Turns-amplitude analysis of the electromyographic recruitment pattern disregarding force measurement. II. Findings in patients with neuromuscular disorders.

Turns-amplitude analysis of the electromyographic recruitment pattern was performed on-line in the brachial biceps muscle of 46 patients with neuromuscular disorders using the mean amplitude as an indicator of force. The parameters, peak-ratio (PR) and number of time intervals (TI) from 0 to 1.5 ms, were increased in patients with myopathy. In patients with neurogenic involvement, the characteristic pattern was a decreased PR and a decreased incidence of TI between 0 and 1.5 ms. The results indicate that the two parameters supplement each other as some of the patients were identified only by one or the other. In patients with myopathy, the method had a higher diagnostic yield than the individual motor unit action potential analysis. The method is objective, fast, and reliable.