Automatic analysis of the EMG interference pattern

Diagnostic yield of noninvasive high spatial resolution electromyography in neuromuscular diseases

“…In the study of Nirkko et al, 14 178 unselected patients with and without neuromuscular disorders were investigated by automated interference pattern analysis (IPA, ''Willison analysis,'' modified by Stål-berg et al 24 ) of needle EMG recordings. The sensitivity for the detection of abnormal vs. normal was 74% (specificity: 80%); the sensitivity for the detection of a myopathy or neuropathy was 75% or 53% (specificity: 84% and 97%, respectively).…”

The utility of interference pattern analysis

“…Therefore, several modifications of turns/amplitude analysis have been suggested, disregarding estimation of muscle force (see below). 24,68,72,90,161,193 Although a curvilinear relationship between cumulated amplitude per second (corresponding to turns × mean amplitude) and turns per second 199 seems promising with respect to differentiating patients with neuromuscular disorders from controls, 89,90 the results have not been compared with those of a known method.…”

“…79,98,196,207,211 The influence of age, sex, and temperature on the turns/amplitude parameter is minor or nonexistent. 58,60,73,130,193 Cloud, Activity, and Number of Small Segments. A plot of mean amplitude as a function of turns can be obtained without measurement of force.…”

“…The distribution of values from control subjects measured at low and high forces of the muscle, respectively, at 20 sites in each muscle has been called "the cloud." 193 If one subject had two points outside this cloud, it was considered pathological. In patients with myopathy, mean amplitude/turns values were found to be low, whereas patients with neurogenic lesions had high values.…”

Determining the shape of the turns–amplitude cloud during anal sphincter quantitative EMG

“…as seen in Table 1. As suggested by Stalberg [14] though, "clouds analysis" theoretically can be used irrespective of the force of muscle contraction, and as described in the "Materials and methods" section, a cloud analysis in fact plots amplitude versus turns-second at varying levels of contraction.…”