Motor unit number index (MUNIX) in myopathic disorders: Clinical correlations and potential pitfalls

Manoel Wilkley Gomes de Sousa; Marcio Luiz Escorcio-Bezerra; Wladimir Bocca Vieira Rezende Pinto; Paulo Victor Sgobbi Souza; Nadia Iandoli de Oliveira Braga; Acary Souza Bulle Oliveira; Gilberto Mastrocola Manzano

doi:10.1016/j.neucli.2019.07.002

Motor unit number index (MUNIX) in myopathic disorders: Clinical correlations and potential pitfalls

Neurophysiol Clin. 2019 Sep;49(4):329-334. doi: 10.1016/j.neucli.2019.07.002. Epub 2019 Jul 19.

Authors

Manoel Wilkley Gomes de Sousa¹, Marcio Luiz Escorcio-Bezerra², Wladimir Bocca Vieira Rezende Pinto¹, Paulo Victor Sgobbi Souza¹, Nadia Iandoli de Oliveira Braga¹, Acary Souza Bulle Oliveira¹, Gilberto Mastrocola Manzano¹

Affiliations

¹ Department of Neurology, Universidade Federal de São-Paulo, São-Paulo, Brazil.
² Department of Neurology, Universidade Federal de São-Paulo, São-Paulo, Brazil. Electronic address: marciobzrra@gmail.com.

PMID: 31331650
DOI: 10.1016/j.neucli.2019.07.002

Abstract

Our aim was to study motor unit number index (MUNIX) in myopathic disorders. We studied 11 patients with myopathy, and healthy controls. We obtained MUNIX, compound muscle action potential (CMAP), motor unit size index (MUSIX) and alpha (α, power exponent from MUNIX equation) measurements from three different muscles. MUNIX and CMAP were significantly lower in one muscle. This MUNIX decrease may not be related to motor neuron loss, but rather to muscle fiber atrophy. MUSIX and α did not change and may be useful in determining whether the MUNIX decrease is indeed due to motor unit loss.

Keywords: MUNE; MUNIX; Motor neuron disease; Motor unit number; Myopathy.

MeSH terms

Adult
Electromyography
Female
Humans
Male
Middle Aged
Motor Neurons / physiology*
Muscle, Skeletal / physiopathology*
Muscular Diseases / diagnosis*
Muscular Diseases / physiopathology*
Young Adult