Carrier detection of Duchenne dystrophy by frequency analysis of the electromyogram

A new method for Duchenne muscular dystrophy (DMD) carrier detection based on frequency analysis of electromyograms (EMG) taken from relative force contractions shows great promise in classifying possible carriers. Nine carriers were examined and compared to nineteen normals in an attempt to define a discriminant function that would be effective in classification of possible carriers of the gene responsible for DMD. EMG data were taken at 20%, 40%, and 60% of maximum effort from the biceps brachii using a specially designed dynamometer apparatus. The apparatus was able to isolate the biceps muscle group and allowed for adjustment to accommodate different body sizes. Three signal processing methods were used to find variables in the frequency domain that would provide the best discriminant function based on the jackknife classification method. Of these methods, the most promising appears to be the high-to-low ratio method at 20% maximum contraction. When combining the high and low values found with this test in conjunction with the peak cepstrum values also found at 20% maximum contraction, discrimination was found to be 83.8% accurate. Because this classification is not based solely on definite carriers, and appears to be independent of serum creatine phosphokinase (CPK) values, it would seem that classification based on a definite carrier population could be performed with greater accuracy, especially with the addition of CPK values.