Nonlinear analysis of electromyogram following gait training with myoelectrically triggered neuromuscular electrical stimulation in stroke survivors

Abstract

Neuromuscular electrical stimulation (NMES) facilitates ambulatory function after paralysis by activating the muscles of the lower extremities. The NMES-assisted stepping can either be triggered by a heel-switch (switch-trigger), or by an electromyogram (EMG)-based gait event detector (EMG-trigger). The command sources-switch-trigger or EMG-trigger-were presented to each group of six chronic (>6 months post-stroke) hemiplegic stroke survivors. The switch-trigger group underwent transcutaneous NMES-assisted gait training for 1 h, five times a week for 2 weeks, where the stimulation of the tibialis anterior muscle of the paretic limb was triggered with a heel-switch detecting heel-rise of the same limb. The EMG-trigger group underwent transcutaneous NMES-assisted gait training of the same duration and frequency where the stimulation was triggered with surface EMG from medial gastrocnemius (MG) of the paretic limb in conjunction with a heel-switch detecting heel-rise of the same limb. During the baseline and post-intervention surface EMG assessment, a total of 10 s of surface EMG was recorded from bilateral MG muscle while the subjects tried to stand steady on their toes. A nonlinear tool-recurrence quantification analysis (RQA)-was used to analyze the surface EMG. The objective of this study was to find the effect of NMES-assisted gait training with switch-trigger or EMG-trigger on two RQA parameters-the percentage of recurrence (%Rec) and determinism (%Det), which were extracted from surface EMG during fatiguing contractions of the paretic muscle. The experimental results showed that during fatiguing contractions, (1) %Rec and %Det have a higher initial value for paretic muscle than the non-paretic muscle, (2) the rate of change in %Rec and %Det was negative for the paretic muscle but positive for the non-paretic muscle, (3) the rate of change in %Rec and %Det significantly increased from baseline for the paretic muscle after EMG-triggered NMES-assisted gait training. Therefore, the study showed an improvement in paretic muscle function during a fatiguing task following gait training with EMG-triggered NMES. This study also showed that RQA parameters-%Rec and %Det-were sensitive to changes in paretic/non-paretic muscle properties due to gait training and can be used for non-invasive muscle monitoring in stroke survivors undergoing rehabilitation.

Recurrence quantification analysis of surface electromyogram supports alterations in motor unit recruitment strategies by anodal transcranial direct current stimulation

“…To determine the embedding dimension, the false nearest neighbors method (Kennel et al, 1992) was used which was set to 15. Therefore, the phase space was assumed to be 15-dimensional, in accordance with parameters chosen in other studies (Dutta et al, 2012;Farina et al, 2002;Webber et al, 1995). Then, 15 dimensional vectors were extracted from 2.56s epoch of the surface EMG signal by lagging the signal by an integer number of samples that minimized the temporal correlations between the samples of the time series.…”

Feasibility of Functional Electrical Stimulation-Assisted Neurorehabilitation following Stroke in India: A Case Series

“…FES-assisted gait training may alleviate these debilitating conditions where increased intensity and frequency of rehabilitation may help [ 40 ]. In fact recent studies in India on therapeutic benefits of FES-assisted gait training in conjunction with conventional physiotherapy have shown the additive effects of FES on reducing spasticity, improving dorsiflexor strength, improving walking ability, and improving metabolic fitness [ 41 – 43 ].…”

Myoelectric control of an implanted neuroprosthesis to restore gait in incomplete spinal cord injury

“…Using the EMG of muscles previously associated with walking that are still under voluntary control can be an accurate way to control stimulation to the paralyzed muscles of the lower extremities. Research has been done to integrate surface EMG activity to initiate electrical stimulation of the dorsiflexors to control footdrop in hemiplegia [5][6][7][8]. However, fully implanted EMG and FES systems for gait in iSCI are not very well explored.…”