Reference values for the motor unit number index and the motor unit size index in five muscles

• Published in: Muscle & nerve Vol. 61; no. 5; pp. 657 - 661
• Main Authors: Cao, Bei, Gu, Xiaojing, Zhang, Lingyu, Hou, Yanbing, Chen, Yongping, Wei, Qianqian, Ou, Ruwei, Shang, Huifang
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.05.2020; Wiley Subscription Services, Inc
• Subjects: healthy individual; Measurement methods; motor unit number index; motor unit size index; Muscles; neuromuscular disease; Neuromuscular diseases; neurophysiological biomarker; reference values; Skeletal muscle; motor unit number index; neuromuscular disease; reference values; neurophysiological biomarker; motor unit size index; healthy individual
• ISSN: 0148-639X; 1097-4598; 1097-4598
• DOI: 10.1002/mus.26837

Introduction Few reference values have been established for the motor unit number index (MUNIX) and motor unit size index (MUSIX). In this study we aimed to investigate the features of MUNIX in healthy individuals for five muscles. Methods We measured the MUNIX in the right abductor pollicis brevis (APB), abductor digiti minimi (ADM), biceps brachii (BB), tibialis anterior (TA), and trapezius (TR) muscles. Results The study enrolled 76 male and 74 female participants. The mean MUNIX and mean MUSIX of the right APB, ADM, BB, TA, and TR muscles were 191.0 ± 43.6, 179.1 ± 38.8, 179.7 ± 36.2, 152.1 ± 38.8, and 166.1 ± 40.7; and 60.4 ± 12.5, 59.3 ± 13.7, 43.8 ± 11.5, 41.3 ± 10.7, and 49.1 ± 15.2, respectively. MUNIX in these five muscles was inversely related to age. Discussion The establishment of reference values for MUNIX and MUSIX in five muscles may help in monitoring the progression of neuromuscular diseases.