Electromyography (EMG) is a diagnostic procedure to detect neuromuscular abnormalities. This technique means the recording of electrical activity (biopotentials) of skeletal muscles and nerves. Using EMG, a topical diagnosis of lesions of the nervous and muscular systems (suprasegmentary pyramidal and extrapyramidal structures, motor neurons of anterior horns, spinal roots and nerves, neuromuscular junction and innervated muscle itself) is made, as well as the severity, stage, progression of the disease, and the treatment efficacy are assessed.