INTRODUCTION

Electromyography (EMG) is the extracellular recording of bioelectrical activity generated by muscle fibres. The term indeed stands for at least two different clinically used methods, which are quite distinct and as a rule performed in different settings (laboratories), for different purposes. On the one hand EMG can reveal the ‘behaviour’ (i.e. patterns of activity) of a particular muscle, or it can also be used to demonstrate whether a muscle is normal, myopathic or denervated/reinnervated. The former can be called ‘kinesiological EMG’ and the latter ‘motor unit’ EMG, but usually this division is not specified and both types of examination are just called ‘EMG’, which can confuse the uninitiated. In clinical neurophysiology, EMG techniques are combined with conduction studies to assess involvement of the neuromuscular