Whole-Body Adaptive Functional Electrical Stimulation Kinesitherapy Can Promote the Restoring of Physiological Muscle Synergies for Neurological Patients

Abstract

Background: Neurological diseases and traumas are major factors that may reduce motor functionality. Functional electrical stimulation is a technique that helps regain motor function, assisting patients in daily life activities and in rehabilitation practices. In this study, we evaluated the efficacy of a treatment based on whole-body Adaptive Functional Electrical Stimulation Kinesitherapy (AFESK™) with the use of muscle synergies, a well-established method for evaluation of motor coordination. The evaluation is performed on retrospectively gathered data of neurological patients executing whole-body movements before and after AFESK-based treatments.

Methods: Twenty-four chronic neurologic patients and 9 healthy subjects were recruited in this study. The patient group was further subdivided in 3 subgroups: hemiplegic, tetraplegic and paraplegic. All patients underwent two acquisition sessions: before treatment and after a FES based rehabilitation treatment at the VIKTOR Physio Lab. Patients followed whole-body exercise protocols tailored to their needs. The control group of healthy subjects performed all movements in a single session and provided reference data for evaluating patients' performance. sEMG was recorded on relevant muscles and muscle synergies were extracted for each patient's EMG data and then compared to the ones extracted from the healthy volunteers. To evaluate the effect of the treatment, the motricity index was measured and patients' extracted synergies were compared to the control group before and after treatment.

Results: After the treatment, patients' motricity index increased for many of the screened body segments. Muscle synergies were more similar to those of healthy people. Globally, the normalized synergy similarity in respect to the control group was 0.50 before the treatment and 0.60 after (p < 0.001), with improvements for each subgroup of patients.

Conclusions: AFESK treatment induced favorable changes in muscle activation patterns in chronic neurologic patients, partially restoring muscular patterns similar to healthy people. The evaluation of the synergic relationships of muscle activity when performing test exercises allows to assess the results of rehabilitation measures in patients with impaired locomotor functions.

Keywords: muscle synergies; neurological patients; whole body FES.

Figure 1

Consolidated Standards of Reporting Trials (CONSORT) flow diagram.

Figure 2

Graphic representation of the VIK16 Workstation and of the set of proposed total-body exercises. Workstation VIK16 has a library of 50 AFESK exercise programs that are used in rehabilitation, athletics and sports training. The programs are created on the basis of polymyographic and biomechanical assessment of the movement of healthy people, considering synergistic, reciprocal and antagonistic relationships of the moments of activation of the main muscle groups of the body. Workstation VIK16 has a wide range of electrical stimulation parameters: including current stabilized in each of 16 channels maximum of 150 mA, duration of a pulse from 100 to 1000 µs, pulse frequency from 50 to 200 Hz, motion cycle time from 200 ms to 10 s, impedance parameters and current level for each muscle group for all exercises performed by the patient, customizable number of cycles (movements) for each program and time for each exercise. In this study, only a subset of the exercises was performed by the enrolled patients.

Figure 2

Graphic representation of the VIK16 Workstation and of the set of proposed total-body exercises. Workstation VIK16 has a library of 50 AFESK exercise programs that are used in rehabilitation, athletics and sports training. The programs are created on the basis of polymyographic and biomechanical assessment of the movement of healthy people, considering synergistic, reciprocal and antagonistic relationships of the moments of activation of the main muscle groups of the body. Workstation VIK16 has a wide range of electrical stimulation parameters: including current stabilized in each of 16 channels maximum of 150 mA, duration of a pulse from 100 to 1000 µs, pulse frequency from 50 to 200 Hz, motion cycle time from 200 ms to 10 s, impedance parameters and current level for each muscle group for all exercises performed by the patient, customizable number of cycles (movements) for each program and time for each exercise. In this study, only a subset of the exercises was performed by the enrolled patients.

Figure 3

Employed set-ups for training at the VIKTOR Physio LAB.

Figure 4

Pipeline for Signal processing. The raw signals (light grey) were filtered to remove movement artefacts and to compute the EMG envelope (dark grey). Muscle synergies were then extracted from the EMG envelope with the NMF algorithm.

Figure 5

Example of synergies extracted on a hemiplegic patient. Spatial synergies before treatment are represented in red; spatial synergies after treatment are represented in blue. Grey bars show the corresponding reference synergies achived averaging synergies on the control group.

Figure 6

Spatial synergy similarity (healthy vs. tetraplegic) before (Pre) and after (Post) treatment. Graphs represent the similarity of the synergies extracted on each patient with the reference dataset of spatial synergies found on healthy controls. Pre-tratment synergy similarity is represented in red, while post-treatment synergy similarity is represented in blue.

Figure 7

Statistical analysis. Statistical analysis was performed on each group of patients separately and for all subjects in the same group. We found that for the “All patients”, “Hemiplegic Patients”, “Paraplegic Patients” results were statistically significant (Post treatment synergy similarity in respect to controls increased), while for the “Tetraplegic Patients” group, there was a slight median increase of the MSS which was not statistically significant.