An electromyogram (EMG) measures electrical activity in muscles using electrodes and a recording instrument. A specially trained neurologist, physiatrist or certified clinician places a tiny needle electrode into the muscle, recording electrical activity while the muscle is still and while the muscle is moving. The information helps physicians identify injuries related to muscles and nerves.
Nerve Conduction Studies
Healthy nerves send electrical signals called impulses to move muscles, but when nerves are damaged, they can cause tingling, numbness, pain and problems with muscle movement. Conduction studies gauge how well a nerve is doing its job by targeting the nerve with low-level electrical pulses and measuring the muscle's reaction. One electrode is placed on the skin above the nerve, and a second is placed above the muscle controlled by that nerve. Surface electrodes are small, round devices about the size of a nickel that sit on the skin.
Follow-up electrodiagnostic studies are generally not required but are occasionally performed to assess progression of disease or to monitor recovery.