Motor unit number index as an individual biomarker: Reference limits of intra-individual variability over time in healthy subjects

Delmont, Émilien; Wang, François‐Charles; Lefaucheur, Jean‐Pascal; Puma, Angela; Brenière, Céline; Beaudonnet, Guillemette; Cintas, Pascal; Collin, Romain; Fortanier, Etienne; Grapperon, Aude-Marie; Jomir, Laurent; Kribich, Hafida; Kouton, Ludivine; Küntzer, Thierry; Lenglet, Timothée; Magot, Armelle; Nordine, Tarik; Ochsner, François; Bolloy, Gaëlle; Péreón, Yann; Salort‐Campana, Emmanuelle; Tard, Céline; Vicino, Alex; Verschueren, Annie; Attarian, Shahram

doi:10.1016/j.clinph.2020.06.019

Cited by 14 publications

(14 citation statements)

References 24 publications

(38 reference statements)

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“…In addition, the MUNIX correlated with muscle strength and disability score, confirming that weakness depends on the severity of denervation. Our results agreed with the results obtained for adults [55][56][57][58] and those obtained for pediatric patients with SMA reported recently. 59 The MUNIX technique had good intrarater variability among patients with Ped-SMA and was feasible for use with those patients compared with other electrophysiological techniques (CMAP amplitude and especially MUNE).…”

Section: Discussionsupporting

confidence: 93%

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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Section: Discussionsupporting

confidence: 93%

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

et al. 2021

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“…Another very interesting aspect of this paper is the results in healthy children: they are similar to those in “younger” adults below 60 years of age 2,5,6 . Although the number of evaluated healthy children was very low, this might support the concepts that (a) lower motor neuron development is mature early in humans and (b) there is physiological loss of lower motor neurons after age > 60 years 2,6 …”

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confidence: 63%

“…2,5,6 Although the number of evaluated healthy children was very low, this might support the concepts that (a) lower motor neuron development is mature early in humans and (b) there is physiological loss of lower motor neurons after age > 60 years. 2,6 Furthermore, Verma et al found the "reverse-split-hand" phenomenon in children with SMA, as shown previously in adult SMA patients. 7 This interesting finding shows us that diseases such as The existing therapeutic options for SMA are encouraging, however very costly, and an objective electrodiagnostic biomarker for disease progression in SMA might be an attractive additional outcome measure to track changes and drug effectiveness in children and adults with SMA.…”

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confidence: 54%

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MUNIX in children with spinal muscular atrophy: An unexpected journey

Neuwirth

Weber

2020

Muscle and Nerve

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“…Our work showed that MUNIX values correlated with muscle strength and CMAP amplitude. Since MUNIX scores closely depend on CMAP amplitude, which of the muscles is especially influenced by the placement of the electrodes, an experienced technician is essential ( 36 ). The sum of the results of deltoid, ADM, QF, and TA resulted in the MRC sum score and the MUNIX sum score.…”

Section: Discussionmentioning

confidence: 99%

Application Value of the Motor Unit Number Index in Patients With Kennedy Disease

Zhang

Yang

et al. 2021

Front. Neurol.

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The aim of this study was to evaluate the usefulness of the motor unit number index (MUNIX) technique in Kennedy disease (KD) and test the correlation between the MUNIX and other clinical parameters. The MUNIX values of the bilateral deltoid, abductor digiti minimi (ADM), quadriceps femoris (QF), and tibialis anterior (TA) were determined and compared with the course of the disease. The MUNIX sum score was calculated by adding the MUNIX values of these 8 muscles. Disability was evaluated using the spinal and bulbar muscular atrophy functional rating scale (SBMAFRS). The MUNIX scores of patients with KD were negatively correlated with the course of the disease (p < 0.05), whereas their motor unit size index (MUSIX) scores were positively correlated with the course the of disease (p < 0.05). MUNIX sum scores were correlated with SBMAFRS scores (r = 0.714, p < 0.05). MUNIX was more sensitive than compound muscle action potentials or muscle strength as an indicator of neuron loss and axonal collateral reinnervation. The MUNIX sum score is an objective and a reliable indicator of disease progression, and it is a potential choice for therapeutic clinical trials. The MUNIX can assess the functional loss of motor axons and is correlated with disability. The MUNIX sum score may be especially suitable as an objective parameter.

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Motor unit number index as an individual biomarker: Reference limits of intra-individual variability over time in healthy subjects

Cited by 14 publications

References 24 publications

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

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

MUNIX in children with spinal muscular atrophy: An unexpected journey

Application Value of the Motor Unit Number Index in Patients With Kennedy Disease

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