Quantitative electromyography using automatic analysis--diagnostic utility of turns per unit amplitude.

Quantitative electromyographic (QEMG) data from 3 muscles recorded with a 50-micronV threshold for the turns and amplitude measurements are presented. Using turns per unit amplitude as the index, consistent and comparable readings were recorded from abductor digiti minimi, biceps brachii and vastus medialis in normal subjects, namely 1.132 +/- 0.08 (31 subjects), 1.059 +/- 0.122 (31 subjects) and 1.007 +/- 0.088 (11 subjects), respectively. It is shown here that the diagnostic yield increases when all 3 values, namely, turns/s, average amplitude and turns/unit amplitude are considered in conjunction rather than considering the first 2 alone.