Disposable concentric needle electromyography electrodes artifact discharge mimicking positive sharp waves

Area of Science:

• Neurology
• Biomedical Engineering
• Electrophysiology

Background:

• Disposable concentric needle (DCN) electrodes are widely used in electromyography (EMG) for muscle activity assessment.
• Accurate interpretation of EMG signals is crucial for diagnosing neuromuscular disorders.
• Potential sources of signal artifact can complicate diagnostic accuracy.

Purpose of the Study:

• To identify and characterize a novel artifact discharge (AD) generated by DCN EMG electrodes.
• To differentiate this artifact from genuine physiological signals like positive sharp waves (PSWs).

Main Methods:

• EMG recordings were obtained from 77 patients (26 males, 51 females) using 41 DCN electrodes (37 mm) and 36 DCN electrodes (50 mm).
• Recordings focused on muscle activity during rest following the initial needle insertion.
• The occurrence and resolution of artifact discharges were observed and documented.

Main Results:

• An artifact discharge (AD), visually similar to positive sharp waves (PSWs), was observed in 31 out of 77 patients.
• The AD appeared in 18 of 41 insertions with 37 mm DCN electrodes and 13 of 36 insertions with 50 mm DCN electrodes.
• The artifact resolved upon repositioning the needle within the muscle or subcutaneous adipose tissue.

Conclusions:

• A distinct artifact discharge (AD) associated with DCN EMG electrodes has been identified.
• This AD can be mistaken for positive sharp waves (PSWs), potentially leading to misinterpretation.
• Awareness and recognition of this artifact are essential for accurate needle EMG interpretation and avoiding false-positive diagnoses.