her lower limbs and improve her lower limb muscle condition for attending the 2016 Cybathlon FES bike competition. Our FES pilot was the only female participant, in the FES cycling competition and she rode for Team Phoenix from the Chinese University of Hong Kong. Due to the weakness of muscles in the lower limb of the subject, and due to scoliosis over her thoracolumbar aéra, the mechanical structure of the trike had to be tailor-made to ensure she sat on the bike in a safe and secure position. A six-phase angle-driven stimulation pattern was developed to stimulate quadriceps and hamstrings without gluteus muscles for contraction through four surface electrodes, thereby creating a cycling movement. To improve the cycling endurance and reduce the muscle fatigue, an on-off mode was developed for controlling the stimulation time that allowed the subject to cycle for 20s, then pause while the trike advanced without stimulation for 5s, followed by a subsequent 20 sec stimulation, to continue cycling. The pilot participated in the training procedure including training exercise at home, trike fitting in the trike by modifying the mechanical structure, and conducting the cycling exercise for six months. We observed significant improvements in the pilot's lower limb condition. The on-off mode enabled our pilot to extend her cycling endurance effectively, from 1 min to 2.5 mins and the distance from 62m to 100m. Over the eight minutes time limit, our team successfully finished 100 m in the Cybathlon FES.