An electrodiagnostic study (EMG/NCS) is a diagnostic assessment of the electrical activity of your nerves and muscles to see how well they function and is sometimes recommended for patients with neck, back, arm or leg pain. Typically there are two parts to EMG testing: a nerve conduction study (NCS) and a needle examination. The NCS tests the nerves' reaction to electrical stimulation and the needle exam tests the muscles at rest and during motion. An EMG reads the output of each of these parts and converts them into information that your physician can evaluate.
Your physician may ask you to have an EMG to check for a potential muscle or nerve disorder. EMGs can help:
- Identify issues that cause nerve or muscle dysfunction
- Locate and diagnose why you may feel weak, have numbness/tingling or feel pain
Here are some frequently asked questions about EMGs.
What are reasons someone may get an EMG/NCS?
An electrodiagnostic study may be ordered if a patient is experiencing numbness or tingling in the hands or feet, has unexplained weakness in the arms or legs, or has pain in the arms or legs in a distinct pattern that suggests nerve injury.
What diagnoses are most commonly evaluated with an EMG/NCS?
Typical diagnoses include cervical/lumbar radiculopathy, brachial/lumbosacral plexopathy, carpal tunnel syndrome, cubital tunnel syndrome, other peripheral nerve entrapments or peripheral neuropathies.
What happens during an EMG/NCS?
During the nerve conduction study, electrodes are gently attached to the skin of the pathway of specific nerves. A small amount of electricity is used to stimulate the nerve, resulting in a wave response captured by the computer. Measurements are then taken to determine how quickly your nerve responds to the electrical stimulus. The second part of the test utilizes small needles which are inserted into certain muscles for the purposes of listening to electrical activity. The muscle will be tested both while it is at rest and as you contract it. The entire EMG/NCS may take up to 45-90 minutes depending on how many limbs are being studied and which condition the ordering physician is trying to diagnose.
Is an EMG painful?
It can be uncomfortable, but most people do quite well with it.
Dr. Alicia Lazeski is a board-certified physiatrist with the OrthoCarolina Spine Center.