Nerve Conduction Studies

Nerve conduction studies are tests that evaluate the conduction of electrical impulses down nerves.  Individual nerves in the arms or legs, called peripheral nerves, can be made to conduct these impulses by being stimulated through the skin.  A hand held electrical stimulator is placed on the arm or leg and individual brief electrical pulses are delivered.  This is usually experienced by the patient as a mild tingling that can become a hard or biting electrical sensation, as the nerve being tested is fully activated.  The stimulation also results in a limited area of involuntary muscle twitching that most patients find odd or surprising, rather than painful. 

The electrical impulses that are generated by the nerve in response to this stimulation are recorded through soft gel pads placed at various points over the length of the nerve.  The result is a series of electrical waveforms that are recorded through the EMG machine.  Waveforms travel down the nerve at a standard speed (velocity) and have a predictable standard size (amplitude) in a normal nerve.  When nerves are injured, pinched or otherwise affected by disease, changes in waveform amplltude or velocity can result.  The pattern of changes is interpreted by the testing physician to determine the location and the severity of the problem.

Nerve function testing is extremely safe for the patient.  There may be some temporary discomfort during or after the testing, but it is temporary and no after effects can be expected.  There is no need to fast beforehand and it is not necessary to hold medications prior to the test.  There are no activity restrictions that need to be followed before or after testing.  Patients are asked to avoid applying lotions or creams to the area being tested, on the day of testing, as this can interfere with the ability of the recording pads to stick to the skin.