Abstract
Objective Muscle weakness and spasticity are common consequences of stroke, leading to a decrease in physical activity. The effective implementation of precision rehabilitation requires detailed rehabilitation evaluation. We aimed to analyze the surface electromyography (sEMG) signal features of elbow flexor muscle (biceps brachii and brachioradialis) spasticity in maximum voluntary isometric contraction (MVIC) and fast passive extension (FPE) in stroke patients and to explore the main muscle groups that affect the active movement and spasticity of the elbow flexor muscles to provide an objective reference for optimizing stroke rehabilitation. Methods Fifteen patients with elbow flexor spasticity after stroke were enrolled in this study. sEMG signals of the paretic and nonparetic elbow flexor muscles (biceps and brachioradialis) were detected during MVIC and FPE, and root mean square (RMS) values were calculated. The RMS values (mean and peak) of the biceps and brachioradialis were compared between the paretic and nonparetic sides. Additionally, the correlation between the manual muscle test (MMT) score and the RMS values (mean and peak) of the paretic elbow flexors during MVIC was analyzed, and the correlation between the modified Ashworth scale (MAS) score and the RMS values (mean and peak) of the paretic elbow flexors during FPE was analyzed. Results During MVIC exercise, the RMS values (mean and peak) of the biceps and brachioradialis on the paretic side were significantly lower than those on the nonparetic side (p < 0.01), and the RMS values (mean and peak) of the bilateral biceps were significantly higher than those of the brachioradialis (p < 0.01). The MMT score was positively correlated with the mean and peak RMS values of the paretic biceps and brachioradialis (r = 0.89, r = 0.91, r = 0.82, r = 0.85; p < 0.001). During FPE exercise, the RMS values (mean and peak) of the biceps and brachioradialis on the paretic side were significantly higher than those on the nonparetic side (p < 0.01), and the RMS values (mean and peak) of the brachioradialis on the paretic side were significantly higher than those of the biceps (p < 0.01). TheMAS score was positively correlated with the mean RMS of the paretic biceps and brachioradialis (r = 0.62, p = 0.021; r = 0.74, p = 0.004), and the MAS score was positively correlated with the peak RMS of the paretic brachioradialis (r = 0.59, p = 0.029) but had no significant correlation with the peak RMS of the paretic biceps (r = 0.49, p > 0.05). Conclusions The results confirm that the biceps is a vital muscle in active elbow flexion and that the brachioradialis plays an important role in elbow flexor spasticity, suggesting that the biceps should be the focus of muscle strength training of the elbow flexors and that the role of the brachioradialis should not be ignored in the treatment of elbow flexor spasticity. This study also confirmed the application value of sEMG in the objective assessment of individual muscle strength and spasticity in stroke patients.
Highlights
Stroke is a destructive neurological disease with high morbidity, disability, and mortality
The results showed that the mean root mean square (RMS) value of the paretic biceps muscle during maximum voluntary isometric contraction (MVIC) was associated with elbow flexor muscle strength in males, those aged no more than 60 years, those with a poststroke duration of less than 6 months, and those with hemiparesis on the left side (Figure 5(c))
To analyze the effect of the biceps and brachioradialis on active contraction and to explore the application value of surface electromyography (sEMG) in the objective evaluation of muscle force, we first compared the sEMG value of the elbow muscle on the paretic side with that on the nonparetic side during MVIC exercise, and the results showed that the RMS values of the paretic elbow flexors were significantly lower than those of the corresponding muscles on the nonparetic side (p < 0:001). sEMG values mainly reflect the recruitment properties of motor units during active contraction of the detected muscle, and orderly recruitment of motor units is crucial for effective muscle power generation [25, 26]
Summary
Stroke is a destructive neurological disease with high morbidity, disability, and mortality. The current clinical rehabilitation assessment of muscle strength mainly involves a manual muscle test (MMT) This method is simple and convenient and subjective. Used assessment methods of spasticity are clinical scales, including the modified Ashworth scale (MAS), the clinical spasticity index (CSI), and the Tardieu scale (TS); of these scales, the MAS is the most widely used [5] These methods are relatively mature in terms of testing procedures, but the results are subjective and difficult to accurately quantify due mainly to the tester’s qualitative or semiquantitative evaluation of muscle tension [6, 7]. These evaluation methods cannot be subdivided into specific muscles. An important issue to be solved in the clinical rehabilitation of stroke is how to more objectively assess the strength and tension of individual muscles and more precisely analyze the dysfunction of stroke survivors
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