Nerve conduction studies measure how quickly electrical signals travel along your nerves. The studies, also called NCS, offer one way to test how well your nerves are working. You might have NCS if an imaging test such as an MRI doesn’t adequately explain all your symptoms or if the doctor thinks more than one health problem could be causing your symptoms. NCS can help identify nerve problems such as polyneuropathies, or damage to several nerves, caused by conditions such as diabetes.

The procedure

It takes about 30 minutes to study one arm or leg. Your doctor does a brief history and physical exam to identify the nerves that need to be tested, then tapes small electrodes over muscles to evaluate individual nerves.

The testing itself takes only a few minutes. The doctor uses a stimulator to send a small electrical charge to the nerves. A machine connected to the electrodes records how long the signal takes to travel along nerves. The machine creates graphs, sounds or numbers that tell your doctor how well the nerves are working.

The electrical charge feels like a small static electricity shock. Some people describe the feeling as a strong tap. The results tell the doctor if a specific nerve in your back, arm or leg is causing the problem.

When this test is used

Doctors use electromyography to help diagnose the causes of:

• Back and neck pain
• Myelopathy
• Numbness or tingling
• Radiculopathy
• Weakness or cramping