What Is An EMG/NCS And How Can It Change Your Life?

At Mount Sinai’s Department of Rehabilitative Medicine, we will sometimes refer patients to complete an Electrodiagnostic test when an underlying muscle issue is unobvious. These tests are helpful in evaluating weakness, numbness, and pain; and there are two main components in the examination – the electromyographic examination (EMG) and the nerve conduction study (NCS). 

While the EMG and NCS are different tests, they’re often used together as the information from each test synergises with the other, giving a more complete analysis.

The tests will inform our physicians on unexplained muscle weakness, twitching, paralysis, and find the cause of numbness and pain the patient may be experiencing. Most importantly, it informs your physician on whether there is a muscle disorder in the muscle itself, or within a nearby nerve.

The EMG and NCS are considered non-invasive imaging tests, although there will be a needle involved. Your physician will insert a very fine needle, which acts as an electrode through the skin and into the problematic muscle. You will be asked to begin contracting the muscle by moving the area local to your symptoms. For example, the needle will be placed into the tricep, and the patient will slowly extend the arm, contracting the tricep with increased force as the electrical activity is recorded. Activity within the localized area will be visualized and available to watch on an oscilloscope and played audially through a speaker. These results can inform our physicians on the muscles ability to respond to nerve stimulation.

Nerve stimulation is often reported to causes a tingling sensation however there are no long-term effects. The EMG and NCS usually require an hour to complete and there are no restrictions in activities or meals before or after the test. Patients however do frequently feel some minor discomfort, similar to an injection, when the needle is inserted – with examined muscles feeling sore for a few days. There may also be light bruising in the affected area.

The results will also be able to help us diagnose neuromuscular diseases, and motor control disorders such as carpal tunnel syndrome or muscular dystrophy. From this point, there is no general direction as results will vary, and diagnosis will simply point you toward the optimal rehabilitation.

If you are suffering from an undiagnosed muscle issue and think you could benefit from a EMG/NCS diagnosis please contact our switch on (212) 241-6321) to see if our physicians can further help.