Electromyography
Electromyography (EMG) has been used since the 1940s in the diagnosis of neuromuscular disorders. It has particularly developed with the advent of computers and recording equipment with integrated software. This has made methods of analysis fast, robust, and precise, helping to deal with increasing numbers of patients. Indications have changed dynamically over the years, with the development of new EMG methods themselves and complementary methods used in this field for diagnosis such as histochemistry, genetics, and imaging techniques. This chapter focuses mainly on the routine methods based on recordings with concentric or monopolar needle electrodes, but will also briefly review some of the other EMG methods. There is an increasing understanding of the relationship between the generators (muscle fibres) and the recorded signal that helps interpretation of the recordings. The parameters used for quantitation of the EMG signal are discussed. The findings in pathological conditions are discussed and some practical hints on EMG studies given.