Sputtering positive potentials in the EMG: an artifact resembling positive waves

Area of Science:

• Neurology
• Electrophysiology
• Clinical Neurophysiology

Background:

• Sputtering positive potentials (SPPs) are observed in electromyogram (EMG) recordings of normal muscles.
• These potentials are often cannula-recorded nerve potentials.
• SPPs can be misidentified as positive sharp waves associated with denervation.

Purpose of the Study:

• To describe the characteristics of sputtering positive potentials (SPPs).
• To differentiate SPPs from pathological waveforms in EMG.
• To aid clinicians in accurate EMG interpretation.

Main Methods:

• Analysis of EMG recordings from normal distal muscles.
• Identification and characterization of SPPs.
• Comparison of SPP features with denervation potentials.

Main Results:

• SPPs present as small, irregularly occurring waveforms.
• Key distinguishing features include amplitude, regularity, and duration.
• These characteristics differ from those of denervation potentials.

Conclusions:

• SPPs are a normal finding in EMG.
• Understanding the specific features of SPPs is essential for accurate diagnosis.
• Distinguishing SPPs prevents misdiagnosis of muscle denervation.