Multi-parameter sEMG analysis combined with MSS score can objectively and quantitatively evaluate the functional status of post-stroke upper limb spasticity.
After treatment, sEMG parameters of forearm flexor and extensor muscle groups significantly increased in post-stroke upper limb spasticity patients.
At rest, RMS and iEMG values of the affected forearm flexor and extensor muscles were significantly higher than those of the unaffected side and healthy controls.
During active movement, RMS and iEMG values of the affected muscles were significantly lower than those of the unaffected side and healthy controls.
The total Motor Status Scale (MSS) score was significantly increased after treatment compared with before treatment.
sEMG parameters were negatively correlated with balance function parameters.
The modified Ashworth Scale assessment showed a total effective rate of 95.24% following treatment.
ROC curve analysis revealed that MPF had the highest area under the curve (AUC) among sEMG parameters for evaluating treatment efficacy.
This research suggests that measuring muscle electrical activity using surface electromyography (sEMG) — a non-invasive technique that records signals from muscles through skin-surface electrodes — provides objective, measurable data about upper limb spasticity (abnormal muscle stiffness) in stroke survivors. The study followed 42 stroke patients through a course of neurological treatment and rehabilitation, measuring multiple sEMG signal characteristics including overall muscle activity levels (iEMG and RMS) and frequency-based measures (MF and MPF), alongside a clinical motor function scale (MSS). A key finding was that spastic muscles behave paradoxically: they show abnormally high electrical activity at rest but reduced activity during intentional movement, which quantitatively captures the functional problem these patients experience. After treatment, all measured sEMG parameters improved significantly, and nearly all patients (95.24%) showed clinical improvement on the modified Ashworth Scale, a standard spasticity rating tool. The mean power frequency (MPF) was the best single sEMG parameter for distinguishing treatment responders from non-responders, with an AUC of 0.826 on receiver operating characteristic analysis, meaning it correctly classified outcomes about 83% of the time. The sEMG parameters were also negatively correlated with balance function, suggesting these electrical muscle signals reflect broader functional impairment. This research suggests that combining multiple sEMG parameters with standardized motor scoring provides a more objective and quantitative way to track spasticity treatment outcomes in stroke rehabilitation, potentially reducing reliance on purely subjective clinical scales. This could be useful for clinicians seeking to monitor patient progress more precisely and adjust rehabilitation strategies accordingly.
Wang R, Li W. (2026). Quantitative evaluation of post-stroke upper limb spasticity based on multi-parameter surface electromyography signal analysis.. Acta of bioengineering and biomechanics. https://doi.org/10.37190/abb/221815