A quantitative analysis of lower limb muscle spasticity in stroke survivors

Abstract

Objective To relate the results of surface electromyography (sEMG) of the femoris among patients with hemiplegia after a brain lesion with scores on the modified Ashworth scale (MAS), and to decide whether sEMG can be used as a quantitative index for evaluating spasm. Methods The affected quadriceps femoris of sixty hemiplegic stroke survivors were assessed by the same therapist using the MAS. sEMGs were also recorded and the root mean square and average sEMG readings from the vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) were extracted. The correlation between these sEMG indexes and the MAS grading was analyzed. Results The average sEMG signals from the VM, RF and VL were strongly correlated with the MAS grading, and they increased with increasing MAS grade. Spearman correlation analysis demonstrated highly significant correlation (P≤0.001) when the quadriceps femoris was moved passively. Conclusions Surface EMG signals from the VM, RF and VL correlate well with MAS grades, rising when the affected quadriceps femoris of a stroke survivor is moved passively. sEMG can present the electrical activity during passive movements of the quadriceps femoris and can be useful in spasticity assessment and clinical treatment. Key words: Stroke; Spasticity; Surface electromyography; Quadriceps femoris