Test / Diagnostic Procedure: Nerve Conduction Studies and EMG

Nerve conduction studies and EMG are used to diagnose peripheral neuropathy. A nerve conduction study measures how quickly an electrical impulse moves through your nerve. During the test, a consultant or physiologist will place small metal wires called electrodes on your skin, which release tiny electric shocks to stimulate your nerves. The speed and strength of the nerve signal is then measured and reported.

Electromyography (EMG) measures muscle response or electrical activity in response to a nerve's stimulation of the muscle. Our clinicians carry out the test to detect neuromuscular abnormalities. During the test, one or more small needles (also called electrodes) are inserted through the skin into the muscle.

On the day of the test, please wear loose-fitting clothes as this will reduce the need for undressing. We often need to get access up to your elbow and we may ask you to take off your shoes and socks, tights or stockings and to get access up to your knee. Some skin creams and make-up (if we need to investigate the face) can interfere with the investigation and it is therefore best to avoid them on the day.

The investigation will be carried out by a consultant in Clinical Neurophysiology. Although some patients find the studies a little uncomfortable, they should not cause too much pain. If, however, you find any procedure too unpleasant or if you need a rest, let us know immediately. Any discomfort will generally disappear within seconds once we stop the procedure.

Prior to or during the investigation, the physician may also ask you questions about the history of your symptoms and medical history.

Nerve Conduction Studies:

We shall apply small electric pulses to stimulate the nerves, usually in the arms or legs. The reactions are recorded by surface electrodes that are temporarily attached to the skin. The electrical stimulation can be a little unpleasant but should not cause too much discomfort and any sensation is very short.

Electromyography (EMG):

We shall insert a fine sterile electrode needle to record muscle activity. Each needle is only ever used on one person so it cannot cause infections. After an insertion we will ask you to move the muscle or relax it.

Depending on the problem, the physician will decide how many and which nerves or muscles need to be examined. Depending on the complexity of the problem, EMG and nerve conduction studies may take anywhere from 15 - 45 minutes. Most tests are completed within half an hour.

Nerve conduction studies are non-invasive and there is no risk of side effects unless you have an implanted medical device. If you carry a pacemaker or a cardiac defibrillator we will take certain precautions. Even then the risk is very small and with proper precautions the malfunction of these devices has not been reported. Needle EMG can be a little painful and may produce small bruises.