A Nerve conduction Study (NCS) is a test to measure the electrical function of nerves in the limbs. Electromyography (EMG) is a test to measure the electrical activity of muscles.
These procedures are used to diagnose any trapped nerves or nerve damage you may have.
Typical reasons you may be referred for NCS are carpal tunnel syndrome, foot or wrist drop, neck or low back pain following injury, sciatica, foot or arm numbness/weakness. The test is carried out on the arm or leg showing symptoms.
Both tests are carried out by a highly experienced consultant neurophysiologist. By talking to you and reading your doctor's referral letter, he/she will decide whether one or both of these tests are needed for your particular problem. Both can be done at the same appointment so that you do not have to attend twice.
Before your appointment
You won't need to make any special preparation for this test.
During your appointment
The consultant will explain the procedure to you and ask you to lie down on the examination couch.
There are two methods of testing the different nerves using NCS. The first method involves small stick-on electrodes which are placed at different points on the muscles of the affected limb. These electrodes are attached by small wires to the EMG machine. The nerve is then stimulated by a small electrical pulse which will feel like a sharp tapping on the skin. By stimulating the nerve, the electrical signal from the muscle can be measured on the machine. The nerve is stimulated in several places along the limb so that the speed with which the electrical impulse is travelling can be measured. If nerves are trapped or damaged then the speed of the travel slows down.
To test the sensory nerves small ring electrodes are fitted around the fingers and stimulated in the same way.
After your appointment
The consultant will need to interpret the computer readings and he will produce a report which will be sent to your referring clinician within 4 working days.