There are two types of electrodiagnostic testing that are commonly used: electromyography, or EMG, and nerve conduction studies. These tests analyze the electrical activity taking place in the nerves and muscles.
EMG tests muscle activity; it involves inserting a needle through the skin and into the muscle. The needle records electrical activity in the muscle as the patient relaxes then contracts the muscle. When a normal muscle is at rest, there is no electrical activity. When the muscle contracts, electrical activity is recorded.