What is an Electromyogram / EMG and Nerve Conduction Test?
The EMG / electromyogram is a test of the electrical activity in nerves and muscles. This test is helpful to find out if the way a person’s nerves send electrical impulses is normal and if their muscles are normal.
The EMG test has two parts:
- Nerve conduction study (NCS): This tests the speed and amount of electrical activity a nerve can send.
- Nerve EMG study: This looks at electrical activity in muscles at rest and when they are moved by choice (if able) to look for certain problems in muscles or nerves.
What Is A Nerve Conduction Test?
The patient will lie on an exam table (very young children can sit on a parents’ lap). Electrodes are placed on the skin over the nerve being tested. These electrodes act as sensors to pick up any electrical signal that goes by them.
An electrical stimulator is then placed on the skin near the electrodes. This makes an electrical current strong enough to fully stimulate the nerve.
A computer records responses as nerves are tested. This lets the doctor measure and figure out how fast the nerve is sending the impulses to the muscle. It also measures the size of the impulse.
Sometimes, a special test called repetitive nerve stimulation is done. This test is set up the same way as other nerve conduction tests. In this test, the nerve is stimulated a few times in a row, the patient then exercises a specific muscle and the nerve is stimulated a few times in a row each minute for up to five minutes.
What Is an EMG?
A pin electrode is put into the muscle to check the muscle. The computer records the muscle response both at rest and with movement. When the electrode is put into the muscle, it feels like being stuck by a pin. (That is if sensory awareness is not a problem.)
It is important for the patient to keep the tested muscle as still as possible to reduce discomfort and to get accurate readings.
What Happens During an EMG or Nerve Conduction Test?
- Please arrive before your appointed time to sign in. The exam runs on time as long as patients are not late.
- Sign in at the Rheumatology and Rehab Center, Location E, 2nd floor.
- You will be called to go back to the room.
- A child / young adult can continue with their usual diet and meds for this test. To get the best results when doing this procedure, it helps to wash their arms and legs to remove any oils or lotions. Let the examiner know if the patient has a bleeding disorder or bleeds easily.
- The doctor will discuss the child's history and explain the steps of the test before starting the EMG.
Frequently Asked Questions
Does it hurt?
Parts of the test are uncomfortable but not severely painful. Often, the worry before the test can be a bigger problem than the test itself. Most of the time spent with the patient is setting up the studies and running the computer. Electrical stimulation and use of the pin electrode is only a very small amount of the time.
The electrical stimulation of the nerve conduction study can feel like a static electricity shock from a doorknob after walking across carpet.
Putting in the pin can feel like a pinch by someone's nails. (And how do we know this? We have done it on ourselves first!)
Is sedation or anesthesia used?
Not in most cases. The test is fairly well tolerated and the patient needs to be awake to follow instructions, if possible, during the exam. A very mild dose of medication can be given if a patient or caregiver feels that it is needed based on how the child has handled tests in the past. You may bring a pacifier or bottle to help soothe a baby.
Please call the Pediatric Rehab office at 513-636-7480 ahead of your appointment to discuss this need or if you have any questions. In order to keep the tests running on time, patients who require medication for the test may need to arrive earlier. This can be confirmed with the Pediatric Rehab office.
Are there any side effects from a nerve conduction test or EMG?
There are no real side effects. Patients may have some minor irritation at the site when the pin is placed. There are no lasting effects from either the nerve conduction test or the EMG.
Is there an age limit on this test?
No, any person from baby to older adult can have an EMG. Baby and toddler exams can be more restricted if they are not able to cooperate because of their young age.
Can the caregiver be in the room during the exam?
Yes, caregivers can be in the clinic room during the test. It is up to these people to decide if they prefer to be in the room or not. It most cases, the parents / caregivers choose to stay in the room. During the rare times a test is done under anesthesia, caregivers are not able to be in the room.
What should be done if the child becomes frightened during the test?
Comfort the child and remind them that each thing will be explained to them before it is done.
We make special effort to make the child as comfortable as possible. We have a large mat table where they can lie down. They can bring a phone, a tablet, or another device to listen to music or what videos if that would be helpful. A Child Life Specialist may also work with your child, using games and media during the test.
Will I get test results the same day?
The doctor doing the test can give you a sense of any obvious abnormal results at the end of the test. A full reading is done at a later time, and the full report is sent to the doctor who referred the child.
The referring doctor is the best person to discuss the results with you. They will have the EMG results along with the results from any other tests done.
Who does the actual testing?
A medical doctor who has received special training and has a great amount of experience will do the test. At times there may be a doctor in training there who will be watching or doing certain parts of the exam under direct supervision of the lead doctor.