Evaluation of Spasticity Changes during Manual Hand Therapy Based on sEMG Features

Manual therapy has been extensively utilized in the clinical management of hand spasticity. Clinicians face challenges in accurately evaluating spasticity during manual therapies due to its dynamic changes, resulting in a heavy reliance on therapists' experience for assessing and adjusting the therapy process. Currently, the Modified Ashworth Scale (MAS) and surface electromyography (sEMG) have been widely used to evaluate spasticity. However, based on these methods, changes in spasticity during complex and sequential manual therapies have not been substantially investigated. In this study, 11 post-stroke patients with hand spasticity were recruited to perform 70 times of manual therapies by an experienced therapist, while sEMG and MAS were collected throughout the process. The results revealed decreasing trends in both MAS and four sEMG features obtained from nine upper limb muscles of the patients during the manual therapy. Particularly, a decreasing trend of the integrated electromyography (iEMG) demonstrated the closest alignment with that of the MAS. In addition, a new index, post-offset integrated electromyography (piEMG) was introduced to quantitatively assess the changes in spasticity during static stretching, presenting a significant correlation with the MAS. These results could inform therapists in dynamically assessing changes in patients' hand spasticity using sEMG data and serve as a reference for future developments in hand exoskeletons that assist manual therapies.