Biomedical Engineering Reference
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4.3.2 Quantification of EMG features
The first effort to quantify EMG was connected with the manual evaluation of
mean MUAP parameters from a representative number of MUs recorded during a
weak effort [Buchthal, 1955, Buchthal, 1985]. The duration and the amplitude of
MUAPs as well as the incidence of polyphasic potentials were evaluated from pho-
tographically recorded signals. The greater availability of computers in the 1970s
and 1980s facilitated the development of computer-aided quantitative EMG process-
ing methods. Automatic systems for EMG-based diagnosis including commercial
systems evolved. These systems perform automatic identification of single MUAPs
and extraction of their features, such as peak amplitude, rise time, duration, area,
or number of phases (connected with baseline crossings). For interference patterns,
usually the smaller fluctuations of amplitude are analyzed (so called turns-amplitude
analysis). These parameters are illustrated in Figure 4.51. In order to increase the
diagnostic yield the combination of the parameters was also introduced, e.g., the
thickness- area divided by amplitude.
FIGURE 4.51: a) Parameters characterizing MUAP; b) parameters characterizing
interference EMG. (By courtesy of M. Piotrkiewicz.)
Besides turns-amplitude analysis, the most popular automatic methods of inter-
ference pattern analysis include amplitude measurements, different spike counting
methods, and power spectrum analyses. The methods of interference pattern analysis
and their applications in diagnosis of myogenic disorders, in assessment of exerted
 
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