Quantitative electromyography using automatic analysis. A comparative study with a fixed fraction of a subject's maximum effort and two levels of thresholds for analysis.

Quantitative electromyographic (QEMG) data recorded with two levels of threshold for the apparatus are compared. Using a fixed fraction of a subject's maximum effort the data are shown to be independent of sex, age and the strength of the muscles. The diagnostic yield of such a method is shown to be better with 50 muV threshold for analysis than with 100 muV, in cases of muscle disorders such as Duchenne muscular dystrophy and polymyositis. However, in cases of neurogenic lesions due to anterior horn cell disease the diagnostic yield remains the same with both thresholds.