Electromyography (EMG) and Nerve Conduction Studies (NCS)

These 2 tests are generally done at the same time. The EMG is similar to an EKG that is done for the heart. It shows the electrical activity of a muscle at rest and when it actively contracts. There are certain electrical abnormalities that appear when a muscle's nerve supply is damaged. By recognizing these abnormalities and knowing which nerve supplies the muscle, a nerve problem can be located. In many ways, it's similar to locating an electrical "short".

Nerves are like electric wires. They carry electricity from the brain, down the spinal cord, and into the arms and legs, making your muscles contract. They also carry electrical information from sensors in the skin and joints, back to the brain. The nerves in the arms and legs are covered with a coat of insulation called myelin. This coating allows the nerves to carry electricity at very rapid rates. If there is pressure on a nerve, from an injury or scar tissue, it can damage the insulation, and the nerve "slows down" over that nerve segment. The Nerve Conduction Study tests and localizes these areas of nerve pressure by determining how fast electricity travels over specific nerve segments. This test can also identify more generalized slowing in nerves, such as neuropathies.