Abstract

Background: Depth and orientation of concentric needle electrode (CNE) insertion during the needle electromyography (EMG) might have influences on motor unit potentials (MUPs). Objective: To examine whether the depth of CNE insertion in m.vastus lateralis significantly affects PMU parameters in patients with myopathy (muscular dystrophy) and neuropathy (hereditary motor and sensory neuropathy). Methods: In order to analyze influences of depth and orientation of insertion of CNE, 11 patients with different neuromuscular disorders (8 with myopathies, and 3 with neuropathies) were examined. MUAPs parameters were compared after automatic (depths of perpendicular CNE insertion were 0, 0.5, 1, 2 and 3 cm in MVL) and manual method of extraction (0 and 1.5 cm). Results: MVL MUAP analysis (with typically changed MUPs features, especially duration) in patients with different neuromuscular disorders (neuropathies, myopathies) showed similar results like in healthy volunteers. Automated analysis of MVL in patients with myopathies showed irregular changes of the most of MUAPs parameters, especially duration. With depth of needle insertion, duration of MUAPs recorded with CNE and it’s componentes is not changed signifficantly, but that was not case with amplitude and area. Conclusion: A discrepancy between MUAPs parameters detected with manual and automatic methods is confirmed. We think that it is necessary to use specific standards for patients with neuropathic and myopathic diseases.

Key words: motor unit; electromyography; neuromuscular disorder; concentric needle electrode.