The Motor Unit Number Index (MUNIX) in sarcopenic patients

• Published in: Experimental gerontology 2013-04, Vol.48 (4), p.381-384
• Main Authors: Drey, M., Grösch, C., Neuwirth, C., Bauer, J.M., Sieber, C.C.
• Format: Article
• Language: English
• Subjects: Action Potentials - physiology; Aged; Aged, 80 and over; Elderly; Electromyography - methods; Female; Hand - innervation; Hand - physiopathology; Humans; Male; Motoneuron; Motor Neurons - pathology; MUNIX; Muscle, Skeletal - innervation; Muscle, Skeletal - physiopathology; Nerve Degeneration - complications; Nerve Degeneration - diagnosis; Nerve Degeneration - physiopathology; Neural Conduction - physiology; Neuromuscular; Sarcopenia; Sarcopenia - diagnosis; Sarcopenia - etiology; Sarcopenia - physiopathology; Statistics as Topic
• ISSN: 0531-5565; 1873-6815
• DOI: 10.1016/j.exger.2013.01.011

The cause of sarcopenia is still not fully understood. A multifactorial aetiology is discussed. Neurodegenerative aspects in the genesis of sarcopenia, such as loss of motoneurons, have not yet been explored to a sufficient extent. The Motor Unit Number Index (MUNIX) is a method for assessing the number and size (Motor Unit Size Index — MUSIX) of Motor Units (MUs) using the Compound Muscle Action Potential (CMAP) and the Surface electromyographic Interference Pattern (SIP). This method was used to study the hypothenar muscle in the right hand of 27 sarcopenic patients. The mean MUNIX (111±51) of all investigated sarcopenic patients lies between the mean MUNIX of healthy persons and the mean MUNIX of ALS patients. 25% of sarcopenic patients exhibit pathologic values for both MUNIX (100μV). A strong correlation (r=0.75, p