The utility of motor unit number index: A systematic review

Fatehi, Farzad; Grapperon, Aude-Marie; Fathi, Davood; Delmont, Émilien; Attarian, Shahram

doi:10.1016/j.neucli.2018.09.001

Cited by 29 publications

(34 citation statements)

References 43 publications

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“…Conduction block due to nerve root compression in LR may be one reason. According to the report of a previous study, the MUNIX can reflect dysfunction of the motor unit caused by conduction block, while distal CMAP amplitudes may remain normal when conduction block is proximal to the stimulation site. A similar condition has been reported in some demyelinating and dysimmune neuropathies associated with conduction block .…”

Section: Discussionmentioning

confidence: 95%

“…According to the report of a previous study, the MUNIX can reflect dysfunction of the motor unit caused by conduction block, while distal CMAP amplitudes may remain normal when conduction block is proximal to the stimulation site. A similar condition has been reported in some demyelinating and dysimmune neuropathies associated with conduction block . Furthermore, the collateral sprouting by axons of the remaining motor units is considered to be another more likely reason for this condition, and increased MUSIX values in the involved muscles in most patients with LR further support the existence of this reinnervation.…”

Section: Discussionmentioning

confidence: 95%

“…The motor unit number index (MUNIX) is a quantitative method that provides an estimated index of the number and size of the functioning motor units in the tested muscle, and this noninvasive technique requires only a small amount of electrical stimulation, thus facilitating patient compliance . Furthermore, MUNIX has been demonstrated to be very sensitive in detecting motor axonal loss and proximal conduction block in many peripheral neuropathies . Both of these have been identified as major pathological processes in LR .…”

Section: Introductionmentioning

confidence: 99%

“…Both of these have been identified as major pathological processes in LR . In studies to date, MUNIX has most often been used to track neuromuscular diseases such as amyotrophic lateral sclerosis and adult spinal muscular atrophy . In recent studies, researchers demonstrated the value of MUNIX in the assessment of peripheral motor unit loss in neurological disorders such as stroke, spinal cord injury, and cerebral palsy .…”

Section: Introductionmentioning

confidence: 99%

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Motor unit number index in quantitatively assessing motor root lesions and monitoring treatment outcomes in patients with lumbosacral radiculopathy

et al. 2020

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Introduction:We investigated the feasibility of motor unit number index (MUNIX) in quantitatively assessing motor root lesions and tracking different treatment outcomes in lumbosacral radiculopathy (LR).Methods: Bilateral MUNIX was recorded from the abductor hallucis, extensor digitorum brevis, and tibialis anterior in 44 normal controls and 108 patients with LR, and this was repeated approximately 12 months after treatment in 60 patients with LR.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Motor unit number index in quantitatively assessing motor root lesions and monitoring treatment outcomes in patients with lumbosacral radiculopathy

et al. 2020

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“…A correlation between MUNIX value and with the size of CMAP area was observed (8,35,36). However, MUNIX can provide more information and is proved more sensitive than CMAP alone (1,4,36).…”

Section: Discussionmentioning

confidence: 96%

A Preliminary Study of Effects of Channel Number and Location on the Repeatability of Motor Unit Number Index (MUNIX)

et al. 2020

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Motor Unit Number Index (MUNIX) is a technique that provides a susceptive biomarker for monitoring innervation conditions in patients with neurodegenerative diseases. A satisfactory repeatability is essential for the interpretation of MUNIX results. This study aims to examine the effect of channel number and location on the repeatability of MUNIX. In this study, 128 channels of high-density surface electromyography (EMG) signals were recorded from the biceps brachii muscles of eight healthy participants, at 10, 20, 30, 40, 50, 60, 70, 80, and 100% of maximal voluntary contraction. The repeatability was defined by the coefficient of variation (CV) of MUNIX estimated from three experiment trials. Single-channel MUNIX (sMUNIX) was calculated on a channel-specific basis and a multi-channel MUNIX (mMUNIX) approach as the weighted average of multiple sMUNIX results. Results have shown (1) significantly improved repeatability with the proposed mMUNIX approach; (2) a higher variability of sMUNIX when the recording channel is positioned away from the innervation zone. Our results have demonstrated that (1) increasing the number of EMG channels and (2) placing recording channels close to the innervation zone (IZ) are effective methods to improve the repeatability of MUNIX. This study investigated two potential causes of MUNIX variations and provided novel perspectives to improve the repeatability, using high-density surface EMG. The mMUNIX technique proposed can serve as a promising tool for reliable neurodegeneration evaluation.

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Motor unit number index: A potential electrophysiological biomarker for pediatric spinal muscular atrophy

et al. 2021

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Introduction/Aims: In adult spinal muscular atrophy (SMA), the motor unit number index (MUNIX) has been shown to be an useful electrophysiological biomarker. This study evaluated the feasibility and the clinical relevance of using the MUNIX technique for patients with pediatric SMA (Ped-SMA) and correlated MUNIX results with clinical scores. Methods: Fourteen patients with type II Ped-SMA (11 females; median age 11 y [interquartile range (IQR), 4.8-17 y]) and 14 controls (nine females; median age 10.75 y [IQR, 6.5-13.4 y]) were enrolled and matched by sex, age, height, weight, and body mass index. Clinical examination included manual muscle testing, dynamometry (grasp and pinch), and motor function measure (MFM). The MUNIX technique was evaluated in the abductor digiti minimi (ADM) and abductor pollicis brevis (APB) on two sides when possible.Results: In the patients with Ped-SMA, the MUNIX and compound muscle action potential (CMAP) amplitudes were significantly decreased and the motor size unit index (MUSIX) was significantly increased in the ADM and APB when compared to controls. The intraclass correlation coefficient was good for the intrarater variability of the CMAP amplitude, MUNIX, and MUSIX in the ADM (0.95, 0.83, and 0.89, respectively) and the APB (0.98, 0.96, and 0.94, respectively). The total CMAP amplitude correlated with the grasp and pinch scores (P < .05), and the MUNIX measurements correlated with the MFM scores.Discussion: The MUNIX technique, which accurately estimated lower motor neuron loss and the number of remaining functional motor units, was shown to be a useful electrophysiological biomarker for disease progression and a potential biomarker for treatment response.

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The utility of motor unit number index: A systematic review

Cited by 29 publications

References 43 publications

Motor unit number index in quantitatively assessing motor root lesions and monitoring treatment outcomes in patients with lumbosacral radiculopathy

Motor unit number index in quantitatively assessing motor root lesions and monitoring treatment outcomes in patients with lumbosacral radiculopathy

A Preliminary Study of Effects of Channel Number and Location on the Repeatability of Motor Unit Number Index (MUNIX)

Motor unit number index: A potential electrophysiological biomarker for pediatric spinal muscular atrophy

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