Examining and monitoring paretic muscle changes during stroke rehabilitation using surface electromyography: A pilot study

Complex neuromuscular changes have been reported to occur in paretic muscles following stroke, but whether and how they can recover under rehabilitation therapy remain unclear. A tracking analysis protocol needs to be designed involving multiple sessions of surface electromyography (sEMG) examinations during the rehabilitation procedure. Following such a protocol, this pilot study is aimed to monitor paretic muscle changes using three sEMG indicators namely clustering index (CI), root mean square (RMS) and medium frequency (MDF). Initially, a single sEMG examination was performed on the abductor pollicis brevis (APB) muscle on both sides of 23 subjects with stroke and one side of 18 healthy control subjects. With these data to establish CI diagnostic criterion, the paretic muscles of all subjects with stroke showed a very board CI distribution pattern from abnormally low values through normality to abnormally high values. Afterwards, 9 out of 23 subjects with stroke had their paretic muscles examined at least twice before and after the treatment. Almost all paretic muscles had an increase of the RMS, a change of the MDF approaching to the value of the contralateral muscle, and a change of the CI returning to its normal range after common rehabilitation treatments. Finally, 4 of the 9 subjects with stroke participated into repeated examinations of their paretic muscles. The combined use of three indicators helped to reveal specific neuromuscular processes contributing to recovery of paretic muscles, due to their complementary diagnostic powers. Furthermore, neuromuscular processes were found to vary across subjects in type, order and timing during rehabilitation. In conclusion, given the 4 cases following the tracking analysis protocol, this pilot study preliminarily demonstrates usability of three sEMG indicators as tools for examining and monitoring stroke rehabilitation procedure in terms of improvements of paretic muscle changes. All the revealed complex neuromuscular processes imply the necessity of applying sEMG examinations in monitoring rehabilitation procedure, with the potential of offering important guidelines for designing better and individualized protocols toward improved stroke rehabilitation.