You are being sent to the EMG lab because you have numbness, tingling, pain, weakness or muscle cramping. Coastal Spine will be using nerve conduction studies and needle EMG to help diagnose your symptoms.
EMG is the study of nerves and muscle diseases. There are two parts of the test: conduction studies and needle electromyography. Both nerve conduction studies and EMGs can help physicians determine the causes of patients back or neck problems.
These show how well the body’s electrical signals are traveling to a nerve. This is done by applying small electrical shocks to the nerve and recording how the nerve works. These shocks cause a quick, mild, tingling feeling. Several nerves will be tested.
For this part of the test, a small, thin pin is put in several muscles to identify problems. There may be a small amount of pain when the pin is inserted, and only the necessary muscles will be tested. Specialists will be listening to and observing electrical signals that travel from the needle to the EMG machine.
Do not use body lotion on the day of the test. Tell your doctor if you are taking aspirin, taking blood thinners (like Coumadin), have a pacemaker, or suffer from hemophilia. Take a bath or shower to remove oil from your skin. You may eat normal meals and continue taking prescribed medications unless your doctor gives other instructions.
Most people describe the procedure as uncomfortable and annoying. During the first part of the EMG test, patients will typically feel a small static shock that builds throughout the process. During the second part of the EMG, patients may experience some pain when the needle is inserted into each of the muscles being tested. We will be testing five to seven muscles so some discomfort should be expected, but the EMG is not acupuncture or a skin treatment of any kind. Nothing is injected into or under the skin.
The test usually takes 45 to 80 minutes. Patients can perform all normal activities, such as eating, driving and exercising, before the tests. There are no lasting side effects. You can also perform all normal activities after the EMG test is complete.
Electromyography (EMG) is a diagnostic test administered to people who may be experiencing muscle or nerve pain, including cramping, tingling, numbness, or weakness.
An EMG involves needle electrodes inserted into the muscle being tested. The test is used to measure electrical activity in particular muscles when contracted. The test is also used to identify whether electrical activity is present when it shouldn’t be (that is, when the muscle is at rest). An EMG can identify whether the problem you are experiencing is with your muscle.
EMGs usually are performed at the same time as a nerve conduction study (NCS), in which electrodes are placed on top of the skin and used to send electrical signals to the muscle being tested. This test measures how fast and strong signals travel from one location to another. It can identify whether the problem is with your signaling of your nerves, rather than the muscle itself.
Preparing for an EMG
It is recommended that you avoid using moisturizers before an EMG. You should also avoid drinking caffeinated beverages at least 2 – 3 hours prior to testing. It is also inadvisable not to smoke before an EMG.
Your doctor should be notified of the medications you take, whether you use a pacemaker, an implanted device that helps to regulate your heartbeat, if you have epilepsy, or any metal implants in your body. Otherwise, follow your doctor’s instructions if any other preparation is needed based on your current health. You may be advised to wear loose clothing, depending on the area being tested.
What Happens During an EMG
An EMG and NCS may be administered by a physician, technologist, or a lab coordinator.
During an EMG, a needle electrode will be inserted into the muscle being tested. The insertion is generally not painful. The end of the needle will pick up signals from contracted muscles and measures and records that activity on a special device, which may emit audible clicks or numerical values, depending on the device being used.
Because an EMG typically occurs in conjunction with a nerve conduction study, an electrode sticker is placed some distance from the muscle, and it deliver a minor electrical current, which should prompt the muscle to work. You may experience minor discomfort as the signals are sent, but it generally doesn’t cause pain.
The combined tests usually take no more than an hour, depending on the body area being tested.
Expected Results
An EMG can help diagnose a variety of neuromuscular problems.
When an electrical activity is noted in resting muscles, it may mean you have a muscle disorder, a connective nerve disorder, or inflammation due to an injury. If responses from the stimulated muscles are abnormal, it could indicate a large number of issues such as a herniated disc or carpal tunnel syndrome. Your doctor will use the results of your EMG together with other factors before making a diagnosis.
Now you know what happens before, during, and after electromyography (EMG), you may wonder if you need to take one. Do you think you might have some sort of nerve or muscle disorder? SC Internal Medicine Associates and Rehabilitation offers a variety of on-site diagnostic services, including electromyography. Call us at (803) 749-1111 or request an appointment now.
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Electromyography (EMG) and nerve conduction studies are tests that measure the electrical activity of muscles and nerves. Nerves send out electrical signals to make your muscles react in certain ways. As your muscles react, they give off these signals, which can then be measured. EMG tests and nerve conduction studies can both help find out if you have a disorder of your muscles, nerves, or both. These tests can be done separately, but they are usually done at the same time. Other names: electrodiagnostic study, EMG test, electromyogram, NCS, nerve conduction velocity, NCV
EMG and nerve conduction studies are used to help diagnose a variety of muscle and nerve disorders. An EMG test helps find out if muscles are responding the right way to nerve signals. Nerve conduction studies help diagnose nerve damage or disease. When EMG tests and nerve conduction studies are done together, it helps providers tell if your symptoms are caused by a muscle disorder or a nerve problem.
You may need these tests if you have symptoms of a muscle or nerve disorder. These symptoms include:
For an EMG test:
- You will sit or lie down on a table or bed.
- Your provider will clean the skin over the muscle being tested.
- Your provider will place a needle electrode into the muscle. A needle electrode is a special wire that a mild electric current flows through. You may have slight pain or discomfort when the electrode is inserted.
- The machine will record the muscle activity while your muscle is at rest.
- Then you will be asked to tighten (contract) the muscle slowly and steadily. The machine will record this activity.
- The electrode may be moved to record activity in different muscles.
- The electrical activity is recorded and shown on a video screen. The activity is displayed as wavy and spiky lines. The activity may also be recorded and sent to an audio speaker. You may hear popping sounds when you contract your muscle.
For a nerve conduction study:
- You will sit or lie down on a table or bed.
- Your provider will attach one or more electrodes to a certain nerve or nerves using tape or a paste. The electrodes, called stimulating electrodes, deliver a mild electrical pulse.
- Your provider will attach different types of electrodes to the muscle or muscles controlled by those nerves. These electrodes will record the responses to the electrical stimulation from the nerve.
- Your provider will send a small pulse of electricity through the stimulating electrodes to stimulate the nerve to send a signal to the muscle.
- This may cause a mild tingling feeling.
- Your provider will record the time it takes for your muscle to respond to the nerve signal.
- The speed of the response is called the conduction velocity.
If you are having both tests, the nerve conduction study will be done first.
Tell your health care provider if you have a pacemaker or cardiac defibrillator. Special steps will need to be taken before the test if you have one of these devices.
Wear loose, comfortable clothing that allows easy access to the test area or can be easily removed if you need to change into a hospital gown.
Make sure your skin is clean. Don't use lotions, creams, or perfumes for a day or two before the test.
You may feel a little pain or cramping during an EMG test. You may have a tingly feeling, like a mild electric shock, during a nerve conduction study.
If your results were not normal, it can indicate a variety of different conditions. Depending on which muscles or nerves are affected, it may mean one of the following:
- Carpal tunnel syndrome, a condition that affects nerves in the hand and arm. It's usually not serious, but can be painful.
- Herniated disc, a condition that happens when a part of your spine, called a disc, is damaged. This puts pressure on the spine, causing pain and numbness
- Guillain-Barré syndrome, an autoimmune disorder that affects the nerves. It can lead to numbness, tingling, and paralysis. Most people recover from the disorder after treatment
- Myasthenia gravis, a rare disorder that causes muscle fatigue and weakness.
- Muscular dystrophy, an inherited disease that seriously affects muscle structure and function.
- Charcot-Marie-Tooth disease, an inherited disorder that causes nerve damage, mostly in the arms and legs.
- Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease. This is a progressive, ultimately fatal, disorder that attacks nerve cells in your brain and spinal cord. It affects all the muscles you use to move, speak, eat, and breathe.
If you have questions about your results, talk to your health care provider.
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