Monopolar and concentric EMG needle electrodes

Monopolar and concentric EMG needle electrodes have different characteristics. Their clinical application in electromyography (EMG) or nerve conduction velocity (NLG) measurement depends on various factors such as physician experience, training of medical staff and type of examination. However, many doctors in Europe tend to use concentric EMG needle electrodes.

Monopolar and concentric EMG needle electrodes

Monopolar and concentric EMG needle electrodes have different characteristics. Their clinical application in electromyography (EMG) or nerve conduction velocity (NLG) measurement depends on various factors such as physician experience, training of medical staff and type of examination. However, many doctors in Europe tend to use concentric EMG needle electrodes.

Monopolar EMG needle electrodes

The monopolar EMG needle electrodes are classified from 26 to 31 gauge. The needles are made of stainless steel, coated with an insulating layer. The monopolar EMG needle electrodes have a conical shape, which enables signal detection from different sides. The recording area of monopolar EMG needle electrodes is three times larger than concentric EMG needle electrodes. In addition, the impedance of monopolar needle electrodes is lower than that of concentric needle electrodes. As a result, the monopolar needle electrodes record more electrical activity compared to concentric needle electrodes. In the EMG examination using monopolar needle electrodes, the needle serves as the active electrode and a reference electrode is placed next to it. The ground electrode is usually placed further away from both (active electrode and reference electrode).

Concentric EMG needle electrode

Concentric EMG needle electrodes consist of an active electrode (core, made of silver) and a reference electrode (cannula, made of stainless steel) as a single unit. The tip has an elliptical shape with an angle of approximately 15 degrees. Compared to monopolar EMG needle electrodes, the results with concentric EMG needle electrodes are more reproducible. In addition, the signals (EMG recording) are more stable than with monopolar EMG needle electrodes. Furthermore, no reference electrode is required when using concentric EMG needle electrodes.