Use of Signal Representation to Identify Abnormal Motor Unit Potentials in Macro EMG

Macro electromyography (EMG) is a recently described recording technique allowing a nonselective recording of motor unit activity. The pick-up area of the electrode, the cannula of a modified single-fiber electrode, covers the entire motor unit territory. The motor unit potential (MUP) is obtained by averaging the cannula signals that are time locked to a single-fiber action potential. The MUP waveform is relatively insensitive to the position of the electrode within the motor unit. The amplitude of the MUP has been used as a measure of the size of the motor unit and normal values for the individual and median MUP amplitude have been defined.