[The new parameters of motor unit potential in the diagnosis of neurogenic lesions in spike-triggered averaging electromyography].

OBJECTIVE

To evaluate the clinical significance of the new parameters of motor unit potential (MUP) to the diagnosis of neurogenic lesions.

METHODS

Three groups of muscles, anterior tibialis, abductor pollicis brevis and vastus medialis were studied with spike-triggered averaging electromyography (EMG). A total of 3,646 MUPs, 1,903 from normal group and 1,743 from neurogenic group, were recorded under slight muscle contraction.

RESULTS

The area, as a single parameter, produced the most significant result in discriminant analysis, about 80% MUPs from neurogenic muscles being judged to be abnormal. Compared with the area, the amplitude and duration were less sensitive, being able to assign about 77% and 70% of MUPs in the neurogenic group as abnormal. A combination of the area/amplitude ratio (thickness) and the amplitude, and a combination of the duration (width) and the amplitude could further improve the discriminating ability, around 80% and 81% MUPs in the neurogenic muscles being classified as abnormal by the combinations. The simplified discriminant functions, 2 x Log10 (amplitude) +Log10 (area/amplitude) -4 for size index, and 5 x Log10 (duration) + 3 x Log10 (amplitude) -10 for width-height index had same discriminating ability as the real discriminant function.

CONCLUSIONS

The new parameters, SI, WHI and area in spike-triggered EMG seemed to be promising, since they produced a better yield in the diagnosis of neurogenic lesions than amplitude or duration alone in the discriminant analysis.