There are two types of electrodiagnostic tests that are commonly used to look at nerve and muscle function to see if a nerve is pinched or not functioning: electromyography tests and nerve conduction studies.
Electromyography (EMG) Tests
An EMG records and analyzes the electrical activity in your muscles. Small, thin needles are placed in the muscle to record the electrical activity as the patient relaxes and contracts the muscle.
Nerve Conduction Studies
NCS tests are usually done along with EMG tests to determine if a nerve is functioning normally. During this procedure, wires are taped to the skin surface along the nerve pathway. Electrical signals are sent along the pathway, and the sensors record the electric activity and measure how fast the impulse travels along the nerve pathway.
Your doctor may recommend electrodiagnostic testing for various conditions that result from pressure on the nerves, particularly in the arm, elbow, or wrist.