Complex Neuromuscular Changes Post-Stroke Revealed by Clustering Index Analysis of Surface Electromyogram

• Published in: IEEE transactions on neural systems and rehabilitation engineering Vol. 25; no. 11; pp. 2105 - 2112
• Main Authors: Zhang, Xu, Wei, Zhongqing, Ren, Xiaoting, Gao, Xiaoping, Chen, Xiang, Zhou, Ping
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.11.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aged; Aged, 80 and over; Algorithms; Cluster Analysis; Clustering; Clustering index; Electrodes; Electromyography; Electromyography - methods; Electromyography - statistics & numerical data; Female; Functional Laterality; Healthy Volunteers; Humans; Indexes; Interference; interference pattern; Male; Middle Aged; Muscle contraction; muscle weakness; Muscle Weakness - etiology; Muscle Weakness - physiopathology; Muscle Weakness - rehabilitation; Muscle, Skeletal - physiopathology; Muscles; Neuromuscular; Neuromuscular Diseases - etiology; Neuromuscular Diseases - physiopathology; Paresis - physiopathology; Quantitative analysis; Rehabilitation; Stroke; Stroke - complications; Stroke - physiopathology; stroke rehabilitation; Stroke Rehabilitation - methods; surface electromyogram; Thumb
• ISSN: 1534-4320; 1558-0210; 1558-0210
• DOI: 10.1109/TNSRE.2017.2707582

The objective of this paper was to characterize complex neuromuscular changes induced by a hemisphere stroke through a novel clustering index (CI) analysis of surface electromyogram (EMG). The CI analysis was performed using surface EMG signals collected bilaterally from the thenar muscles of 17 subjects with stroke and 12 age-matched healthy controls during their performance of varying levels of isometric muscle contractions. Compared with the neurologically intact or contralateral muscles, mixed CI patterns were observed in the paretic muscles. Two paretic muscles showed significantly increased CI implying dominant neurogenic changes, whereas three paretic muscles had significantly reduced CI indicating dominant myopathic changes; the other paretic muscles did not demonstrate a significant CI alternation, likely due to a deficit of descending central drive or a combined effect of neuromuscular factors. Such discrimination of paretic muscles was further highlighted using a modified CI method that emphasizes between-side comparison for each individual subject. The CI findings suggest that there appears to be different central and peripheral processes at work in varying degrees after stroke. This paper provides a convenient and quantitative analysis to assess the nature of neuromuscular changes after stroke, without using any special equipment but conventional surface EMG recording. Such assessment is helpful for the development of appropriate rehabilitation strategies for recovery of motor function.