What is an EMG?
An electromyography (EMG) is a test used to measure the electrical activity of your nerves and muscles. It is usually conducted by neurology specialists.
There are two parts to an EMG. The first part comprises of nerve conduction studies (NCS), which measures the rate at which electrical impulses move through your nerves. During this test, small patches which deliver electrical pulses will be attached to your skin. This process may cause you some discomfort depending on the strength of the electrical pulse but is generally painless.
The second part is known as a needle electrode examination, which measures the electrical activities in your muscles. During this test, five or more thin needles, also known as electrodes, will be inserted into your muscle. After the electrodes have been inserted, your doctor may ask you to contract the muscle that is being tested. For example, your doctor may ask you to bend or lift your leg.
You may experience a slight pain during the insertion of the electrodes. However, this test is otherwise painless.
Why would I need to have a EMG?
An EMG is a very useful tool for diagnosing nerve or muscle abnormalities. Some of the conditions that can be diagnosed with an EMG include:
- Myopathy. Myopathy is a general term that refers to diseases that affect muscles in the body, also known as neuromuscular disorders.
- Motor neurone disease (MND). MND refers to a group of neurodegenerative diseases that deteriorate your body’s motor neurons, causing the nerves in your spine and brain to gradually lose function over time.
- Dystonia. Dystonia is a neurological movement disorder, where your muscles involuntarily co-contract against each other or spasm abnormally. This causes abnormal and often debilitating postures and repetitive movements.
- Radiculopathy – EMG is used to diagnose cervical or lumbar radiculopathy.
What happens before an EMG?
There are no restrictions on dietary and fluid intake before an EMG and you may eat, drink, or take your medications per normal. However, avoid putting on lotions and oils on your skin on the day of the test.
Let your doctor and nurse know if you are on any blood-thinning medications, other anticoagulants, or any antibiotics. Notify your doctor if you have a pacemaker or implanted defibrillator as well.
What happens after an EMG?
Following the test, you may experience some muscle soreness which typically lasts for only a few hours. If you experience any increasing pain, swelling or pus at the areas where the electrodes were inserted, visit your doctor immediately as this is a likely indication of infection.
How long does an EMG take?
An EMG typically takes 30 to 90 minutes, but varies depending on your condition and the results obtained from it.
You will be able to go home on the same day if you feel well enough, but do arrange for transport back as you will not be able to drive yourself home.
What are the risks of having an EMG?
An EMG is an extremely safe test, and most patients face little to no complications during and after the test.
Some rare but possible complications of an EMG include:
- Infection at electrode insertion site
- Nerve trauma
- Pneumothorax, also known as a collapsed lung (occurs during examination of muscles near the lungs)
If you have any other questions regarding EMGs, consult your doctor and clarify your doubts.
- Electromyography (EMG). (2019). John Hopkins Medicine. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/electromyography-emg
- Gechev, A., Kane, N. M., Koltzenburg, M., Rao, D. G., & van der Star, R. (2016). Potential risks of iatrogenic complications of nerve conduction studies (NCS) and electromyography (EMG). Clinical Neurophysiology Practice, 1, 62–66. https://doi.org/10.1016/j.cnp.2016.09.003
- H. Feinberg, J. (2009, October 21). EMG Tests: What to Know About Electromyographic Nerve Tests. Hospital for Special Surgery. https://www.hss.edu/conditions_emg-testing-a-patient-guide.asp#:~:text=EMG%20testing%20usually%20takes%20anywhere
- Kishner, S. (2019, January 8). Electromyography and Nerve Conduction Studies: Background, Indications, Contraindications. Medscape.com. https://emedicine.medscape.com/article/2094544-overview
- Mills, K. R. (2005). The basics of electromyography. Journal of Neurology, Neurosurgery & Psychiatry, 76(suppl_2), ii32–ii35. https://doi.org/10.1136/jnnp.2005.069211