[The neurophysiological diagnosis of myopathies]

Electromyography is a technique widely used to assist diagnosis of neuromuscular disorders. The neuromuscular system as a whole (neuron, nerve, neuromuscular junction and muscle) have several electrochemical properties which may be detected by suitable apparatus and are the basis of electromyography.

Healthy muscle has particular characteristics which are affected by structural/functional changes, whether they are of primary origin (myopathies) or secondary to alterations at other levels (secondary muscle involvement). In this paper we wish to summarize the electromyographic findings typical of myopathies, those which differentiate these from other neuromuscular disorders and to establish when possible the characteristic signs of each form of presentation. Finally we give a brief bibliography which we consider to be basic to understanding this diagnostic technique in this type of illness.