[Automatic methods of measurement of motor potential units]

The study of motor unit potentials (MUP) may be carried out using qualitative or quantitative methods. The considerable usefulness of quantitative methods in the diagnosis of neuromuscular disorders has led to development of new automatic techniques which permit greater speed and accuracy of clinical investigation. In this review we consider traditional electromyographic techniques and describe some automatic methods.

Qualitative techniques are simpler but give limited information since they only permit recording of very marked alterations. The introduction of trigger and averaging permit quantitative analysis and thus the evaluation of less obvious changes. Although they do not identify all the potentials of an electromyographic signal, the new automatic techniques using partial decomposition avoid the loss of time occurring with earlier techniques, give reliable objective measurements of the MUP and also the possibility of measuring new parameters, such as the area or frequency of discharge.

New methods of evaluation of the MUP have significant advantages over traditional methods, namely increased speed and objectivity. However, this makes it necessary to redefine normal values since different methods are used for obtaining and processing the signals, otherwise the results may not be strictly comparable.