Motor unit number index (MUNIX)

• Published in: IEEE transactions on biomedical engineering Vol. 51; no. 12; pp. 2209 - 2211
• Main Authors: Nandedkar, S.D., Nandedkar, D.S., Barkhaus, P.E., Stalberg, E.V.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.12.2004; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Action Potentials; Adult; Aged; Algorithms; ALS; Amyotrophic Lateral Sclerosis - diagnosis; Amyotrophic Lateral Sclerosis - physiopathology; Degenerative diseases; Diagnosis, Computer-Assisted - methods; Drugs; Electrical stimulation; Electromyography; Electromyography - methods; Humans; Instruments; Interference; Middle Aged; Motor Neurons; motor units; MUNE; Muscle Fibers, Skeletal; Muscle, Skeletal - physiopathology; Muscles; Needles; Reproducibility of results; surface EMG; Testing
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2004.834281

The surface-recorded compound muscle action potential (CMAP) and electromyographic (EMG) interference pattern is used to compute the motor unit number index (MUNIX). The MUNIX demonstrated all known changes in the number of motor units in normal subjects, and in patients with amyotrophic lateral sclerosis (ALS). In normal subjects MUNIX decreased slightly with age and showed excellent reproducibility. In many ALS patients MUNIX was reduced even when the CMAP was normal. Lower MUNIX values were seen in weaker muscles. This is a noninvasive method that requires minimal electrical stimulation. It is performed in less than 5 min. This makes it suitable for serial EMG investigations.