EMG Test
An EMG, or electromyography, test checks the health of your muscles and the nerves that control them. The test looks for problems in both. It also tests how they work together. An EMG test is usually paired with a nerve conduction study. Baptist Health neurologists use the EMG test to gather information, make a diagnosis and guide your treatment.
How an EMG Works
To understand how an EMG works, it is helpful to know how nerves and muscles interact. Nerves send signals to muscles. These signals come in the form of electrical pulses. They tell muscles to move. When muscles move, or tighten, they also give off electrical activity. An EMG test captures these signals from nerves and muscles.
A healthy muscle does not produce electrical activity when at rest. However, an injured muscle does. A damaged muscle might also send abnormal signals when used.
The EMG machine converts the signals into graphs, sounds and numbers. It shows if the problem is with the muscles, nerves or the connection between them. A neurologist reads that information to help treat you.
Why a Provider May Order an EMG
Your primary care provider or neurologist may order an EMG. The main purpose is evaluation.
An EMG evaluates:
- Muscle weakness
- Numbness
- Tingling
- Cramps
- Pain
- Twitching
The EMG test results will help your provider know if your symptoms come from a muscle problem or a nerve problem.
Potential conditions an EMG test might point to:
- Carpal tunnel syndrome
- Myasthenia gravis
- Pinched nerves
- ALS
- Sciatica
- Radiculopathy
- Myopathy
- Peripheral neuropathy
- Muscular dystrophy
The Two Parts of an EMG
Most EMG tests have two parts. One part is a nerve conduction study, and the other is a needle EMG.
Nerve Conduction Study
During a nerve conduction study, a provider will place sticker electrodes on your skin. Then they will send a small electrical pulse to the nerve. The pulse can feel like a quick, low-voltage shock. A nerve conduction study measures the speed and strength of nerve signals. A slower signal can mean there is damage to the nerve.
Needle EMG
A needle EMG is when a provider slides a thin needle electrode through the skin. There is no electrical pulse with this part of the test. The needle records the signals from your muscle when it is at rest, slightly tightened and strongly contracted. You might hear the machine make popping or crackling sounds. Your provider often checks several of your muscles, one at a time.
How to Prepare for an EMG
There are a few actions you can take to prepare for an EMG.
Preparations can include the following:
- Shower or bathe.
- Avoid using lotion, cream or oil.
- Eat normally. No fasting is needed.
- Avoid caffeine for two to three hours.
- Wear loose, comfortable clothing.
Be sure to tell your provider if you take blood thinners or use a pacemaker. Do not stop taking any medication
What to Expect During an EMG
An EMG involves several steps. The nerve conduction study happens first. You will sit or lie down. A provider will clean your skin with an antiseptic. Your provider will place the sticker electrodes and apply the mild pulses of electricity. Next, you'll receive the needle EMG portion of the test. You may feel a slight pinch as the needle is inserted. The provider will ask you to relax your muscle and then tighten it. You may be asked to do this a few times with different muscles. Your provider might ask you to change positions. Mild discomfort during the tests is common.
After an EMG
After an EMG, your provider will remove all electrodes and any needles. Sedation is not used during the test. Therefore, you will likely be able to go back to normal activities as soon as you leave the medical facility. You may feel light soreness or tingling. There may be small bruising where the needles were inserted.
Your neurologist reads the results, prepares the report and sends them to the provider who ordered the test. This might be your primary care provider. Your test results might also be sent to your MyChart account.
Is an EMG Test Safe?
EMG is considered a safe medical test. In rare cases, there may be minor bleeding, infection or skin irritation. If you experience any of these or other symptoms, let your Baptist Health provider know. The most common experience is temporary mild discomfort.