To quantify the electromyographic interference pattern, we analysed the turn and amplitude of the electromyographic interference pattern of twenty healthy males, nineteen healthy females as controls and the various neuromuscular disease patients at optional non-controlled force levels. The value of turns per sec and total amplitude per sec in the interference pattern were transformed into the logarithmic scale and the regression equation was calculated with log (turns per sec), log (total amplitude per sec). The normal range is defined as "within±3 standard error of estimate from the regression equation" and the unit residue is defined as "observed log (total amplitude per sec) minus calculated log (total amplitude per sec), divided by the standard error of estimate of the regression equation". We used the above normal range and the unit reside as a diagnostic tool in the electromyographic diagnosis of the neuromuscular diseases. The purpose of this study is to obtain the normal reference value and the diagnostic sensitivity of our turn-amplitude method, and also to evaluate its usefulness in monitoring the disease activity, progression.

The results were as follows;

1) With this turn-amplitude analysis, the normal reference value was obtained and the high diagnostic yield for the neuropathy and myopathy was obtained.

2) The turn-amplitude analysis was very useful in infants or children who could not cooperate in the conventional subjective electromyography and also useful in the borderline myopathy cases who were not diagnosed definitely by the conventional subjective electromyography.

3) The turn-amplitude analysis shows the possibility of monitoring the disease activity, progression in the neuropathy and myopathy.

Thus, we can suggest that our turn-amplitude analysis technique is a quantitative, objective method which could be done with ease. Further studies are recommanded for the evaluation of monitoring the various neuropathic and myopathic disease activity, progression. Borderline neuropathy and myopathy such as the carriers of progressive muscular dystrlphy also need to be evaluated by this technique.