A new quantitative motor unit potential (MUP) analysis method, called multi-MUP analysis, is described. Multi-MUP analysis is a type of decomposition analysis of the EMG signal. At each site 6 different MUPs may be recorded during an epoch of 4.8 sec. Calculation time is about 3 sec. A study of 20–30 MUPs including editing takes 4–8 min. Compared to many earlier MUP analysis methods it is faster and more user friendly, therefore it can be used in daily routine EMG analysis. The accuracy and reliability of the method are good. The differences from methods based on manual analysis, spike triggered averaging, template matching and decomposition are discussed. The main advantages of multi-MUP analysis are: (1) quick acquisition of many MUPs; (2) simultaneous collection of several MUPs at one recording site; (3) possibility to analyze not only low threshold MUPs; (4) less bias in the selection of MUPs; and (5) the reproducibility of the results that allow the same reference values to be used in different laboratories. So far we have successfully used this method for 2 years on more than 2000 patients.

Multi-MUP EMG analysis--a two year experience in daily clinical work.

The motor unit number index (MUNIX) is a method for assessment of number and size (MUSIX) of motor units (MUs) using the compound muscle action potential (CMAP) and surface electromyographic interference pattern (SIP). This method was used to study the hypothenar muscle in 34 healthy subjects to define normal range, and to study reproducibility. Four healthy subjects and 13 patients with amyotrophic lateral sclerosis (ALS) were studied serially over a 1-year period. In healthy subjects, MUNIX showed good reproducibility. In serial studies, healthy subjects showed no change in the CMAP amplitude and MUNIX. ALS patients with minimal change in CMAP amplitude had a significant drop in MUNIX and increase in MUSIX, indicating MU loss compensated by reinnervation. When the CMAP changed significantly (>30%) in 1 year, the CMAP and MUNIX decreased in parallel. MUNIX would be useful to study MU loss in degenerative diseases of motor neurons. Muscle Nerve 42: 798-807, 2010.

Motor unit number index (MUNIX): principle, method, and findings in healthy subjects and in patients with motor neuron disease†

Characterizing EMG data using machine-learning tools

Pathologic progression in amyotrophic lateral sclerosis (ALS) results from motor neuron death, while the clinical expression also reflects the compensatory effects of collateral reinnervation consequent to lower motor neuron loss. In a cross-sectional study of ALS subjects, we made comparisons between motor unit number estimation (MUNE) values and several measures reflecting collateral reinnervation, including isometric strength, compound muscle action potential (CMAP) amplitude, surface motor unit action potential (S-MUAP) amplitude, fiber density (FD), macro-EMG potential amplitude, turns-to-amplitude (T/A) ratio, and amplitude and recruitment pattern of low threshold voluntary motor units in elbow flexor muscles. Before comparisons were made, test-retest reproducibility of these measures was assessed in ALS subjects, and is highest for isometric strength, and lower but similar for EMG measures. When the effects of multiple comparisons are considered, borderline significant correlations are found between MUNE values and isometric strength. Neither MUNE values nor isometric strength are significantly correlated with macro-EMG amplitude, FD, T/A ratio, or amplitude and recruitment rate of low threshold voluntary motor units. There are significant correlations of CMAP and S-MUAP with MUNE values, but these are statistical artifacts with no independent interpretation. We conclude that collateral reinnervation prevents isometric strength and EMG measures from accurately reflecting lower motor neuron death in ALS. MUNE measurements are better suited to provide insight into the true natural history of the disease process and may be clinically useful to follow progression and response in drug trials.

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Motor unit number estimation, isometric strength, and electromyographic measures in amyotrophic lateral sclerosis

http://uu.diva-portal.org/smash/get/diva2:1350104/FULLTEXT01

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Automatic analysis of the EMG interference pattern