Recruited Motor Units Number Count in First Dorsal Interosseous Muscles of Normal Subjects and Neuropathic Patients

• Published in: Rihabiritēshon igaku Vol. 39; no. 9; pp. 557 - 564
• Main Author: HOTTA, Fujiko
• Format: Journal Article
• Language: English
• Published: The Japanese Association of Rehabilitation Medicine 2002
• Subjects: electromyography; motor unit action potentials; neurogenic disease; recruitment
• ISSN: 0034-351X; 1880-778X; 1880-778X
• DOI: 10.2490/jjrm1963.39.557

The most essential feature of neurogenic change is loss of recruitable motor units. This concept is very important but we do not much care of it on a daily EMG examination. The purpose of this study is to demonstrate it electromyographically. We studied 5 normal subjects, 5 patients with acute neuropathy who had pathological resting activities in routine EMG study and other 5 patients with chronic neuropathy. Respective investigations were repeated 5 to 10 times depending their muscle power. Motor unit action potentials (MUAPs) were collected from each first dorsal interosseous (FDI) using a concentric needle electrode during voluntary 3 type isometric contractions (50, 150 and 300gf). They were analysed employing multi MUP analysis program which extracted single MUAPs in continuous EMG-signals. This system counted number of recruited motor units automatically. Such MUAPs were examined by amplitude and duration which were ordinary MUP parameters, too. The result of our experiment clearly shows that number of recruited motor units gives better discrimination results than amplitude or duration. The number of recruitable motor units contributes as a new parameter for the diagnosis of neuromuscular disorders.