Nerve Conduction Studies
Your nerves send electrical signals that tell muscles to move and carry sensations. Nerve conduction studies (NCS) measure how quickly electrical signals travel along your nerves. They are one way of testing how you’re your nerves are working. Doctors use nerve conduction studies to help diagnose the causes of:
- Arm or leg pain
- Numbness or tingling
- Weakness or cramping
If an imaging test such as an MRI does not adequately explain all your symptoms, you might have NCS. You may also have NCS if the doctor thinks more than one health problem could be causing your symptoms.
Nerve conduction studies can help evaluate nerve problems such as polyneuropathies (damage to several nerves). These can be caused by conditions such as diabetes. If you have spine problems, your doctor might do NCS to evaluate a pinched nerve in your neck or lower back (radiculopathy).
It takes about 25 to 30 minutes to study a single arm or leg. Your doctor does a brief history and physical exam to identify the nerves that need to be tested. The testing part of the nerve study only takes a few minutes. The rest of the time, your doctor will tape small electrodes over different muscles to evaluate individual nerves.
Once the electrodes are in place, 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 the nerve. 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.”
If there is damage to the nerve supplying the muscle, the doctor can easily see it. The doctor can tell if a specific nerve in your back is causing the problem, or a nerve in in an arm or leg (such as the arm in carpal tunnel syndrome).